Important Notes (EXAM # 3)

Sign of Benediction

-High Median nerve injury -Active sign that occurs when the person attempts to make a fist -The default position is the ape hand -High Median nerve injury results in paralysis of flexor digitorum superficialis, flexor pollicis longus, and flexor pollicis brevis, and radial 1/2 of flexor digitorum profundus -The only remaining function is thus the radial 1/2 of flexor digitorum profundus which flexes digits 4 and 5 only

Ape Hand

-Median nerve injury -Hands held in the same dorsal-ventral plane in the resting position but the thumb is in a more ventral plane due to the action of the thenar muscles (abductor pollicis brevis and opponens pollicis) -Median nerve injury paralyzes the thenar muscles and the thumb falls into the dorsal plane by the unopposed action of the adductor pollicis muscle (innervated by the ulnar nerve). This causes the ape hand.

The intertubercular sulcus is the site of three important muscle attachments:

-Pectoralis major -Latissmus dorsi -Teres major The pectoralis major attaches to the lateral lip of the intertubercular sulcus. The latissimus dorsi attaches to the floor of the intertubercular sulcus. The teres major attaches to the medial lip of the intertubercular sulcus.

KNOW THIS:

Rupture of rotator cuff may occur by a chronic wear and tear or an acute fall on the outstretched arm and is manifested by severe limitation of shoulder joint motion, chiefly abduction. A rupture of the rotator cuff, most frequently attrition of the supraspinatus tendon by friction among middle-aged persons may cause degenerative inflammatory changes (degenerative tendonitis) of the rotator cuff, resulting in a painful abduction of the arm or a painful shoulder.

Filum Terminale (Internum)

Is a prolongation of the pia mater from the tip (conus medullaris) of the spinal cord at the level of L2.

Fracture of the clavicle

It may cause injury to the brachial plexus (lower trunk), fatal hemorrhage from the subclavian artery, and thrombosis of the subclavian vein, leading to pulmonary embolism.

Denticulate ligament

Lateral extension of the pia mater

KNOW THIS:

S2 is the level at which the dural sac normally terminates.

Meningocele

Meningocele is protrusion of the meninges through the defective vertebral arch.

Anterior wall of axilla

Pectoralis major and pectoralis minor muscles and clavipectoral fascia

Spine of the Scapula

Provides an origin for the deltoid and an insertion for the trapezius *Acromion also provides this.*

Injury to the musculocutaneous nerve:

Results in weakness of supination (biceps) and flexion (biceps and brachialis) of forearm and loss of sensation on the lateral side of forearm.

The posterior longitudinal ligament:

Runs within the vertebral canal supporting the posterior aspect of the vertebrae and prevents hyperflexion.

KNOW THIS:

Scoliosis can be a secondary condition in such disorders as muscular dystrophy and polio in which abnormal muscle does not keep the normal alignment of the vertebral column and results in a lateral curvature.

Abduction of the arm above 90 degrees and protraction of the scapula are possible due to the action of:

Serratus anterior, which is supplied by the long thoracic nerve.

Posterior wall of axilla

Subscapularis, teres major, and latissimus dorsi muscles;

Abduction of the arm through 0 to 15 degrees is produced by:

Supraspinatus

A 24-year-old woman comes to a hospital to deliver her baby. Her obstetrician uses a caudal anesthesia during labor and childbirth to block the spinal nerves in the epidural space. Local anesthetic agents are most likely injected via which of the following openings? (A) Intervertebral foramen (B) Sacral hiatus (C) Vertebral canal (D) Dorsal sacral foramen (E) Ventral sacral foramen

The Answer is B. *Caudal (epidural) anesthesia is used to block the spinal nerves in the epidural space by injecting local anesthetic agents via the sacral hiatus* located between the sacral cornua. An intervertebral foramen transmits the dorsal and ventral primary rami of the spinal nerves. The vertebral canal accommodates the spinal cord. Dorsal and ventral sacral foramina transmit the dorsal and ventral primary rami of the sacral nerves

BONES

■ Are calcified connective tissue consisting of cells (osteocytes) embedded in a matrix of ground substance and collagen fibers, have a superficial thin layer of compact bone around a central mass of spongy bone, and contain internal soft tissue, the marrow, where blood cells are formed. ■ Serve as a reservoir for calcium and phosphorus and act as biomechanical levers on which muscles act to produce the movements permitted by joints. ■ Are classified, according to shape, into long, short, flat, irregular, and sesamoid bones and, according to their developmental history, into endochondral and membranous bones.

Aponeuroses

■ Are flat fibrous sheets or expanded broad tendons that attach to muscles and serve as the means of origin or insertion of a flat muscle.

Bursae

■ Are fluid-filled flattened sacs of synovial membrane that facilitate movement by minimizing friction.

Vertebral Foramina

■ Are formed by the vertebral bodies and vertebral arches (pedicles and laminae). ■ Collectively form the vertebral canal and transmit the spinal cord with its meningeal coverings, nerve roots, and associated vessels.

Intervertebral Foramina

■ Are located between the inferior and superior surfaces of the pedicles of adjacent vertebrae. ■ *Transmit the spinal nerves* and accompanying vessels as they exit the vertebral canal.

Transverse Foramina

■ Are present in transverse processes of the cervical vertebrae. ■ Transmit the vertebral artery (except for C7), vertebral veins, and autonomic nerves.

Basilic vein

■ Arises from the dorsal venous arch of the hand and accompanies the medial antebrachial cutaneous nerve along the ulnar border of the forearm and passes anterior to the medial epicondyle. ■ Pierces the deep fascia of the arm and joins the brachial veins (the venae comitantes of the Bbrachial artery) to form the axillary vein at the lower border of the teres major muscle.

Cubital Fossa

■ At its lower end, the brachial artery divides into the radial and ulnar arteries, with a fascial roof strengthened by the bicipital aponeurosis. ■ Contains (from lateral to medial) the radial nerve, biceps tendon, brachial artery, and median nerve (mnemonic device: Ron Beats Bad Man).

Cephalic vein

■ Begins as a radial continuation of the dorsal venous network, runs on the lateral side, and is often connected with the basilic vein by the median cubital vein in front of the elbow. ■ Ascends along the lateral surface of the biceps, pierces the brachial fascia, and lies in the deltopectoral triangle with the deltoid branch of the thoracoacromial trunk. ■ Pierces the costocoracoid membrane of the clavipectoral fascia and ends in the axillary vein

Contents of the Axilla

■ Brachial plexus and its branches ■ Axillary artery has many branches, including the superior thoracic, thoracoacromial, lateral thoracic, thoracodorsal, and circumflex humeral (anterior and posterior) arteries. ■ Axillary vein is formed by the union of the brachial veins (venae comitantes of the brachial artery) and the basilic vein, receives the cephalic vein and veins that correspond to the branches of the axillary artery, and drains into the subclavian vein. ■ Lymph nodes and areolar tissue are present. ■ Axillary tail (tail of Spence) is a superolateral extension of the mammary gland.

Median Cubital Vein

■ Connects the cephalic vein to the basilic vein over the cubital fossa. ■ Lies superficial to the bicipital aponeurosis, and thus separates it from the brachial artery, which is vulnerable to being punctured during intravenous injections and blood transfusions.

Cranial Nerves

■ Consist of 12 pairs and are connected to the brain rather than to the spinal cord. ■ Have motor fibers with cell bodies located within the CNS and sensory fibers with cell bodies that form sensory ganglia located outside the CNS. ■ Emerge from the ventral aspect of the brain (except for the trochlear nerve, cranial nerve IV).

Spinal Nerves

■ Consist of 31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal ■ Are formed from dorsal and ventral roots; each dorsal root has a ganglion that is within the intervertebral foramen. ■ Are connected with the sympathetic chain ganglia by *rami communicantes* ■ Contain sensory fibers with cell bodies in the dorsal root ganglion (general somatic afferent [GSA] and general visceral afferent [GVA] fibers), motor fibers with cell bodies in the anterior horn of the spinal cord (general somatic efferent [GSE] fibers), and motor fibers with cell bodies in the lateral horn of the spinal cord (general visceral efferent [GVE] fibers) between T1 and L2. ■ Are divided into the ventral and dorsal primary rami. The ventral primary rami enter into the formation of plexuses (i.e., cervical, brachial, and lumbosacral); *the dorsal primary rami innervate the skin and deep muscles of the back*.

Spiral Groove of Humerus

■ Contains the radial nerve, separating the origin of the lateral head of the triceps above and the origin of the medial head below.

Spinal Cord

■ Has a conical end known as the *conus medullaris* and ends at the level of L2 (or between L1 and L2) in the adult and at the level of L3 in the newborn.

Brachial Plexus

■ Has roots that pass between the scalenus anterior and medius muscles. ■ Is enclosed with the axillary artery and vein in the axillary sheath, which is formed by a prolongation of the prevertebral fascia.

Short Bones

■ Include the carpal and tarsal bones and are approximately cuboid-shaped. ■ Are composed of spongy bone and marrow surrounded by a thin outer layer of compact bone.

Flat Bones

■ Include the ribs, sternum, scapulae, and bones in the vault of the skull. ■ Consist of two layers of compact bone enclosing spongy bone and marrow space (diploë). ■ Have articular surfaces that are covered with fibrocartilage and grow by the replacement of connective tissue.

KNOW THIS:

There is no disk between the atlas and the axis

Branches from the Roots of Brachial Plexus

*1. Dorsal Scapular Nerve (C5)* ■ Pierces the scalenus medius muscle to reach the posterior cervical triangle and descends deep to the levator scapulae and the rhomboid minor and major muscles. ■ Innervates the rhomboids and frequently the levator scapulae muscles. *2. Long Thoracic Nerve (C5-C7)* ■ Descends behind the brachial plexus and runs on the external surface of the serratus anterior muscle, which it supplies.

Branches from the Lateral Cord of Brachial Plexus

*1. Lateral Pectoral Nerve (C5-C7)* ■ Innervates the pectoralis major muscle primarily and also supplies the pectoralis minor muscle by way of a nerve loop. ■ Sends a branch over the first part of the axillary artery to the medial pectoral nerve and forms a nerve loop through which the lateral pectoral nerve conveys motor fibers to the pectoralis minor muscle. ■ Pierces the costocoracoid membrane of the clavipectoral fascia. ■ Is accompanied by the pectoral branch of the thoracoacromial artery. --------------------------------------------- *2. Musculocutaneous Nerve (C5-C7)* ■ Pierces the coracobrachialis muscle, descends between the biceps brachii and brachialis muscles, and innervates these three muscles.

Branches from the Medial Cord of Brachial Plexus

*1. Medial Pectoral Nerve (C8-T1)* ■ Passes forward between the axillary artery and vein and forms a loop in front of the axillary artery with the lateral pectoral nerve. ■ Enters and supplies the pectoralis minor muscle and reaches the overlying pectoralis major muscle. ----------------------------------------------------- *2. Medial Brachial Cutaneous Nerve (C8-T1)* ■ Runs along the medial side of the axillary vein. ■ Innervates the skin on the medial side of the arm. ■ May communicate with the intercostobrachial nerve, which arises as a lateral branch of the second intercostal nerve. ------------------------------------------------------ *3. Medial Antebrachial Cutaneous Nerve (C8-T1)* ■ Runs between the axillary artery and vein and then runs medial to the brachial artery. ■ Innervates the skin on the medial side of the forearm. ------------------------------------------------------ *4. Ulnar Nerve (C7-T1)* ■ Runs down the medial aspect of the arm but does not branch in the brachium.

Branches from the Upper Trunk of Brachial Plexus

*1. Suprascapular Nerve (C5-C6)* ■ Runs laterally across the posterior cervical triangle. ■ Passes through the scapular notch under the superior transverse scapular ligament, whereas the suprascapular artery passes over the ligament. (Thus, it can be said that the army [artery] runs over the bridge [ligament], and the navy [nerve] runs under the bridge.) ■ Supplies the supraspinatus muscle and the shoulder joint and then descends through the notch of the scapular neck to innervate the infraspinatus muscle. -------------------------------------------------------- *2. Nerve to Subclavius (C5)* ■ Descends in front of the brachial plexus and the subclavian artery and behind the clavicle to reach the subclavius muscle. ■ Also innervates the sternoclavicular joint. ■ Usually branches to the accessory phrenic nerve (C5), which enters the thorax to join the phrenic nerve.

KNOW THIS:

*Aneurysm* is a circumscribed dilation of the wall of an artery or the heart and is caused by a weakness of the arterial wall, an atherosclerosis (accumulation of fat, cholesterol, and calcium which form plaque in the arterial wall), or high blood pressure, giving a greater risk of rupture. *Varicose veins* are enlarged and tortuous veins that develop most commonly in the superficial veins of the lower limb because of reduced elasticity and incompetent valves in the veins or thrombophlebitis of the deep veins.

Claw Hand, Ape Hand, and the Sign of Benediction:

*Hand deformities that result from injuries to either the ulnar nerves or the median nerve* *Loss of muscles that act on digits 2-5 with the thumb being on peripherally involved *More specifically they result from impaired function of muscles that act on the metacarpophalangeal joint and interphalangeal (IP) joints of digits 2-5 *On digit 2 and digit 5 extensor digitorum is accompanied by the extensor indicis and extensor digiti minimi *Under normal circumstances extensor digitorum is an extensor only of the metacarpophalangeal joint. It is ineffective at extending the IP joints. *Flexor digitorum superficialis and flexor digitorum profundus are flexor of proximal interphalageal and distal interphalangeal joints respectively and extensor digitorum by itself cannot overcome their actions. *The extensor expansion (extensor hood) is a tendinous aponeurosis that spreads out from the extensor digitorum tendons on the dorsum of the metacarpals and phalanges. The lumborum and interossei transmit force via this expansion and extend the IP joints *Radial nerve innervates extensor digitorum muscle. *Median nerve innervates: a) flexor digitorum superficiali b) radial 1/2 of flexor digitorum profundus c) 1st and 2nd lumbrical muscles d) muscles of thenar eminence (abductor pollicis brevis, flexor pollicis brevis, opponens pollicis) that moves the thumb *Ulnar nerve innervates: a) Ulnar 1/2 of flexor digitorum profundus b) 3rd and 4th lumbricals c) Interosseus muscles d) Adductor pollicis muscle

Deep Back Muscles

-erector spinae -splenius capitis -splenius cervicis *The dorsal primary rami of the spinal nerves innervate the deep muscles of the back*

Spina bifida

1) A developmental anomaly characterized by defective closure of the vertebral arch associated with maternal folic acid deficiency and is classified as follows: (a) spina bifida occulta—failure of the vertebral arch to fuse (bony defect only with a small tuft of hair over the affected area of skin) (b) meningocele—protrusion of the meninges through the unfused arch of the vertebra (spina bifida cystica) (c) meningomyelocele—protrusion of the spinal cord and the meninges, and (d) myeloschisis (rachischisis)—a cleft spinal cord due to failure of neural folds to close.

KNOW THIS:

1) Intervertebral discs are associated with disc herniation, not compression fractures 2)Fracture of vertebral body occurs when you have a compression fractures to vertebrae L4 and L5

The suboccipital triangle is a region of the neck bounded by the following three muscles of the suboccipital group of muscles:

1) Rectus capitis posterior major - above and medially 2) Obliquus capitis superior - above and laterally 3) Obliquus capitis inferior - below and laterally

Claw Hand

1) Results from injury to the ulnar nerve 2)Lose innervation of all interosseus muscles 3) Lose innervation of ulnar lumbricals 4) Digits 2 and 3 are unaffected but they lose abduction and adduction provided by interosseus muscles 5) Digits 4 and 5 are dramatically affected 6) Lose of lumbrical and interosseus function here means action of extensor digitorum is unopposed-- leads to hyperextension at MCP joint 7) Extensor digitorum unable to counteract powerful flexsion by flexor digitorum superficialis and profundus at IP joints 8) Digits 4 and 5 stuck in hyperextension at MCP joints and hyperflexion at IP joints

The order of structures pierced during an epidural procedure is:

1) Skin 2) Subcutaneous tissue 3) Muscle 4) Supraspinous ligament 5) Interspinous ligament 6) Ligamentum flavum (there is often a midline gap in the ligamentum flavum).

KNOW THIS:

1) Spinal tab (removal of CSF)--> from the subarachnoid

Two muscles that cause medial rotation and adduction:

1) Teres major 2) Latissimus dorsi

Atlantooccipital joints

1) The condyloid (ellipsoidal) joints 2) The carpometacarpal joint of the thumb is the saddle (sellar) joint 3) The proximal tibiofibular joint is the plane (gliding) joint

Branches from the Posterior Cord of Brachial Plexus

1. *Upper Subscapular Nerve (C5-C6)* ■ Innervates the upper portion of the subscapularis muscle. 2. *Thoracodorsal Nerve (C7-C8)* ■ Runs behind the axillary artery and accompanies the thoracodorsal artery to enter the latissimus dorsi muscle. 3. *Lower Subscapular Nerve (C5-C6)* ■ Innervates the lower part of the subscapularis and teres major muscles. ■ Runs downward behind the subscapular vessels to the teres major muscle. --------------------------------------------- 4. *Axillary Nerve (C5-C6)* ■ Innervates the deltoid and teres minor muscles and gives rise to the lateral brachial cutaneous nerve. ■ Passes posteriorly through the quadrangular space accompanied by the posterior circumflex humeral artery and winds around the surgical neck of the humerus (may be injured when this part of the bone is fractured). --------------------------------------------- 5. *Radial Nerve (C5-T1)* ■ Is the largest branch of the brachial plexus and occupies the musculospiral groove on the back of the humerus with the profunda brachii artery.

A. Components of Neurons

1. Cell bodies are located in the gray matter of the CNS, and their collections are called ganglia in the PNS and nuclei in the CNS

Circulatory Loops

1. Pulmonary Circulation ■ Transports blood from the right ventricle through the pulmonary arteries to the lungs for the exchange of oxygen and carbon dioxide and returns it to the left atrium of the heart through the pulmonary veins. 2. Systemic Circulation ■ Transports blood from the left ventricle through the aorta to all parts of the body and returns it to the right atrium through the superior and inferior venae cavae and the cardiac veins.

Classification of Neurons

1. Unipolar (Pseudounipolar) Neurons -Are sensory neurons of the PNS and found in spinal and cranial nerve ganglia. 2. Bipolar Neurons -Found in the olfactory epithelium, the retina, and the inner ear Multipolar Neurons -Have several dendrites and one axon and are most common in the CNS (e.g., motor cells in anterior and lateral horns of the spinal cord, autonomic ganglion cells).

Capillaries

Are absent in the cornea, epidermis, and hyaline cartilage and may be absent in some areas where the arterioles and venules have direct connections (arteriovenous anastomoses or shunts), which may occur in the skin of the nose, lips, fingers, and ears, where they conserve body heat.

Spondylosis (ankylosis or immobility of the vertebra)

A degenerative change due to osteoarthritis of the vertebral joints. It may cause pressure on nerve roots, producing pain and muscle weakness.

Spondylolisthesis

A forward displacement of one vertebra over another, usually of the fifth lumbar over the body of the sacrum, or of the fourth lumbar over the fifth; it is usually due to a developmental defect or traumatic fracture of the pedicle, lamina, or facets (pars interarticularis). It causes lower back pain, stiffness, muscle tightness, sciatica, or a shortened trunk.

KNOW THIS:

A herniated (slipped) disk is a protrusion of the nucleus pulposus through the annulus fibrosus of the intervertebral disk into the intervertebral foramen or into the vertebral canal, compressing the spinal nerve root. It commonly occurs posterolaterally where the annulus fibrosus is not reinforced by the posterior longitudinal ligament and frequently affects the lumbar region. A posterolateral herniation of the disk at the level L4 to L5, for example, would be likely to damage fifth lumbar nerve roots, not fourth lumbar nerve roots, due to a more oblique descending of the fourth and fifth lumbar nerve roots within the subarachnoid space.

KNOW THIS:

A lesion of the radial nerve causes paralysis of the supinator and brachioradialis. The biceps brachii muscle is a flexor of the elbow and also a strong supinator; thus, supination is still possible through action of the biceps brachii muscle.

KNOW THIS:

A lumbar puncture is performed by taking a sample of CSF from the lumbar cistern (the subarachnoid space below the spinal cord) between vertebrae L4 and L5 or sometimes between L3 and L4. It is done in this region because the spinal cord typically ends at the level of L1 to L2 and the dural sac ends at the level of S2. Therefore, it is the safest place to do the procedure because it lies between these areas and the risk of injuring the spinal cord is minimized. (Remember in children the cord ends more caudally.)

Cruciform (also called cruciate or transverse ligament of the atlas)

A stabilizing ligament found at the skull base and C1/C2. It attaches to the pedicles and helps stabilize the dens.

The anterior longitudinal ligament:

A strong fibrous band that covers and connects the anterolateral aspect of the vertebrae and intervertebral discs; it maintains stability and prevents hyperextension. It can be torn by cervical hyperextension.

A 22-year-old pregnant woman underwent epidural anesthesia in anticipation of labor. After delivery she developed back pain and right lower extremity weakness. Imaging revealed a hematoma in the epidural space resulting in compression of the nerve that exits at the level of L2 to L3. Which of the following vessels is most likely responsible for the hematoma? A. Internal vertebral plexus B. Great radicular artery (of Adamkiewicz) C. Anterior spinal artery D. Posterior spinal artery E. External vertebral plexus

A. *An epidural anesthetic procedure is performed in the epidural space which contains fat and the internal vertebral (Batson's) plexus.* A hematoma in this region would cause compression on the spinal nerves and possibly the cord resulting in severe pain and deficits. The great anterior medullary artery of Adamkiewicz is the largest of the spinal segmental arteries and is usually located at around T10, much higher than L2 to L3. The anterior and posterior spinal arteries are located in the anterior median and posterolateral fissures of the spinal cord, respectively, and are not located in the epidural space. The external vertebral plexus is located external to the vertebral canal and a hematoma of this plexus will not produce the symptoms of this patient.

Which of the following muscles is most likely located immediately deep to the semispinalis muscles, pass from a lateral point of origin in a superomedial direction to attach to spinous processes, and cross between 2 and 4 vertebrae? A. Multifidus B. Rotatores C. Longissimus D. Iliocostalis E. Spinalis

A. Multifidus is a deep muscle, which attaches from the transverse processes to the spinous processes usually crossing four to six segments. *Longissimus, iliocostalis, and spinalis are not deep to semispinalis but are superficial.* The rotators typically attach between the spinous processes or lamina of vertebrae and the transverse processes of the vertebra one or two segments below.

A 7-year-old boy is undergoing a surgery to remove a tumor from his spinal cord. During surgery of the spinal cord, which of the following structures is used as a landmark to identify anterior rootlets from posterior rootlets? A. Denticulate ligament B. Filum terminale C. Conus medullaris D. Posterior longitudinal ligament E. Ligamenta flava

A. The denticulate ligament is a sheet of pia mater running longitudinally on either side of the spinal cord, connecting it to the dura mater. Medially, the denticulate ligament lies between the origin of the anterior and posterior rootlets serving as a landmark to differentiate between them. The conus medullaris is the terminal end of the spinal cord and the filum terminale is an extension of the pia mater that connects the conus medullaris to the dural sac. The posterior longitudinal ligament lies posterior to the vertebral bodies, while the ligamentum flavum connects the lamina of adjacent vertebrae.

A 48-year-old man underwent suboccipital surgery whereby the surgeon made a midline incision through the ligamentum nuchae that began 1-cm inferior to the external occipital protuberance and ended at the level of the C2 vertebra. The surgeon then placed self-retaining retractors into the incision to forcibly separate the tissue so that an adequate surgical field existed for the duration of the surgery which lasted for 3 hours. During recovery, the patient complained of severe occipital pain and was diagnosed with postsurgical occipital neuralgia. Which of the following nerves was most likely directly stretched by the retractors during the surgery and resulted in this patient's post-surgical pain? A. Third occipital B. Suboccipital C. Greater occipital D. Lesser occipital E. Spinal accessory

A. The third occipital nerve is the medial branch of the dorsal ramus of C3. It pierces the trapezius muscle medially in the neck below the external occipital protuberance and supplies the skin of the nuchal region. The greater occipital and lesser occipital nerves lie lateral to the midline and are less likely to be affected in this patient. The suboccipital nerve lies within and supplies the muscles of the suboccipital triangle. The spinal accessory nerve supplies the trapezius and sternocleidomastoid muscles and has no cutaneous supply in the neck.

A 24-year-old woman presents with severe headache, photophobia, and stiffness of her back. Physical examination reveals positive signs for meningitis. The attending physician decides to perform a lumbar puncture to determine if a pathogen is in the cerebrospinal fluid (CSF). What is the last structure the needle will penetrate before reaching the lumbar cistern? A. Arachnoid mater B. Dura mater C. Pia mater D. Ligamentum flavum E. Posterior longitudinal ligament

A. When a lumbar puncture is performed, the needle must penetrate the ligamentum flavum, the dura mater, and finally the arachnoid mater to reach the subarachnoid space where the CSF is located. The lumbar cistern is a continuation of the subarachnoid space below the conus medullaris. The pia mater is adherent to the spinal cord, and the posterior longitudinal ligament is attached to the posterior aspect of the vertebral bodies.

KNOW THIS:

Abnormal curvatures of the vertebral column include: (a) kyphosis (hunchback or humpback), an abnormally increased thoracic curvature resulting from osteoporosis; (b) lordosis (swayback or saddle back), an abnormally increased lumbar curvature resulting from trunk muscular weakness or osteomalacia; and (c) scoliosis, a condition of lateral deviation resulting from unequal growth of the vertebral column, pathologic erosion of vertebral bodies, or asymmetric paralysis or weakness of vertebral muscles.

General somatic afferent fibers (GSA, or somatic sensory fibers):

Afferent fibers arise from cells in the spinal ganglia and are found in all the spinal nerves, except occasionally the first cervical, and conduct impulses of pain, touch and temperature from the surface of the body through the dorsal roots to the spinal cord.

KNOW THIS:

Although the conus medullaris rests at the level of L1 and L2 in adults, it is often situated at L3 in newborns. The cauda equina and filum terminale extend beyond the conus medullaris.

Kyphosis (hunchback or humpback)

An abnormally increased thoracic curvature, usually resulting from osteoporosis.

Spondylitis (inflammation of the vertebrae)

Ankylosing spondylitis is a form of rheumatoid arthritis that affects the vertebral joints, especially the lower back. It produces pain, stiffness, swelling, and limited motion. The affected vertebrae fuse or grow together, resulting in a rigid spine (bamboo spine), poor posture, and deformities.

KNOW THIS:

At the funny bone the nerve is close to your skin, and bumping it causes a shock-like feeling. The ulnar nerve runs behind the medial epicondyle on the inside of the elbow.

Base of axilla

Axillary fascia and skin; and apex: interval between the clavicle, first rib, and upper border of the scapula

A 65-year-old man complains of severe back pain and the inability to move his left lower limb. Radiologic studies demonstrate compression of nerve elements at the intervertebral foramen between vertebrae L5 and S1. Which structure is most likely responsible for this space-occupying lesion? A. Anulus fibrosus B. Nucleus pulposus C. Posterior longitudinal ligament D. Anterior longitudinal ligament E. Ligamentum flavum

B. Compression of nerves at the intervertebral foramen indicates a disc herniation. A disc herniation is characterized by protrusion of the nucleus pulposus through the anulus fibrosus posterolaterally into the spinal canal or intervertebral foramen. In general, the ligaments may be affected by the herniation but are not responsible for the compression of the spinal nerve roots.

A drug that preferentially destroys sclerotomes during embryogenesis would most likely result in underdevelopment of which of the following structures? A. Nucleus pulposus of intervertebral disc B. Vertebral bodies C. Dorsal root ganglion D. Spinal cord E. Anulus fibrosus of intervertebral disc

B. Sclerotomes are the derivatives of somites that develop into bone and if eliminated will result in underdevelopment of the vertebrae. The nucleus pulposus is a remnant of the notochord. The dorsal root ganglion is formed by neural crest cells that migrate during development. The neural tube is the precursor for the spinal cord and the anulus fibrosus develops from the sclerotome component of the somite.

A 62-year-old man visits his physician for his annual medical check-up. During physical examination it is noted that the patient has noticeable pulsations on palpation of the lower abdomen. Ultrasound examination reveals a large abdominal aortic aneurysm. The patient is operated on and during the repair his aorta is temporarily clamped. Which of the following arterial anastomoses will most likely prevent ischemia of the spinal cord if the blood pressure drops dangerously low? A. Segmental arteries from the vertebral, intercostals, superficial epigastric, lumbar, and medial sacral arteries B. Segmental arteries from the vertebral, intercostal, lumbar, spinal anterior, and posterior and lateral sacral arteries C. Anterior and posterior spinal arteries D. Radicular arteries of the vertebral, lumbar, intercostal, lateral sacral arteries, and artery of Adamkiewicz E. Segmental arteries from vertebral and intercostals

B. The anterior and posterior spinal arteries do not provide sufficient blood supply to the spinal cord below cervical levels and will receive additional supply segmentally along its course from multiple sources. The largest of these vessels are usually termed the artery of Adamkiewicz and arises at the lower thoracic or upper lumbar region.

A 19-year-old man is diagnosed with a herniated disc but he has no symptoms of spinal cord injury. In the event of intervertebral disc herniation in the cervical region, which of the following ligaments is in an anatomic position to protect the spinal cord from direct compression? A. Supraspinous B. Posterior longitudinal C. Anterior longitudinal D. Ligamentum flavum E. Nuchal ligament

B. The posterior longitudinal ligament is the only ligament spanning the posterior aspect of the vertebral bodies and intervertebral discs. *With intervertebral disc herniation, the nucleus pulposus of the intervertebral disc protrudes posterolaterally.* The anterior longitudinal ligament traverses the anterior side of the vertebral bodies and thus would not protect the spinal cord from direct compression. The supraspinous and ligamentum flavum ligaments connect the spinous processes and the laminae of adjacent vertebrae, respectively. The nuchal ligament is a continuation of the supraspinous ligaments near the C7 vertebrae and runs to the occipital protuberance.

A 53-year-old man was in a head-on collision resulting in the dens crushing the spinal cord. Which ligament was most likely torn for the dens to crush the spinal cord? A. Anterior and posterior longitudinal ligaments B. Transverse ligament of the atlas C. Interspinous ligament D. Supraspinous ligament E. Nuchal ligament

B. The transverse ligament of the atlas anchors the dens laterally to prevent posterior displacement of the dens, which has been torn in this injury

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Batson's venous plexus, in general, is a valveless network of veins located in the epidural space of the vertebral canal. The lack of valves can provide a route for the metastasis of cancer (e.g., from prostate or breast to brain) because the flow of blood is bidirectional due to local pressures

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Cerebrospinal fluid (CSF) is absorbed into the venous system primarily through the arachnoid villi projecting into the cranial dural venous sinuses, particularly the superior sagittal sinus.

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Cerebrospinal fluid (CSF) is found in the subarachnoid space, which is a wide interval between the arachnoid layer and the pia mater.

An orthopedic surgeon was teaching two residents during a workshop. For the purpose of learning, one resident acted as the patient and the other as the clinician. The surgeon asked the resident-clinician to use a marker and draw a horizontal line connecting the highest points of the iliac crests on the skin of the resident-patient. The surgeon then asked the resident clinician to palpate the midline area on the skin where the subarachnoid space terminates inferiorly. Which of the following most likely represents the area on the skin where the resident-physician palpated? A. Three spinous processes superior to the horizontal line B. Two spinous processes inferior to the horizontal line C. Three spinous processes inferior to the horizontal line D. Two spinous processes superior to the horizontal line E. The spinous process bisected by the horizontal line

C. A horizontal line that connects the highest points of the iliac crests typically bisects the spinous process of the L4 vertebra or L4-L5 interspace (Tuffier's line). The lumbar cistern, which represents the subarachnoid space, terminates at the level corresponding to the S2 spinous process. Three spinous processes inferiorly from the drawn line between the iliac crests would correspond to S2 spinous processes. Two and three spinous processes above the drawn line would be at the vertebral level L2 and L1, respectively, which would correspond to the approximate location where the spinal cord ends and therefore the pia mater.

A 45-year-old man is admitted to the hospital because of severe pain in the back and lower limb. Radiologic examination reveals spinal canal stenosis syndrome. Which of the following conditions is most likely to be confirmed by a magnetic resonance imaging (MRI) examination? A. Hypertrophy of supraspinous ligament B. Hypertrophy of interspinous ligament C. Hypertrophy of ligamentum flavum D. Hypertrophy of anterior longitudinal ligament E. Hypertrophy of nuchal ligament

C. The ligamentum flavum connects the laminae of two adjacent vertebrae and forms the posterior wall of the vertebral canal. It is the only answer choice that is in direct contact with the vertebral foramen. Therefore, hypertrophy of only the ligamentum flavum would present as spinal canal stenosis. The supraspinous and interspinous ligaments connect spinous processes. The anterior longitudinal ligament connects the anterior portion of the vertebral bodies and intervertebral discs. Finally, the nuchal ligament is a thickened extension of the supraspinous ligament above the level of C7.

The following statement was found in the radiology report of a magnetic resonance imaging scan of the cervical spine: "An acute posterolateral herniation of the most superiorly located intervertebral disc is located within the corresponding intervertebral foramen and compressing the exiting nerve." Which of the following nerves was the radiologist most likely referring to in the report? A. C1 B. C2 C. C3 D. C4 E. C5

C. The most superiorly positioned intervertebral disc is between the C2 to C3 vertebrae. In the cervical region the spinal nerves exit superior to their corresponding vertebrae and take a somewhat horizontal path. The C3 nerve therefore exits through the C2 to C3 intervertebral foramen and would be affected by a posterolateral disc herniation at this level. The C1 nerve exists between the C1 vertebra and the occipital bone of the cranium and would not be affected. The C2 nerve passes superior to the second vertebra and would not be affected by a herniated disc between C2 and C3. C4 and C5 both exit superior to their corresponding vertebrae which is below the level of the herniated disc and will therefore not be affected.

In a report of a radiograph of the cervical spine the radiologist wrote the following: "Severe narrowing of the C7-T1 intervertebral foramen (IVF) on the left." Which nerve was most likely compressed as a result of this finding? A. C6 B. C7 C. C8 E. T1

C. There are seven (7) cervical vertebrae and eight (8) cervical spinal nerves. Nerves C1 to C7 exit superior to their corresponding vertebrae, whereas nerve C8 exits inferiorly to the C7 vertebra. The nerves of the thoracic and subsequent regions all exit inferior to their corresponding vertebrae.

What is the difference between the sign of benediction and the claw hand?

CLAW HAND -Damage to ulnar nerve -Permanent position of hand at rest SIGN OF BENEDICTION - Median nerve injury -On active attempt to flex digits

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Calcification of the superior transverse scapular ligament may trap or compress the suprascapular nerve as it passes through the scapular notch under the superior transverse scapular ligament, affecting functions of the supraspinatus and infraspinatus muscles

Injury to the ulnar nerve:

Commonly caused by a fracture of the medial epicondyle and results in a claw hand, in which the ring and little fingers are hyperextended at the metacarpophalangeal joints and flexed at the interphalangeal joints. It results in loss of abduction and adduction of the fingers and flexion of the metacarpophalangeal joints because of the paralysis of the palmar and dorsal interossei muscles and the medial two lumbricals. It also produces wasting of the hypothenar eminence and palm and also leads to loss of adduction of the thumb because of the paralysis of the adductor pollicis muscle.

Skeletal System

Consists of the axial skeleton (bones of the head, vertebral column, ribs, and sternum) and the appendicular skeleton (bones of the extremities).

Veins

Contain valves that prevent the reflux of blood and have venae comitantes that closely accompany muscular arteries in the limbs.

A 36-year-old man was found guilty of first-degree murder and sentenced to death by judicial hanging. The radiological image below shows the vertebra that is fractured as a result of the hanging. The mechanism of injury resulting in death is forcible hyperextension resulting in a fracture of which of the following structures? A. Odontoid process B. Transverse process C. Lateral mass D. Pedicle (pars articularis) E. Spinous process

D. *Hangman's fracture:* -Fracture of the Pars Interarticularis -Hyperextension of the head on the neck C2 vertebrae is displaced anteriorly -Injury to spinal cord or brainstem occurs resulting in quadriplegia or death

A 45-year-old male driver involved in a motor vehicle crash was taken to the emergency department and MRI revealed a complete tear of the right alar ligament. None of the other ligaments of the upper cervical spine were torn. Upon physical examination, which of the following cervical spine movements will be most likely increased as a result of the tear? A. Flexion B. Extension C. Lateral flexion D. Rotation E. Abduction

D. *The alar ligament connects the dens to the medial surface of the occipital condyles.* It limits excessive rotation of the atlanto-axial joints. Flexion and extension of the upper cervical spine occur at the atlanto-occipital joints and the zygapophysial joints. Lateral flexion (abduction) as a combination movement at the uncovertebral joints (of Luschka). These are not limited by the alar ligament.

A 62-year-old man is admitted to the emergency department after a severe car crash resulting in a whiplash injury. MRI examination reveals several hairline vertebral fractures in the cervical region impinging the dorsal primary rami of the same levels. Two months after the injury the patient recovered well, however, there is still some weakness in the function of a muscle. Which of the following muscles is most likely affected? A. Rhomboid major B. Levator scapulae C. Rhomboid minor D. Semispinalis capitis E. Latissimus dorsi

D. Semispinalis capitis is the only muscle among the choices that is supplied by the dorsal rami. All of the other muscles are supplied by the ventral rami. The rhomboid major and minor are innervated by the ventral primary rami of the dorsal scapular nerve. The levator scapulae is innervated by branches of C4 and C5, as well as from branches of dorsal scapular nerve. The latissimus dorsi is innervated by thoracodorsal nerve.

A 32-year-old man was lifting heavy weights during an intense training session. He felt severe pain radiating to the posterior aspect of his right thigh and leg. He was taken to hospital where an MRI scan revealed a ruptured intervertebral disc. Which of the following nerves was most likely affected? A. L2 B. L3 C. L4 D. L5 E. S1

D. The herniated disc is between vertebrae L4 and L5. In the lumbar region spinal nerves exit below their corresponding vertebrae in which case the L4 nerve would pass superior to the herniation. As the L5 nerve crosses the intervertebral disc to exit below the fifth lumbar vertebra it will be compressed by the herniation. Compression of nerves L2, L3, and S1 would produce symptoms different to those seen in this patient.

A 45-year-old man was injured in a motor vehicle crash and brought to the emergency department. Radiographs of the upper cervical spine revealed a type III dens fracture demonstrated by a horizontal radiolucent line on the superior half of the posterior aspect of the C2 vertebral body. Which of the following ligaments most likely has direct attachment to the bony area where the fracture was located? A. Apical ligament of dens B. Superior longitudinal band of cruciform ligament C. Transverse ligament of atlas D. Inferior longitudinal band of cruciform ligament E. Ligamenta flava

D. The inferior longitudinal band of the cruciform ligament runs inferiorly from the transverse ligament of the atlas and attaches to the posterosuperior aspect of the vertebral body of the axis (C2). The transverse ligament of the atlas spans the distance between the medial aspects of the lateral masses, holding the dens in place. The superior longitudinal band of the cruciform ligament runs from the transverse cervical ligament superiorly to attach to the occiput. The apical ligament runs from the tip of the dens to the anterior margin of the foramen magnum. The ligamentum flavum is located in the vertebral canal and connects the laminae of adjacent vertebrae

A 38-year-old man presents to the emergency department with complaints of lower back pain during the past 5 days. Examination revealed tenderness of the spine over the L5 vertebra with an obvious "step-off" defect at that level. There was some weakness of the limbs. An MRI examination revealed an anterior displacement of the L5 vertebral body and narrowing of the vertebral canal. This pathology will most likely be associated with which of the following? A. Compression of the spinal cord and bilateral lower limb weakness B. Compression of the spinal cord and unilateral lower limb weakness C. Compression of the spinal nerve roots and L5 with unilateral lower limb weakness D. Compression of the cauda equina and bilateral lower limb weakness E. Compression of the cauda equina and low back pain only

D. The spinal cord ends at the level between the L1/L2 vertebra but the spinal nerves continue as the caudal equina below this level. As a result, narrowing of the canal at the level of L5 will impact on all of the nerves resulting in bilateral lower limb weakness.

A 54-year-old woman is admitted to the emergency department due to increasing back pain over the preceding year. MRI reveals that her intervertebral discs have been compressed. It is common for the discs to decrease in size in people older than 40, and this can result in spinal stenosis and disc herniation. At which locations are the spinal nerves most likely to be compressed? A.Between the denticulate ligaments B.As they pass through the vertebral foramen C.Between the superior and inferior articular facets D.Between inferior and superior vertebral notches E.Between the superior and inferior intercostovertebral joints

D. This question tests anatomic knowledge relating to typical vertebra and the spinal cord. Intervertebral disc herniations occur when the nucleus pulposus of the intervertebral disc protrudes through the anulus fibrosus into the intervertebral foramen or vertebral canal.

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Dislocation (subluxation) of the shoulder joint occurs usually in the anteroinferior direction because of the lack of support by tendons of the rotator cuff. It may damage the axillary nerve and the posterior humeral circumflex vessels. Referred pain to the shoulder most probably indicates involvement of the phrenic nerve (or diaphragm). The supraclavicular nerve (C3-C4), which supplies sensory fibers over the shoulder, has the same origin as the phrenic nerve (C3-C5), which supplies the diaphragm. Examples of referred pain are gallbladder pain radiating to right shoulder and splenic pain radiating to left shoulder.

A 70-year-old man with prostate cancer is experiencing sharp shooting pains radiating from his neck into the upper limb. An MRI of his spine demonstrates a small metastatic mass in the cervical region extending into the left intervertebral foramen between C6 and C7. The intervertebral discs appear normal. Which neural structure is most likely being compressed by the metastatic mass to account for the pain? A. C8 spinal nerve B. Dorsal horn of C6 spinal cord segment C. C6 spinal nerve D. Dorsal horn of C7 spinal nerve E. C7 spinal nerve

E. In the cervical region, spinal nerves exit the vertebral column above their named vertebrae. From the thoracic region and below the spinal nerves exit the vertebral column below their named vertebrae

A 45-year-old woman states that she has experienced moderate pain for 2 years over her left lower back; pain that radiates to her left lower limb. She states that after lifting a case of soft drinks, the pain suddenly became intense. She was admitted to the emergency department. Radiologic examination revealed intervertebral disc herniation between vertebral levels L4 and L5. Which of the following nerves was most likely affected by the disc herniation? A. L1 B. L2 C. L3 D. L4 E. L5

E. Disc herniation in the lumbar region between L4 and L5 affects the L5 spinal nerve roots. Even though the L4 spinal nerve root lies directly between the L4 and L5 vertebrae, it exits from the spinal canal superior to the intervertebral disc, whereas the L5 spinal nerve root lies directly posterior to the disc. *EXCEPTION TO THE RULE*

An 8-year-old girl was brought to a pediatrician for a routine physical examination. The figure associated with this question is a photograph of the child. Which of the following best describes the embryologic basis for this child's condition? A.Underdevelopment of the secondary ossification center in the vertebral arch B.Underdevelopment of the primary ossification center in the spinous process C.Underdevelopment of the primary ossification center in the vertebral body D.Underdevelopment of the secondary ossification center in the vertebral body E.Underdevelopment of the primary ossification center in the vertebral arch

E. The patient in the figure above has spina bifida occulta. This is a developmental condition resulting from incomplete ossification and failure of fusion of the vertebral arches. Three primary ossification centers should be present in the fetus by the eighth week: one in the centrum (to form the vertebral body) and one in each half of the vertebral arch. Five secondary ossification centers develop in the vertebrae after puberty: one at the tip of the spinous processes, the tips of the transverse processes, and on the inferior and superior rims of the vertebral body.

A 35-year-old man is admitted to the emergency department after a severe car crash. The emergency medicine physician examines the patient and observes what is shown in Figure 1-1. Which of the following functions will the patient most likely be unable to perform during physical examination? A.Lateral rotation of the shoulder joint B.Abduction of the shoulder joint from 0 to 90 degrees C.Flexion of the shoulder joint D.Extension of the shoulder joint E.Abduction of the shoulder joint above 90 degrees

E: In this image, the patient has a winged scapula. This occurs as a result of damage to the long thoracic nerve, which innervates the serratus anterior muscle. The functions of this muscle are protraction of the scapula and superior rotation of the glenoid fossa. The supraspinatus abducts the arm for about the first 12 degrees, and then the deltoid abducts the arm to about 90 degrees. Elevating the arm further requires rotation of the scapula (including superior rotation of the glenoid fossa) that is normally done by the serratus anterior.

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Fertilization occurs in the ampulla of the uterine tube, and a fertilized oocyte forms a blastocyst by day 7 after fertilization and becomes embedded or implanted in the wall of the uterus during the progestational (secretory) phase of the menstrual cycle. Fertilization is the process beginning with the penetration of the secondary oocyte by the sperm and completed by fusion of the male and female pronuclei.

Spinal epidural space

Found superficially to the dura mater. It is a fat-filled space extending from C1 to the sacrum.

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Fracture of the greater tuberosity commonly occurs by direct trauma or by violent contractions of the supraspinatus muscle. The bone fragment has the attachments of the supraspinatus, infraspinatus, and teres minor muscles, whose tendons form parts of the rotator cuff. Fracture of the *esser tuberosity accompanies* posterior dislocation of the shoulder joint, and the bone fragment has the insertion of the *subscapularis tendon.* Fracture of the surgical neck may injure the axillary nerve and the posterior humeral circumflex artery as they pass through the quadrangular space.

KNOW THIS:

Hangman fracture is a fracture of the pedicles of the axis (C2), which may occur as a result of judicial hanging or automobile accidents. In this fracture, the cruciform ligament is torn and the spinal cord is crushed, causing death.

Pia Mater

Has lateral extensions (denticulate ligaments) between dorsal and ventral roots of spinal nerves and an inferior extension known as the filum terminale

The ligamentum flavum:

Helps maintain upright posture by connecting the laminae of two adjacent vertebrae.

Lateral wall of axilla

Intertubercular groove of the humerus

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If you are given a question which discusses the dislocation of the shoulder joint then the affected muscle may be a SITS muscle.

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Injury to the axillary nerve is commonly caused by a fracture of the surgical neck of the humerus or inferior dislocation of the humerus. It results in weakness of lateral rotation and abduction of the arm (the supraspinatus can abduct the arm but not to a horizontal level).

Injury to the radial nerve

Injury to the radial nerve is commonly caused by a fracture of the midshaft of the humerus. It results in loss of function in the extensors of the forearm, hand, metacarpals, and phalanges. It also results in the loss of wrist extension, leading to wrist drop, and produces a weakness of abduction and adduction of the hand.

Posterior Longitudinal Ligament

Interconnects the vertebral bodies and intervertebral disks posteriorly and narrows as it descends. Limits flexion of the vertebral column and resists gravitational pull.

Ligamentum nuchae:

Limits excessive flexion of the cervical spine and serves as an attachment for muscles.

Secondary curvatures

Located in the *cervical and lumbar regions* and develop after birth and during infancy.

Primary curvatures

Located in the *thoracic and sacral regions* and develop during embryonic and fetal periods The primary curves (thoracic and sacral curvatures) form during fetal development. The secondary curves develop after birth. The cervical curvature forms as a result of lifting the head and the lumbar curvature forms as a result of walking.

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Lumbar puncture is generally performed at the level of L4, L5. The spinal cord ends at the level of L1/L2 in adults and at the level of L2/L3 in newborns.

Fracture of the medial epicondyle

May damage the ulnar nerve. This nerve may be compressed in a groove behind the medial epicondyle "funny bone," causing numbness.

Fracture of the shaft of the humerus

May injure the radial nerve and deep brachial artery in the spiral groove

KNOW THIS:

Posterior intercostal arteries supply the deep back muscles, which are responsible for extending and laterally bending the trunk.

Whiplash injury of the neck:

Produced by a force that drives the trunk forward while the head lags behind, causing the head (with the upper part of the neck) to hyperextend and the lower part of the neck to hyperflex rapidly, as occurs in rear-end automobile collisions. This injury occurs frequently at the junction of vertebrae C4 and C5; thus, vertebrae C1 to C4 act as the lash, and vertebrae C5 to C7 act as the handle of the whip. It results in neck pain, stiff neck, and headache and can be treated by supporting the head and neck with a cervical collar that is higher in the back than in the front; the collar keeps the cervical vertebral column in a flexed position.

Meningomyelocele

Protrusion of the meninges and spinal cord through the unfused arch of the vertebra.

Seventh Cervical Vertebra (C7)

Provides an attachment site for the ligamentum nuchae, supraspinous ligaments, and numerous back muscles.

A 25-year-old man with congenital abnormalities at birth has a lesion of the dorsal scapular nerve, making him unable to adduct his scapula. Which of the following muscles is most likely paralyzed? (A) Semispinalis capitis (B) Rhomboid major (C) Multifidus (D) Rotator longus (E) Iliocostalis

The Answer is B. *The rhomboid major is a superficial muscle of the back; is innervated by the dorsal scapular nerve, which arises from the ventral primary ramus of the fifth cervical nerve; and adducts the scapula.* The semispinalis capitis, multifidus, rotator longus, and iliocostalis muscles are deep muscles of the back, are innervated by dorsal primary rami of the spinal nerves, and have no attachment to the scapula.

After a 26-year-old man's car was broadsided by a large truck, he is brought to the emergency department with multiple fractures of the transverse processes of the cervical and upper thoracic vertebrae. Which of the following muscles might be affected? (A) Trapezius (B) Levator scapulae (C) Rhomboid major (D) Serratus posterior superior (E) Rectus capitis posterior major

The Answer is B. The levator scapulae arise from the transverse processes of the upper cervical vertebrae and inserts on the medial border of the scapula. The other muscles are attached to the spinous processes of the vertebrae.

A middle-aged coal miner injures his back after an accidental explosion. His magnetic resonance imaging (MRI) scan reveals that his spinal cord has shifted to the right because the lateral extensions of the pia mater were torn. Function of which of the following structures is most likely impaired? (A) Filum terminale internum (B) Coccygeal ligament (C) Denticulate ligament (D) Choroid plexus (E) Tectorial membrane

The Answer is C. The denticulate ligament is a lateral extension of the pia mater. *The filum terminale (internum) is an inferior extension of the pia mater* from the tip of the conus medullaris. The coccygeal ligament, which is also called the filum terminale externum or the filum of the dura, extends from the tip of the dural sac to the coccyx. The vascular choroid plexuses produce the cerebrospinal fluid (CSF) in the ventricles of the brain. The tectorial membrane is an upward extension of the posterior longitudinal ligaments from the body of the axis to the basilar part of the occipital bone.

A 27-year-old stuntman is thrown out of his vehicle prematurely when the car used for a particular scene speeds out of control. His spinal cord is crushed at the level of the fourth lumbar spinal segment. Which of the following structures would most likely be spared from destruction? (A) Dorsal horn (B) Ventral horn (C) Lateral horn (D) Gray matter (E) Pia mater

The Answer is C. The lateral horns, which contain sympathetic preganglionic neuron cell bodies, are present between the first thoracic and second lumbar spinal cord levels (T1-L2). The lateral horns of the second, third, and fourth sacral spinal cord levels (S2-S4) contain parasympathetic preganglionic neuron cell bodies. The entire spinal cord is surrounded by the pia mater and has the dorsal horn, ventral horn, and gray matter. Note that the fourth lumbar spinal cord level is not the same as the fourth vertebral level.

A crush injury of the vertebral column can cause the spinal cord to swell. Which structure would be trapped between the dura and the vertebral body by the swelling spinal cord? (A) Anterior longitudinal ligament (B) Alar ligament (C) Posterior longitudinal ligament (D) Cruciform ligament (E) Ligamentum nuchae

The Answer is C. The posterior longitudinal ligament interconnects the vertebral bodies and intervertebral disks posteriorly and runs anterior to the spinal cord within the vertebral canal. The ligamentum nuchae is formed by supraspinous ligaments that extend from the seventh cervical vertebra to the external occipital protuberance and crest. The anterior longitudinal ligament runs anterior to the vertebral bodies. The alar and cruciform ligaments also lie anterior to the spinal cord.

In a freak hunting accident, a 17-year-old boy was shot with an arrow that penetrated into his suboccipital triangle, injuring the suboccipital nerve between the vertebral artery and the posterior arch of the atlas. Which of the following muscles would be unaffected by such a lesion? (A) Rectus capitis posterior major (B) Semispinalis capitis (C) Splenius capitis (D) Obliquus capitis superior (E) Obliquus capitis inferior

The Answer is C. The splenius capitis is innervated by dorsal primary rami of the middle and lower cervical nerves. The suboccipital nerve (dorsal primary ramus of C1) supplies the muscles of the suboccipital area, including the rectus capitis posterior major, obliquus capitis superior and inferior, and the semispinalis capitis.

A 44-year-old woman comes to her physician and complains of headache and backache. On examination, she is found to have fluid accumulated in the spinal epidural space because of damage to blood vessels or meninges. Which of the following structures is most likely ruptured? (A) Vertebral artery (B) Vertebral vein (C) External vertebral venous plexus (D) Internal vertebral venous plexus (E) Lumbar cistern

The Answer is D. *The internal vertebral venous plexus is located in the spinal epidural space.* The vertebral artery and vein occupy the transverse foramina of the upper six cervical vertebrae. The external vertebral venous plexus consists of the anterior part, which lies in front of the vertebral column, and the posterior part, which lies on the vertebral arch. The lumbar cistern is the enlargement of the subarachnoid space between the inferior end of the spinal cord and the inferior end of the subarachnoid space.

A 42-year-old woman with metastatic breast cancer is known to have tumors in the intervertebral foramina between the fourth and fifth cervical vertebrae and between the fourth and fifth thoracic vertebrae. Which of the following spinal nerves may be damaged? (A) Fourth cervical and fourth thoracic nerves (B) Fifth cervical and fifth thoracic nerves (C) Fourth cervical and fifth thoracic nerves (D) Fifth cervical and fourth thoracic nerves (E) Third cervical and fourth thoracic nerves

The Answer is D. All cervical spinal nerves exit through the intervertebral foramina above the corresponding vertebrae, except the eighth cervical nerves, which run inferior to the seventh cervical vertebra. All other spinal nerves exit the intervertebral foramina below the corresponding vertebrae. Therefore, the fifth cervical nerve passes between the fourth and fifth cervical vertebrae, and the fourth thoracic nerve runs between the fourth and fifth thoracic vertebrae.

A 38-year-old homebuilder was involved in an accident and is unable to supinate his forearm. Which of the following nerves are most likely damaged? (A) Suprascapular and axillary (B) Musculocutaneous and median (C) Axillary and radial (D) Radial and musculocutaneous (E) Median and ulnar

The answer is D. The supinator and biceps brachii muscles, which are innervated by the radial and musculocutaneous nerves, respectively, produce supination of the forearm. This is a question of two muscles that can supinate the forearm.

A 25-year-old soldier suffers a gunshot wound on the lower part of his back and is unable to move his legs. A neurologic examination and magnetic resonance imaging (MRI) scan reveal injury of the cauda equina. Which of the following is most likely damaged? (A) Dorsal primary rami (B) Ventral primary rami (C) Dorsal roots of the thoracic spinal nerves (D) Ventral roots of the sacral spinal nerves (E) Lumbar spinal nerves

The Answer is D. The cauda equina is the collection of dorsal and ventral roots of the lower lumbar and sacral spinal nerves below the spinal cord. Dorsal and ventral primary rami and dorsal roots of the thoracic spinal nerves and lumbar spinal nerves do not participate in the formation of the cauda equina.

A 34-year-old woman crashes into a tree during a skiing lesson and is brought to a hospital with multiple injuries that impinge the dorsal primary rami of several spinal nerves. Such lesions could affect which of the following muscles? (A) Rhomboid major (B) Levator scapulae (C) Serratus posterior superior (D) Iliocostalis (E) Latissimus dorsi

The Answer is D. The dorsal primary rami of the spinal nerves innervate the deep muscles of the back, including the iliocostalis. The other muscles are the superficial muscles of the back, which are innervated by the ventral primary rami of the spinal nerves.

A 37-year-old man is brought to the emergency department with a crushed second cervical vertebra (axis) that he suffered after a stack of pallets fell on him at work. Which of the following structures would be intact after the accident? (A) Alar ligament (B) Apical ligament (C) Semispinalis cervicis muscle (D) Rectus capitis posterior minor (E) Obliquus capitis inferior

The Answer is D. The rectus capitis posterior minor arises from the posterior tubercle of the atlas and inserts on the occipital bone below the inferior nuchal line. The alar ligament extends from the apex of the dens to the medial side of the occipital bone. The apical ligament extends from the dens of the axis to the anterior aspect of the foramen magnum of the occipital bone. The semispinalis cervicis arises from the transverse processes and inserts on the spinous processes. The obliquus capitis inferior originates from the spine of the axis and inserts on the transverse process of the atlas.

An 18-year-old boy involved in an automobile accident presents with an arm that cannot abduct. His paralysis is caused by damage to which of the following nerves? (A) Suprascapular and axillary (B) Thoracodorsal and upper subscapular (C) Axillary and musculocutaneous (D) Radial and lower subscapular (E) Suprascapular and dorsal scapular

The answer is A. The abductors of the arm are the deltoid and supraspinatus muscles, which are innervated by the axillary and suprascapular nerves, respectively. The thoracodorsal nerve supplies the latissimus dorsi, which can adduct, extend, and rotate the arm medially. The upper and lower subscapular nerves supply the subscapularis, and the lower subscapular nerve also supplies the teres major; both of these structures can adduct and rotate the arm medially. The musculocutaneous nerve supplies the flexors of the arm, and the radial nerve supplies the extensors of the arm. The dorsal scapular nerve supplies the levator scapulae and rhomboid muscles; these muscles elevate and adduct the scapula, respectively.

A 29-year-old man presents with difficulty with fine motor control in his hand. A few weeks ago he fell from a ladder; as he was falling he reached out and grabbed a limb of a tree. Examination reveals a deficit in his ability to abduct and adduct his digits and inability to oppose his thumb on his right hand. Which of the following was most likely injured? A. Lower trunk of the brachial plexus B. Median nerve C. Musculocutaneous nerve D. Ulnar nerve E. Upper trunk of the brachial plexus

The answer is A. The nerve responsible for innervation of the interosseus muscles that are weakened in this patient is the deep branch of the ulnar nerve. Innervation of the muscles responsible for opposition of the thumb is via the recurrent branch of the median nerve. Both of these nerves are formed by the C8 and T1 ventral rami, which combine to form the inferior trunk of the brachial plexus. Damage to either the median or ulnar nerves would not produce both of these symptoms. Median nerve damage would involve all of the exors of the wrist except the exor carpi ulnaris and most digits except for the interphalangeal joints of the 4th and 5th ngers. It will also result in loss of function of the thumb entirely. Ulnar nerve damage will result in weakness of the medial half of exor digitorum profundus (4th and 5th interphalangeal joint exion), as well as the intrinsic muscles of the hand except for the lateral two lumbricals.

A 22-year-old man presented to his family physician with a laceration of the fibrous sheets or bands that cover his body under the skin and invest the muscles. Which of the following structures would most likely be injured? (A) Tendon (B) Fascia (C) Synovial tendon sheath (D) Aponeurosis (E) Ligament

The answer is B. *The fascia is a fibrous sheet or band that covers the body under the skin and invests the muscles.* Although fasciae are fibrous, tendons connect muscles to bones or cartilage, aponeuroses serve as the means of origin or insertion of a flat muscle, and ligaments connect bones to bones or cartilage. Synovial tendon sheaths are tubular sacs filled with synovial fluid that wrap around the tendons.

A 19-year-old college student came to his doctor's office for a neurologic examination. His physician told him that normally synapses are absent in or on which of the following structures? (A) Anterior horn of the spinal cord (B) Dorsal root ganglia (C) Sympathetic chain ganglia (D) Dendrites (E) Cell bodies

The answer is B. Dorsal root ganglia consist of cell bodies of the unipolar or pseudounipolar neurons and have no synapses.

A 27-year-old woman involved in a car accident is brought into the emergency department. Her magnetic resonance imaging reveals that she has a laceration of the spinal cord at the L4 spinal cord level. Which of the following structures would you expect to be intact? (A) Dorsal horn (B) Lateral horn (C) Ventral horn (D) Gray matter (E) White matter

The answer is B. The lateral horns are found in the gray matter of the spinal cord between T1 and L2 and also between S2 and S4. Therefore, the lateral horns are absent at the L4 spinal cord level.

General somatic efferent (GSE)

These fibers provide general motor innervation to skeletal muscles derived from embryonic somites.

A 29-year-old woman with abdominal pain was admitted to a local hospital, and examination shows that a retroperitoneal infection is affecting a purely endocrine gland. Which of the following structures is infected? (A) Ovary (B) Suprarenal gland (C) Pancreas (D) Liver (E) Stomach

The answer is B. The suprarenal gland is a retroperitoneal organ and is a purely endocrine gland. The pancreas is a retroperitoneal organ and contains endocrine cells, but it is not a purely endocrine gland. The liver and stomach contain endocrine cells, but they are not purely endocrine glands and also are surrounded by peritoneum. The ovary contains endocrine cells and is located in the pelvic cavity.

A 17-year-old boy is injured in an automobile accident. He has a fracture of the shaft of the humerus. Which of the following nerves is most likely damaged? (A) Axillary nerve (B) Radial nerve (C) Musculocutaneous nerve (D) Median nerve (E) Ulnar nerve

The answer is B. *The radial nerve runs in the radial groove on the back of the shaft of the humerus with the profunda brachii artery.* The axillary nerve passes around the surgical neck of the humerus. The ulnar nerve passes the back of the medial epicondyle. The musculocutaneous and median nerves are not in contact with the bone, but the median nerve can be damaged by supracondylar fracture.

Which of the following nerves is most likely injured as a result of this accident? (A) Musculocutaneous (B) Axillary (C) Radial (D) Median (E) Ulnar

The answer is B. The axillary nerve runs posteriorly around the surgical neck of the humerus and is vulnerable to injury such as fracture of the surgical neck of the humerus or inferior dislocation of the humerus. The other nerves listed are not in contact with the surgical neck of the humerus.

Which of the following conditions is most likely to occur secondary to the fractured clavicle? (A) A fatal hemorrhage from the brachiocephalic vein (B) Thrombosis of the subclavian vein, causing a pulmonary embolism (C) Thrombosis of the subclavian artery, causing an embolism in the ascending aorta (D) Damage to the upper trunk of the brachial plexus (E) Damage to the long thoracic nerve, causing the winged scapula

The answer is B. The fractured clavicle may damage the subclavian vein, resulting in a pulmonary embolism; cause thrombosis of the subclavian artery, resulting in embolism of the brachial artery; or damage the lower trunk of the brachial plexus.

Following this accident, the boy has weakness in rotating his arm laterally. Which of the following muscles are paralyzed? (A) Teres major and teres minor (B) Teres minor and deltoid (C) Infraspinatus and deltoid (D) Supraspinatus and subscapularis (E) Teres minor and infraspinatus

The answer is B. The lateral rotators of the arm include the teres minor, deltoid, and infraspinatus muscles, but the infraspinatus muscle is innervated by the suprascapular nerve.

A 23-year-old man complains of numbness on the medial side of the arm following a stab wound in the axilla. On examination, he is diagnosed with an injury of his medial brachial cutaneous nerve. In which of the following structures are the cell bodies of the damaged nerve involved in numbness located? (A) Sympathetic chain ganglion (B) Dorsal root ganglion (C) Anterior horn of the spinal cord (D) Lateral horn of the spinal cord (E) Posterior horn of the spinal cord

The answer is B. The medial brachial cutaneous nerve contains sensory (general somatic afferent [GSA]) fibers that have cell bodies in the dorsal root ganglia, and an injury of these GSA fibers causes numbness of the medial side of the arm.

During the procedure, the needle hits a nerve medial to the artery. Which of the following nerves is most likely damaged? (A) Radial (B) Median (C) Ulnar (D) Lateral antebrachial (E) Medial antebrachial

The answer is B. The median nerve is damaged because it lies medial to the brachial artery. The bicipital aponeurosis lies on the brachial artery and the median nerve. The V-shaped cubital fossa contains (from medial to lateral) the median nerve, brachial artery, biceps tendon, and radial nerve. The ulnar nerve runs behind the medial epicondyle; the lateral and medial antebrachial cutaneous nerves are not closely related to the brachial artery.

A 21-year-old patient has a lesion of the upper trunk of the brachial plexus (Erb-Duchenne paralysis). Which of the following is the most likely diagnosis? (A) Paralysis of the rhomboid major (B) Inability to elevate the arm above the horizontal (C) Arm tending to lie in medial rotation (D) Loss of sensation on the medial side of the arm (E) Inability to adduct the thumb

The answer is C. *A lesion of the upper trunk of the brachial plexus results in a condition called "waiter's tip hand," in which the arm tends to lie in medial rotation because of paralysis of lateral rotators and abductors of the arm.* The long thoracic nerve, which arises from the root (C5-C7) of the brachial plexus, innervates the serratus anterior muscle that can elevate the arm above the horizontal. The dorsal scapular nerve, which arises from the root (C5), innervates the rhomboid major. The medial side of the arm receives cutaneous innervation from the medial brachial cutaneous nerve of the medial cord. The adductor pollicis is innervated by the ulnar nerve.

A patient presents with a loss of sensation to the skin over the shoulder. Injury to which of the following nerve cells would most likely affect the conduction of sensory information to the central nervous system? (A) Multipolar neurons (B) Bipolar neurons (C) Unipolar or pseudounipolar neurons (D) Neurons in the ventral horn (E) Neurons in sympathetic chain ganglia

The answer is C. *Sensation from the skin is carried by GSA fibers, and their cells are unipolar or pseudounipolar types located in the dorsal root ganglia.* Multipolar neurons and neurons in the ventral horn and in sympathetic chain ganglia are motor neurons. Bipolar neurons are sensory neurons, but they are not somatic sensory neurons.

A 9-year-old boy is diagnosed with multiple sclerosis (MS). Which of the following nervous structures would most likely be affected by this disease? (A) Trigeminal ganglion (B) Superior cervical ganglion (C) Optic nerve (D) Facial nerve (E) Spinal accessory nerve

The answer is C. Multiple sclerosis affects only axons in the CNS (spinal cord and brain) that have myelin sheaths formed by oligodendrocytes. The optic nerve is considered to be part of the CNS, as it is derived from an outpouching of the diencephalon. All other nervous structures are in the PNS and have their myelin sheaths formed by Schwan cells.

Which of the following muscles is most likely paralyzed as a result of this accident? (A) Extensor pollicis brevis (B) Abductor pollicis longus (C) Abductor pollicis brevis (D) Adductor pollicis (E) Opponens pollicis

The answer is D. The ulnar nerve innervates the adductor pollicis muscle. The radial nerve innervates the abductor pollicis longus and extensor pollicis brevis muscles, whereas the median nerve innervates the abductor pollicis brevis and opponens pollicis muscles.

A 12-year-old boy walks in; he fell out of a tree and fractured the upper portion of his humerus. Which of the following nerves are intimately related to the humerus and are most likely to be injured by such a fracture? (A) Axillary and musculocutaneous (B) Radial and ulnar (C) Radial and axillary (D) Median and musculocutaneous (E) Median and ulnar

The answer is C. *The axillary nerve passes posteriorly around the surgical neck of the humerus, and the radial nerve lies in the radial groove of the middle of the shaft of the humerus.* The ulnar nerve passes behind the medial epicondyle, and the median nerve is vulnerable to injury by supracondylar fracture of the humerus, but these nerves lie close to or in contact with the lower portion of the humerus. The musculocutaneous nerve is not in direct contact with the humerus.

A 17-year-old boy with a stab wound received multiple injuries on the upper part of the arm and required surgery. If the brachial artery were ligated at its origin, which of the following arteries would supply blood to the profunda brachii artery? (A) Lateral thoracic (B) Subscapular (C) Posterior humeral circumflex (D) Superior ulnar collateral (E) Radial recurrent

The answer is C. *The posterior humeral circumflex artery anastomoses with an ascending branch of the profunda brachii artery*, whereas the lateral thoracic and subscapular arteries do not. The superior ulnar collateral and radial recurrent arteries arise inferior to the origin of the profunda brachii artery.

A 17-year-old boy fell from his motorcycle and complains of numbness of the lateral part of the arm. Examination reveals that the axillary nerve is severed. Which of the following types of axons is most likely spared? (A) Postganglionic sympathetic axons (B) Somatic afferent axons (C) Preganglionic sympathetic axons (D) General somatic efferent axons (E) General visceral afferent axons

The answer is C. The axillary nerve contains no preganglionic sympathetic general visceral efferent (GVE) fibers, but it contains postganglionic sympathetic GVE fibers. The axillary nerve also contains GSA, GSE, and general visceral afferent (GVA) fibers.

This accident most likely leads to the damage of which of the following arteries? (A) Axillary (B) Deep brachial (C) Posterior humeral circumflex (D) Superior ulnar collateral (E) Scapular circumflex

The answer is C. The posterior humeral circumflex artery accompanies the axillary nerve that passes around the surgical neck of the humerus.

A man is unable to hold typing paper between his index and middle fingers. Which of the following nerves was likely injured? (A) Radial nerve (B) Median nerve (C) Ulnar nerve (D) Musculocutaneous nerve (E) Axillary nerve

The answer is C. To hold a typing paper, the index finger is adducted by the palmar interosseous muscle, and the middle finger is abducted by the dorsal interosseous muscle. Both muscles are innervated by the ulnar nerve.

A 16-year-old patient received a laceration of the posterior intercostal nerves by a penetrated knife blade. A pathologist obtained needle biopsy tissues and observed numerous degenerated cell bodies of the unipolar or pseudounipolar neurons. Which of the following structures would most likely provide the abnormal cell morphology? (A) Ventral horn of the spinal cord (B) Lateral horn of the spinal cord (C) Dorsal horn of the spinal cord (D) Dorsal root ganglion (E) Sympathetic chain ganglion

The answer is D. *Ventral, lateral, and dorsal horns and sympathetic chain ganglia contain multipolar neurons, whereas the dorsal root ganglion contains unipolar or pseudounipolar neurons.* A laceration of the intercostal nerve injures GSE, postganglionic sympathetic general visceral efferent (GVE), general visceral afferent (GVA), and general somatic afferent (GSA) fibers, whose cell bodies are located in the anterior horn, sympathetic chain ganglia, and dorsal root ganglia.

A 7-year-old boy falls from a tree house and is brought to the emergency department of a local hospital. On examination, he has weakness in rotating his arm laterally because of an injury of a nerve. Which of the following conditions is most likely to cause a loss of this nerve function? (A) Injury to the lateral cord of the brachial plexus (B) Fracture of the anatomic neck of the humerus (C) Knife wound on the teres major muscle (D) Inferior dislocation of the head of the humerus (E) A tumor in the triangular space in the shoulder region

The answer is D. Inferior dislocation of the head of the humerus may damage the axillary nerve, which arises from the posterior cord of the brachial plexus, runs through the quadrangular space accompanied by the posterior humeral circumflex vessels around the surgical neck of the humerus, and supplies the deltoid and teres minor, which are lateral rotators of the arm.

The police bring in a murder suspect who has been in a gunfight with a police officer. The suspect was struck by a bullet in the arm; his median nerve has been damaged. Which of the following symptoms is likely produced by this nerve damage? (A) Waiter's tip hand (B) Claw hand (C) Wrist drop (D) Ape hand (E) Flattening of the hypothenar eminence

The answer is D. Injury to the median nerve produces the ape hand (a hand with the thumb permanently extended). Injury to the radial nerve results in loss of wrist extension, leading to wrist drop. Damage to the upper trunk of the brachial plexus produces waiter's tip hand. A claw hand and flattening of the hypothenar eminence or atrophy of the hypothenar muscles result from damage to the ulnar nerve.

A 36-year-old woman received a firstdegree burn on her neck, arm, and forearm from a house fire. Which of the following skin structures or functions is most likely damaged or impaired? (A) GSE nerves (B) Parasympathetic general visceral efferent nerves (C) Trophic hormone production (D) Exocrine gland secretion (E) Vitamin A production

The answer is D. Skin has sweat glands and sebaceous glands, which are exocrine glands. Skin produces vitamin D, but it does not produce a trophic hormone and does not produce vitamin A. In addition, skin contains no GSE and parasympathetic GVE nerve fibers.

A 14-year-old boy falls on his outstretched hand and has a fracture of the scaphoid bone. The fracture is most likely accompanied by a rupture of which of the following arteries? (A) Brachial artery (B) Ulnar artery (C) Deep palmar arterial arch (D) Radial artery (E) Princeps pollicis artery

The answer is D. The scaphoid bone forms the floor of the anatomic snuffbox, through which the radial artery passes to enter the palm. The radial artery divides into the princeps pollicis artery and the deep palmar arch.

KNOW THIS:

The functions of the serratus anterior are protraction and rotation of the scapula. The rhomboid major and minor adduct the scapula, the serratus posterior inferior depresses the lower ribs, the levator scapulae elevates the scapula, and the latissimus dorsi adducts, extends, and medially rotates the arm.

A 29-year-old man comes in with a stab wound, cannot raise his arm above horizontal, and exhibits a condition known as "winged scapula." Which of the following structures of the brachial plexus would most likely be damaged? (A) Medial cord (B) Posterior cord (C) Lower trunk (D) Roots (E) Upper trunk

The answer is D. Winged scapula is caused by paralysis of the serratus anterior muscle that results from damage to the *long thoracic nerve, which arises from the roots of the brachial plexus (C5-C7).*

A 35-year-old man walks in with a stab wound to the most medial side of the proximal portion of the cubital fossa. Which of the following structures would most likely be damaged? (A) Biceps brachii tendon (B) Radial nerve (C) Brachial artery (D) Radial recurrent artery (E) Median nerve

The answer is E. The contents of the cubital fossa from medial to lateral side are the median nerve, the brachial artery, the biceps brachii tendon, and the radial nerve. Thus, the median nerve is damaged. The radial recurrent artery ascends medial to the radial nerve.

A 16-year-old patient has weakness flexing the metacarpophalangeal joint of the ring finger and is unable to adduct the same finger. Which of the following muscles is most likely paralyzed? (A) Flexor digitorum profundus (B) Extensor digitorum (C) Lumbrical (D) Dorsal interosseous (E) Palmar interosseous

The answer is E. The dorsal and palmar interosseous and lumbrical muscles can flex the metacarpophalangeal joints and extend the interphalangeal joints. The palmar interosseous muscles adduct the fingers, while the dorsal interosseous muscles abduct the fingers. The flexor digitorum profundus flexes the distal interphalangeal (DIP) joints.

A patient comes in with a gunshot wound and requires surgery in which his thoracoacromial trunk needs to be ligated. Which of the following arterial branches would maintain normal blood flow? (A) Acromial (B) Pectoral (C) Clavicular (D) Deltoid (E) Superior thoracic

The answer is E. The superior thoracic artery is a direct branch of the axillary artery. The thoracoacromial trunk has four branches: the pectoral, clavicular, acromial, and deltoid.

The lateral portion of the fractured clavicle is displaced downward by which of the following? (A) Deltoid and trapezius muscles (B) Pectoralis major and deltoid muscles (C) Pectoralis minor muscle and gravity (D) Trapezius and pectoralis minor muscles (E) Deltoid muscle and gravity

The answer is E. The lateral fragment of the clavicle is displaced downward by the pull of the deltoid muscle and gravity. The medial fragment is displaced upward by the pull of the sternocleidomastoid muscle. None of the other muscles are involved.

KNOW THIS:

The brachialis and supinator muscles form the floor of the cubital fossa. The brachioradialis and pronator teres muscles form the lateral and medial boundaries, respectively.

KNOW THIS:

The cerebrospinal fluid (CSF) is found in the lumbar cistern, which is a subarachnoid space in the lumbar area. CSF is produced by vascular choroid plexuses in the ventricles of the brain, circulated in the subarachnoid space, and filtered into the venous system through the arachnoid villi and arachnoid granulations.

KNOW THIS:

The cerebrospinal fluid (CSF) is located in the subarachnoid space, between the arachnoid layer and the pia mater. *In a lumbar puncture, the needle penetrates the skin, fascia, ligamentum flavum,* epidural space, dura mater, subdural space, and arachnoid mater.

KNOW THIS:

The clavicle is the only upper limb bone to develop through intramembranous ossification. It is the first upper limb bone to begin ossification and is the last bone to complete ossification.

The cruciform ligament of atlas:

The cruciform ligament of atlas is a cruciate ligament in the neck forming part of the atlanto-axial joint.

The axillary nerve innervates:

The deltoid and teres minor muscles

KNOW THIS:

The dorsal scapular artery (or descending scapular artery) is a blood vessel which supplies the levator scapulae, rhomboids, and trapezius. It most frequently arises from the subclavian artery (the second or third part), but a quarter of the time it arises from the transverse cervical artery.

KNOW THIS:

The dorsal scapular nerve innervates the levator scapulae and rhomboid muscles, whereas the accessory nerve innervates the trapezius and sternocleidomastoid muscles. The serratus posterior superior is innervated by ventral primary rami of the spinal nerves, whereas the splenius cervicis and erector spinae are innervated by dorsal primary rami of the spinal nerves.

KNOW THIS:

The erector spinae muscle is supplied by the dorsal rami, which carry motor, sensory, and autonomic fibers. The cell bodies of the motor part are found in the anterior horn, while the cell bodies of the sensory fibers are found in the dorsal root ganglia. The cell bodies of the sympathetic fibers are found in the paravertebral ganglia.

KNOW THIS:

The highest points of the iliac crests are used as a landmark for locating the position of L4 to L5 for a lumbar puncture; they are identified and traced medially toward the vertebral column (Tuffier's line).

KNOW THIS:

The infraspinatus is responsible for lateral rotation of the humerus (along with the teres minor)

KNOW THIS:

The intercostobrachial nerve arises from the lateral cutaneous branch of the second intercostal nerve and pierces the intercostal and serratus anterior muscles.

KNOW THIS:

The internal vertebral plexus (of Batson) surrounds the dura mater in the spinal epidural space; hence the bleeding would cause the hematoma in that space.

KNOW THIS:

The intervertebral disc consists of an outer anulus fibrosus and inner nucleus pulposus. The tensile strength comes from the anulus fibrosus, which limits rotation between vertebrae.

What is the secondary cartilaginous (symphysis) joint?

The intervertebral disk

KNOW THIS:

The trapezius receives blood from the superficial branch of the transverse cervical artery. The latissimus dorsi receives blood from the thoracodorsal artery. The rhomboid major receives blood from the deep or descending branch of the transverse cervical artery.

KNOW THIS:

The latissimus dorsi attaches to the spinous processes of vertebrae T7 to L5 and the floor of the intertubercular sulcus.

KNOW THIS:

The ligamentum flavum lies within the vertebral canal on the anterior aspect of the vertebral arches connecting the lamina of adjacent vertebrae. Puncturing this ligament allows the needle to enter into the epidural/extradural space for the injection of the anesthetic. Although the posterior longitudinal ligament lies within the spinal canal, it will not be punctured during the procedure.

KNOW THIS:

The loss of CN XI results in drooping of the shoulder due to paralysis of the trapezius

KNOW THIS:

The median cubital vein lies superficial to the bicipital aponeurosis and thus separates it from the brachial artery, which can be punctured during intravenous injections and blood transfusions.

KNOW THIS:

The musculocutaneous nerve arises from the lateral cord of the brachial plexus. Its terminal branch, the lateral cutaneous nerve of the forearm, supplies the sensation of the lateral side of the forearm from the elbow to the wrist.

The thoracoacromial trunk has four branches:

The pectoral, clavicular, acromial, and deltoid

Atlantoaxial joint

The pivot or trochoid joint

KNOW THIS:

The radial nerve accompanies the profunda brachii artery in the radial groove on the posterior aspect of the shaft of the humerus. The posterior humeral circumflex artery accompanies the axillary nerve around the surgical neck of the humerus.

KNOW THIS:

The region bounded by the upper border of the latissimus dorsi, the lateral border of the trapezius, and the medial border of the scapula is known as the triangle of auscultation. Lung sounds can be heard most clearly from this location because minimal tissue intervenes between the skin of the back and the lungs.

KNOW THIS:

The rhomboids are responsible for retraction of the scapula. Therefore, if this nerve is damaged, individuals present with a laterally displaced scapula

KNOW THIS:

The scapular notch transmits the suprascapular nerve below the superior transverse ligament, whereas the suprascapular artery and vein run over the ligament.

KNOW THIS:

The space between the vertebral canal and the dura mater is the epidural space, which contains the internal vertebral venous plexus.

KNOW THIS:

The splenius capitis is supplied by the dorsal rami. The obliquus capitis muscles are innervated by branches of the suboccipital nerve which also supplies the rectus capitus posterior major and minor. The greater occipital nerve supplies the semispinalis capitis

KNOW THIS:

The suprascapular nerve passes through the suprascapular notch, deep to the superior transverse scapular ligament.

KNOW THIS:

The suprascapular notch is closed by superior transverse scapular ligament to form a foramen

The suprascapular nerve supplies

The supraspinatus and infraspinatus muscles

The subscapular nerves innervate:

The teres major and subscapularis muscles

Elevation of the scapula is carried out mainly by:

The trapezius and levator scapulae muscles

Triangle of Auscultation

Triangle of Auscultation ■Is bounded by the upper border of the latissimus dorsi, the lateral border of the trapezius, and the medial border of the scapula. ■Has a floor formed by the rhomboid major. ■Is the site where breathing sounds can be heard most clearly using a stethoscope

Medial wall of axilla

Upper ribs and their intercostal muscles and serratus anterior muscle;

Thoracolumbar (Lumbodorsal) Fascia

■ Invests the deep muscles of the back, having an anterior layer that lies anterior to the erector spinae and attaches to the vertebral transverse process, and a posterior layer that lies posterior to the erector spinae and attaches to the spinous processes. ■ Provides the origins for the latissimus dorsi and the internal oblique and transverse abdominis muscles.

Ganglion

■ Is a collection of neuron cell bodies outside the CNS, and a nucleus is a collection of neuron cell bodies within the CNS.

Surgical Neck

■ Is a narrow area distal to the tubercles that is a common site of fracture and is in contact with the axillary nerve and the posterior humeral circumflex artery.

Triangle of Auscultation

■ Is bounded by the upper border of the latissimus dorsi muscle, the lateral border of the trapezius muscle, and the medial border of the scapula; its floor is formed by the rhomboid major muscle. ■Is the site at which breathing sounds are heard most clearly

Quadrangular Space

■ Is bounded superiorly by the teres minor and subscapularis muscles, inferiorly by the teres major muscle, medially by the long head of the triceps, and laterally by the surgical neck of the humerus. ■ Transmits the axillary nerve and the posterior humeral circumflex vessels.

Triangular Space (Upper)

■ Is bounded superiorly by the teres minor muscle, inferiorly by the teres major muscle, and laterally by the long head of the triceps. ■ Contains the circumflex scapular vessels

Scapular Notch

■ Is bridged by the superior transverse scapular ligament and converted into a foramen that transmits the suprascapular nerve.

Branches from the Medial and Lateral Cords: Median Nerve (C5-T1) of Brachial Plexus

■ Is formed by heads from both the medial and lateral cords. ■ Runs down the anteromedial aspect of the arm but does not branch in the brachium.

Rotator (Musculotendinous) Cuff

■ Is formed by the tendons of the supraspinatus, infraspinatus, teres minor, and subscapularis (SITS); fuses with the joint capsule; and provides mobility. ■ Keeps the head of the humerus in the glenoid fossa during movements and thus stabilizes the shoulder joint.

Clavicle (Collarbone)

■ Is the first bone to begin ossification during fetal development, but it is the last one to complete ossification, at approximately 21 years of age. ■ Is the only long bone to be ossified intramembranously and forms from somatic lateral plate mesoderm.

Intertubercular (Bicipital) Groove

■ Lies between the greater and lesser tubercles, lodges the tendon of the long head of the biceps brachii muscle, and is bridged by the transverse humeral ligament. ■ Provides insertions for the pectoralis major on its lateral lip, the teres major on its medial lip, and the latissimus dorsi on its floor.

Greater Tubercle of Humerus

■ Lies just lateral and distal to the anatomic neck and provides attachments for the supraspinatus, infraspinatus, and teres minor muscles.

KNOW THIS:

■ Preganglionic neurons with cell bodies are located in the CNS, whereas postganglionic neurons with cell bodies are in ganglia in the PNS.

Supraglenoid and Infraglenoid Tubercles

■ Provide origins for the tendons of the long heads of the biceps brachii and triceps brachii muscles, respectively.

Coracoid Process

■ Provides the origin of the coracobrachialis and short head of biceps brachii, the insertion of the pectoralis minor, and the attachment site for the coracoclavicular, coracohumeral, and coracoacromial ligaments and the costocoracoid membrane

Lumbar Vertebrae

■Are distinguished by their large bodies, sturdy laminae, and absence of costal facets. The fifth lumbar vertebra has the largest body of the vertebrae. ■Are characterized by a strong, massive transverse process and have mamillary and accessory processes.

Ligamentum Flavum

■Connects the laminae of two adjacent vertebrae and functions to maintain the upright posture. ■Forms the posterior wall of the vertebral canal between the vertebrae and may be pierced during lumbar (spinal) puncture

Annulus Fibrosus

■Consists of concentric layers of fibrous tissue and fibrocartilage. ■Binds the vertebral column together, retains the nucleus pulposus, and permits a limited amount of movement. ■Acts as a shock absorber.

Nucleus Pulposus

■Is a remnant of the embryonic notochord and is situated in the central portion of the intervertebral disk. ■Consists of reticular and collagenous fibers embedded in mucoid material. ■May herniate or protrude through the annulus fibrosus, thereby impinging on the roots of the spinal nerve. ■Acts as a shock-absorbing mechanism by equalizing pressure.

Coccyx

■Is a wedge-shaped bone formed by the union of the four coccygeal vertebrae. ■Provides attachment for the coccygeus and levator ani muscles.

Lumbar Triangle (of Petit)

■Is formed by the iliac crest, latissimus dorsi, and posterior free border of the external oblique abdominal muscle; its floor is formed by the internal oblique abdominal muscle. It may be the site of an abdominal hernia.

Triangular Space (Lower)

■Is formed superiorly by the teres major muscle, medially by the long head of the triceps, and laterally by the medial head of the triceps. ■ Contains the radial nerve and the profunda brachii (deep brachial) artery