Required Readings Notes

spinalis group

the most medially placed of the erector spinae muscles, attaches to the spinous process of the vertebrae (hence name of the muscle group). The spinalis group is composed of cervical and thoracic parts

latissimus dorsi

broad, triangular muscle located on the infe- rior part of the back. Often, it is referred to as the "swimmer's muscle," because many of its actions are required for certain swimming strokes. It is the prime arm extensor, and also adducts and medially rotates the arm.

coccygeus

pulls the coccyx anteriorly after its posterior deflection during defecation or childbirth.

urogenital triangle

contains the external genitalia and urethra

pia mater

deep to the subarachnoid space, is a delicate, innermost meningeal layer composed of elastic and collagen fibers. This meninx directly adheres to the spinal cord and supports some of the blood vessels supplying the spinal cord

perineum

diamond-shaped region between the lower appendages The perineum has four sig- nificant bony landmarks: the pubic symphysis anteriorly, the coccyx posteriorly, and both ischial tuberosities laterally

gray matter

domi- nated by dendrites, neuron cell bodies, glial cells, and unmyelinated axons centrally located, and its shape resembles a letter H or a butterfly. The gray matter may be subdivided into the following components: anterior horns, lateral horns, posterior horns, and the gray commissure

8. Scalene muscles

help elevate the 1st and 2nd ribs during forced inhalation, thereby increasing the dimensions of the thoracic cavity

5. Cauda Equina

inferior to the conus medullaris; is a group of axons that project inferiorly from the spinal cord (resemble horse tail; cauda = tail, equus = horse)

gray commissure

is a horizontal bar of gray matter that surrounds a narrow central canal The gray commissure primar- ily contains unmyelinated axons and serves as a communication route between the right and left sides of the gray matter.

Anterior horns

left and right anterior masses of gray matter. The anterior horns primarily house the cell bodies of somatic motor neurons, which innervate skeletal muscle The anterior horns contain the somatic motor neurons, just as the anterior part of a car houses the motor.

Rhomboid minor + Rhomboid major

. Located deep to the trapezius o 2. Parallel bands run inferolaterally from the vertebrae to the scapula o 3. Help elevate and retract (adduct) the scapula, "stand straight with your shoulders back", also inferiorly rotate the scapula

most superior (deepest) layer of the pelvic diaphram

con- sists of the coccygeus and the levator ani.

white matter

composed primarily of myelinated axons.

Clinical View: Hernias

condition in which a portion of the viscera protrudes through a weakened point of the muscular wall of the abdomi- nopelvic cavity is called a hernia (her ́nē-ă; rupture). A sig- nificant medical problem may develop if the herniated portion of the intestine swells, becoming trapped. Blood flow to the trapped segment may diminish, causing that portion of the intestine to die. This condition, called a strangulated intestinal hernia, is very painful and can be life-threatening if not treated promptly.

11. Transversus thoracis

extends across the inner surface of the thoracic cage and attaches to ribs 2-6. It helps depress the ribs

lumbosacral enlargement

extends through the lumbar and sacral parts of the spinal cord and innervates the lower limbs.

4. Conus medullaris

the tapering inferior end of the spinal cord a. Marks the end of the official end of the spinal cord proper (usually at the level of the first lumbar vertebra)

quadratus lumborum

10. The quadratus lumborum extends the vertebral column when the muscles bilaterally contract (when the left and right move at the same time); they are located primarily on the lumbar region, when either the left or right quadratus lumborum muscle unilaterally contacts, it laterally flexes the vertebral column

transversus abdominis

4. Deepest muscle is the transversus abdominis a. Fibers project transversely across the abdomen

intervertebral foramina

4. Lateral openings between adjacent vertebrae are the intervertebral foramina • Intervertebral foramina provide a horizontally directed passageway through which spinal nerves travel to other parts of the body

each side of the spinal cord contains

8 cervical nerves (called C1-C8), 12 thoracic nerves (T1-T12), 5 lumbar nerves (L1-L5), 5 sacral nerves (S1-S5), and 1 coccygeal nerve (Co1). Spinal nerve names can be distinguished from cranial nerve names (discussed in section 15.8) because cranial nerves are designated by CN followed by a Roman numeral.

Multifidus

9. The deep multifidus connects vertebrae to each other from the cervical to the lumbar region

subarachnoid space

Deep to the arachnoid mater is the subarachnoid space, which is a real space filled with cerebrospinal fluid (CSF)

Subclavius

Names for its location, inferior to the clavicle o 2. Extends from the first rib to the clavicle o Main action is to stabilize and depress the clavicle

Anterior thoracic muscles

Pectoralis minor, serratus anterior, and subclavius

biceps brachii and triceps brachii also cross the glenohumeral joint

Specifically, the long head of the biceps brachii attaches proximally to the supraglenoid tubercle of the scap- ula and distally attaches to the radial tuberosity. This portion of the muscle assists in flexing the arm. The long head of the triceps brachii attaches to the infraglenoid tubercle of the scapula proximally, and distally to the olecranon of the ulna. This part of the muscle helps extend and adduct the arm.

Which rotator cuff muscle tends to suffer the most injuries, and why?

Supraspinatus, smaller but still has to use a lot of force

4. Sacrum (S1-S5)

• Fuses into a single bony structure by the mid to late 20's • The sacrum articulates with L5 superiorly and with the first coccygeal vertebra inferiorly • The sacrum articulates laterally with the two ossa coxae (hip bones)

pedicles

• The pedicles originate from the posterolateral margins of the body

Muscles that Move the Pectoral Girdle

The muscles of the pectoral girdle attach the axial skeleton to the scapula and clavicle, they stabilize the scapula and move it to increase the arm's angle of movements Some superficial muscles of the thorax are grouped together based on the type of scapular movement they direct o Elevation o Depression o Retraction o Protraction Muscles that move the pectoral girdle are either anterior or posterior thoracic muscles based on their location to the thorax

spinal cord

31 pairs of spinal nerves that connect the CNS to receptors and effectors (muscles and glands). Spinal nerves are considered mixed nerves because they contain both motor and sensory axons.

Clinical View

Lumbar Puncture (Spinal Tap)

Clinical view: hiatal hernia + Umbilical hernia

Hiatal hernia: Condition in which part of the stomach protrudes through the diaphragm into the thoracic cavity, most common obese individuals over age 40, may cause heartburn due to regurgitation of stomach acid into esophagus, but most cases goo undetected Umbilical hernia, abdominal viscera protrudes through the naval

teres major

Works synergistically with the latissimus dorsi by extending, adducting, and medially rotating the arm

floor of the pelvic cavity

formed by three layers of muscles and associated fasciae, collectively known as the pelvic diaphragm The pelvic diaphragm extends from the ischium and pubis of the ossa coxae across the pelvic outlet to the sacrum and coccyx. These muscles collectively form the pelvic floor and support the pelvic viscera

levator ani

largest and most important collection of muscles in the pelvic floor supports the pelvic viscera and functions as a sphincter at the ano- rectal junction, urethra, and vagina. The levator ani is formed by the iliococcygeus, the pubococcygeus, and the puborectalis (not shown)

epidural (ep′i-dū′răl) space

lies between the dura mater and the periosteum covering the inner walls of the vertebra, and houses areolar connective tissue, blood vessels, and adipose connec- tive tissue. Epidural anesthesia is administered into this space.

encircle the spinal cord

listed from outermost to innermost, are as follows: vertebra, epidural space, dura mater, subdural space, arachnoid mater, subarachnoid space, and pia mater

cervical enlargement of spinal cord

located in the inferior cervical part of the spinal cord, contains the neurons that innervate the upper limbs.

external anal sphincter

located within a region called the anal triangle) assists in defecation

6. Filum terminale

within the cauda equina; it is a thin strand of pia mater that helps anchor the conus medullaris at the coccyx 7. Viewed in cross section, the spinal cord is roughly cylindrical, but slightly flattened both posteriorly and anteriorly

4. Lordosis

- An exaggerated lumbar curvature, often called "sway back," that is noted as a protrusion of the abdomen and buttocks - May have the same causes as kyphosis, or it may result from the added abdominal weight associated with pregnancy or obesity

1. Distortion of normal spinal curvature causes:

- Poor posture, congenital defects in the structure of the vertebrae, or weakness or paralysis of muscles in the trunk

true ribs

3. Ribs 1-7 are called true ribs a. At the anterior body wall, the true ribs articulate individually to the sternum by separate cartilaginous extensions called costal cartilages b. The smallest true rib is the first

2. The spinal chord is divided into 5 parts

a. Cervical part- the superiormost region of the spinal cord; continuous with the medulla oblongata; cervical part contains motor neurons whose axons contribute to the cervical spinal nerves, the motor neurons receive input from sensory neurons through the spinal nerve fibers b. Thoracic part- inferior to the cervical part, contains the neurons for the thoracic spinal nerves c. Lumbar part- is a shorter segment of the spinal cord that contains the neurons for the lumbar spinal nerves d. Sacral part- lies inferior to the lumbar part and contains the neurons for the sacral spinal nerves e. Coccygeal part- the most inferior tip of the spinal cord 3. The different parts of the spinal chord do not line up to the different parts of the vertebra of the same name a. The reason is that the growth of the vertebra continues longer than the growth of the spinal chord itself b. Thus, the spinal in an adult is shorter than the vertebral canal that houses it c. Ex: the lumbar part of the spinal cord is closer to the inferior thoracic vertebrae than to the lumbar vertebrae

8. The external surface of the of the spinal cord has two longitudinal depressions

a. Posterior (dorsal) median sulcus- narrow grove, that dips internally on the posterior surface, b. Anterior median fissure (ventral) slightly wider groove, on the anterior surface

Denticulate ligaments

are paired, lateral triangular extensions of the spinal pia mater that attach to the dura mater (figure 16.2a). These ligaments help suspend and anchor the spinal cord laterally to the dura mater

1. Adult vertebral: from lateral perspective, the adult vertebral column has 4 spinal curvatures

cervical curvature, thoracic, lumbar, sacral

inferior articular processes

• The inferior articular processes of each vertebra articulate with the superior articular processes of the vertebra immediately inferior to it

Clinical View- Paralysis of the Serratus Anterior Muscle

The serratus anterior muscle recieves innervation from the long thoracic nerve- which travels inferiorly from the anterolateral chest wall Location of thoracic nerve makes it possible to be cut during surgical removal of the breast (radical mastectomy) Damage of the thoracic nerve causes paralysis of the serratus anterior muscle Serratus anterior is the primary protractor of the scapula o Its pull on the scapula is counterbalanced by the posterior thoracic muscles Paralysis of the serratus anterior muscle leaves the posterior thoracic muscles unopposed Pt with condition pus both arms anteriorly on a wall and then pushes, the scapula on the injured side will poke posterior like a bird's wing —>winged scapula Scapula on unaffected side will remain in the expected anatomical position close to the thoracic wall

Spinal cord and attached spinal nerves serve two functions

They are a pathway for sensory and motor impulses Spinal cord and spinal nerve are responsible for reflexes, which are our quickest reactions to a stimulus 1. The spinal chord extends inferiorly from the medulla oblongata through the foramen magnum and the vertebral canal, ending at the inferior border of the L1 vertebra

body of vertebra

1. Anterior region of each vertebra is a rounded of cylindrical body, also called the centrum • Is the weight-bearing structure of almost all vertebra

Clinical Considerations

1. Muscle injuries can be caused a. Direct- trauma b. Indirect- interruption of blood or nerve supply 2. Diminished or absence of muscle function(s) range a. Muscle weakness (mild damage) b. Loss of muscle function (Extreme) 3. Clinical Signs of muscle damage a. Atrophy (decreased muscle mass) b. Deformity (changed muscle shape) c. Changes in body contour

Vertebra Prominens (C7)

1. The 7th cervical vertebra represents a transition to the thoracic vertebral region and has some features of thoracic vertebrae 2. The spinous process of C7 is typically not bifurcated, and it is much longer and bigger than the spinous processes of the other cervical vertebrae a. This large spinous process is easily palpated through the skin, sometimes appears as a slight protrusion between the shoulder blades and inferior to the neck 3. C7 is called the vertebra prominens a. If you drop your head forward (place your chin to your chest) and run your fingers down the back of your neck, it is the first bony lump you feel

internal oblique

2. Immediately deep to the external oblique is the internal oblique a. Muscle fibers project superomedially (at right angles to external oblique) b. Forms an aponeurosis as it projects anteriorly 3. Together the external and the opposite sides internal oblique work together to rotate the vertebral column

dura mater

Deep to the epidural space is the outermost of the meninges spinal dura mater consists of a single meningeal layer, which differs from cranial dura mater's two layers. The dura mater provides stability to the spinal cord. In addition, at each interver- tebral foramen, the dura mater extends between adjacent vertebrae and fuses with the connective tissue layers that surround the spinal nerves.

Muscles of the Abdominal Wall

External oblique, internal oblique, rectus abdominis, transversus adominis - They compress and hold the abdominal organs in place, work together to flex and stabilize the vertebral column, when they unilaterally contract they flex the vertebral column

When studying appendicular muscle function, remember these two basic rules:

If a muscle crosses over or spans a joint, it must move that joint. For example, because the biceps brachii crosses over the elbow joint, it must move the elbow joint. 2. Conversely, if a muscle doesn't cross over or span a joint, it cannot move that joint. For example, the deltoid is found in the shoulder, and it does not cross over the wrist joint. Therefore, there is no possible way the deltoid can move the wrist joint! If you can visualize where a muscle is located in your body, you can usually figure out what type of movement the muscle performs.

Clinical View Lumbar Puncture (Spinal Tap)

It is sometimes necessary to analyze the cerebrospinal fluid (CSF) to determine whether an infection or a disorder of the central ner- vous system is present. The clinical procedure for obtaining CSF is known as a lumbar puncture (commonly referred to as a spinal tap). The needle must be inserted through the skin, back muscles, and ligamentum flavum (between vertebrae). Then the needle must pass through the epidural space, dura mater, arachnoid mater, and enter the subarachnoid space to obtain about 3 to 9 milliliters of CSF. Because the adult spinal cord typically ends at the level of the L1 vertebra, a lumbar puncture must be performed inferior to this level to ensure the spinal cord is not pierced by the needle. A lumbar puncture typically is made at the level of either the L3 and L4 vertebrae or the L4 and L5 vertebrae. To locate this level, the physician palpates the highest points of the iliac crests, which are at the same horizontal level as the spinous process of the L4 vertebra. The physician can then insert the lumbar puncture needle either directly above or directly below the spinous process of L4 when the vertebral column is flexed.

Posterior horns

are the left and right posterior masses of gray matter. The axons of sensory neurons and the cell bodies of interneurons are located in the poste- rior horns. (The cell bodies of these sensory neurons are not found in the posterior horns; rather, they are located in the posterior root ganglia

puborectalis (not shown in figures

The puborectalis muscle forms a circular "sling" around the anorectal junction. When this muscle is contracted, it increases the bend or angle of the anorectal junction. When an individual wishes to defecate, the puborectalis muscle must be consciously re- laxed to decrease the bend of the anorectal junction and allow for the easy passage of feces through the rectum.

scapular muscles

The seven remaining muscles that move the humerus at the gle- nohumeral joint are termed the scapular muscles, because their proxi- mal attachment is entirely on the scapula. These muscles include the deltoid, coracobrachialis, teres major, and the four rotator cuff muscles.

Posterior thoracic muscles

Trapezius (superior part), levator scapulae, rhomboid minor, and rhomboid major

3. Secondary Curves (concave)

are the cervical and lumbar curvatures and appear after birth; these curves arch anteriorly and are also known as compensation curves b/c they help shift the trunk weight over the legs • The cervical curvature appears around 3-4 months of age, when the child is first able to hold up his head

Clinical View Episiotomy

is a surgical incision made in the perineal skin and soft tissues between the vagina and the anus during childbirth to prevent tearing of the mother's tissues and to minimize fetal injury. It was long believed that a clean surgical incision heals more rapidly and effectively than a laceration or tear, but its routine use came into question in the late twentieth century. Studies have indicated that serious perineal lacerations, infection, and bleeding are more common in women who have had an episiotomy, and its benefits are seen in only limited deliveries. Now, many obstetricians and gynecologists have recommended against routine use of episiotomy. Women approaching childbirth are advised to talk in advance with their health-care provider about the necessity of having an episiotomy.

Lateral horns

occur in the T1-L2 parts of the spinal cord only. The lateral horns contain the cell bodies of autonomic motor neurons, which innervate cardiac muscle, smooth muscle, and glands

Clinical View femoral hernia

occurs in the upper thigh, just inferior to the inguinal ligament, originating in a region called the femoral triangle. The medial part of the femoral triangle is relatively weak and prone to stress injury, thus allowing a loop of small intestine to protrude. Women more commonly develop femoral hernias because of the greater width of their femoral triangle, which equates to the wider hip span of the female anatomy.

The deep layer of the urogenital triangle is composed of two muscles

the deep transverse perineal and the external urethral sphincter. These mus- cles are collectively referred to as the urogenital diaphragm, because they serve as a partition for the urogenital portion of the pelvic floor

Clinical View inguinal hernia

the most common type of hernia. The inguinal region is one of the weakest areas of the abdominal wall. Within this region is a canal (inguinal canal) that allows the passage of the spermatic cord in males (see section 28.3b), and a smaller structure called the round ligament in females (see section 28.2c). The inguinal canal, or the superficial inguinal ring associated with it, is often the site of a rupture or separation of the abdominal wall. Males are more likely to develop inguinal hernias than females, because their inguinal canals and superfi- cial inguinal rings are larger to allow room for the spermatic cord. Rising pressure in the abdominopelvic cavity, as might develop while straining to lift a heavy object, provides the force to push a o common types of hernias are inguinal hernias and femo- ral hernias. An inguinal hernia is the most common type of hernia. The inguinal region is one of the weakest areas of the abdominal wall. Within this region is a canal (inguinal canal) that allows the passage of the spermatic cord in males (see section 28.3b), and a smaller structure called the round ligament in females (see section 28.2c). The inguinal canal, or the superficial inguinal ring associated with it, is often the site of a rupture or separation of the abdominal wall. Males are more likely to develop inguinal hernias than females, because their inguinal canals and superfi- cial inguinal rings are larger to allow room for the spermatic cord. Rising pressure in the abdominopelvic cavity, as might develop while straining to lift a heavy object, provides the force to push a ■ In a direct inguinal hernia, the loop of small intestine protrudes directly through the superficial inguinal ring, but not through the entire length of the inguinal canal, and creates a bulge in the lower anterior abdominal wall. This type of hernia is typically seen in middle-aged males with poorly developed abdominal muscles and protruding abdomens. ■ In an indirect inguinal hernia, the herniation travels through the entire inguinal canal and may even extend all the way into the scrotum, because the path of the herniation follows the path of the spermatic cord. This type of hernia tends to occur in younger males or male children who have a congenital anomaly called patent process vaginalis, in which the embryonic path taken by the testis into the scrotum fails to regress.

subdural space

separates the dura mater from the arachnoid mater. This space is found only in tissue preparations, and in life it is merely a potential space.

urogenital triangle is subdivided into a superficial layer and a deep layer

superficial layer of the urogenital triangle is composed of three muscles: bulbospongiosus, ischiocavernosus, and superficial transverse perineal The ischiocavernosus attaches to the pubic symphysis, whereas the bulbospongiosus and superficial transverse perineal muscles attach to a tendinous central structure called the perineal body

anal triangle

that contains the anus

Urogenital triangle and anal triangle

transverse line drawn between the ischial tuberosities partitions the perineum into an anterior urogenital triangle that contains the external genitalia and urethra, and a posterior anal triangle that contains the anus

3. Lumbar vertebrae (L1-L5)

• Form the inferior concave region of the back • L5 articulates inferiorly with the sacrum

3. Kyphosis

- An exaggerated thoracic curvature that is directed posteriorly, producing a "hunchback" look - Often results from osteoporosis, but can also occur if individual experiences i. A vertebral compression fracture that affects the anterior region of the vertebral column, osteomalacia (a disease in which adult bones become demineralized), heavy weight lifting during adolescence, abnormal vertebral growth, or chronic contractions in muscles that insert on the vertebrae

Appendicular Muscles

- Control the movements of the upper and lower limbs, and stabilize and control the movements of the pectoral and pelvic girdles 1. Muscles are organized into groups based on part of the skeleton they move or where there are located in the body 2. For Appendicular Muscles a. origin —> proximal attachment b. Insertion —> distal attachment (usually more moveable attachment of the muscle)

5. Scoliosis

- Is the most common spinal curvature deformity - An abnormal lateral curvature that sometimes results during development when both the vertebral arch and body fail to form, or form incompletely, on one side of the vertebra - Can also be caused by unilateral muscular paralysis, or spasm, in the back - Mild causes can be treated in adolescence by wearing a back brace, whereas most severe cases may require surgical intervention

Trapezius

. Generally it can elevate, depress, retract, or rotate the scapula, depending on which fibers of the muscle are actively contracting o 2. The superior fibers of the Trapezius elevate and superiorly rotate the scapula o 3. The Middle fibers + rhomboid muscles work to retract the scapula o 4. The inferior fibers depress the scapula

Thoracic Vertebrae

1. 12 thoracic vertebra, T1-T12 2. Each vertebra articulates with the ribs 3. Lack the mobility of the other vertebrae due to their stabilizing articulation with the ribs 4. Also lack the transverse foramina and bifid spinous processes of the cervical vertebrae 5. Own distinct features: has a heart-shaped body that is larger and more massive than the body of a cervical vertebra 6. It's spinous process is pointed and long; in some thoracic vertebrae, it angles sharply in an inferior direction 7. *Thoracic vertebrae are distinguished from all other types of vertebral by the presence of costal facets or costal demifacets on the lateral side of the body and on the sides of the transverse process* 8. A costal facet is a circular depression that articulates with the entire head or tubercle of the rib, and a costal demifacet is a semicircular depression that articulates with either the superior or inferior edge of the head of the rib 9. The head of the rib articulates with the costal facet on the body of the thoracic vertebra 10. The tubercle of the rib articulates with the costal facets on the transverse processes of the vertebra 11. The thoracic vertebrae vary slightly in terms of their transverse costal facets a. T1-T10 have transverse costal facets on their transverse processes; T11 and T12 lack these transverse costal facets b/c the 11th and 12th ribs do not have tubercles (and thus do not articulate with the transverse processes) 12. The costal facets on the bodies of the thoracic vertebrae also display variations a. The body of the vertebra T1 bears a full costal facet for the first rib and a demifacet for the second rib b. The bodies of vertebrae T2-T8 have two demifacets each; one on the superior edge of the body, and the other on the inferior edge of the body c. The body of vertebra T9 has only a superior demifacet for the articulation with the ninth rib d. The bodies of vertebrae T10-T12 has a single whole facet to articulate with their respective ribs

Coccyx

1. 4 small coccygeal vertebrae fuse to form the coccyx 2. The individual vertebrae begin to fuse by about age 25 3. The coccyx is an attachment site for several ligaments and some muscles 4. The first and second coccygeal vertebrae have unfused vertebra arches and transverse processes 5. The prominent laminae of the 1st coccygeal vertebrae are known as the coccygeal cornua, which curve to meet the sacral cornua 6. Fusion of the coccygeal vertebrae is not complete until adulthood 7. In males the coccyx tends to project anteriorly, but in females it tends to project more inferiorly, so as not to obstruct the birth canal 8. In very old individuals, the coccyx may fuse with the sacrum

Cervical Vertebrae

1. C1-C7 are the most superiorly placed vertebra 2. They extend inferiorly from the occipital bone of the skull through the neck to the thorax 3. Support only the weight of the head so their vertebral bodies are relatively small and light 4. The body of cervical vertebra C3-C6 is small compared to its foramen 5. The superior surface of a cervical vertebral body is concave from side to side, it exhibits a superior slope from the posterior edge to the anterior edge 6. The spinous process is short, usually less than the diameter of the vertebral foramen 7. The tip of each process, other than C7, is usually bifurcated (bindi), emanating that the posterior end of the spinous process appears to be split in two 8. The transverse process of the first six (and sometimes the seventh) cervical vertebrae are unique in that they contain prominent, round transverse foramina, which provide a protective bony passageway for the vertebral arteries and veins supplying the brain 9. Head is a large structure that is carefully balanced on the cervical vertebrae; small muscles keep the head stable a. If the body changes positions suddenly (fall, car crash) the "balancing" muscles cannot stabilize the head - a cervical dislocation called "whiplash" may result - characterized by injury to muscles and ligaments and potential injury to the spinal chord

Axis (C2)

1. During development, the body of the atlas fuses to the body of the second vertebra, called the axis a. Fusion produces the prominent dens, or odontoid process b. The dens rests on the articular facet for dens of the atlas, where it is held in place by a transverse ligament c. The dens acts as a pivot for the rotation of both the atlas and the skull d. The articulation between the atlas and axis, called the atlantoaxial joint, permits us to shake our heads "no" 2. B/c both the dens and the spinal chord occupy the vertebral foramen at the level of the axis, any trauma that dislocates the dens often results in severe injury a. Ex: an impact to the head or severe shaking of a child can dislocate the dens and cause severe damage to the spinal chord b. In adults, a severe blow at or near the base of the skull is often equally dangerous b/c dislocation of the atlantoaxial joint can force the dens into the base of the brain, with fatal results

Sternal Foramen

1. In 4-10% of all adults, a midline sternal foramen is present in the body of the sternum 2. The sternal foramen represents an ossification anomaly- failure of the left and right ossification centers of the sternal body to fuse completely a. This opening may be misidentified as a bullet wound 3. The location of the sternal foramen is typically used as an acupuncture point a. In rare instances individuals with previously undetected sternal foramina have died after an acupuncture session, when the acupuncture needle was unwittingly inserted through the sternal foramen into the heart

Muscle Attachments

1. In order to move muscles extend over a joint and have attachments to both articulating bones of that joint (red circle) a. Ex: using the muscle bicep briachi spanning a joint we call the elbow joint; contraction of the bicep briachi muscles will lead to the movement of the muscle of the limbs from its attachment we call the insertion towards its origin; the resulting movement of the contraction of the bicep briachi muscle when this shortens up is the flection of the fore arm 2. Upon contraction of the muscle, one of the articulating bones moves and the other one doesn't 3. The point of attachment to the bone that does not move is called the origin (Superior attachment) 4. The point of attachment to the bone that does move is called the insertion (inferior attachment)

Clinical view: Paralysis of the Diaphragm

1. Injury to parts of brain, spinal chord, or phrenic nerves- can cause loss of diaphragmatic innervation and cause paralysis 2. Paralyzed diaphragm leads to it not being able to contract—- which causes no air to be exchanged in the lungs—- leads to death unless have artificial breathing 3. Most common cause of diaphragm paralysis today occurs with injury at or above 4th cervical vertebra. In the 4th cervical vertebra is where there is motor neurons that inner age the diaphragm. 4. Long time ago, diaphragm paralysis was caused by poliovirus, a viral infection that destroyed the motor neurons in the brain and spinal chord 5. Before the modern ventilator was invented people infected with the poliovirus and suffering from diaphragm paralysis where placed in the iron lung —> chamber where air pressure was clinically depressed to facilitate inhalation and it was clinically then increased to facilitate exhalation, only a persons head was extending

Lumbar Vertebrae

1. Largest vertebrae and bear the most weight of the body 2. Typical lumbar vertebra body is thicker than those of all the other vertebrae, and its superior and inferior surfaces are oval or round, rather than heart shaped 3. Lumbar vertebra are distinguished by the features they lack a. Has neither transverse foramina nor costal facets b. Transverse processes are thin and projected dorsolaterally c. The spinous processes are thick and project posteriorly, unlike the thoracic vertebrae spinous processes, which are long, slender, and point posteroinferiorly

Muscles of the Vertebra Column

1. Muscles of the vertebral column are very detailed and complex; they can have multiple attachment sites, they have extensive overlap a. The most superficial back muscles cover all of the muscles of the vertebral column b. The most superficial back muscles move the upper limb, including the trapezius and the latissimus dorsi

Herniated Disc

1. Occurs when the gelatinous nucleus pulposus protrudes into or through the anulus fibrosus 2. This herniation produces a "bulging" of the disc posterolaterally into the vertebral canal and pinches the spinal cord and/or nerves of the spinal cord 3. Cervical and lumbar intervertebral discs are the most common discs to be injured, b/c the vertebral column has a great deal of mobility in these regions, and the lumbar region bears increased weight 4. Cervical herniated discs can cause neck pain and pain down the upper limb, as the nerves that supply the upper limb originate in this region of the spinal cord; muscle weakness in the upper limb may also occur 5. Lumbar herniated discs frequently cause low back pain; if disc starts to pinch nerve fibers, the pt may feel pain down the entire lower limb, condition known as sciatica 6. Treatment options for herniated disc: "wait-and-see" if the disc heals on its own, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, steroid drugs, and PT a. If conservative treatments fail and the pt is still in pain, surgical treatments - microdiscectomy, a microsurgical technique where the herniated portion of the disc is removed b. Or discectomy, more invase technique in which the laminae of the nearby vertebrae and the back muscles are incised before removing the herniated portions of the disc c. Also, artificial discs made of synthetic material have been developed to replace herniated discs

external oblique

1. On the anterior surface the external oblique has an aponeurosis (a sheet of pearly-white fibrous tissue that takes that place of a tendon in sheetlike muscles having a wide area of attachment ) a. The aponeurosis inferiorly of the external oblique forms a strong, cordlike inguinal ligament that extends from the anterior superior iliac spine to the pubic tubercle b. Muscle fibers project inferomedially

Ribs

1. Ribs are elongated, curved, flat bones that articulate (connect) with the thoracic vertebrae and end in the anterior wall of the thorax 2. Both males and females have the same number of ribs-12 pairs

Sacrum

1. Sacrum is anteriorly curved, somewhat triangular bone that forms the posterior wall of the pelvic cavity 2. Apex of the sacrum is a narrow, pointed portion of the bone that projects inferiorly, whereas the bone's broad superior surface forms its base 3. The lateral sacral curvature is more pronounced in males than in females 4. Sacrum is composed of 5 fused sacral vertebrae a. These vertebra start to fuse shortly after puberty and are usually completely fused between ages 20 and 30 b. The horizontal lines of fusion that remain are called transverse ridges 5. Superiorly, the sacrum articulates with L5 via a pair of superior articular processes, and inferiorly it articulates with the coccyx 6. The vertebral canal becomes much narrower and continues through the sacrum as the sacral canal 7. The sacral canal terminates in an inferior opening called the sacral hiatus a. The sacral hiatus represents an area where the laminae of the last sacral vertebra failed to fuse b. On either side of the sacral hiatus are bony projections called sacral cornua 8. The anterosuperior edge of the first sacral vertebra bulges anteriorly into the pelvic cavity and is called the promontory 9. 4 anterior lines cross the anterior surface of the sacrum, marking the lines of fusion of the sacral vertebrae 10. The paired anterior sacral foramina permit the passage of nerves to the pelvic organs 11. A dorsal ridge, termed the median sacral crest, is formed by the fusion of the spinous process of individual sacral vertebrae 12. Also on the dorsal surface of the sacrum are 4 pairs of openings for spinal nerves, called the posterior sacral foramina 13. On each lateral surface of the sacrum is the ala (meaning "wing") 14. On the lateral side of the ala is the auricular surface, which marks the site of articulation with the os coxae of the pelvic girdle, forming the strong sacroiliac joint

Sternum

1. The adult sternum is also called the breastbone; it is a flat bone that forms in the anterior midline of the thoracic wall a. It's shape has been likened to that of a sword b. Composed of 3 parts: manubrium, the body, and the xiphoid process 2. The manubrium is the widest and most superior portion of the sternum (handle of the bony sword) a. 2 clavicular notches articulate the sternum with the left and right clavicles b. The shallow superior indentation between the clavicular notches is called the suprasternal notch (jugular notch) c. A single pair of costal notches represent articulation for the first ribs' costal cartilages 3. The body is the longest part of the sternum and forms the bulk ("blade" of the bony sword) a. Individual costal cartilages from ribs 2-7 are attached to the body at indented articular costal notches 4. The body and manubrium articulate at the sternal angle, a horizontal ridge that may be palpated under the skin a. The sternal angle is an important landmark in that the costal cartilages of the second ribs attach there; thus, it may bee used to count the ribs 5. The xiphoid process represents the very tip of the "sword blade" a. This small, inferiorly pointed projection is cartilaginous and often does not ossify until after age 40 6. The connection of the xiphoid process to the body of the sternum may be broken by an impact or strong pressure; the resulting internal projection of bone can severely damage the heart or liver

Chapter Summary Axial Skeleton

1. The axial skeleton includes the bones of the skull, the vertebral column, and the thoracic cage 2. The appendicular skeleton includes the bones of the pectoral and pelvic girdles and the upper and lower limbs 3. Cranial bones enclose the cranial cavity. Facial bones protect and support the entrances to the digestive and respiratory systems 4. The vertebral column is composed of 26 vertebrae 5. There are 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, the sacrum, and the coccyx 6. The adult spinal column exhibits 4 curvatures. The thoracic and sacral curvatures are called primary (accommodation) curves, and the cervical and lumbar curvatures are termed secondary (compensation) curves 7. A typical vertebra has a body and a posterior vertebral arch. The vertebral arch is formed by pedicles and laminae. The vertebral foramen houses the spinal chord. 8. Between adjacent vertebrae are fibrocartilaginous intervertebral discs 9. Cervical vertebrae have transverse foramina and bifid spinous processes 10. Thoracic vertebrae have heart-shaped bodies, long spinous processes, costal facets on the body, and transverse processes that articulate with the ribs 11. The lumbar vertebrae are the most massive 12. The skeleton of the thoracic cage is composed of the thoracic vertebrae, the ribs, and the sternum 13. The sternum consists of a superiorly placed manubrium, a middle body, and an inferiorly placed xiphoid process 14. Ribs 1-7 are called true ribs, and ribs 8-12 are called false ribs (while ribs 11-12 are also known as floating ribs) 15. Skeletal mass and density are often reduced with age, and articulation surfaces deteriorate, leading to arthritis

Thoracic Cage

1. The bony framework of the chest is called the thoracic cage; it consists of the thoracic vertebrae posteriorly, the ribs laterally, and the sternum anteriorly 2. Thoracic cage acts acts as a protective framework around the vital organs, including the heart, lungs, trachea, and esophagus 3. Also, provides attachment points for many muscles supporting the pectoral girdles (the bones that hold the upper limb in place), the chest, the neck, the shoulders, the back, and the muscles involved in respiration

Atlas (C1)

1. The first cervical vertebra supports the head via its articulation with the occipital condyles of the occipital bone 2. Named after the Greek mythological figure Atlas, who carried the world on his shoulders 3. Articulation between the occipital condyles and the atlas, called the atlanto-occipital joint permits us to nod our heads "yes" 4. Atlas distinguished from the other vertebrae b/c it lacks a body and a spinous process a. Instead, the atlas has lateral masses that are connected by semicircular anterior and posterior arches, each containing slight protuberances, the anterior and posterior tubercles 5. Atlas has depressed, oval superior articular facets that articulate with the occipital condyles of the skull 6. Atlas also has inferior articular facets that articulate with the superior articular facets of the axis 7. Atlas has an articular facet for dens on its anterior arch where it articulates with the dens of the axis

vertebrae

11. The vertebrae are smallest near the skull, and become gradually larger moving inferiorly through the body trunk as weight bearing increases • Thus, the cervical vertebrae are the smallest, followed by the thoracic, lumbar, and sacral vertebrae • Also, the vertebral foramen is largest in the cervical vertebrae and smallest in the sacral vertebrae 12. Although, vertebrae are divided into regions, there are no anatomically discrete "cutoffs" between the regions • Ex: the most inferior cervical vertebra has some structural similarities to the most superior thoracic vertebra, as the two vertebrae are adjacent to one another; likewise, the most inferior thoracic vertebrae may look similar to the first to the first lumbar vertebra

vertebral arch

2. Posterior to the vertebral body is the vertebral arch, also called the neural arch • Together, the vertebral arch and the body enclose a roughly circular opening called the vertebral foramen 3. Collectively, all the stacked vertebral foramina from a superior-to-inferior directed vertebral canal that contains the spinal cord

false ribs

4. Ribs 8-12 are called false ribs b/c their costal cartilages do not attach directly to the sternum 5. The costal cartilages of ribs 8-10 fuse to the costal cartilages of rib 7 and thus indirectly articulate with the sternum

Illiocostalis group

4. The Illiocostalis group is the most laterally placed of the 3, it is composed of three parts: cervical m., thoracic m., and lumbar m., which attach either to the angles of the ribs or the transverse processes of cervical vertebrae

spinous process

6. A spinous process projects posteriorly from the left and right laminae • Most of these spinous processes can be palpated through the skin of the back

floating ribs

6. The last 2 pairs of false ribs (ribs 11 and 12) are called floating ribs b/c they have no connection to the sternum

linea alba

6. The left and right rectus sheaths are connected by a vertical fibrous strip

Transversospinalis

7. Deep to the erector spinae, a group of muscles collectively called the transversospinalis muscles connect and stabilize the vertebrae

transverse processes

7. Lateral projections on both sides of the vertebral arch are called transverse processes

Articulation of the rib with the vertebra

7. The vertebral end of a typical rib articulates with the vertebral column at the head (or capitulum) 8. The articular surface of the head is divided into superior and inferior articular facets by an interarticular crest a. The surfaces of these facets articulate with the costal facets on the bodies of the thoracic vertebrae 9. The neck of the rib lies between the head and the tubercle 10. The tubercle for the rib has an articular facet for the costal facet on the transverse process of the thoracic vertebra 11. Rib1 articulates with vertebra T1. The head of the rib articulates at the costal facet on the body, and the tubercle of the rib articulates at a transverse costal facet on the transverse process of T1 12. Ribs 2-9 articulate with vertebra T2-T9 a. Each of these vertebrae has two demifacets on the lateral side of its body b. The superior articular facet on the head of the rib articulates with the more superior vertebra, and the inferior articular facet articulates with the more inferior vertebra i. Ex: The superior articular facet on the head of the rib 2 articulates with the inferior costal demifacet on the body of T1, and the inferior articular facet on the head of rib 2 articulates with the superior costal demifacet on the body of T2 c. The tubercle of each rib articulates with the transverse costal facet on the transverse process of each vertebra i. Ex: the tubercle of rib 3 articulates with the transverse costal facet on the transverse process of T3 13. Ribs 10-12 articulate with vertebrae T10-T12 a. Each of these vertebrae has a whole costal facet on the lateral body to articulate with the head of its respective rib b. Vertebra T10 also has transverse costal facets on its transverse processes to articulate with the tubercle of each rib 10 c. Ribs 11 and 12 do not have tubercles, so there are no costal facets on the transverse processes of T11 and T12 14. The angle (border) of the rib indicates the site where the tubular shaft (or body) begins curving anteriorly toward the sternum 15. A prominent costal groove along its inferior internal border makes the path of intercostal nerves and blood vessels to the thoracic wall

articular processes

8. Each vertebra has articular processes on both its superior and inferior surfaces that project from the junction between the pedicles and laminae

interspinales and intertransversarii

8. Minor deep back muscles called interspinales and intertransversarii assist the transversospinalis with moving the vertebral column

articular facet

9. Each articular process has a smooth surface, called an articular facet • The angles of these facets differ along the length of the vertebral column contributing to different movements along the vertebral column

Muscles of the Pectoral Girdle and Upper Limb

Different organizations for these muscles - Muscles that move the pectoral girdle - Muscles that move the glenohumeral joint/arm - Arm and forearm muscles that move the elbow joint/forearm - Forearm muscles that move the wrist joint, hand, and fingers - Intrinsic muscles of the hand - Some superficial and others are deep

Levator Scapulae

Has multiple heads that attach to the transverse processes of the cervical vertebrae and attaches inferiorly to the superior angle of the scapula o 2. Primary action is to elevate the scapula o 3. Can also inferiorly rotate the scapula so that the glenoid cavity points inferiorly

Pectoralis minor

Helps depress and protract (pull anteriorly) the scapula o 2. When your shoulders are haunches forward than your pectoralis minor is contracting

Serratus anterior

Positioned between the ribs and the scapula o 2. Prime mover in scapula protraction, works with pectoralis minor o 3. Primary muscle that helps stabilize the scapula against the posterior side of the rib cage + powerful superior rotator of the scapula by moving the glenoid cavity superiorly, as occurs when you abduct the upper limb

MusclesThatMovetheGlenohumeral Joint/Arm

The phrases "moving the glenohumeral joint" and "moving the arm or humerus" mean the same thing. A movement such as flexion of the arm requires movement at the glenohumeral joint The glenohumeral joint is crossed by 11 muscles that attach to the arm (humerus) or the forearm (radius and ulna)

Muscles of Respiration

The process of respiration involves inhalation and exhalation 2. When a person inhales, several muscles contract in the thoracic cavity to allow the lungs to fill with air 3. When a person exhales, some respiratory muscles contract and others relax in order to decrease the dimensions of the thoracic cavity and force air out of the lungs 4. There are muscles for quiet and forced breathing 5. Muscles of respiration are on the anterior and posterior surface of the thorax • these muscles are covered by more superficial muscles (such as the pectoral muscles, trapezius, and latissimus dorsi) that move the upper limb • 2 posterior thorax muscles assist with respiration o These muscles are located deep to the trapezius and latissimus dorsi, but superficial to the erector spinae muscles

5. Rectus abdominis

a. Extends vertically the entire length of the anteromedial abdominal wall between the sternum and the pubic symphysis b. Has 3 tendinous intersections, which separate it into 4 segments c. Enclosed within a fibrous sleeve called the rectus sheath (formed from the aponeuroses of the external oblique, internal oblique, and transverse abdominis muscles )

latissimus dorsi and pectoralis major muscles

are the pri- mary attachments of the arm to the trunk, and they are the prime movers of the glenohumeral joint. These muscles are antagonists with respect to arm flexion and arm extension. However, these same two muscles work together (synergistically) when performing other movements, such as adducting and medially rotating the humerus.

Clinical View: Rotator Cuff Injuries

ator cuff musculature or tendons. Extensive and repetitive use of the rotator cuff muscles can cause tearing of muscle fibers or rupture of tendon attachments. Injury to the supraspinatus muscle is most common, likely because the tendon of this muscle may become impinged (pinched) inferior to the acromion when using the muscle. This syndrome is especially common in baseball players because of the repetitive shoulder movements while pitching and throwing the ball. Painters also may experience rotator cuff injuries due to the repetitive overhead upper limb movements involved with their work. Treatment depends upon severity of the injury and includes use of NSAIDs, corticosteroid shots, and physical therapy. Typically, severe rotator cuff injuries require surgical repair. Even after surgery, some individuals never regain full athletic use of the injured shoulder.

6. Serratus posterior superior

attaches to ribs 2-5 and elevates these ribs during forced inhalation, thereby increasing the lateral dimensions of the thoracic cavity

7. Serratus posterior inferior

attaches to ribs 8-12 and depresses those ribs during forced exhalation

Appendicular

bones of the appendages; upper and lower limbs) as well as the bones that hold the limbs to the trunk of the body (the pectoral and pelvic girdles)

9. External intercostals

extend inferomedially from the superior rib to the adjacent inferior rib - Assist in expanding the thoracic cavity by elevating the ribs during inhalation

laminae

extend posteromedially from the posterior edge of each pedicle 5. The vertebral arch is composed of two pedicles and two laminae

2. Erector Spinae

function to maintain posture and to help an individual stand erect a. When the left and right erector spinae muscles contract together, they extend the vertebral column b. If the erector spinae muscles on only ones side contract, the vertebral column flexes laterally toward the same side 3. The erector spinae muscles are organized into three groups; a series of multipart, overlapping muscles compose each of these groups a. These muscles share a common tendinous connection from the posterior part of the iliac crest, posterior sacrum, and spinous processes of the lumbar vertebrae b. The muscles are named based upon the body region with which they are associated c. Erector spinae —> 3 groups of overlapping muscles: i. 1) Illiocostalis, 2) Longissimus, 3) Spinalis (I Love Shark) (Going from lateral to medial) d. Erector spinae is covered by the most superficial back muscles: i. Trapezius + lattissimus dorsi e. Action i. 1) bilaterally (both sides) contraction- extend vertebral column (muscle in both side) ii. 2) Unilaterally (one side) contraction - lateral flex vertebral column on same side (muscles on one side)

1. Axial Muscles

have both their origins and insertions on parts of the axial skeleton 2. Muscles of the axial skeleton move and support the head and spinal column, [ (skip functions of the head and neck muscles) affect facial features, move the lower jaw during chewing, assist in food processing and swallowing], aid breathing, and support and protect the abdominal and pelvic organs 3. Muscles of the axial skeleton are NOT responsible for stabilizing or moving the pectoral or pelvic girdles or their attached limbs; those are functions of the appendicular muscles 4. Axial Muscles are organized into 5 groups based on location a. [Muscles of the head and neck]- not covered yet b. Muscles of the vertebral column c. Muscles of respiration d. Muscles of the abdominal wall e. Muscles of the pelvic floor 5. Innervation- refers to the nerve(s) that supplies a muscle and stimulates it to contract 6. For axial muscles a. Superior attachment- same as origin b. Inferior attachment- insertion 7. For appendicular muscles a. Proximal attachment b. Distal attachment

infraspinatus and teres minor

help slow down the pitching arm upon completion of the pitch. These two muscles adduct and laterally rotate the arm.

12. Diaphragm

internally placed, dome-shaped muscle that forms a partition between the thoracic and abdominopelvic cavities; most important muscle associated with breathing - Muscle fibers of the diaphragm converge from its margins toward a fibrous central tendon - When the diaphragm contracts, the central tendon is pulled inferiorly toward the abdominopelvic cavity thereby increasing the vertical dimensions of the thoracic cavity - As it compresses the abdominopelvic cavity, it increases the intra-abdominal pressure, needed for urination, defection, and childbirth

pectoralis major

is a large, thick, fan-shaped muscle that covers the superior part of the thorax. It is the principal flexor of the arm, and also adducts and medially rotates the arm.

10. Internal intercostals

lie deep to the external intercostals - Depress the ribs, but only during forced exhalation; normal exhalation takes no active muscular effort

Longissimus group

medial to the Illiocostalis group. Attaches to the transverse processes of the the vertebrae; composed of three parts: capitis, cervical, and thoracic

Axial Skeleton (bones in the central axis of the body)

skull, vertebral column, and thoracic cage

rotator cuff muscles

subscapularis, supraspinatus, in- fraspinatus, and teres minor) provide strength and stability to the glenohumeral joint (figure 12.5). The rotator cuff muscles attach the scapula to the humerus. The specific movements of each muscle are best learned when equating them to pitching a ball:

deltoid

thick, powerful muscle that functions as a prime abductor of the arm and forms the rounded contour of the shoulder. There are three different proximal attachment points for the deltoid muscle fibers, and these different fiber groups all perform different functions: (1) The anterior fibers flex and medially rotate the arm. (2) The middle fibers abduct the arm; in fact, the deltoid is the prime abductor of the arm. (3) The posterior fibers extend and laterally rotate the arm

supraspinatus

used when you start to execute the pitch, by fully abducting the arm.

subscapularis

used when you wind up for a pitch. It medially rotates the arm.

coracobrachialis

works as a synergist to the pectora- lis major in flexing and adducting the arm

intervertebral disc

• Adjacent vertebral bodies are separated by pads of fibrocartilage called the intervertebral disc i. Intervertebral discs are composed of an outer ring of fibrocartilage, called the anulus fibrosus and an inner circular region, called the nucleus pulposus 1. The nucleus pulposus has a high water content, giving it a gelatinous consistency 2. Intervertebral discs make up about one-quarter of the entire vertebral column 3. They act as shock absorbers between the vertebral bodies, and also allow the vertebral column to bend 4. Intervertebral discs are able to withstand a certain amount of compression a. Over the course of the day, as body weight and gravity act on the vertebral column, the intervertebral discs become compressed and flattened; but, while a person sleeps, lying horizontally, the intervertebral discs are able to spring back to their original shape

2. Primary Curves (convex): The thoracic and sacral curvatures; appear late in fetal development

• Called accommodation curves b/c they accommodate the thoracic and abdominopelvic viscera; in newborns, only these primary curves are present, and the vertebral column is C-shaped

1. Cervical (7) C1-C7

• Form the bones of the neck • C1 articulates superiorly with the occipital condyles of the occipital bone of the skull • C7 articulates inferiorly with the first thoracic vertebra

2. Thoracic vertebrae T1-T12

• Form the superior regions of the back; and each articulates laterally with one or two pairs of ribs • The twelfth thoracic vertebra articulates inferiorly with the first lumbar vertebra

5. The coccyx (commonly called the tailbone)

• Formed from four coccygeal vertebrae (C01-C04) that start to unite during puberty • The first coccygeal vertebra (C01) articulates with the inferior end of the sacrum • When a person is much older, the coccyx may also fuse to the sacrum

Axial Skeleton (bones in the central axis of the body)

• Houses special sense organs (the organs for hearing, balance, taste, smell, and vision) • Provides areas for the attachment of skeletal muscles • Spongy bone of most of the axial skeleton contains hemopoietic tissue; responsible for blood cell formation • Main function of the axial skeleton: to form a framework that supports and protects the organs