PM Gross: Back: Reading

Symphyses between vertebral bodies

(intervertebral discs) The symphysis between adjacent vertebral bodies is formed by a layer of hyaline cartilage on each vertebral body and an intervertebral disc, which lies between the layers.

lateral flexion of spine

(side bending) movement of head and/or trunk laterally away from midline; abduction of spine

Where do the erector spinae muscle?

-The muscles lie posterolaterally to the vertebral column between the spinous processes medially and the angles of the ribs laterally. -They are covered in the thoracic and lumbar regions by thoracolumbar fascia and the serratus posterior inferior, rhomboid, and splenius muscles. -The mass arises from a broad, thick tendon attached to the sacrum, the spinous processes of the lumbar and lower thoracic vertebrae, and the iliac crest -It divides in the upper lumbar region into three vertical columns of muscle, each of which is further subdivided regionally (lumborum, thoracis, cervicis, and capitis), depending on where the muscles attach superiorly.

CLINICAL: Vertebral column stability is divided into three arbitrary clinical "columns"

-anterior column -middle column -posterior column

The external surface of the spinal cord is marked by a number of fissures and sulci

-anterior median fissure -posterior median sulcus -posterolateral sulcus

Superficial groups of back muscles

-are immediately deep to the skin and superficial fascia -They attach the superior part of the appendicular skeleton (clavicle, scapula, and humerus) to the axial skeleton (skull, ribs, and vertebral column). -Because these muscles are primarily involved with movements of this part of the appendicular skeleton, they are sometimes referred to as the appendicular group .

CLINICAL: Ligamenta flava

-are important structures associated with the vertebral canal -In degenerative conditions of the vertebral column, the ligamenta flava may hypertrophy -This is often associated with hypertrophy and arthritic change of the zygapophysial joints. -In combination, zygapophysial joint hypertrophy, ligamenta flava hypertrophy, and a mild disc protrusion can reduce the dimensions of the vertebral canal, producing the syndrome of spinal stenosis.

CLINICAL: Lumbar cerebrospinal fluid tap

-A lumbar tap (puncture) is carried out to obtain a sample of CSF for examination. -In addition, passage of a needle or conduit into the subarachnoid space (CSF space) is used to inject antibiotics, chemotherapeutic agents, and anesthetics.

What do the erector spinae group muscles do?

-Acting bilaterally, they straighten the back, returning it to the upright position from a flexed position, and pull the head posteriorly. -They also participate in controlling vertebral column flexion by contracting and relaxing in a coordinated fashion. -Acting unilaterally, they bend the vertebral column laterally. -In addition, unilateral contractions of muscles attached to the head turn the head to the actively contracting side.

What is blood supply is associated with the latissimus dorsi?

-Associated with this nerve is the thoracodorsal artery, which is the primary blood supply of the muscle. -Additional small arteries come from dorsal branches of posterior intercostal and lumbar arteries.

Characteristics of thoracic vertebrae

-articulation with ribs -A typical thoracic vertebra has two partial facets (superior and inferior costal facets) on each side of the vertebral body for articulation with the head of its own rib and the head of the rib below -The superior costal facet is much larger than the inferior costal facet. -Each transverse process also has a facet (transverse costal facet) for articulation with the tubercle of its own rib -vertebral body is heart shaped -vertebral foramen is circular

Vertebral spinous processes

-can be palpated through the skin in the midline in thoracic and lumbar regions of the back. -Between the skin and spinous processes is a layer of superficial fascia. -In lumbar regions, the adjacent spinous processes and the associated laminae on either side of the midline do not overlap, resulting in gaps between adjacent vertebral arches.

CLINICAL: craniocervical junction

-At the craniocervical junction, a complex series of ligaments create stability. -If the traumatic incident disrupts craniocervical stability, the chances of a significant spinal cord injury are extremely high. -this results in quadriplegia -In addition, respiratory function may be compromised by paralysis of the phrenic nerve (which arises from spinal nerves C3 to C5), and severe hypotension (low blood pressure) may result from central disruption of the sympathetic part of the autonomic division of the nervous system.

Multifidus

-Deep to the semispinalis is the second group of muscles, the multifidus . -Muscles in this group span the length of the vertebral column, passing from a lateral point of origin upward and medially to attach to spinous processes and spanning between two and four vertebrae. -The multifidus muscles are present throughout the length of the vertebral column but are best developed in the lumbar region.

Arachnoid trabeculae

-Delicate strands of tissue ( arachnoid trabeculae ) are continuous with the arachnoid mater on one side and the pia mater on the other; they span the subarachnoid space and interconnect the two adjacent membranes. - Large blood vessels are suspended in the subarachnoid space by similar strands of material, which expand over the vessels to form a continuous external coat.

Posterior spaces between the vertebral arches

-In most regions of the vertebral column, the laminae and spinous processes of adjacent vertebrae overlap to form a reasonably complete bony dorsal wall for the vertebral canal -EXCEPT in lumbar region where large gaps exist between the posterior components of adjacent vertebral arches

CLINICAL: mid and lower cervical vertebral column

-disruption may produce a range of complex neurological problems involving the upper and lower limbs, although below the level of C5, respiratory function is unlikely to be compromised.

CLINICAL: enlarging abdominal aorta

-enlarging abdominal aorta (abdominal aortic aneurysm) may cause back pain as it enlarges without rupture. -Therefore it is critical to think of this structure as a potential cause of back pain, because treatment will be lifesaving. -Moreover, a ruptured abdominal aortic aneurysm may also cause acute back pain in the first instance.

CLINICAL: back pain

-extremely common -can be related to mechanical problems or to disc protrusion impinging on a nerve -disc cases may require an operation to remove the disc that is pressing on the nerve

Levator scapulae

-is a slender muscle that descends from the transverse processes of the upper cervical vertebrae to the upper portion of the scapula on its medial border at the superior angle -It elevates the scapula and may assist other muscles in rotating the lateral aspect of the scapula inferiorly.

How do cervical nerves affect where other nerves emerged?

-The first cervical nerve (C1) emerges from the vertebral canal between the skull and vertebra CI ( Fig. 2.63 ). -Therefore cervical nerves C2 to C7 also emerge from the vertebral canal above their respective vertebrae. -Because there are only seven cervical vertebrae, C8 emerges between vertebrae CVII and TI. -As a consequence, all remaining spinal nerves, beginning with T1, emerge from the vertebral canal below their respective vertebrae.

Surface features of the back are used to

-locate muscle groups for testing peripheral nerves, to determine regions of the vertebral column, and to estimate the approximate position of the inferior end of the spinal cord. -located organs that occur posteriorly in the thorax and abdomen

What makes up the skeletal framework of the back?

-mainly vertebrae and intervertebral discs -skull, scapulae, pelvic bones, and ribs also contribute to the bony framework of the back and provide sites for muscle attachment.

CLINICAL: Spina bifida occulta

-most common -defect in vertebral arch of LV or SI -10% of individuals -results in failure of the posterior arch to fuse in the midline -clinically asymptomatic -may have tuft of hair over the spinous process

Interspinous ligaments

-pass between adjacent vertebral spinous processes - attach from the base to the apex of each spinous process and blend with the supraspinous ligament posteriorly and the ligamenta flava anteriorly on each side.

How many thoracic vertebrae are there?

12 (T1-T12)

How many pairs of thoracic nerves are there?

12 pairs (T1-T12)

How many spinal nerves are there? Where do they come from?

31 pairs The 31 pairs of spinal nerves are segmental in distribution and emerge from the vertebral canal between the pedicles of adjacent vertebrae.

How many lumbar vertebrae are there?

5 (L1-L5)

How many pairs of lumbar nerves are there?

5 (L1-L5)

How many pairs of sacral nerves are there?

5 (S1-S5)

How many sacral vertebrae are there?

5 (S1-S5) fused The sacral vertebrae fuse into a single bony element, the sacrum.

How many cervical nerves are there?

8 (C1-C8)

Filum terminale and conus medullaris

A fine filament of connective tissue (the pial part of the filum terminale ) continues inferiorly from the apex of the conus medullaris .

How can you identify LIV, LIII, AND LV via palpitations

A horizontal line between the highest point of the iliac crest on each side crosses through the spinous process of vertebra LIV. The LIII and LV vertebral spinous processes can be palpated above and below the LIV spinous process, respectively

How is the intervertebral foramen formed?

An intervertebral foramen is formed by the inferior vertebral notch on the pedicle of the vertebra above and the superior vertebral notch on the pedicle of the vertebra below

All major somatic plexuses (cervical, brachial, lumbar, and sacral) are formed by which rami?

Anterior rami

Serratus posterior inferior innervation

Anterior rami of lower thoracic nerves (T9 to T12)

Serratus posterior superior innervation

Anterior rami of upper thoracic nerves (T2 to T5)

Longitudinal vessels consist of

Anterior spinal artery Posterior spinal arteries

Why are lower back problems common? Where are they common?

As stresses on the back increase from the cervical to lumbar regions, lower back problems are common.

Trapezius function

Assists in rotating the scapula during abduction of humerus above horizontal; upper fibers elevate, middle fibers adduct, and lower fibers depress scapula

Segmental spinal arteries

At various vertebral levels, the segmental spinal arteries also give off segmental medullary arteries. These vessels pass directly to the longitudinally oriented vessels, reinforcing these.

Superior and inferior vertebral notches

Between the vertebral body and the origin of the articular processes, each pedicle is notched on its superior and inferior surfaces. These superior and inferior vertebral notches participate in forming intervertebral foramina.

CLINICAL: What other disorders can produce scoliosis?

Bone tumors, spinal cord tumors, and localized disc protrusions

cervical vertebrae

C1-C7 -characterized mainly by their small size and the presence of a foramen in each transverse process

levator scapulae innervation

C3 to C4 and dorsal scapular nerve (C4, C5)

Serratus posterior inferior function

Depresses ribs IX to XII and may prevent lower ribs from being elevated when the diaphragm contracts

Rhomboid major innervation

Dorsal scapular nerve (C4, C5)

Rhomboid minor innervation

Dorsal scapular nerve (C4, C5)

Condyle of the skull

Each lateral mass of the atlas articulates above with an occipital condyle of the skull and below with the superior articular process of vertebra CII (the axis ).

Intervertebral foramina

Each spinal nerve exits the vertebral canal laterally through an intervertebral foramen.

Somites and developing embryonic vertebrae

Each vertebra is derived from the cranial parts of the two somites below, one on each side, and the caudal parts of the two somites above. The spinal nerves develop segmentally and pass between the forming vertebrae.

Latissimus dorsi function

Extends, adducts, and medially rotates humerus

Rectus capitis posterior minor function

Extension of head

Obliques capitis superior function

Extension of head and bends it to same side

True/false: The size of the vertebral body decreases as we go down the vertebral column

False: The size of vertebral bodies increases inferiorly as the amount of weight supported increases.

Ligamentum nuchae

From vertebra CVII to the skull, the ligament becomes structurally distinct from more caudal parts of the ligament and is called the ligamentum nuchae. -a triangular, sheet-like structure in the median sagittal plane:

Myelomeningocele

Hernia of a portion of the spinal cord

Ligaments

Joints between vertebrae are reinforced and supported by numerous ligaments, which pass between vertebral bodies and interconnect components of the vertebral arches.

Veins that drain the spinal cord form a number of

Longitudinal channels

Rootlets

Medially, the posterior and anterior roots divide into rootlets, which attach to the spinal cord

How can you identify CVII via palpitations?

Most of the other spinous processes, except for that of vertebra CVII, are not readily palpable because they are obscured by soft tissue. The spinous process of CVII is usually visible as a prominent eminence in the midline at the base of the neck ( Fig. 2.67B ), particularly when the neck is flexed. Extending between CVII and the external occipital protuberance of the skull is the ligamentum nuchae, which is readily apparent as a longitudinal ridge when the neck is flexed

Trapezius innervation

Motor—accessory nerve [XI]; proprioception—C3 and C4

The superficial group consists muscles related to and involved in

Movements of the upper limb

How are the muscles on the back organized?

Muscles of the back are organized into superficial, intermediate, and deep groups

Function of the back: movement

Muscles of the back consist of extrinsic and intrinsic groups:

CLINICAL: Pancreatic pain

Pancreatic pain in particular refers to the back and may be associated with pancreatic cancer and pancreatitis.

CLINICAL: How can we identify if a patient is likely to develop osteoporosis?

Patients likely to develop osteoporosis can be identified by dual-photon X-ray absorptiometry (DXA) scanning. Low-dose X-rays are passed through the bone, and by counting the number of photons detected and knowing the dose given, the number of X-rays absorbed by the bone can be calculated. The amount of X-ray absorption can be directly correlated with the bone mass, and this can be used to predict whether a patient is at risk for osteoporotic fractures.

sacral vertebrae

S1-S5 -fused into one single bone called the sacrum, which articulates on each side with a pelvic bone and is a component of the pelvic wall.

CLINICAL: Scoliosis

Scoliosis is an abnormal lateral curvature of the vertebral column A true scoliosis involves not only the curvature (right- or left-sided) but also a rotational element of one vertebra upon another.

Extension

Straightening of a joint Leaning back

What is largest in the region inferior to the terminal end of the spinal cord, where it surrounds the cauda equina? What does it mean for a clinical setting?

Subarachnoid space -As a consequence, CSF can be withdrawn from the subarachnoid space in the lower lumbar region without endangering the spinal cord.

Lumbar region relationship to other regions in the body

Support for abdomen

Thoracic region relationship to other regions in the body

Support for thorax

Cervical region relationship to other regions in the body

Supports and moves head Transmits spinal cord and vertebral arteries between head and neck

Anterior and posterior longitudinal ligaments

The anterior and posterior longitudinal ligaments are on the anterior and posterior surfaces of the vertebral bodies and extend along most of the vertebral column

Anterior layer of the thoracolumbar fascia

The anterior layer covers the anterior surface of the quadratus lumborum muscle (a muscle of the posterior abdominal wall) and is attached medially to the transverse processes of the lumbar vertebrae—inferiorly, it is attached to the iliac crest and, superiorly, it forms the lateral arcuate ligament for attachment of the diaphragm.

Anterior median fissure

The anterior median fissure extends the length of the anterior surface.

What does the anterior rami form?

The anterior rami form the major somatic plexuses (cervical, brachial, lumbar, and sacral) of the body. Major visceral components of the PNS (sympathetic trunk and prevertebral plexus) of the body are also associated mainly with the anterior rami of spinal nerves.

Anterior root

The anterior root contains motor nerve fibers, which carry signals away from the CNS—the cell bodies of the primary motor neurons are in anterior regions of the spinal cord

Middle layer of the thoracolumbar fascia

The middle layer is attached medially to the tips of the transverse processes of the lumbar vertebrae and intertransverse ligaments—inferiorly, it is attached to the iliac crest and, superiorly, to the lower border of rib XII.

Spinalis

The most medial muscle column is the spinalis , which is the smallest of the subdivisions and interconnects the spinous processes of adjacent vertebrae. -The spinalis is most constant in the thoracic region and is generally absent in the cervical region. It is associated with a deeper muscle (the semispinalis capitis) as the erector spinae group approaches the skull.

Inferior border of the suboccipital triangle

The obliquus capitis inferior muscle forms the inferior border.

Posterior layer of the thoracolumbar fascia

The posterior layer is thick and is attached to the spinous processes of the lumbar vertebrae and sacral vertebrae and to the supraspinous ligament—from these attachments, it extends laterally to cover the erector spinae.

Posterior median sulcus

The posterior median sulcus extends along the posterior surface.

Describe the posterior and anterior surface of the sacrum

The posterior surface of the sacrum has four pairs of posterior sacral foramina, and the anterior surface has four pairs of anterior sacral foramina for the passage of the posterior and anterior rami, respectively, of S1 to S4 spinal nerves.

Primary curvature

The primary curvature of the vertebral column is concave anteriorly, reflecting the original shape of the embryo, and is retained in the thoracic and sacral regions in adults.

Function of the back: support

The skeletal and muscular elements of the back support the body's weight, transmit forces through the pelvis to the lower limbs, carry and position the head, and brace and help maneuver the upper limbs

Vertebral canal

The spinal cord lies within a bony canal formed by adjacent vertebrae and soft tissue elements (the vertebral canal)

Dura mater

The thickest and most external of the membranes, the dura mater, lies directly against, but is not attached to, the arachnoid mater.

What innervates the latissimus dorsi?

The thoracodorsal nerve of the brachial plexus innervates the latissimus dorsi muscle.

How can you identify the coccyx via palpitations

The tip of the coccyx is palpable at the base of the vertebral column between the gluteal masses

What are the two groups of segmental muscles?

The two groups of segmental muscles are deeply placed in the back and innervated by posterior rami of spinal nerves -Levatores costarum -interspinales

Spinotransversales muscles

The two spinotransversales muscles run from the spinous processes and ligamentum nuchae upward and laterally

Tectorial membrane

The upper part of the posterior longitudinal ligament that connects CII to the intracranial aspect of the base of the skull is termed the tectorial membrane

What is the vascular supply of the suboccipital muscles?

The vascular supply to the muscles in this area is from branches of the vertebral and occipital arteries.

Vertebral arch

The vertebral arch is firmly anchored to the posterior surface of the vertebral body by two pedicles, which form the lateral pillars of the vertebral arch. The roof of the vertebral arch is formed by right and left laminae, which fuse at the midline.

Vertebral canal: how are vertebral arches related?

The vertebral arches of the vertebrae are aligned to form the lateral and posterior walls of the vertebral canal, which extends from the first cervical vertebra (CI) to the last sacral vertebra (vertebra SV). This bony canal contains the spinal cord and its protective membranes, together with blood vessels, connective tissue, fat, and proximal parts of spinal nerves.

What is the vascular supply of the serratus posterior muscles?

Their vascular supply is provided by a similar segmental pattern through the intercostal arteries

How many vertebrae are there and how are they subdivided?

There are approximately 33 vertebrae, which are subdivided into five groups based on morphology and location

Why are there large gaps between the posterior components of adjacent vertebral arches in the lumbar region?

These gaps between adjacent laminae and spinous processes become increasingly wide from vertebra LI to vertebra LV. The spaces can be widened further by flexion of the vertebral column. These gaps allow relatively easy access to the vertebral canal for clinical procedures.

Where do the longitudinal channels drain into?

These longitudinal channels drain into an extensive internal vertebral plexus in the extradural (epidural) space of the vertebral canal, which then drains into segmentally arranged vessels that connect with major systemic veins, such as the azygos system in the thorax. -The internal vertebral plexus also communicates with intracranial veins.

Where are the two rhomboid muscles?

They are inferior to Levator scapulae

Latissimus dorsi innervation

Thoracodorsal nerve (C6 to C8)

What doe the spinotransversales muscle do together? Individually?

Together the spinotransversales muscles draw the head backward, extending the neck. Individually, each muscle rotates the head to one side—the same side as the contracting muscle.

Thoracic Zygapophysial joint

Vertical -joints are oriented vertically and their shape limits flexion and extension, but facilitates rotation

spinal ganglion

a collection of cell bodies of afferent nerves located just outside the spinal cord

CLINICAL: Kyphosis

abnormal curvature of the vertebral column in the thoracic region, producing a "hunchback" deformity

After entering an intervertebral foramen, the segmental spinal arteries give rise to

anterior and posterior radicular arteries -occurs at every vertebral level -The radicular arteries follow, and supply, the anterior and posterior roots.

Dermatomes

area of skin innervated by cutaneous branches of single spinal nerve

Flexion

bending a joint Anterior bending

Degenerative changes in the annulus fibrosus

can lead to herniation of the nucleus pulposus. Posterolateral herniation can impinge on the roots of a spinal nerve in the intervertebral foramen.

Alar ligaments

check excessive rotation of the head and atlas relative to the axis -The two superolateral surfaces of the dens possess circular impressions that serve as attachment sites for strong alar ligaments, one on each side, which connect the dens to the medial surfaces of the occipital condyles.

CLINICAL: middle column

comprises the vertebral body and the posterior longitudinal ligament

supraspinous ligament

connects and passes along the tips of the vertebral spinous processes from vertebra CVII to the sacrum

annulus fibrosus

consists of an outer ring of collagen surrounding a wider zone of fibrocartilage arranged in a lamellar configuration. This arrangement of fibers limits rotation between vertebrae.

What does contraction of the suboccipital muscles do?

extends and rotates the head at the atlanto-occipital and atlanto-axial joints, respectively

What is in between the dura mater and the arachnoid mater in the vertebral canal?

extradural (epidural) space containing loose connective tissue, fat, and a venous plexus

Nucleus pulposus

fills the center of the intervertebral disc, is gelatinous, and absorbs compression forces between vertebrae

Movements by the vertebral colum

flexion, extension, lateral flexion, rotation, and circumduction.

Vertebral arch

forms the lateral and posterior parts of the vertebral foramen.

Meningocele

herniation of the meninges with cerebrospinal fluid

transverse ligament of atlas

holds dens of C2 against the anterior arch C1 -The dens is held in position by a strong transverse ligament of atlas posterior to it and spanning the distance between the oval attachment facets on the medial surfaces of the lateral masses of the atlas

arachnoid mater

is a thin delicate membrane against, but not adherent to, the deep surface of the dura mater -It is separated from the pia mater by the subarachnoid space. The arachnoid mater ends at the level of vertebra SII

Vertebral body

is anterior and is the major weightbearing component of the bone. It increases in size from vertebra CII to vertebra LV. Fibrocartilaginous intervertebral discs separate the vertebral bodies of adjacent vertebrae.

Posterior longitudinal ligament

is on the posterior surfaces of the vertebral bodies and lines the anterior surface of the vertebral canal. -Like the anterior longitudinal ligament, it is attached along its length to the vertebral bodies and intervertebral discs. -The upper part of the posterior longitudinal ligament that connects CII to the intracranial aspect of the base of the skull is termed the tectorial membrane

Spinal segment

is the area of the spinal cord that gives rise to the posterior and anterior rootlets , which will form a single pair of spinal nerves. Laterally, the posterior and anterior roots on each side join to form a spinal nerve.

Vertebral body

is the weight-bearing part of the vertebra and is linked to adjacent vertebral bodies by intervertebral discs and ligaments. The size of vertebral bodies increases inferiorly as the amount of weight supported increases.

Posterior rami

▪ The posterior rami innervate only intrinsic back muscles (the epaxial muscles) and an associated narrow strip of skin on the back.

What are the spinotransversales muscles?

splenius capitis and splenius cervicis

Functions of the back

support, movement, protection

At the lateral border of the quadratus lumborum, the anterior layer joins them and forms

the aponeurotic origin for the transversus abdominis muscle of the abdominal wall.

Anterior ramus

the much larger anterior rami innervate most other regions of the body except the head, which is innervated predominantly, but not exclusively, by cranial nerves

Movements by vertebrae in a specific region (cervical, thoracic, and lumbar) are determined by

the shape and orientation of joint surfaces on the articular processes and on the vertebral bodies.

the extensors and rotators of the head and neck

the splenius capitis and cervicis (spinotransversales muscles),

The medial attachments of the latissimus dorsi and serratus posterior inferior muscles blend into the

thoracolumbar fascia

Posterolateral sulcus

▪ The posterolateral sulcus on each side of the posterior surface marks where the posterior rootlets of spinal nerves enter the cord.

Posterior spinal arteries

two posterior spinal arteries , which also originate in the cranial cavity, usually arising directly from a terminal branch of each vertebral artery (the posterior inferior cerebellar artery)—the right and left posterior spinal arteries descend along the spinal cord, each as two branches that bracket the posterolateral sulcus and the connection of posterior roots with the spinal cord.

Typical vertebra consists of

vertebral body and a vertebral arch

The ligamentum nuchae is a triangular, sheet-like structure in the median sagittal plane:

▪ The base of the triangle is attached to the skull, from the external occipital protuberance to the foramen magnum. ▪ The apex is attached to the tip of the spinous process of vertebra CVII. ▪ The deep side of the triangle is attached to the posterior tubercle of vertebra CI and the spinous processes of the other cervical vertebrae.

The vertebral arch of a typical vertebra has a number of characteristic projections, which serve as:

▪ attachments for muscles and ligaments, ▪ levers for the action of muscles, and ▪ sites of articulation with adjacent vertebrae

The contents of the suboccipital triangle include:

▪ posterior ramus of CI, ▪ vertebral artery, and ▪ veins

The intervertebral foramen is bordered

▪ posteriorly by the zygapophysial joint between the articular processes of the two vertebrae, and ▪ anteriorly by the intervertebral disc and adjacent vertebral bodies.

Conus medullaris

The distal end of the cord (the conus medullaris ) is cone shaped.

Zygapophysial joints

The synovial joints between superior and inferior articular processes on adjacent vertebrae are the zygapophysial joints - A thin articular capsule attached to the margins of the articular facets encloses each joint.

What are discs made of?

The discs between the vertebrae are made up of a central portion (the nucleus pulposus) and a complex series of fibrous rings (anulus fibrosus).

What innervates the rhomboid muscles?

The dorsal scapular nerve, a branch of the brachial plexus, innervates both rhomboid muscles

How can yo ID the erector spinae muscle?

The erector spinae muscles are visible as two longitudinal columns separated by a furrow in the midline

occipital protuberance

The external occipital protuberance is palpable in the midline at the back of the head just superior to the hairline.

What do extrinsic muscles of the back do? What innervates them?

The extrinsic muscles are involved with movements of the upper limbs and thoracic wall and, in general, are innervated by anterior rami of spinal nerves. The superficial group of these muscles is related to the upper limbs, while the intermediate layer of muscles is associated with the thoracic wall.

Extrinsic muscles

The extrinsic muscles of the back move the upper limbs and the ribs.

Superior articular surfaces vs inferior articular surfaces of the axis

The superior articular surfaces are bean shaped and concave, whereas the inferior articular surfaces are almost circular and flat

What is the function of the ligamentum nuchae?

-The ligamentum nuchae supports the head. -It resists flexion and facilitates returning the head to the anatomical position. -The broad lateral surfaces and the posterior edge of the ligament provide attachment for adjacent muscles.

CLINICAL: Variation in vertebral numbers: Cervical

-Usually 7 cervical vertebrae but certain diseases fuse them -Fusion of cervical vertebrae can be associated with other abnormalities, for example Klippel-Feil syndrome, in which there is fusion of vertebrae CI and CII or CV and CVI, and may be associated with a high-riding scapula (Sprengel's shoulder) and cardiac abnormalities.

CLINICAL: vertebral injuries and soft tissues and supporting structures between the vertebrae

- Typical examples of this are the unifacetal and bifacetal cervical vertebral dislocations that occur in hyperflexion injuries.

Pia mater

- is a vascular membrane that firmly adheres to the surface of the spinal cord -extends into the anterior median fissure and reflects as sleeve-like coatings onto posterior and anterior rootlets and roots as they cross the subarachnoid space. -As the roots exit the space, the sleeve-like coatings reflect onto the arachnoid mater.

CLINICAL: Congenital scoliosis

- is usually associated with other developmental abnormalities - strong association with other abnormalities of the chest wall, genitourinary tract, and heart disease. - require careful evaluation by many specialist

CLINICAL: spondylolisthesis

-It is possible for a vertebra to slip anteriorly upon its inferior counterpart without a pars interarticularis fracture. -Usually this is related to abnormal anatomy of the facet joints, facet joint degenerative change. -This disorder is termed spondylolisthesis.

Superficial and intermediate group

-Muscles in the superficial and intermediate groups are extrinsic muscles because they originate embryologically from locations other than the back. -They are innervated by anterior rami of spinal nerves

CLINICAL: joint diseases

-Some diseases have a predilection for synovial joints rather than symphyses. -A typical example is rheumatoid arthritis, which primarily affects synovial joints and synovial bursae, resulting in destruction of the joint and its lining. -Symphyses are usually preserved.

CLINICAL: Nerve injuries affecting superficial back muscles; weakness of trapezius

-Weakness in the trapezius, caused by an interruption of the accessory nerve [XI], may appear as drooping of the shoulder, inability to raise the arm above the head because of impaired rotation of the scapula, or weakness in attempting to raise the shoulder (i.e., shrug the shoulder against resistance).

Absence of lateral curvatures

-When viewed from behind, the normal vertebral column has no lateral curvatures. -The vertical skin furrow between muscle masses on either side of the midline is straight

CLINICAL: osteoporosis

-a pathophysiologic condition in which bone quality is normal but the quantity of bone is deficient. -It is a metabolic bone disorder that commonly occurs in women in their 50s and 60s and in men in their 70s. -common to have "crush" vertebral body fractures, distal fractures of the radius, and hip fractures

Subarachnoid space

-between the arachnoid and pia mater contains CSF -The subarachnoid space around the spinal cord is continuous at the foramen magnum with the subarachnoid space surrounding the brain. -Inferiorly, the subarachnoid space terminates at approximately the level of the lower border of vertebra SII

CLINICAL: Vertebral fractures

-can occur anywhere along the vertebral column -usually will heal under appropriate circumstances -At the time of injury, it is not the fracture itself but related damage to the contents of the vertebral canal and the surrounding tissues that determines the severity of the patient's condition.

Characteristics of the sacrum

-single bone for 5 fused vertebrae -triangular shape with apex pointed inferiorly -curved so that it has a concave anterior surface and a correspondingly convex posterior surface -articulates with LV and coccyx above and below -It has two large L -shaped facets, one on each lateral surface, for articulation with the pelvic bones.

features of cervical vertebrae

-small size and presence of a foramen in each transverse process -short in height and square shaped vertebral body with concave superior surface and convex inferior surface -transverse process is trough shaped and perforated by a round foramen transversarium -short and bifid spinous process -vertebral foramen is triangular

What are the two major types of joints between vertebrae?

-symphyses between vertebral bodies -synovial joints between articular processes

Each spinal nerve divides, as it emerges from an intervertebral foramen, into two major branches: a small posterior ramus and a much larger anterior ramus

Posterior rami Anterior rami

Intertransversarii function

Postural muscles that stabilize adjoining vertebrae during movements of vertebral column

The vertebral column is positioned posteriorly in the body at the midline. When viewed laterally, it has a number of curvatures. What are they

Primary curvature Secondary curvature

Which regions of the spine are in the primary curvature? Secondary?

Primary: thoracic and sacral regions Secondary: cervical and lumbar

CLINICAL: Renal pain

Renal pain, which may be produced by stones in the renal collecting system or renal tumors, also typically refers to the back. More often than not this is usually unilateral; however, it can produce central posterior back pain.

How can you ID the rhomboid muscle?

Retracting the scapulae toward the midline can accentuate the rhomboid muscles, which lie deep to the trapezius muscle.

Rhomboid major function

Retracts (adducts) and elevates scapula

Rhomboid minor function

Retracts (adducts) and elevates scapula

Obliquus capitis inferior function

Rotation of face to same side

Dentriculate ligament

On each side of the spinal cord, a longitudinally oriented sheet of pia mater (the denticulate ligament ) extends laterally from the cord toward the arachnoid and dura mater

Pia mater

The pia mater is the innermost membrane and is intimately associated with the surface of the spinal cord.

How can you identify the sacrum via palpitations?

The sacral dimples that mark the position of the posterior superior iliac spine are level with the SII vertebral spinous process

arachnoid mater

The second membrane, the arachnoid mater, is separated from the pia by the subarachnoid space, which contains cerebrospinal fluid.

How can you identify CII via palpatations?

The spinous process of vertebra CII can be identified through deep palpation as the most superior bony protuberance in the midline inferior to the skull.

Meninges

Within the vertebral canal, the spinal cord is surrounded by a series of three connective tissue membranes (the meninges)

Circumduction

circular movement of a limb at the far end

CLINICAL: anterior column

consists of the vertebral bodies and the anterior longitudinal ligament

Posterior root

contains the processes of sensory neurons carrying information to the CNS—the cell bodies of the sensory neurons, which are derived embryologically from neural crest cells, are clustered in a spinal ganglion at the distal end of the posterior root, usually in the intervertebral foramen.

Thorocolumbar fascia

covers the deep muscles of the back and trunk -This fascial layer is critical to the overall organization and integrity of the region:

Transverse process

extends posterolaterally from the junction of the pedicle and lamina on each side and is a site for muscle and ligament attachment, and for articulation with ribs in the thoracic region.

Muscles in the superficial group include

the trapezius, latissimus dorsi, rhomboid major, rhomboid minor, and levator scapulae. -The rhomboid major, rhomboid minor, and levator scapulae muscles are located deep to the trapezius muscle in the superior part of the back.

Anterior rami

▪ The anterior rami innervate most other skeletal muscles (the hypaxial muscles) of the body, including those of the limbs and trunk, and most remaining areas of the skin, except for certain regions of the head.

CLINICAL: hemivertebra

Occurs when a vertebra develops only on one side

Serratus posterior superior function

Elevates ribs II to V

the short segmental muscles

the interspinales and intertransversarii.

How many pairs of coccygeal nerves are there?

1 (Co)

How many pairs of spinal nerves are there?

31

The vertebral canal is bordered:

▪ anteriorly by the bodies of the vertebrae, intervertebral discs, and posterior longitudinal ligament ▪ laterally, on each side by the pedicles and intervertebral foramina; and ▪ posteriorly by the laminae and ligamenta flava, and in the median plane the roots of the interspinous ligaments and vertebral spinous processes.

The arterial supply to the spinal cord comes from two sources. It consists of:

▪ longitudinally oriented vessels, arising superior to the cervical portion of the cord, which descend on the surface of the cord; and ▪ feeder arteries that enter the vertebral canal through the intervertebral foramina at every level; these feeder vessels, or segmental spinal arteries , arise predominantly from the vertebral and deep cervical arteries in the neck, the posterior intercostal arteries in the thorax, and the lumbar arteries in the abdomen.

Deep group of back muscles include

▪ the extensors and rotators of the head and neck—the splenius capitis and cervicis (spinotransversales muscles), ▪ the extensors and rotators of the vertebral column—the erector spinae and transversospinales, and ▪ the short segmental muscles—the interspinales and intertransversarii.

CLINICAL: Herniation of intervertebral discs

- A tear can occur within the anulus fibrosus through which the material of the nucleus pulposus can track. - After a period of time, this material may track into the vertebral canal or into the intervertebral foramen to impinge on neural structures. - This is a common cause of back pain. - A disc may protrude posteriorly to directly impinge on the cord or the roots of the lumbar nerves, depending on the level, or may protrude posterolaterally adjacent to the pedicle and impinge on the descending root.

CLINICAL: extradural anesthesia

-A needle is placed through the skin, supraspinous ligament, interspinous ligament, and ligamenta flava into the areolar tissue and fat around the dura mater. - Anesthetic agent is introduced and diffuses around the vertebral canal to anesthetize the exiting nerve roots and diffuse into the subarachnoid space.

CLINICAL: Surgical procedures on the back: Discectomy/laminectomy

-A prolapsed intervertebral disc may impinge upon the meningeal (thecal) sac, cord, and most commonly the nerve root, producing symptoms attributable to that level. -In some instances the disc protrusion will undergo a degree of involution that may allow symptoms to resolve without intervention -In some instances pain, loss of function, and failure to resolve may require surgery to remove the disc protrusion.

CLINICAL: scoliosis with muscle abnormalities

-A rare but important group of scoliosis is that in which the muscle is abnormal. -Muscular dystrophy is the commonest example -abnormal muscle does not retain the normal alignment of the vertebral column resulting in curvature -muscle biopsy is needed to diagnose

suboccipital muscles

-A small group of deep muscles in the upper cervical region at the base of the occipital bone move the head. - They connect vertebra CI (the atlas) to vertebra CII (the axis) and connect both vertebrae to the base of the skull. -Because of their location they are sometimes referred to as suboccipital muscles

CLINICAL: Destruction of the clinical columns

-Destruction of one of the clinical columns is usually a stable injury requiring little more than rest and appropriate analgesia. -Disruption of two columns is highly likely to be unstable and requires fixation and immobilization - A three-column spinal injury usually results in a significant neurological event and requires fixation to prevent further extension of the neurological defect and to create vertebral column stability.

CLINICAL: Spinal local anesthetic

-Local anesthetics can be injected into the extradural space or the subarachnoid space to anesthetize the sacral and lumbar nerve roots. -useful for operations on the pelvis and the legs, which can then be carried out without the need for general anesthesia. -When procedures are carried out, the patient must be in the erect position and not lying on his or her side or in the head-down position. -If a patient lies on his or her side, the anesthesia is likely to be unilateral. -If the patient is placed in the head-down position, the anesthetic can pass cranially and potentially depress respiration.

Semispinalis capitis

-One muscle in the transversospinales group, the semispinalis capitis , has a unique action because it attaches to the skull. -Contracting bilaterally, this muscle pulls the head posteriorly, whereas unilateral contraction pulls the head posteriorly and turns it, causing the chin to move superiorly and turn toward the side of the contracting muscle. -These actions are similar to those of the upper erector spinae.

The thoracolumbar fascia is critical to the overall organization and integrity of the deep muscles. Describe it:

-Superiorly, it passes anteriorly to the serratus posterior muscle and is continuous with deep fascia in the neck. -In the thoracic region, it covers the deep muscles and separates them from the muscles in the superficial and intermediate groups. -Medially, it attaches to the spinous processes of the thoracic vertebrae and, laterally, to the angles of the ribs.

Levatores costarum

-The first group of segmental muscles are the levatores costarum muscles, which arise from the transverse processes of vertebrae CVII and TI to TXI. -They have an oblique lateral and downward direction and insert into the rib below the vertebra of origin in the area of the tubercle. -Contraction elevates the ribs.

Palpable iliac crest

-The iliac crest is palpable along its entire length, from the anterior superior iliac spine at the lower lateral margin of the anterior abdominal wall to the posterior superior iliac spine near the base of the back. -The position of the posterior superior iliac spine is often visible as a "sacral dimple" just lateral to the midline.

Interspinales

-The second group of segmental muscles are the true segmental muscles of the back—the interspinales , which pass between adjacent spinous processes, and the intertransversarii, which pass between adjacent transverse processes. -These postural muscles stabilize adjoining vertebrae during movements of the vertebral column to allow more effective action of the large muscle groups.

Rotatores

-The small rotatores muscles are the deepest of the transversospinales group. -They are present throughout the length of the vertebral column but are best developed in the thoracic region. -Their fibers pass upward and medially from transverse processes to spinous processes crossing two vertebrae (long rotators) or attaching to an adjacent vertebra (short rotators).

Visualizing the inferior ends of the spinal cord and subarachnoid space

-The spinal cord does not occupy the entire length of the vertebral canal. -Normally in adults, it terminates at the level of the disc between vertebrae LI and LII; however, it may end as high as TXII or as low as the disc between vertebrae LII and LIII. -The subarachnoid space ends at approximately the level of vertebra SII

How do the tips of thoracic vertebrae through us off in palpitations?

-The tips of the vertebral spinous processes do not always lie in the same horizontal plane as their corresponding vertebral bodies. -In thoracic regions, the spinous processes are long and sharply sloped downward so that their tips lie at the level of the vertebral body below. - In other words, the tip of the TIII vertebral spinous process lies at vertebral level TIV.

CLINICAL: Vertebra and cancer

-common for metastatic disease (secondary spread of cancer) -destroy bone or form bone that destroys the mechanical properties of the bone -minor injury could lead to vertebral collapse -Cancer cell have a much higher glucose metabolism compared with normal adjacent bone cells -Use this property to detect by using radioisotope-labeled glucose to a patient and tracing it -May extrude tumor fragments into the VERTEBRAL CANAL, compressing nerves and spinal cord

CLINICAL: Spina bifida more severe

-complete failure of the fusion of the posterior arch at the lumbosacral junction, with a large outpouching of the meninges -may contain cerebrospinal fluid (meningocele) or a portion of the spinal cord (mylomeningocele). -may result in a variety of neurological deficits, including problems with walking and bladder function

How do the transversospinales group work?

-contract bilaterally, they extend the vertebral column, an action similar to that of the erector spinae group. -However, when muscles on only one side contract, they pull the spinous processes toward the transverse processes on that side, causing the trunk to turn or rotate in the opposite direction.

The vertebral column and the thorax, abdomen, and pelvis

-framework -support -attachments for muscles and fascia -articulation sites for other bones -anterior rami of spinal nerves pass through back

CLINICAL: Lumbar vertebral column

-injuries are rare -usually involve significant force -Knowing that a significant force is required to fracture a vertebra, one must assess the abdominal organs and the rest of the axial skeleton for further fractures and visceral rupture.

CLINICAL: Pars interarticularis fractures

-is a clinical term to describe the specific region of a vertebra between the superior and inferior facet (zygapophysial) joints -is susceptible to trauma, especially in athletes. -If a fracture occurs around the pars interarticularis, the vertebral body may slip anteriorly and compress the vertebral canal.

latissimus dorsi

-is a large, flat triangular muscle that begins in the lower portion of the back and tapers as it ascends to a narrow tendon that attaches to the humerus anteriorly -as result, movements associated with this muscle include extension, adduction, and medial rotation of the upper limb. -The latissimus dorsi can also depress the shoulder, preventing its upward movement.

CLINICAL: Spinal fusion

-is performed when it is necessary to fuse one vertebra with the corresponding superior or inferior vertebra, and in some instances multilevel fusion may be necessary. -Indications are varied, though they include stabilization after fracture, stabilization related to tumor infiltration, and stabilization when mechanical pain is produced either from the disc or from the posterior elements.

Characteristics of lumbar vertebrae

-large size -lack facets for articulation with ribs -transverse processes usually thin and long (except L5) -vertebral body is cylindrical -vertebral foramen is triangular in shape and larger than in the thoracic vertebrae

Characteristics of the axis

-large tooth-like dens, which extends superiorly from the vertebral body -The anterior surface of the dens has an oval facet for articulation with the anterior arch of the atlas.

CLINICAL: Idiopathic scoliosis

-most common but know very little about -maybe some initial axial rotation of the vertebrae, which then alters the locations of the mechanical compressive and distractive forces applied through the vertebral growth plates, leading to changes in speed of bone growth and ultimately changes to spinal curvature -never present at birth -tend to occur in either the infantile, juvenile, or adolescent age groups -normal vertebral bodies and posterior elements (Pericles and laminate)

CLINICAL: Variation in vertebral numbers: Lumbar

-most common is lumbar vertebrae is the partial fusion of vertebra LV with the sacrum (sacralization of the lumbar vertebra) -Partial separation of vertebra SI from the sacrum (lumbarization of first sacral vertebra) may also occur -The LV vertebra can usually be identified by the iliolumbar ligament, which is a band of connective tissue that runs from the tip of the transverse process of LV to the iliac crest bilaterally

Semispinalis

-muscles are the most superficial collection of muscle fibers in the transversospinales group. -These muscles begin in the lower thoracic region and end by attaching to the skull, crossing between four and six vertebrae from their point of origin to point of attachment. -Semispinalis muscles are found in the thoracic and cervical regions, and attach to the occipital bone at the base of the skull.

CLINICAL Kyphosis and gibbous deformity

-occurs in certain disease states, the most dramatic of which is usually secondary to tuberculosis infection of a thoracic vertebral body where the kyphosis becomes angulated at the site of the lesion - This produces the gibbus deformity, a deformity that was prevalent before the use of antituberculous medication

CLINICAL: How do they find the level of the disc protrusion before disectomy/laminectomy?

-of upmost importance to know the level before surgery -may use MRI and notable fluoroscopy to make sure they operate on the right level -A midline approach to the right or to the left of the spinous processes will depend upon the most prominent site of the disc bulge. - In some instances removal of the lamina will increase the potential space and may relieve symptoms. -Some surgeons perform a small fenestration (windowing) within the ligamentum flavum providing access to the canal -The meningeal sac and its contents are gently retracted, exposing the nerve root and the offending disc. -The disc is dissected free, removing its effect on the nerve root and the canal. I

Ligaments flava

-on each side, pass between the laminae of adjacent vertebrae - thin, broad ligaments consist predominantly of elastic tissue and form part of the posterior surface of the vertebral canal. -Each ligamentum flavum runs between the posterior surface of the lamina on the vertebra below to the anterior surface of the lamina of the vertebra above. -The ligamenta flava resist separation of the laminae in flexion and assist in extension back to the anatomical position.

CLINICAL: how a spinal tap done

-patient prone or lateral -needle passed in the midline in between the spinous processes into the extradural space -Further advancement punctures the dura and arachnoid mater to enter the subarachnoid space. -Most needles push the roots away from the tip without causing the patient any symptoms. -Once the needle is in the subarachnoid space, fluid can be aspirated. -In some situations, it is important to measure CSF pressure.

The vertebral column and the limbs

-provide extensive attachments for muscles for anchoring and moving upper limbs -upper and lower are innervated by anterior rami of spinal nerves that emerge from cervical and lumbosacral levels, respectively, of the vertebral column.

Transversospinales muscles

-run obliquely upward and medially from transverse processes to spinous processes, filling the groove between these two vertebral projections -They are deep to the erector spinae and consist of three major subgroups—the semispinalis, multifidus, and rotatores muscles.

Describe muscles of the deep group

-they are intrinsic muscles because they develop in the back. - They are innervated by posterior rami of spinal nerves and are directly related to movements of the vertebral column and head.

CLINICAL: Back pain-alternative explanations

-very common/almost all individuals at some stage during life -key clinical importance to ID whether back pain is from vertebral column and its attachments or relates to other structures -failure to consider other potential structures can lead to mortality and morbidity -pain may refer to the back from a number of organs situated in the retroperitoneum

coccygeal vertebrae

3-4 -which fuse into a single small triangular bone called the coccyx.

How many coccygeal vertebrae are there?

3-4 fused The coccygeal vertebrae are rudimentary in structure, vary in number from three to four, and often fuse into a single coccyx.

What are the major bones of the back?

33 vertebrae

How many cervical vertebrae are there?

7 (C1-C7)

Cervical enlargement

A cervical enlargement occurs in the region associated with the origins of spinal nerves C5 to T1, which innervate the upper limbs.

Case 5: Sacral tumor A 55-year-old woman came to her physician with sensory alteration in the right gluteal (buttock) region and in the intergluteal (natal) cleft. Examination also demonstrated low-grade weakness of the muscles of the foot and subtle weakness of the extensor hallucis longus, extensor digitorum longus, and fibularis tertius on the right. The patient also complained of some mild pain symptoms posteriorly in the right gluteal region.

A lesion was postulated in the left sacrum. Pain in the right sacro-iliac region could easily be attributed to the sacro-iliac joint, which is often very sensitive to pain. The weakness of the intrinsic muscles of the foot and the extensor hallucis longus, extensor digitorum longus, and fibularis tertius muscles raises the possibility of an abnormality affecting the nerves exiting the sacrum and possibly the lumbosacral junction. The altered sensation around the gluteal region toward the anus would also support these anatomical localizing features. An X-ray was obtained of the pelvis. The X-ray appeared on first inspection unremarkable. However, the patient underwent further investigation, including CT and MRI, which demonstrated a large destructive lesion involving the whole of the left sacrum extending into the anterior sacral foramina at the S1, S2, and S3 levels. Interestingly, plain radiographs of the sacrum may often appear normal on first inspection, and further imaging should always be sought in patients with a suspected sacral abnormality. The lesion was expansile and lytic. Most bony metastases are typically nonexpansile. They may well erode the bone, producing lytic type of lesions, or may become very sclerotic (prostate metastases and breast metastases). From time to time we see a mixed pattern of lytic and sclerotic. There are a number of uncommon instances in which certain metastases are expansile and lytic. These typically occur in renal metastases and may be seen in multiple myeloma. The anatomical importance of these specific tumors is that they often expand and impinge upon other structures. The expansile nature of this patient's tumor within the sacrum was the cause for compression of the sacral nerve roots, producing her symptoms. The patient underwent a course of radiotherapy, had the renal tumor excised, and is currently undergoing a course of chemoimmunotherapy.

Lumbosacral enlargment

A lumbosacral enlargement occurs in the region associated with the origins of spinal nerves L1 to S3, which innervate the lower limbs.

Spinous process on vertebral arches

A spinous process projects posteriorly and generally inferiorly from the roof of the vertebral arch.

CLINICAL: What does true scoliosis involve?

A true scoliosis involves not only the curvature (right- or left-sided) but also a rotational element of one vertebra upon another.

What is the total of joints a typical vertebra has? What are they specifically

A typical vertebra has a total of six joints with adjacent vertebrae: four synovial joints (two above and two below) and two symphyses (one above and one below). Each symphysis includes an intervertebral disc.

CLINICAL: Nerve injuries affecting superficial back muscles; weakness of latissimus dorsi

A weakness in, or an inability to use, the latissimus dorsi, resulting from an injury to the thoracodorsal nerve, diminishes the capacity to pull the body upward while climbing or doing a pull-up.

What do intrinsic muscles of the back do? What innervates them?

All of the intrinsic muscles of the back are deep in position and are innervated by the posterior rami of spinal nerves. They support and move the vertebral column and participate in moving the head. One group of intrinsic muscles also moves the ribs relative to the vertebral column.

CLINICAL: Lordosis

Lordosis is abnormal curvature of the vertebral column in the lumbar region, producing a swayback deformity.

Superior and inferior articular processes

Also projecting from the region where the pedicles join the laminae are superior and inferior articular processes, which articulate with the inferior and superior articular processes, respectively, of adjacent vertebrae.

A number of readily palpable bony features provide useful landmarks for defining muscles and for locating structures associated with the vertebral column.

Among these features are the external occipital protuberance, the scapula, and the iliac crest

CLINICAL: Paraplegia

An injury in upper levels of the cervical vertebral column can result in death because of loss of innervation to the diaphragm. An injury to the spinal cord below the level of TI can lead to varying degrees of impairment in motor and sensory function (paralysis) in the lower limbs, termed paraplegia.

CLINICAL: Nerve injuries affecting superficial back muscles; weakness of rhomboids

An injury to the dorsal scapular nerve, which innervates the rhomboids, may result in a lateral shift in the position of the scapula on the affected side (i.e., the normal position of the scapula is lost because of the affected muscle's inability to prevent antagonistic muscles from pulling the scapula laterally).

CLINICAL: tetraplegia

An injury to the spinal cord in the cervical portion of the vertebral column can lead to varying degrees of impairment of sensory and motor function (paralysis) in all 4 limbs, termed quadriplegia or tetraplegia.

What happens if the intervertebral foramen are occluded or reduced?

Any pathology that occludes or reduces the size of an intervertebral foramen, such as bone loss, herniation of the intervertebral disc, or dislocation of the zygapophysial joint (the joint between the articular processes), can affect the function of the associated spinal nerve.

Why is it important to be able to to ID the position of the lumbar vertebral spinous processes?

Because the subarachnoid space can be accessed in the lower lumbar region without endangering the spinal cord, it is important to be able to identify the position of the lumbar vertebral spinous processes.

Cauda equina

Below the end of the spinal cord, the posterior and anterior roots of lumbar, sacral, and coccygeal nerves pass inferiorly to reach their exit points from the vertebral canal. This terminal cluster of roots is the cauda equina.

What is the vascular supply of the vertebral canal?

Between the walls of the vertebral canal and the dural sac is an extradural space containing a vertebral plexus of veins embedded in fatty connective tissue.

Atlas

C1 -articulates with the head -no vertebral body!! -the vertebral body of CI fuses onto the body of CII during development to become the dens of CII. As a result, there is no intervertebral disc between CI and CII. -ring shaped and composed of two lateral masses interconnected by an anterior arch and a posterior arch

Interspinales function

Postural muscles that stabilize adjoining vertebrae during movements of vertebral column

Rotation

Circular movement around the spine Turning body side to side

Levatores costarum

Contraction elevates rib

What can affect the structure of the intervertebral foramen

Each intervertebral foramen is a confined space surrounded by bone and ligament, and by joints. Pathology in any of these structures, and in the surrounding muscles, can affect structures within the foramen.

How are the spinal nerves attached to the spinal cord?

Each nerve is attached to the spinal cord by a posterior root and an anterior root

Levator scapulae function

Elevates scapula

CLINICAL: enlarged lymph nodes

Enlarged lymph nodes in the pre- and para-aortic region may produce central posterior back pain and may be a sign of solid tumor malignancy, infection, or Hodgkin's lymphoma.

What is the largest group of intrinsic back muscles?

Erector spinae

What are the primary extensors of the vertebral column and head?

Erector spinae group muscles

Rectus Capitis Posterior Major function

Extension of head; rotation of face to same side as muscle

True/false: The amount of movement between any two vertebrae is unlimited

False: Although the amount of movement between any two vertebrae is limited, the effects between vertebrae are additive along the length of the vertebral column. Also, freedom of movement and extension are limited in the thoracic region relative to the lumbar part of the vertebral column. Muscles in more anterior regions flex the vertebral column.

True/false: Movement between two vertebrae is unlimited

False: Although the movement between any two vertebrae is limited, the summation of movement among all vertebrae results in a large range of movement by the vertebral column.

True/False: Only thoracic vertebra have rib elements

False: Each vertebra also contains rib elements. In the thorax, these costal elements are large and form ribs, which articulate with the vertebral bodies and transverse processes. In all other regions, these rib elements are small and are incorporated into the transverse processes. Occasionally, they develop into ribs in regions other than the thorax, usually in the lower cervical and upper lumbar regions.

True/false: The posterior wall of the vertebral canal is always complete near the inferior end of the sacrum

False: The posterior wall of the vertebral canal may be incomplete near the inferior end of the sacrum.

Serrated posterior superior and serrated posterior inferior

Fibers from these two serratus posterior muscles ( serratus posterior superior and serratus posterior inferior ) pass obliquely outward from the vertebral column to attach to the ribs. This positioning suggests a respiratory function, and at times, these muscles have been referred to as the respiratory group

CLINICAL: Fractures of the axis

Fractures of the axis usually occur due to severe hyperextension and flexion, which can result in fracture of the tip of the dens, base of the dens, or through the body of the atlas. In judicial hangings, there is hyperextension and distraction injury causing fracture through the atlas pedicles and spondylolisthesis of C2 on C3. This type of fracture is often called a hangman's fracture . In many cases of upper neck injuries, even in the absence of fractures to the atlas or axis, there may be injury to the atlanto-axial ligaments, which can render the neck unstable and pose severe risk to the brainstem and upper spinal cord.

What does the dens do?

The dens acts as a pivot that allows the atlas and attached head to rotate on the axis, side to side.

CLINICAL: Fractures of the atlas

Fractures of vertebra CI (the atlas) and vertebra CII (the axis) can potentially lead to the worst types of spinal cord injury including death and paralysis due to injury of the brainstem, which contains the cardiac and respiratory centers. The atlas is a closed ring with no vertebral body. Axial-loading injuries, such as hitting the head while diving into shallow water or hitting the head on the roof of a car in a motor vehicle accident, can cause a "burst" type of fracture, where the ring breaks at more than one site ( Fig. 2.58 ). The British neurosurgeon, Geoffrey Jefferson, first described this fracture pattern in 1920, so these types of fractures are often called Jefferson fractures .

Case 2: Cervical spinal cord injury A 45-year-old man was involved in a serious car accident. On examination he had a severe injury to the cervical region of his vertebral column with damage to the spinal cord. In fact, his breathing became erratic and stopped.

If the cervical spinal cord injury is above the level of C5, breathing is likely to stop. The phrenic nerve takes origin from C3, C4, and C5 and supplies the diaphragm. Breathing may not cease immediately if the lesion is just below C5, but does so as the cord becomes edematous and damage progresses superiorly. In addition, some respiratory and ventilatory exchange may occur by using neck muscles plus the sternocleidomastoid and trapezius muscles, which are innervated by the accessory nerve [XI]. The patient was unable to sense or move his upper and lower limbs. The patient has paralysis of the upper and lower limbs and is therefore quadriplegic. If breathing is unaffected, the lesion is below the level of C5 or at the level of C5. The nerve supply to the upper limbs is via the brachial plexus, which begins at the C5 level. The site of the spinal cord injury is at or above the C5 level. It is important to remember that although the cord has been transected in the cervical region, the cord below this level is intact. Reflex activity may therefore occur below the injury, but communication with the brain is lost.

What does the termination of the spinal cord have to do with posterior and anterior roots?

In adults, the spinal cord terminates at a level approximately between vertebrae LI and LII, but this can range between vertebra TXII and the disc between vertebrae LII and LIII. Consequently, posterior and anterior roots forming spinal nerves emerging between vertebrae in the lower regions of the vertebral column are connected to the spinal cord at higher vertebral levels.

CLINICAL: disc osteophyte bars

In cervical regions of the vertebral column, cervical disc protrusions often become ossified and are termed disc osteophyte bars

Lumbar and sacral regions palpitation

In lumbar and sacral regions, the spinous processes are generally shorter and less sloped than in thoracic regions, and their palpable tips more closely reflect the position of their corresponding vertebral bodies. As a consequence, the palpable end of the spinous process of vertebra LIV lies at approximately the LIV vertebral level.

How far does the spinal cord extend in neonates?

In neonates, the spinal cord extends approximately to vertebra LIII but can reach as low as vertebra LIV

C1 and C2 and how the head moves

In the cervical region, the first two vertebrae and associated muscles are specifically modified to support and position the head. The head flexes and extends, in the nodding motion, on vertebra CI, and rotation of the head occurs as vertebra CI moves on vertebra CII

Sclerotomes

In the embryo, the vertebrae are formed intersegmentally from cells called sclerotomes, which originate from adjacent somites

How can you identify TI via palpitations?

Inferior to the spinous process of CVII is the spinous process of TI, which is also usually visible as a midline protuberance. Often it is more prominent than the spinous process of CVII

CLINICAL: Kyphoplasty

Is a similar technique to vertebroplasty -aims to restore some or all of the lost vertebral body height from the wedge fracture by injecting liquid bone cement into the vertebral body

lumbar vertebrae

L1-L5 -form the skeletal support for the posterior abdominal wall and are characterized by their large size

CLINICAL: most common sites for pars interarticularis fractures

LIV and LV level - (Clinicians often refer to parts of the back in shorthand terms that are not strictly anatomical; for example, facet joints and apophyseal joints are terms used instead of zygapophysial joints, and spinal column is used instead of vertebral column.)

CLINICAL: What factors influence the development of osteoporosis?

Many factors influence the development of osteoporosis, including genetic predetermination, level of activity and nutritional status, and, in particular, estrogen levels in women.

What do we base our classification of a back muscle as intrinsic or extrinsic on?

Muscles in the back can be classified as extrinsic or intrinsic based on their embryological origin and type of innervation Extrinsic: innervated by anterior rami of spinal nerves or cranial nerve XI (trapezius) Intrinsic: true back muscles innervated by posterior rami of spinal nerves

Characteristics of the atlas

No spinous process, no vertebral body, small anterior arch and a larger posterior arch, anterior tubercle, posterior tubercle, large vertebral foramen, two lateral masses both with inferior and superior articular facets

CLINICAL: Back pain caused by degenerative disease

Not infrequently, patients complain of pain and no immediate cause is found; the pain is therefore attributed to mechanical discomfort, which may be caused by degenerative disease. One of the treatments is to pass a needle into the facet joint and inject it with local anesthetic and corticosteroid.

Superior articulate process and inferior articular process

On each side of the vertebral arch, a transverse process extends laterally from the region where a lamina meets a pedicle. From the same region, a superior articular process and an inferior articular process articulate with similar processes on adjacent vertebrae

The vertebral arch of each vertebra consists of

Pericles and laminae

Name the meninges that surround the spinal cord

Pia mater Arachnoid mater Dura mater

Splenius cervicis innervation

Posterior rami of lower cervical nerves

Splenius capitis innervation

Posterior rami of middle cervical nerves

After exiting the vertebral canal, each spinal nerve branches into:

Posterior ramus and Anterior ramus

Obliques capitis superior innervation

Posterior ramus of C1

Obliquus capitis inferior innervation

Posterior ramus of C1

Rectus capitis posterior major innervation

Posterior ramus of C1

Rectus capitis posterior minor innervation

Posterior ramus of C1

Cervical Zygapophysial joint

Sloped from anterior to posterior -shape facilitates flexion and extension

Characteristics of the coccyx

Small triangular bone that articulates with the inferior end of the sacrum and represents three to four fused coccygeal vertebrae -It is characterized by its small size and by the absence of vertebral arches and therefore a vertebral canal.

CLINICAL: Spina bifida

Spina bifida is a disorder in which the two sides of vertebral arches, usually in lower vertebrae, fail to fuse during development, resulting in an "open" vertebral canal

CLINICAL: 2 types of spina bifida

Spina bifida occulta: defect in the vertebral arch of LV or SI Spina bifida MORE SEVERE: complete failure of fusion of the posterior arch at the lumbosacral junction

At what angle does the spinal cord leave the vertebrae?

Spinal nerves originate from the spinal cord at increasingly oblique angles from vertebrae CI to Co, and the nerve roots pass in the vertebral canal for increasingly longer distances. Their spinal cord level of origin therefore becomes increasingly dissociated from their vertebral column level of exit. This is particularly evident for lumbar and sacral spinal nerves.

Thoracic vertebrae

T1-T12 -characterized by their articulated ribs

Deep group of back muscles

The deep or intrinsic muscles of the back extend from the pelvis to the skull and are innervated by segmental branches of the posterior rami of spinal nerves.

Finding the position of the lumbar vertebral spinous processes

The LIV vertebral spinous process is level with a horizontal line between the highest points on the iliac crests. In the lumbar region, the palpable ends of the vertebral spinous processes lie opposite their corresponding vertebral bodies. The subarachnoid space can be accessed between vertebral levels LIII and LIV and between LIV and LV without endangering the spinal cord ( Fig. 2.68B ). The subarachnoid space ends at vertebral level SII, which is level with the sacral dimples marking the posterior superior iliac spines.

Case 4: Dissecting thoracic aneurysm A 72-year-old fit and healthy man was brought to the emergency department with severe back pain beginning at the level of the shoulder blades and extending to the midlumbar region. The pain was of relatively acute onset and was continuous. The patient was able to walk to the gurney as he entered the ambulance; however, at the emergency department the patient complained of inability to use both legs.

The attending physician examined the back thoroughly and found no significant abnormality. He noted that there was reduced sensation in both legs, and there was virtually no power in extensor or flexor groups. The patient was tachycardic, which was believed to be due to pain, and the blood pressure obtained in the ambulance measured 120/80 mm Hg. It was noted that the patient's current blood pressure was 80/40 mm Hg; however, the patient did not complain of typical clinical symptoms of hypotension. On first inspection, it is difficult to "add up" these clinical symptoms and signs. In essence we have a progressive paraplegia associated with severe back pain and an anomaly in blood pressure measurements, which are not compatible with the clinical state of the patient. It was deduced that the blood pressure measurements were obtained in different arms, and both were reassessed. The blood pressure measurements were true. In the right arm the blood pressure measured 120/80 mm Hg and in the left arm the blood pressure measured 80/40 mm Hg. This would imply a deficiency of blood to the left arm. The patient was transferred from the emergency department to the CT scanner, and a scan was performed that included the chest, abdomen, and pelvis. The CT scan demonstrated a dissecting thoracic aortic aneurysm. Aortic dissection occurs when the tunica intima and part of the tunica media of the wall of the aorta become separated from the remainder of the tunica media and the tunica adventitia of the aorta wall. This produces a false lumen. Blood passes not only in the true aortic lumen but also through a small hole into the wall of the aorta and into the false lumen. It often reenters the true aortic lumen inferiorly. This produces two channels through which blood may flow. The process of the aortic dissection produces considerable pain for the patient and is usually of rapid onset. Typically the pain is felt between the shoulder blades and radiating into the back, and although the pain is not from the back musculature or the vertebral column, careful consideration of structures other than the back should always be sought. The difference in the blood pressure between the two arms indicates the level at which the dissection has begun. The "point of entry" is proximal to the left subclavian artery. At this level a small flap has been created, which limits the blood flow to the left upper limb, giving the low blood pressure recording. The brachiocephalic trunk has not been affected by the aortic dissection, and hence blood flow remains appropriate to the right upper limb. The paraplegia was caused by ischemia to the spinal cord. The blood supply to the spinal cord is from a single anterior spinal artery and two posterior spinal arteries. These arteries are fed via segmental spinal arteries at every vertebral level. There are a number of reinforcing arteries (segmental medullary arteries) along the length of the spinal cord—the largest of which is the artery of Adamkiewicz. This artery of Adamkiewicz, a segmental medullary artery, typically arises from the lower thoracic or upper lumbar region, and unfortunately during this patient's aortic dissection, the origin of this vessel was disrupted. This produces acute spinal cord ischemia and has produced the paraplegia in the patient. Unfortunately, the dissection extended, the aorta ruptured, and the patient succumbed.

CASE 1: Cauda equina syndrome A 50-year-old man was brought to the emergency department with severe lower back pain that had started several days ago. In the past 24 hours he has had two episodes of fecal incontinence and inability to pass urine and now reports numbness and weakness in both his legs.

The attending physician performed a physical examination and found that the man had reduced strength during knee extension and when dorsiflexing his feet and toes. He also had reduced reflexes in his knees and ankles, numbness in the perineal (saddle) region, as well as reduced anal sphincter tone. The patient's symptoms and physical examination findings raised serious concern for compression of multiple lumbar and sacral nerve roots in the spine, affecting both motor and sensory pathways. His reduced power in extending his knees and reduced knee reflexes was suggestive of compression of the L4 nerve roots. His reduced ability to dorsiflex his feet and toes was suggestive of compression of the L5 nerve roots. His reduced ankle reflexes was suggestive of compression of the S1 and S2 nerve roots, and his perineal numbness was suggestive of compression of the S3, S4, and S5 nerve roots. A diagnosis of cauda equina syndrome was made, and the patient was transferred for an urgent MRI scan, which confirmed the presence of a severely herniating L2-3 disc compressing the cauda equina, giving rise to the cauda equina syndrome ( Fig. 2.70 ). The patient underwent surgical decompression of the cauda equina and made a full recovery. The collection of lumbar and sacral nerve roots beyond the conus medullaris has a horsetail-like appearance, from which it derives its name "cauda equina." Compression of the cauda equina may be caused by a herniating disc (as in this case), fracture fragments following traumatic injury, tumor, abscess, or severe degenerative stenosis of the central canal. Cauda equina syndrome is classed as a surgical emergency to prevent permanent and irreversible damage to the compressed nerve roots.

The back in general

The back consists of the posterior aspect of the body and provides the musculoskeletal axis of support for the trunk

Where is the blood supply of the trapezius?

The blood supply to the trapezius is from the superficial branch of the transverse cervical artery, the acromial branch of the suprascapular artery, and the dorsal branches of posterior intercostal arteries.

Case 3: Psoas abscess A 25-year-old woman complained of increasing lumbar back pain. Over the ensuing weeks she was noted to have an enlarging lump in the right groin, which was mildly tender to touch. On direct questioning, the patient also complained of a productive cough with sputum containing mucus and blood, and she had a mild temperature.

The chest radiograph revealed a cavitating apical lung mass, which explains the pulmonary history. Given the age of the patient a primary lung cancer is unlikely. The hemoptysis (coughing up blood in the sputum) and the rest of the history suggest the patient has a lung infection. Given the chest radiographic findings of a cavity in the apex of the lung, a diagnosis of tuberculosis (TB) was made. This was confirmed by bronchoscopy and aspiration of pus, which was cultured. During the patient's pulmonary infection, the tuberculous bacillus had spread via the blood to vertebra LI. The bone destruction began in the cancellous bone of the vertebral body close to the intervertebral discs. This disease progressed and eroded into the intervertebral disc, which became infected. The disc was destroyed, and the infected disc material extruded around the disc anteriorly and passed into the psoas muscle sheath. This is not an uncommon finding for a tuberculous infection of the lumbar portion of the vertebral column. As the infection progressed, the pus spread within the psoas muscle sheath beneath the inguinal ligament to produce a hard mass in the groin. This is a typical finding for a psoas abscess. Fortunately for the patient, there was no evidence of any damage within the vertebral canal. The patient underwent a radiologically guided drainage of the psoas abscess and was treated for over 6 months with a long-term antibiotic regimen. She made an excellent recovery with no further symptoms, although the cavities within the lungs remain. It healed with sclerosis.

What forms the intervertebral foramen?

The foramen is formed between adjacent vertebral arches and is closely related to intervertebral joints. ▪ The superior and inferior margins are formed by notches in adjacent pedicles. ▪ The posterior margin is formed by the articular processes of the vertebral arches and the associated joint. ▪ The anterior border is formed by the intervertebral disc between the vertebral bodies of the adjacent vertebrae.

CLINICAL: What is the function of the bone cement in vertebroplasty of osteoporotic wedge fractures?

The function is two fold: 1. Increases the strength of the vertebral body and prevents further loss of height 2. As the bone cement sets, there is a degree of heat generated that is believed to disrupt pain nerve endings

What do intervertebral disc consist of?

The intervertebral disc consists of an outer anulus fibrosus, which surrounds a central nucleus pulposus

CLINICAL: Discitis

The intervertebral discs are poorly vascularized; however, infection within the bloodstream can spread to the discs from the terminal branches of the spinal arteries within the vertebral body endplates, which lie immediately adjacent to the discs -Common sources of infection include the lungs and urinary tract.

Intrinsic muscles

The intrinsic muscles of the back maintain posture and move the vertebral column; these movements include flexion (anterior bending), extension, lateral flexion, and rotation

Where do the lateral attachments of the denticulate ligaments generally occur?

The lateral attachments of the denticulate ligaments generally occur between the exit points of adjacent posterior and anterior rootlets. The ligaments function to position the spinal cord in the center of the subarachnoid space.

"Uncovertebral" joints

The lateral margins of the upper surfaces of typical cervical vertebrae are elevated into crests or lips termed uncinate processes. -These may articulate with the body of the vertebra above to form small "uncovertebral" synovial joints

What is the nerve and blood supply of the Levator scapulae?

The levator scapulae is innervated by branches from the anterior rami of spinal nerves C3 and C4 and the dorsal scapular nerve, and its arterial supply consists of branches primarily from the transverse and ascending cervical arteries.

CLINICAL: Why is the lumbar region an ideal site to access the subarachnoid space?

The lumbar region is an ideal site to access the subarachnoid space because the spinal cord terminates around the level of the disc between vertebrae LI and LII in the adult. The subarachnoid space extends to the region of the lower border of the SII vertebra. There is therefore a large CSF-filled space containing lumbar and sacral nerve roots but no spinal cord.

Longissimus

The middle or intermediate column is the longissimus , which is the largest of the erector spinae subdivision extending from the common tendon of origin to the base of the skull. -Throughout this vast expanse, the lateral positioning of the longissimus muscle is in the area of the transverse processes of the various vertebrae.

Intermediate group of back muscles

The muscles in the intermediate group of back muscles consist of two thin muscular sheets in the superior and inferior regions of the back, immediately deep to the muscles in the superficial group

Lateral border of the suboccipital triangle

The obliquus capitis superior muscle forms the lateral border.

Iliocostalis

The outer or most laterally placed column of the erector spinae muscles is the iliocostalis , which is associated with the costal elements and passes from the common tendon of origin to multiple insertions into the angles of the ribs and the transverse processes of the lower cervical vertebrae.

How do the vertebral arteries enter the skull?

The paired vertebral arteries ascend, one on each side, through foramina in the transverse processes of cervical vertebrae and pass through the foramen magnum to participate, with the internal carotid arteries, in supplying blood to the brain.

Dens of axis

The posterior surface of the anterior arch has an articular facet for the dens , which projects superiorly from the vertebral body of the axis. The dens is held in position by a strong transverse ligament of atlas posterior to it and spanning the distance between the oval attachment facets on the medial surfaces of the lateral masses of the atlas.

The primary curvatures are ___________ _____________. The secondary curvatures are __________ _____________.

The primary curvatures are concave anteriorly. The secondary curvatures are concave posteriorly.

Medial border of the suboccipital triangle

The rectus capitis posterior major muscle forms the medial border of the triangle.

How can you identify TIII and TVII via palpitations?

The root of the spine of the scapula is at the same level as the spinous process of vertebra TIII, and the inferior angle of the scapula is level with the spinous process of vertebra TVII

How far does the spinal cord extend in adults?

The spinal cord extends from the foramen magnum to approximately the level of the disc between vertebrae LI and LII in adults, although it can end as high as vertebra TXII or as low as the disc between vertebrae LII and LIII

True/false: The spinal cord is uniform in diameter

The spinal cord is not uniform in diameter along its length. It has two major swellings or enlargements in regions associated with the origin of spinal nerves that innervate the upper and lower limbs

How can you identify TXII via palpitations?

The spinous process of vertebra TXII is level with the midpoint of a vertical line between the inferior angle of the scapula and the iliac crest

Splenius capitis

The splenius capitis is a broad muscle attached to the occipital bone and mastoid process of the temporal bone.

Splenius cervicis

The splenius cervicis is a narrow muscle attached to the transverse processes of the upper cervical vertebrae.

How far does the subarachnoid space extend?

The subarachnoid space extends farther inferiorly than the spinal cord. The spinal cord ends at approximately the disc between vertebrae LI and LII, whereas the subarachnoid space extends to approximately the lower border of vertebra SII

Transverse processes of lumbar vertebrae

The transverse processes are generally thin and long, with the exception of those on vertebra LV, which are massive and somewhat cone shaped for the attachment of iliolumbar ligaments to connect the transverse processes to the pelvic bones.

Atlanto-axial joints

The transverse processes of the atlas are large and protrude further laterally than those of the other cervical vertebrae and act as levers for muscle action, particularly for muscles that move the head at the atlanto-axial joints .

What do the two rhomboid muscles do?

The two rhomboid muscles work together to retract or pull the scapula toward the vertebral column. With other muscles they may also rotate the lateral aspect of the scapula inferiorly

What is the vascular supply to this deep group of muscles

The vascular supply to this deep group of muscles is through branches of the vertebral, deep cervical, occipital, transverse cervical, posterior intercostal, subcostal, lumbar, and lateral sacral arteries.

Function of the back: protection of the nervous system

The vertebral column and associated soft tissues of the back contain the spinal cord and proximal parts of the spinal nerves

Vertebral canal

The vertebral foramina of all the vertebrae together form the vertebral canal , which contains and protects the spinal cord. Superiorly, the vertebral canal is continuous, through the foramen magnum of the skull, with the cranial cavity of the head.

CLINICAL: Spinal fusion surgical methods

There are a number of surgical methods in which a fusion can be performed, through either a posterior approach and fusing the posterior elements, an anterior approach by removal of the disc and either disc replacement or anterior fusion, or in some instances a 360° fusion where the posterior elements and the vertebral bodies are fused

Near the point of division into anterior and posterior rami, each spinal nerve gives rise to two to four small recurrent meningeal (sinuvertebral) nerves

These nerves reenter the intervertebral foramen to supply dura, ligaments, intervertebral discs, and blood vessels.

What are the suboccipital muscles?

They include, on each side: ▪ rectus capitis posterior major, ▪ rectus capitis posterior minor, ▪ obliquus capitis inferior, and ▪ obliquus capitis superior

arteria radicularis magna or the artery of Adamkiewicz

This vessel arises in the lower thoracic or upper lumbar region, usually on the left side, and reinforces the arterial supply to the lower portion of the spinal cord, including the lumbar enlargement.

Splenius capitis function

Together—draw head backward, extending neck; individually—draw and rotate head to one side (turn face to same side)

Splenius cervicis function

Together—extend neck; individually—draw and rotate head to one side (turn face to same side)

Sacral region relationship to other regions in the body

Transmits weight to lower limbs through pelvic bones Framework for posterior aspect of pelvis

True/False Because the spinal cord is much shorter than the vertebral column, the roots of spinal nerves become longer and pass more obliquely from the cervical to coccygeal regions of the vertebral canal ( Fig. 2.62 ).

True

True/False: During development, the vertebral column grows much faster than the spinal cord.

True: As a result, the spinal cord does not extend the entire length of the vertebral canal

True/false: all vertebrae have rib elements

True: although all vertebrae have rib elements, these elements are small and are incorporated into the transverse processes in regions other than the thorax; but in the thorax, the ribs are separate bones and articulate via synovial joints with the vertebral bodies and transverse processes of the associated vertebrae.

Iliolumbar ligaments

Unite the transverse processes of L5 to the ilia (pelvic bones)

CLINICAL: Variation in vertebral numbers: thoracic

Variations in the number of thoracic vertebrae also are well described

Lumbar puncture

When carrying out a lumbar puncture (spinal tap), the needle passes between adjacent vertebral spinous processes, through the supraspinous and interspinous ligaments, and enters the extradural space. -The needle continues through the dura and arachnoid mater and enters the subarachnoid space, which contains CSF.

lateral masses

When viewed from above, the atlas is ring shaped and composed of two lateral masses interconnected by an anterior arch and a posterior arch .

Primary and secondary curvatures in the sagittal plane

When viewed from the side, the normal vertebral column has primary curvatures in the thoracic and sacral/coccygeal regions and secondary curvatures in the cervical and lumbar regions

CLINICAL: outlook of osteoporosis

With increasing age and poor-quality bone, patients are more susceptible to fracture. -Healing tends to be impaired in these elderly patients, who consequently require long hospital stays and prolonged rehabilitation.

Lumbar Zygapophysial joint

Wrapped -In lumbar regions, the joint surfaces are curved and adjacent processes interlock, thereby limiting range of movement, through flexion and extension are still major movements in the lumbar region

Posterior ramus

a posterior ramus—collectively, the small posterior rami innervate the back

Anterior spinal artery

a single anterior spinal artery , which originates within the cranial cavity as the union of two vessels that arise from the vertebral arteries—the resulting single anterior spinal artery passes inferiorly, approximately parallel to the anterior median fissure, along the surface of the spinal cord; and

How are spinal nerves named?

according to their position with respect to associated vertebrae: ▪ eight cervical nerves—C1 to C8, ▪ twelve thoracic nerves—T1 to T12, ▪ five lumbar nerves—L1 to L5, ▪ five sacral nerves—S1 to S5, ▪ one coccygeal nerve—Co.

Intervertebral foramina

are formed on each side between adjacent parts of vertebrae and associated intervertebral discs -The foramina allow structures, such as spinal nerves and blood vessels, to pass in and out of the vertebral canal.

The spine, medial border, and inferior angle of the scapula

are often visible and are easily palpable.

The anterior and posterior spinal arteries are reinforced along their length by eight to ten segmental medullary arteries ( Fig. 2.55 ). The largest of these is the

arteria radicularis magna or the artery of Adamkiewicz

atlanto-occipital joint

articulation between the atlas and the cranium -The atlanto-occipital joint allows the head to nod up and down on the vertebral column

The posterior and middle layers of the thoracolumbar fascia come together

at the lateral margin of the erector spinae

Where does the spinal cord typically end on an adult?

between vertebrae LI and LII, although it can end as high as vertebra TXII and as low as the disc between vertebrae LII and LIII.

CLINICAL: Vertebroplasty

is a relatively new technique in which the body of a vertebra can be filled with bone cement (typically methyl methacrylate). -indications include vertebral body collapse and pain from the vertebral body, which may be secondary to tumor infiltration. -most commonly performed for osteoporotic wedge fractures, which are considerable cause of morbidity and pain in older patients

Anterior longitudinal ligament

is attached superiorly to the base of the skull and extends inferiorly to attach to the anterior surface of the sacrum. -Along its length it is attached to the vertebral bodies and intervertebral discs.

CLINICAL: posterior column

is made up of the ligamenta flava, interspinous ligaments, supraspinous ligaments, and the ligamentum nuchae in the cervical vertebral column

Rhomboid minor

is superior to rhomboid major, and is a small, cylindrical muscle that arises from the ligamentum nuchae of the neck and the spinous processes of vertebrae CVII and TI and attaches to the medial scapular border opposite the root of the spine of the scapula.

Spinal dura mater

is the outermost meningeal membrane and is separated from the bones forming the vertebral canal by an extradural space -Superiorly, it is continuous with the inner meningeal layer of cranial dura mater at the foramen magnum of the skull - Inferiorly, the dural sac dramatically narrows at the level of the lower border of vertebra SII and forms an investing sheath for the pial part of the filum terminale of the spinal cord. -This terminal cord-like extension of dura mater (the dural part of the filum terminale) attaches to the posterior surface of the vertebral bodies of the coccyx. -As spinal nerves and their roots pass laterally, they are surrounded by tubular sleeves of dura mater, which merge with and become part of the outer covering (epineurium) of the nerves.

CLINICAL: Herpes zoster

is the virus that produces chickenpox in children. - In some patients the virus remains dormant in the cells of the spinal ganglia. -Under certain circumstances, the virus becomes activated and travels along the neuronal bundles to the areas supplied by that nerve (the dermatome). -A rash ensues, which is characteristically exquisitely painful. Importantly, this typical dermatomal distribution is characteristic of this disorder.

Trapezius

muscle is flat and triangular, with the base of the triangle situated along the vertebral column (the muscle's origin) and the apex pointing toward the tip of the shoulder (the muscle's insertion - The muscles on both sides together form a trapezoid.

The intermediate group consists of

muscles attached to the ribs and may serve a respiratory function.

Rhomboid major

originates from the spinous processes of the upper thoracic vertebrae and attaches to the medial scapular border inferior to rhomboid minor.

foramen transversarium

passageway for the vertebral artery through the cervical vertebrae

Each spinal nerve is connected to the spinal cord by

posterior and anterior roots

Spinous process

projects posteriorly and inferiorly from the junction of the two laminae and is a site for muscle and ligament attachment

Laminae

roof of the vertebral arch ▪ The two laminae are flat sheets of bone that extend from each pedicle to meet in the midline and form the roof of the vertebral arch.

The suboccipital muscles form the boundaries of the

suboccipital triangle , an area that contains several important structures

the extensors and rotators of the vertebral column

the erector spinae and transversospinales, and

CLINICAL: Osteoporotic wedge fractures and vertebroplasty

typically occur in the thoracolumbar region, and the approach to performing vertebroplasty is novel and relatively straightforward -sedation or light general anesthetic -Using X-ray guidance the pedicle is identified on the anteroposterior image. -A metal cannula is placed through the pedicle into the vertebral body. - Liquid bone cement is injected via the cannula into the vertebral body

Pedicles

walls of the vertebral arch ▪ The two pedicles are bony pillars that attach the vertebral arch to the vertebral body

Secondary curvatures

which are concave posteriorly, form in the cervical and lumbar regions and bring the center of gravity into a vertical line, which allows the body's weight to be balanced on the vertebral column in a way that expends the least amount of muscular energy to maintain an upright bipedal stance.

Where is denticulate ligament attached medically and laterally?

▪ Medially, each denticulate ligament is attached to the spinal cord in a plane that lies between the origins of the posterior and anterior rootlets. ▪ Laterally, each denticulate ligament forms a series of triangular extensions along its free border, with the apex of each extension being anchored through the arachnoid mater to the dura mater.

What forms the anterior wall of the vertebral canal?

▪ The anterior wall is formed by the vertebral bodies of the vertebrae, intervertebral discs, and associated ligaments

Gray matter around spinal cord

▪ The gray matter is rich in nerve cell bodies, which form longitudinal columns along the cord, and in cross section these columns form a characteristic H -shaped appearance in the central regions of the cord.

Internally, the cord has a small central canal surrounded by gray and white matter:

▪ The gray matter is rich in nerve cell bodies, which form longitudinal columns along the cord, and in cross section these columns form a characteristic H -shaped appearance in the central regions of the cord. ▪ The white matter surrounds the gray matter and is rich in nerve cell processes, which form large bundles or tracts that ascend and descend in the cord to other spinal cord levels or carry information to and from the brain

What forms the lateral walls and roof of the vertebral canal?

▪ The lateral walls and roof are formed by the vertebral arches and ligaments.

In the lumbar region, the thoracolumbar fascia consists of three layers:

▪ The posterior layer is thick and is attached to the spinous processes of the lumbar vertebrae and sacral vertebrae and to the supraspinous ligament—from these attachments, it extends laterally to cover the erector spinae. ▪ The middle layer is attached medially to the tips of the transverse processes of the lumbar vertebrae and intertransverse ligaments—inferiorly, it is attached to the iliac crest and, superiorly, to the lower border of rib XII. ▪ The anterior layer covers the anterior surface of the quadratus lumborum muscle (a muscle of the posterior abdominal wall) and is attached medially to the transverse processes of the lumbar vertebrae—inferiorly, it is attached to the iliac crest and, superiorly, it forms the lateral arcuate ligament for attachment of the diaphragm.

White matter around spinal cord

▪ The white matter surrounds the gray matter and is rich in nerve cell processes, which form large bundles or tracts that ascend and descend in the cord to other spinal cord levels or carry information to and from the brain.

Veins of the spinal cord

▪ Two pairs of veins on each side bracket the connections of the posterior and anterior roots to the cord. ▪ One midline channel parallels the anterior median fissure. ▪ One midline channel passes along the posterior median sulcus.