Vertebral Column

Thoracic Vertebrae Movement

Movement is limited due to: -Thin discs - Attachment of ribs - Attachment to sternum - Frontal orientation of articular processes - Overlapping of laminae and spinous processes - Flexion and extension is limited (lateral bending and rotation is limited by the ribs and sternum)

Atlantooccipital Joint

- A paired synovial joint - Occurs between the occipital condyle and superior articular facet of the atlas - The posterior atlantooccipital membrane is penetrated by the vertebral artery and suboccipital nerve. - Allows flexion and extension of head - Allows little lateral bending but no rotation

Basic Curvatures of Adult Vertebral Column

- Cervical: Convex Anteriorly - Thoracic: Concave Anteriorly - Lumbar: Convex Anteriorly -Sacrococccygeal: Concave Anteriorly

Non Typical Characteristics of Thoracic Vertebrae (T1-T4) and (T9-T12)

- T1 has a long spinous process similar to that of C7 - T1-T4 resemble cervicals in having a similar shaped body (small and wider from side-toside) and vertebral foramen large and triangular - T9-T12 have tubercles similar to the accessory and mamillary processes of lumbar vertebrae - A demifacet is a partial facet, as compared to an entire facet. See T1 which has a facet on the superior edge to receive the first rib and a demifacet on its inferior edge which contributes to the articular surface for the head of the adjacent, lower rib.

Nucleus Pulposus

--Cartilaginous - Highly elastic - Located posteriorly (not centered) - High water content (decreases with age) - Shock absorbing feature of discs (axial forces)

Scoliosis

-A lateral curvature of the spine in the thoracic, lumbar or thoracolumbar area that is beyond normal. -The curvature is designated right or left according to the convex side of the major curve. -This type of curvature may be nonstructural and reversible (length of lower limbs differ). In contrast, it may be structural and irreversible (idiopathic or fractures/dislocations). -Idiopathic right thoracic scoliosis in adolescent females is the most common form. An individual with such a condition may develop a spinal curve in the neck region to help maintain both eyes in a horizontal plane (compensation)

Uncovertebral Joint (of Luschka)

-Joint-like structures that can develop postnatally in cervical vertebrae between the lips of the bodies of adjacent vertebrae - Osteophyte formation here may cause neck pain

Fractures of Cervical Vertebrae

-On the C2, the dens may fracture as a result of a fall on the head. Displacement of the fractured dens may injure the spinal cord, causing quadriplegia (paralysis of all limbs) or the medulla oblongata causing death. -The Hangman's fracture is a fracture through the pedicles of the axis with or without subluxation (incomplete dislocation) of the axis on C3 and may injure the spinal cord and/or medulla causing quadriplegia or death.

Sacral and Coccygeal Characteristics (S1-S5 and C01-C05)

-The sacrum is formed by a fusion of five vertebrae forming a triangular or wedge-shaped bone. The base articulates with L5 and its apex with the C01. - The posterior surface is convex and has a median sacral crest formed by reduced spinous processes. The sacral groove (over the laminae) gives rise to the multifidus. Four pairs of dorsal sacral foramina are lateral to the median sacral crest and transmit the dorsal rami of S1-S4. - The laminae of the fifth segment often do not fuse, and so produce the sacral hiatus (interior entrance to the vertebral canal and site of anesthetic injections). The articular processes (lateral sacral crest) are produced by the fusion of transverse processes. - The coccyx may be fused in some of its segments (usually four) or the first segment may be separate from the others. The vertebrae are much reduced. The pelvic surface provides an attachment for part of the coccygeus and levator ani muscles. The posterior surface provides an attachment for the gluteus maximus and the external anal sphincter.

Lordosis

-is a curvature that is convex anteriorly. -Normal compensation of the lumbar spine during pregnancy but may develop with obesity in either gender.

Kyphosis

-is a curvature that is convex posteriorly (beyond normal) -In osteoporosis, kyphosis of the thoracic spine may occur after compression fractures of the vertebral bodies.

Characteristics of C2 (axis)

-is the strongest of all cervical vertebrae -The dens, large bifid spinous process, transverse ligament (holds axis in place which prevents horizontal displacement of the atlas), anterior facet that receives the arch of the atlas and is grooved posteriorly for a transverse ligament, and the longus colli muscle attaches to a median ridge on ventral surface of the body

Cartoid Tubercle

-on transverse process of C6 can function as a pressure point to control bleeding from carotid artery.

Transverse Ligament of the Atlas

-prevents the dens from crushing the spinal cord. -In a hanging injury, the cruciform ligament is torn (crushes the spinal cord and death results).

Composition and Structures of Typical Vertebrae

1. Body is weight bearing and anteriorly placed 2. Vertebral arches occur posteriorly and are associated with several processes (spinous, transverse, and articular), which form important structures or foramina - Pedicles, laminae, vertebral foramen, vertebral notches (intervertebral foramen) - A vertebral foramen is large and triangular for accommodation of the upper and largest portion of the spinal cord

Movements of Vertebral Column (general)

1. flexion, extension, lateral bending, and rotation 2.Mobility arises primarily from compressibility and elasticity of the intervertebral discs 3. Amount of movement depends upon the ratio between the height of the discs and the vertebral bodies 4 Articular capsule joint acts in checking the action of ligaments and muscle, and contributes to the wide range of motion 5. The planes of articulation of the articular process vary with each region, which allows for different degrees of lateral flexion and rotation.

Osteoarthritis/rheumatoid arthritis, and injury to facet joints can cause what?

Diseases (osteoarthritis or rheumatoid arthritis) and injury to facet joints can impinge on an adjacent spinal nerve causing severe pain because of their proximity to the IV foramen.

Dislocations of Cervical Vertebrae

Dislocations are associated with less force than is required to fracture them (due to the size of the vertebral canal, slight dislocation can occur without damaging the spinal cord). The vertebra may self-reduce (slip into proper place) so that a radiograph or MRI may not indicate that the cord has been injured.

Cervical Vertebrae Movement

In the cervical region, discs are thick and articular processes are horizontally oriented allowing flexion, extension, lateral bending, and rotation.

Lumbar Vertebrae Movement

In the lumbar region, the thickness of the discs and the sagittally-oriented articular processes permit considerable flexion and extension. The articular facets are loosely bound allowing rotation, but this movement is limited by their orientation.

Typical Characteristics of Thoracic Vertebrae (T5-T8)

Lack transverse foramina and have heart-shaped bodies, which increase in size from T1 to T12. The vertebral foramina are smaller and circular compared to cervical or lumbar 4 vertebrae. They have two costal (rib) facets (except T10, T11, T12) at the junction of the body and arch (a characteristic feature). The laminae are broad and overlap one another. Spinous processes of the middle four are nearly vertical, whereas in T1-T2 and T10-T12 the processes are nearly horizontal. Transverse processes are thick and strong and have a concave facet for articulation with the tubercle of a corresponding rib. - The plane of articulation for the articular process is frontal, which favors lateral bending and rotation of the column. The T1 possesses resembles the C7. The T12 resembles L1. The bodies of thoracic vertebrae are closely related to the thoracic aorta and may possess an impression on the left side.

Annulus Fibrosus

Outer fibrous part (of discs) - Concentric lamillae of fibrocartilage - Fibers run oblique from vertebrae to vertebrae and are at right angles to each lamellae - Allows movement between adjacent vertebrae (creates strong bond between them) - Firmly attached to anterior and posterior longitudinal ligaments

Intervertebral Discs

Semifluid ball bearing which allows flexion, extension, and rotation 5 - Permits little movement between individual discs (cumulatively allows considerable flexibility of vertebral column) - No disc between C1 and C2 - 2 major components: Annulus Fibrosus and Nucleus Pulposus

Zygapophyseal Joints (Facet Joints)

Synovial joints between superior and inferior articular facets of adjacent vertebrae provide varying amounts of flexion, extension, rotation, or lateral bending based on vertebral level (different planes of articulation at each level)

Adult Vertebral Column

The adult vertebral column is composed of 33 or more vertebrae arranged in five regions. - 7 cervical (C1-C7) - 12 thoracic (T1-T12) - 5 lumbar (L1-L5) - 5 sacral (S1-S5) (fused) - 3-5 coccygeal (CO1- CO5)

Lumbar Characteristics

The kidney-shaped bodies are the largest and most massive to support the increase in body weight in this region - Inferior vertebral notches deep - Vertebral foramina triangular - Spinous processes thick, broad, and hatchet-shaped - Articular processes project upward and downward, lying in the sagittal plane; facilitates flexion and extension and side-to-side bending but not rotation. - Transverse processes long and slender - Mammillary process smoothly rounded projection at back of each superior articular process (origin of multifidus muscle) - Accessory process at the back of the root of the transverse process (insertion of the longissimus muscle)

Whiplash

a forceful hyperextension of the cervical spine that stretches the anterior longitudinal ligament. Rear-end collisions cause whiplash. Symptoms include rapid onset of neck pain, headache, and pain and numbness radiating into the upper extremities.

Ligamentum Flavum

a paired structure that connects the laminae of adjacent vertebrae limits flexion and the elastic tissue provides the yellow color. The spinal cord may be injured after transient inward bulging of the ligamentum flavum during sudden forced hyperextension. A radiograph may not indicate vertebral damage.

Nuchal Ligament

also prevents excessive flexion.

Cervical Vertebrae Characteristics

are distinguished by their small size and a transverse process which is perforated by a transverse foramen for the passage of several structures (vertebral artery and vein). - The spinous processes are typically short, but those of the sixth and seventh are much longer; the third through the sixth are usually bifid; and there is no spinous process on the first. The vertebral artery usually enters the transverse foramen of C6 (NOT C7). The bodies of cervical vertebrae possess lateral lips on the upper anterior surface, which articulate with the vertebral body above.

Anterior Longitudinal Ligament

attaches to the anterior surface of each vertebral body and IV disc, limits extension (prevents hyperextension), supports annulus fibrosus and may be strained or torn in a whiplash; strong fibrous band (extends from the occipital bone to the pelvic surface of the sacrum)

Posterior Longitudinal Ligament

attaches to the posterior surface of the vertebral bodies and IV discs, lies within vertebral canal, limits flexion (prevents hyperflexion and herniation of IV discs), supports annulus fibrosus and directs herniation of IV disc posterolaterally, weaker than anterior longitudinal ligament, extends from posterior edge of centrum of C2 and continues to the sacrum, and has many nociceptive (pain) nerve endings present.

Intraspinous Ligament

connects spinous processes of adjacent vertebrae and limits flexion

Supraspinous Ligament

connects the tips of the spinous processes, limits flexion, and expanded in cervical region as the ligamentum nuchae

Characteristics of C1 (Atlas)

differs from most other cervical vertebrae in that it lacks a true body and spinous process. Anterior and posterior arches occur along with two lateral masses (= tubercle for transverse ligament, superior articular surface), transverse process with foramen are present as well. Lateral masses are bulky and support the skull and articulate below with the axis. - Anterior arch is smooth and has an oval concavity which receives the dens

Subluxation (atlantoaxial dislocation)

may injure the spinal cord and medulla. Subluxation can occur after a rupture of the cruciform ligament caused by trauma or rheumatoid arthritis, or can result from a congenital absence of the dens or failure of the dens to fuse with the body of the axis. -may be associated with Down syndrome.

Atlantoaxial Joint

onsists of three articulations: 1-2) paired lateral atlantoaxial joints (between inferior facet and lateral mass of C1 and superior facet of C2) 3) median between the dens of C2 and the anterior arch of the atlas - held in place by the transverse ligament (of atlas) - Allows rotation of head