Back Questions (Chapter 1)

A 55-year-old man with severe coughing is admitted to the hospital. Radiographic examination reveals tuberculosis of the right lung, with extension to the thoracic vertebral bodies of T6 and T7, producing a "gibbus deformity." Which of the following conditions is most likely also to be confirmed by radiographic examination?

1 B. Kyphosis is characterized by a "hunchback" due to an abnormal increase in curvature of the thoracic region of the vertebral column. Lordosis, or "swayback," is an increase in lumbar curvature of the spine. Lordosis can be physiologic, such as seen in a pregnant woman. Scoliosis is a lateral curvature of the spine with rotation of the vertebrae. Spina bifida is a neural tube defect characterized by failure of closure of the vertebral arch. Osteoarthritis is a degenerative disorder that affects the articular cartilage of joints and is not specifically related to the thoracic region of the spine.

A 65-year-old male complains of severe back pain and inability to move his left lower limb. Radiographic studies demonstrate the compression of nerve elements at the intervertebral foramen between vertebrae L5 and S1. Which structure is most likely responsible for this space-occupying lesion?

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

A 27-year-old man is admitted to the emergency department after a car crash. Physical examination reveals weakness in medial rotation and adduction of the humerus. Which of the following nerves was most probably injured?

11 A. The thoracodorsal nerve innervates the latissimus dorsi, one of three major muscles that adduct and medially rotate the humerus. The axillary nerve supplies the deltoid muscle, the dorsal scapular supplies the rhomboids and levator scapulae, whereas the spinal accessory innervates the trapezius. None of these nerves medially rotates or adducts the humerus. The radial nerve is responsible for the innervation on the posterior aspect of the arm. The medial and lateral pectoral nerves and the lower subscapular nerve supply the other two medial rotators of the humerus.

A 39-year-old woman complains of an inability to reach the top of her head to brush her hair. History reveals that she had undergone a bilateral mastectomy procedure 2 months earlier. Physical examination demonstrates winging of both of her scapulae. Which nerves were most likely damaged during surgery?

12 C. The long thoracic nerve innervates the serratus anterior, which is responsible for elevation and abduction of the scapula beyond the horizontal level while maintaining its position against the thoracic wall. Along with the thoracodorsal nerve, the long thoracic nerve runs superficially along the thoracic wall and is commonly subject to injury during mastectomy procedures. The axillary nerve, the spinal accessory nerve, and the thoracodorsal nerve supply the deltoid muscle, trapezius muscle, and latissimus dorsi muscles, respectively. The dorsal scapular nerve is responsible for innervation of the rhomboids and levator scapulae. Aside from the long thoracic and thoracodorsal nerves, the remaining nerves do not course along the lateral thoracic wall.

A 19-year-old man is brought to the emergency department after dislocating his shoulder while playing football. Following treatment of the dislocation, he cannot initiate abduction of his arm. An MRI of the shoulder shows a torn muscle. Which muscle was most likely damaged by the injury?

13 D. The rotator cuff muscles are common sites of damage during shoulder injuries. These muscles include the supraspinatus, infraspinatus, teres minor, and subscapularis (SITS). Initiation of abduction of the humerus (the first 15°) is performed by the supraspinatus, followed by the deltoid from 15° to 90°. Above the horizontal, the humerus is abducted by the trapezius and serratus anterior. The teres major and the pectoralis major are responsible for medial rotation and adduction of the humerus. These muscles are therefore not involved in abduction at the glenohumeral joint.

A 1-year-old girl is brought to the clinic for a routine checkup. The child appears normal except for a dimpling of the skin in the lumbar region with a tuft of hair growing over the dimple. You reassure the mother that this condition is seen in 10% to 25% of births and normally has no ill effects. What is this relatively common condition that results from incomplete embryologic development?

14 C. Spina bifida is a developmental condition resulting from incomplete fusion of the vertebral arches within the lumbar region. Spina bifida occulta commonly presents asymptomatically with a tuft of hair and a small dimple in the overlying skin. More severe forms (spina bifida cystica) are categorized into three types: Spina bifida cystica with meningocele presents with protrusion of the meninges through the unfused vertebral arches. Spina bifida with meningomyelocele is characterized by protrusion both of the meninges and CNS tissues and is often associated with neurologic deficits. Rachischisis, also known as spina bifida cystica with myeloschisis, results from a failure of neural folds to fuse and is characterized by protrusion of the spinal cord or spinal nerves and meninges. GAS 76; GA 21-35

Which nerve fibers carry the sensation of a mosquito bite on the back, just lateral to the spinous process of the T4 vertebra?

15 A. Somatic afferents are responsible for conveying pain, pressure, touch, temperature, and proprioception to the CNS. Afferent fibers carry only sensory stimuli, whereas efferent fibers convey motor information. Visceral innervation is associated with the autonomic nervous system. Visceral afferents generally carry information regarding the physiologic changes of the internal viscera whereas visceral efferents deliver autonomic motor function to three types of tissue: smooth muscle, cardiac muscle, and glandular epithelium.

A 15-year-old female was suspected to have meningitis. To obtain a sample of cerebrospinal fluid by spinal tap in the lumbar region (lumbar puncture), the tip of the needle must be placed in which of the following locations?

16 E. Cerebrospinal fluid is found within the subarachnoid space and is continuous with the ventricles of the brain (CSF flows from the ventricles to the subarachnoid space). The epidural space, positioned between the dura mater and periosteum, is characterized by fat deposits and contains the internal vertebral venous plexus (of Batson). The subdural space, between the arachnoid mater and dura mater, exists only as a potential space and does not contain cerebrospinal fluid. The anterior and posterior longitudinal ligaments traverse the length of the vertebral body.

In the event of intervertebral disk herniation in the cervical region, which of the following ligaments is in an anatomic position to protect the spinal cord from direct compression?

17 B. The posterior longitudinal ligament is the only ligament spanning the posterior aspect of the vertebral bodies and intervertebral disks. With intervertebral disk herniation, the nucleus pulposus of the intervertebral disk 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.

In spinal anesthesia the needle is often inserted between the spinous processes of the L4 and L5 vertebrae to ensure that the spinal cord is not injured. This level is safe because in the adult the spinal cord usually terminates at the disk between which of the following vertebral levels?

18 C. L1 and L2. This is the location of the conus medullaris, a tapered conical projection of the spinal cord at its inferior termination. 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 filium terminale extend beyond the conus medullaris.

A 22-year-old female is diagnosed with Raynaud's disease. In such a case the patient suffers chronic vasospasm in response to cold. This can lead to arterial constriction and painful ischemia, especially in the fingers or toes. Relief from the symptoms in the hands would require surgical division of which of the following neural elements?

19 A. Lower cervical and upper thoracic sympathetic fibers. The sympathetic division of the autonomic nervous system is primarily responsible for vasoconstriction. Separation of ventral or dorsal roots would lead to undesired consequences, such as a loss of motor or sensory activity. Similarly, surgical division of spinal nerves would also have unwanted consequences, but such are not related to the increased arterial constriction and the painful ischemia in the digits. Division of selected sympathetic chain ganglia, however, would decrease the sympathetic outflow to the upper limbs.

A 68-year-old man is admitted to the hospital due to severe back pain. Radiographic examination reveals severe osteoporosis of the vertebral column, with crush fractures of vertebrae L4 and L5. Which of the following parts of the vertebrae are most likely to be fractured in this patient?

2 B. A crush fracture is characterized by compression of the entire vertebral body. The wedge fracture is similar in that it affects the vertebral bodies, but it involves small fractures around the perimeter of the vertebral body. Both of these fractures cause reductions in overall height. Fracture of the spinal, transverse, or superior articular processes can be due to an oblique, transverse, or comminuted fracture. Intervertebral disks are associated with disk herniation, not compression fractures.

A 69-year-old female visits her physician due to severe neck pain. Radiographic studies reveal bony growths (osteophytes) in the intervertebral foramen between vertebrae C2 and C3. Which of the following muscles would be most likely affected by this condition?

20 D. The diaphragm is innervated by the phrenic nerve, which arises from C3 to C5. The rhomboid, serratus anterior, supraspinatus, and latissimus dorsi are innervated by the ventral rami of the brachial plexus (C5 to T1).

A 42-year-old female is diagnosed with constriction of the cervical vertebral canal. A laminectomy of two vertebrae is performed. Which of the following ligaments will most likely also be removed?

21 C. The anterior longitudinal ligament runs along the anterior-most aspect of the vertebral column from C1 to the sacrum and would therefore be unaffected by laminectomy. Denticulate ligaments extend laterally from the pia mater to the arachnoid mater along the length of the spinal cord. The ligamentum flavum is one of the two ligaments found in the vertebral canal and is adherent to the anterior aspect of the vertebral arches. It is thus simultaneously removed upon excision of the lamina. The nuchal ligament is a thick longitudinal extension continuing from the supraspinous ligament at the level of C6 to the external occipital protuberance. The cruciate ligament is an incorrect answer because it is located anterior to the spinal cord, and thus would not be involved in laminectomy.

A 28-year-old pregnant woman is admitted to the obstetrics department for delivery. In the final stages of labor a caudal anesthetic is administered via the sacral hiatus. Into which of the following spaces in the sacral canal is the anesthetic placed?

22 C. The vertebral canal is the longitudinal canal that extends through the vertebrae, containing the meninges, spinal cord, and associated ligaments. The vertebral venous plexus is the valveless network of veins extending longitudinally along the vertebral canal. Neither of these answer choices describes a specific space. The epidural space is found superficially to the dura mater. It is a fat-filled space extending from C1 to the coccyx. The subarachnoid space is a true space containing CSF. It is found within the CNS and extends to the level of S2. The subdural space is a potential space between the dura and the arachnoid mater. Normally these two layers are fused due to the pressure of CSF in the subarachnoid space.

A 12-year-old child was brought to the emergency department by his parents because he has been suffering from a very high fever and severe stiffness in his back. The initial diagnosis is meningitis. The attending physician orders a lumbar puncture to confirm the diagnosis. Upon microscopic examination of the cerebrospinal fluid, hematopoetic cells are seen. Which of the following ligaments is most likely to be penetrated by the needle?

23 D. Lumbar puncture is generally performed at the level of L4, L5. The supraspinous ligament extends between spinous processes on the dorsal aspect of the vertebrae. The needle would bypass this structure. The denticulate ligaments are not correct because they terminate with the conus medullaris at the level of L2 and are located laterally. The anterior longitudinal ligament extends along the most anterior aspect of the vertebral bodies and can be reached only ventrally. The posterior longitudinal ligament is present at the correct vertebral level but will be punctured only if the procedure is performed incorrectly as in this case, where hematopoetic cells were aspirated from the vertebral body anterior to the ligament. The nuchal ligament extends cranially from the supraspinous ligament in the lower cervical region to the skull.

A 25-year-old male race car driver is admitted to the emergency department after a severe car crash. Radiographic studies reveal damage to the tip of the transverse process of the third cervical vertebra, with a significantly large pulsating hematoma. What artery is the most likely to have been damaged?

24 B. The anterior spinal artery is located anteriorly along the spinal cord and is not directly associated with the vertebrae. The vertebral arteries run through the transverse foramina of cervical vertebrae C6 through C1 and are therefore most closely associated with injury to the transverse processes. The ascending cervical artery is a very small branch from the thyrocervical trunk of the subclavian artery, running on the anterior aspect of the vertebrae. The deep cervical artery arises from the costocervical trunk is also a very small artery and courses along the posterior aspect of the cervical vertebrae. The posterior spinal arteries are adherent to the posterior aspect of the spinal cord.

A 79-year-old male retired military veteran presents to the outpatient clinic with an abnormal curva4 ture of the vertebral column. He complains that it has become increasingly painful to walk around town. Upon physical examination he has an abnormally increased thoracic curvature resulting from osteoporosis. Which of the following is the most likely clinical condition of this patient's spine?

25 B. Scoliosis is defined as a lateral deviation of the spinal column to either side. Kyphosis is an increased primary curvature of the spinal column. This curvature is associated with thoracic and sacral regions and is most likely this patient's clinical condition. Spinal stenosis is a narrowing of the vertebral canal and is not directly associated with a displacement of the spinal column. Lordosis is the increased secondary curvature affecting the cervical and lumbar regions. A herniated disk is a rupture of the anulus fibrosus of the intervertebral disk, commonly causing a posterolateral displacement of the nucleus pulposus into the vertebral canal.

A 42-year-old woman complains of pain and stiffness in her neck. She was injured sliding into second base headfirst during her company softball game. Radiographs reveal no fractures of her spine. However, upon physical examination her right shoulder is drooping and she has difficulty in elevating that shoulder. If you ordered an MRI, it would most likely reveal soft tissue damage to which of the following nerves?

26 B. The thoracodorsal nerve innervates the latissimus dorsi, which has no action on the shoulder girdle. The spinal accessory nerve is the eleventh cranial nerve (CN XI) and innervates both the trapezius and sternocleidomastoid muscles. The loss of CN XI results in drooping of the shoulder due to paralysis of the trapezius. In addition to the clinical findings of the MRI, one can test the innervation of this nerve by asking the patient to shrug his or her shoulders against resistance (testing the trapezius), as well as turning his or her head against resistance (testing the sternocleidomastoid). The dorsal scapular nerve innervates the levator scapulae muscle, as well as the rhomboids. The greater occipital nerve is a sensory nerve innervating the posterolateral aspect of the scalp. The axillary nerve is a branch of the brachial plexus and innervates the deltoid and teres minor. It is not involved in shoulder elevation.

A 53-year-old male was in a head-on vehicle collision that resulted in compression of the spinal cord by the dens of the axis, with resulting quadriplegia. Which of the following ligaments was most probably torn?

27 B. The anterior longitudinal ligament runs on the anterior aspect of the vertebrae and is not affected. The transverse ligament of the atlas anchors the dens laterally to prevent posterior displacement of the dens. This ligament has been torn in this injury. The ligamentum flavum is found on the posterior aspect of the vertebral canal and does not contact the anteriorly placed dens. The supraspinous ligament is located along the spinous processes of the vertebrae. The nuchal ligament is a longitudinal extension of the supraspinous ligament above the level of C7.

An 18-year-old female passenger injured in a rollover car crash was rushed to the emergency department. After the patient is stabilized she undergoes physical examination. She demonstrates considerable weakness in her ability to flex her neck, associated with injury to CN XI. Which of the following muscles is most probably affected by nerve trauma?

28 B. The iliocostalis thoracis muscle is found in the deep back and functions to maintain posture. It is not associated with neck flexion. The sternocleidomastoid muscle is innervated by CN XI and functions in contralateral rotation and bilateral flexion of the neck. Rhomboid major and minor are both innervated by the dorsal scapular nerve and serve to adduct the scapulae. Teres major is innervated by the lower subscapular nerve and serves to medially rotate and adduct the humerus.

A 23-year-old male was killed in a high-speed motor vehicle collision after racing his friend on a local highway. When the medical examiner arrives upon the scene, it is determined that the most likely cause of death was a spinal cord injury. Upon confirmation by the autopsy, the medical examiner officially reports that the patient's cause of death was a fracture of the pedicles of the axis (C2). Breaking of which of the following ligaments would be most likely implicated in this fatal injury?

29 C. The pedicles are bony structures connecting the vertebral arches to the vertebral body. The ligamentum flavum runs on the posterior aspect of the vertebral canal and is more closely associated with the lamina than to the pedicles of the vertebrae. The nuchal ligament is a longitudinal extension of the supraspinous ligament from C7 to the occiput, both running on the most posterior aspect of the vertebrae along the spinous processes. The cruciform (also called cruciate) ligament is a stabilizing ligament found in C1/C2. It attaches to the pedicles and helps anchor the dens in situ, but it has been broken in this case. The posterior longitudinal ligament extends the length of the anterior aspect of the vertebral canal and is anterior to the pedicles.

A 45-year-old man is admitted to the hospital because of severe pain in the back and lower limb. Radiographic examination reveals spinal stenosis syndrome. Which of the following conditions is most likely to be confirmed by MRI examination?

3 C. The ligamentum flavum connects the lamina of two adjacent vertebrae and forms the posteriorwall 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 stenosis. The supraspinous and interspinous ligaments connect spinous processes. The anterior longitudinal ligament connects the anterior portion of the vertebral bodies and intervertebral disks. Finally, the nuchal ligament is a thickened extension of the supraspinous ligament above the level of C7.

A 65-year-old male is injured when a vehicle traveling at a high rate of speed hits his car from behind. Radiographic examination reveals that two of his articular processes are now locked together, a condition known as "facet jumping." In which region of the spine is this injury most likely to occur?

30 A. Spondylolysis, also known as "facet jumping," is the anterior displacement of one or more vertebrae. This is most commonly seen with the cervical vertebrae because of their small size and structure and the oblique angle of the articular facets. Lumbar vertebrae are somewhat susceptible to this problem because of the pressures at lower levels of the spine and the sagittal angles of the articular facets. It is much less common in the thoracic vertebrae due to the stabilizing factor of the ribs. It is never seen in the sacral vertebrae because they are fused together. GAS 85-86; GA 21-29

Following a car crash a 47-year-old female complains of severe headache and back pain. Radiographic examination reveals bleeding of the internal vertebral venous plexus (of Batson), resulting in a large hematoma. In what space has the blood most likely accumulated?

31 D. The internal vertebral plexus (of Batson) surrounds the dura mater in the epidural space; hence, the bleeding would cause the hematoma in that space. The subarachnoid space, containing the CSF, is located between pia and arachnoid mater. A subarachnoid bleed would most likely result from a ruptured intercerebral aneurysm. A subdural hematoma would result most likely from a venous bleed from a torn cerebral vein as it enters the superior sagittal venous sinus within the skull. The central canal is located within the gray matter of the spinal cord. The lumbar cistern is an enlargement of the subarachnoid space between the conus medullaris of the spinal cord and the inferior end of the subarachnoid space.

A 32-year-old male elite athlete was lifting heavy weights during an intense training session. The athlete felt severe pain radiating to the posterior aspect of his right thigh and leg. The patient was taken to the hospital where MRI revealed a ruptured L4/L5 intervertebral disk. Which nerve is most probably affected?

32 D. In the lumbar region spinal nerves exit the vertebral column below their named vertebrae. In an L4, L5 intervertebral disk herniation, the L5 spinal nerve would be affected as it descends between L4, L5 vertebrae to exit below the L5 level. L2, L3, and L4 spinal nerves have already exited above the level of herniation; therefore, they would not be affected by this herniation. An "L6" spinal nerve normally does not exist. (The NBME does not allow "made up" structures, but in cases of lumbarization of S1, some people recognize an L6 nerve.)

A 24-year-old patient suffered a lower back strain after a severe fall while snow skiing. MRI studies reveal injury to the muscles responsible for extending and laterally bending the trunk. What arteries provide blood supply for these muscles?

33 E. Posterior intercostal arteries supply the deep back muscles that are responsible for extending and laterally bending the trunk. The subscapular supplies subscapularis muscle, the thoracodorsal supplies latissimus dorsi, the anterior intercostal supplies the upper nine intercostal spaces, and the suprascapular supplies supraspinatus and infraspinatus muscles. These muscles are not responsible for extension and lateral flexion of the trunk.

A 22-year-old male soccer player is forced to leave the game following a head-to-head collision with another player. He is admitted to the hospital, and radiographic examination reveals slight dislocation of the atlantoaxial joint. As a result, he experiences decreased range of motion at that joint. What movement of the head would most likely be severely affected?

34 A. The atlantoaxial joint is a synovial joint responsible for rotation of the head, not flexion, abduction, extension, or adduction. The atlanto-occipital joint is primarily involved in flexion and extension of the head on the neck.

A 42-year-old male is struck in the back, rupturing the internal vertebral venous plexus (of Batson). Radiographic studies reveal a hematoma causing compression of the spinal cord. When aspirating the excess blood, the physician performing the procedure must stop the needle just before puncturing which of the following structures?

35 D. The internal vertebral plexus (of Batson) lies external to the dura mater in the epidural space. To aspirate excess blood, the physician must pass the needle through the ligamentum flavum to reach the epidural space wherein the blood would accumulate. The spinal cord, pia mater, and arachnoid mater are located deep to the epidural space.

A 35-year-old male pedestrian is crossing a busy intersection and is hit by a truck. He is admitted to the emergency department, and a CT scan reveals a dislocation of the fourth thoracic vertebra. Which of the following costal structures is most likely also involved in the injury?

36 E. The T4 thoracic vertebra articulates with the head of the fifth rib. The head of the rib has two facets. The rib articulates with the superior facet on the body of its own vertebra (fourth rib articulates with the superior facet T4 vertebra) and with the inferior facet on the body of the vertebra above (fourth rib articulates with the inferior facet of T3 vertebra). Taking the T4 vertebra into consideration, the superior facet of this vertebra articulates with the head of the fourth rib and the inferior facet articulates with the head of the fifth rib. The head of the fourth rib has two points of articulation (a joint with the vertebral body and costotransverse joint) on T4, so when it is injured it moves as a unit, whereas the fifth rib has only one articulation with T4.

A 20-year-old hiker suffers a deep puncture between the trapezius and latissimus dorsi muscles on the right lateral side of his back. Upon admission to the hospital, physical examination reveals weak adduction and medial rotation of his arm. Which of the following muscles is most probably injured?

37 E. Teres major is responsible for adduction and medial rotation of the humerus. Teres minor is responsible for lateral rotation of the humerus. Triceps brachii is responsible for extension of the forearm. Supraspinatus is responsible for the 0° to 15° of abduction, and infraspinatus is a lateral rotator.

A 22-year-old male is thrown through a plate glass wall in a fight. Radiologic examination reveals that the lateral border of his right scapula is shattered. He is admitted to the emergency department, and physical examination reveals difficulty laterally rotating his arm. Which of the following muscles is most probably injured?

38 B. Infraspinatus is responsible for lateral rotation (along with the teres minor, not a choice here). Teres major is responsible for adduction and medial rotation of the humerus. Latissimus dorsi is responsible for adduction, extension, and medial rotation of the humerus. Trapezius is an elevator of the scapula and rotates the scapula during abduction of the humerus above the horizontal plane. Supraspinatus is responsible for the 0° to 15° of abduction.

A 24-year-old female 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 CSF. What is the last structure the needle will penetrate before reaching the lumbar cistern?

39 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.

A 35-year-old man is admitted to the hospital after a severe car crash. Radiographic examination reveals an injury to the dorsal surface of the neck and a fracture in the medial border of the right scapula. During physical examination the patient presents with the scapula retracted laterally on the affected side. Which of the following nerves has most likely been injured on that side?

4 C. The dorsal scapular nerve (from the ventral ramus of C5) is responsible for innervating rhomboids major and minor. The rhomboids are responsible for medial retraction (adduction) of the scapula. Therefore, if this nerve is damaged, individuals present with a laterally displaced (abducted) scapula. In this case the levator scapular remains functional due to additional innervation provided by C3-4 spinal nerves. The axillary nerve innervates the deltoid and teres minor muscles. The deltoid muscle abducts the humerus, and the teres minor laterally rotates the humerus. The long thoracic nerve innervates the serratus anterior, which functions to abduct and upwardly rotate the scapula. The greater occipital nerve is mainly sensory and is also contributing to the innervation of the semispinalis capitis. In addition, greater occipital nerve is implicated in occipital neuralgias. The suprascapular nerve innervates the supraspinatus and infraspinatus muscles. The supraspinatus abducts the humerus, and the infraspinatus muscles laterally rotate the humerus. Injury to any of these other nerves would not present with a laterally retracted scapula.

A 19-year-old presents at the emergency department with high fever, severe headache, nausea, and stiff neck for 3 days. The attending physician suspects meningitis and obtains a sample of CSF using a lumbar puncture. From which of the following spaces was the CSF collected?

40 C. The subarachnoid space, containing the CSF, is located between the pia and the arachnoid mater. Neither the epidural space, the subdural space, nor the pretracheal space contains CSF. Although the central canal, contained within the substance of the spinal cord, does contain CSF, extraction of CSF from this region would result in spinal cord injury. CSF circulates in the area of the subarachnoid space and can be aspirated only from that location. The subdural space is only a potential space between the dura and arachnoid mater. The epidural space contains the epidural fat and Batson's venous plexus and is the preferred site for aspirating CSF for diagnostic purposes (and epidural anesthesia). CSF is not located in the pretracheal space.

A 38-year-old male is admitted to the emergency department after a car collision. During physical examination several lacerations in the back are discovered. Pain from lacerations or irritations of the skin of the back is conveyed to the central nervous system by which of the following?

41 A. General somatic afferent fibers are conveyed from the skin of the back via the dorsal primary rami. Communicating rami contain general visceral efferent (sympathetic) fibers and general visceral afferent fibers of the autonomic nervous system. Ventral primary rami convey mixed spinal nerves to/from all other parts of the body excluding the back, and parts of the head innervated by cranial nerves. The ventral roots contain only efferent (motor) fibers. Intercostal nerves are the ventral rami of T1 to T11. The ventral ramus of T12 is the subcostal nerve.

A 66-year-old female had been diagnosed with a tumor on her spine. She has started to retain urine and is experiencing decreased anal and rectal tone. Both of these symptoms are signs of conus medullaris syndrome. At which of the following vertebral levels is the tumor probably located?

42 D. The conus medullaris is located at the L1-2 vertebral level; therefore, any choice that contains that region is the correct answer. L3-4 is a common location to perform lumbar puncture, but it is caudal to the apex of the conus medullaris. L3 and L4 are caudal to the conus medullaris. T11 is superior to the conus medullaris.

Examination of a 3-day-old male infant reveals protrusion of his spinal cord and meninges from a defect in the lower back. Which of the following describes this congenital anomaly?

43 D. Because the meninges and spinal cord are included in the protrusion, the patient's condition is a classic presentation of spina bifida with meningomyelocele. If the protrusion contains only meninges but no CNS tissue, it is known as spina bifida with meningocele. Meningitis is an inflammation of the meninges caused by bacteria, viral, or numerous other irritants. It does not cause deformation of vertebrae or result in protrusion of spinal cord contents. Spina bifida occulta is a normally asymptomatic condition in which the vertebral lamina fail to fuse completely during embryologic development. A tuft of hair is commonly seen growing over the affected region (usually lumbar in position).

A 32-year-old mother complains of serious pain in the coccygeal area some days after giving birth. To determine whether the coccyx is involved, a local anesthetic is first injected in the region of the coccyx and then dynamic MRI studies are performed. The MRI reveals coccydynia, which confirms that her coccyx dislocates upon sitting. The local anesthetic is used to interrupt which of the following nerve pathways?

44 C. Somatic afferent fibers convey localized pain, typically from the body wall and limbs. Visceral afferents convey autonomic nervous system sensory information. Pain from these fibers will present as dull and diffuse. Somatic efferent fibers convey motor information to skeletal muscle. Sympathetic preganglionic fibers are visceral efferent fibers and do not contain sensory information. Parasympathetic preganglionic fibers are also visceral efferents and do not contain sensory information.

During a routine physical examination a 65-yearold male patient is tested for ease and flexibility of the movements of his lumbar region. Which of the following movements is most characteristic of the intervertebral joints in the lumbar region?

45 B. Lateral flexion is the best answer because other movements of the lumbar portion of the vertebral column are very limited due to the orientation of the articular facets.

A 72-year-old man with cancer of the prostate gland presents with loss of consciousness and seizures. A CT scan is performed and a brain tumor is diagnosed. The tumor spread to the brain from the abdomen via the internal vertebral venous plexus (of Batson). What feature of the plexus allows this to happen?

46 D. Batson's venous plexus 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 (i.e., from prostate or breast to brain) because the flow of blood is not unidirectional. The length of Batson's plexus is irrelevant to the question. B is incorrect because Batson's plexus does not have valves or one-way movement of blood. Batson's plexus is located within the epidural space, not the subarachnoid or subdural spaces.

A 26-year-old man painting his house slipped and fell from the ladder, landing on the pavement below. After initial examination in the emergency department, the patient is sent to the radiology department. Radiographs reveal that the portion of his left scapula that forms the tip, or point, of the shoulder has been fractured. Which part of the bone was fractured?

47 E. The acromion (the highest point of the shoulder) is the part of the scapula that forms the "point" of the shoulder. The coracoid process is located more medially. The superior angle of the scapula is located near the midline of the back. The glenoid of the scapula articulates with the head of the humerus to form the glenohumeral joint. The spine of the scapula is located posteriorly and separates supraspinous and infraspinous fossae.

A 43-year-old male construction worker survived a fall from a two-story building but lost all sensation from his lower limbs and was admitted to the hospital for examination and treatment. Radiographic studies revealed that he crushed his spinal cord at vertebral level C6. Which of the following muscles will most likely be paralyzed?

48 D. All of the spinal nerves below the C7 vertebral level will be affected. This includes the C7 spinal nerve because it exits the vertebral column above the C7 vertebra. The trapezius would be intact because it is innervated by the spinal accessory nerve. The deltoid muscles and supraspinatus muscles will be unaffected because they receive motor supply from C5 and C6. The rhomboid muscles should function normally because they are innervated by the dorsal scapular nerve (C5). The latissimus dorsi muscles would not function normally because they are innervated by the thoracodorsal nerves, which receive contributions especially from the C7 spinal nerves.

A maternal serum sample with high alphafetoprotein alerted the obstetrician to a possible neural tube defect. Ultrasound diagnosis revealed a meningocele protruding from the back of the child. Which of the following is the most likely diagnosis of this congenital anomaly?

49 C. Spina bifida cystica refers to spina bifida with meningocele and is the correct answer. Cranium bifida could present with meningocele in the skull, but it would not be located in the lower back. Spina bifida occulta is a defect in the formation of the vertebral arches and does not present with meningocele. Hemothorax refers to blood accumulation in the pleural space surrounding the lungs. ArnoldChiari malformation is a herniation of the medulla oblongata and cerebellum through the foramen magnum and would not present with pathologies in the lower back.

A 64-year-old man arrived at the clinic with a severely painful rash and skin eruptions that are localized entirely on one side of his body, closely following the dermatome level of spinal nerve C7. The patient was diagnosed with herpes zoster virus. In what structure has the virus most likely proliferated to cause the patient's current condition?

5 B. Herpes zoster is a viral disease that remains latent in the dorsal root ganglia of sensory nerves and presents as a painful skin lesion. It is associated only with sensory nerve fibers and has no motor involvement. The only answer choice that is solely responsible for sensory innervation is the dorsal root ganglion. GAS 110; GA 45-49

A 7-year-old female who is somewhat obese is brought to the emergency department because of a soft lump above the buttocks. Upon physical examination you note the lump is located just superior to the iliac crest unilaterally on the left side. The protrusion is deep to the skin and pliable to the touch. Which of the following is the most probable diagnosis?

50 B. The lumbar triangle (of Petit) is bordered medially by the latissimus dorsi, laterally by the external abdominal oblique, and inferiorly by the iliac crest. The floor of Petit's triangle is formed by the internal abdominal oblique, and this is a possible site of herniation. An indirect inguinal hernia is located in the inguinal canal of the anterior abdominal wall. A direct inguinal hernia is located in the Hesselbach triangle of the anterior abdominal wall. A femoral hernia occurs below the inguinal ligament. Answer A is not the best answer because this lump is described as soft and pliable, which would not likely indicate a tumor, as tumors tend to be hard masses.

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 disks have been compressed. It is common for the disks to shrink in people older than 40, and it can result in spinal stenosis and disk herniation. At which locations are the spinal nerves most likely to be compressed?

51 D. This question tests anatomic knowledge relating to typical vertebrae and the spinal cord. Intervertebral disk herniations occur when the nucleus pulposus of the intervertebral disk protrudes through the anulus fibrosus into the intervertebral foramen or vertebral canal. The most common protrusion is posterolaterally, where the anulus fibrosus is not reinforced by the posterior longitudinal ligament. The inferior and superior vertebral notches frame the intervertebral foramen, so this is the most likely location of compression. The denticulate ligaments are lateral extensions of pia mater that anchor to the dura mater, and they hold the spinal cord in position within the subarachnoid space. The vertebral foramen is the canal through which the spinal cord passes; while this may also be a place of compression, it is not the most likely site of herniation. Articular facets are the locations where vertebral bodies articulate with each other. Intercostovertebral joints are locations where vertebral bodies articulate with ribs. GAS 80-86; GA 32-35

A 37-year-old pregnant woman is administered a caudal epidural block to alleviate pain during delivery. Caudal epidural block involves injection of local anesthetic into the sacral canal. Which of the following landmarks is most commonly used for the caudal epidural block?

52 C. Caudal anesthesia is used to block the spinal nerves that carry sensation from the perineum. This procedure is commonly used by obstetricians to relieve pain during labor and childbirth. Administration of local anesthetic to the epidural space is via the sacral hiatus, which opens between the sacral cornua. The anterior sacral foramina are located on the pelvic surface of the sacrum and are not palpable from a dorsal approach. The posterior sacral foramina and intervertebral foramina are the openings through which sacral nerves exit and are not palpable landmarks. The medial sacral crest is cranial to the injection site.

A 34-year-old pregnant woman in the maternity ward was experiencing considerable pain during labor. Her obstetrician decided to perform a caudal epidural block within the sacral canal. What are the most important bony landmarks used for the administration of such anesthesia?

53 D. The sacral cornua lie on either side of the sacral hiatus, from which one can gain access to the sacral canal. This is the best landmark for administration of anesthesia. The ischial tuberosities are more commonly used as landmarks for a pudendal nerve block. The ischial spines cannot be palpated. The posterior superior iliac spines, though palpable, are not proximal enough for an epidural block within the sacral canal. The coccyx is not part of the sacral canal.

A 22-year-old man is brought into the emergency department following a brawl in a tavern. He has severe pain radiating across his back and down his left upper limb. He supports his left upper limb with his right, holding it close to his body. Any attempt to move the left upper limb greatly increases the pain. A radiograph is ordered and reveals an unusual sagittal fracture through the spine of the left scapula. The fracture extends superiorly toward the suprascapular notch. Which nerve is most likely affected?

54 A. The suprascapular nerve passes through the suprascapular notch, deep to the superior transverse scapular ligament. This nerve is most likely affected in a fracture of the scapula as described in the question. The thoracodorsal nerve runs behind the axillary artery and lies superficial to the subscapularis muscle and would therefore be protected. The axillary nerve passes posteriorly through the quadrangular space, which is distal to the suprascapular notch. The subscapular nerve originates from the posterior cord of the brachial plexus, which is distal to the site of fracture.

A 5-year-old boy is admitted to the hospital because of pain in the upper back. Radiographic examination reveals abnormal fusion of the C5 and C6 vertebrae and a high-riding scapula. Which of the following conditions is characteristic of his symptoms?

55 E. Klippel-Feil syndrome is a congenital defect in which there is a reduction, or extensive fusion, in the number of cervical vertebrae. It often manifests as a short, stiff neck with limited motion. Lordosis is an abnormal increase in lumbar curvature. Kyphosis ("hunchback") is an abnormal increase in thoracic curvature. Scoliosis is a lateral curvature. Spina bifida often presents with deformities in the lumbar region. GAS 76-79; GA 21-33

A 53-year-old male is admitted to the emergency department due to severe back pain. MRI examination reveals anterior dislocation of the body of the L5 vertebra upon the sacrum. Which of the following is the most likely diagnosis?

56 B. Spondylolisthesis is an anterior vertebral displacement created by an irregularity in the anterior margin of the vertebral column such that L5 and the overlying L4 (and sometimes L3) protrude forward rather than being restrained by S1. Spondylolysis is a condition in which the region between the superior and inferior articular facets (on the posterior arch of the L5 vertebra) is damaged or missing, which is not the case in this example. Herniation is a protrusion of the nucleus pulposus through the anulus fibrosus, and this is not associated with vertebral dislocation. Lordosis and scoliosis are excessive curvatures that do not involve dislocations.

A male newborn infant is brought to the clinic by his mother and diagnosed with a congenital malformation. MRI studies reveal that the cerebellum and medulla oblongata are protruding inferiorly through the foramen magnum into the vertebral canal. What is this clinical condition called?

57 C. Arnold-Chiari malformation results from herniation of the medulla and cerebellum into the foramen magnum. Meningocele is a small defect in the cranium in which only the meninges herniate. Klippel-Feil syndrome results from an abnormal number of cervical vertebral bodies. Hydrocephalus results from an overproduction of cerebrospinal fluid, obstruction of its flow, or interference with CSF absorption. Tethered cord syndrome is a congenital anomaly caused by a defective closure of the neural tube. This syndrome is characterized by a low conus medullaris and a thick filum terminale.

A 62-year-old woman is admitted to the hospital because of her severe back pain. Radiographic examination reveals that the L4 vertebral body has slipped anteriorly, with fracture of the zygapophysial joint (Fig. 1-1). What is the proper name of this condition?

58 A. Spondylolisthesis is an anterior displacement created by an irregularity in the anterior margin of the vertebral column such that L5 and the overlying L4 (and sometimes L3) protrude forward. Spondylolysis is a condition in which the region between the superior and inferior articular facets (on the posterior arch of the L5 vertebra) is damaged or missing, which is not the case in this example. Crush vertebral fracture is a collapse of vertebral bodies as a result of trauma. Intervertebral disk herniations occur when the nucleus pulposus protrudes through the anulus fibrosus into the intervertebral foramen or vertebral canal. The most common protrusion is posterolaterally, where the anulus fibrosus is not reinforced by the posterior longitudinal ligament. Klippel-Feil syndrome results from an abnormal number of cervical vertebral bodies.

A 40-year-old woman survived a car crash in which her neck was hyperextended when her vehicle was struck from behind. At the emergency department a plain radiograph of her cervical spine revealed a fracture of the odontoid process (dens). Which of the following was most likely injured?

59 A. The odontoid process, or the dens, projects superiorly from the body of the axis and articulates with the anterior arch of the atlas. The posterior and anterior tubercles of the atlas are bony eminences on the outer surface. The inferior articular facet is where the axis joins to the C3 vertebra.

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 became intense. She was admitted to the emergency department. Radiographic examination revealed disk herniation between vertebral levels L4 and L5. Which of the following nerves was most likely affected by the disk herniation?

6 E. Disk 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 disk, whereas the L5 spinal nerve root lies directly posterior to the disk. GAS 81; GA 32-34

A 34-year-old woman is admitted to the emergency department after a car crash. Radiographic examination reveals a whiplash injury in addition to hyperextension of her cervical spine. Which of the following ligaments will most likely be injured?

60 B. The anterior longitudinal ligament is a strong fibrous band that covers and connects the anterolateral aspect of the vertebrae and intervertebral disks; it maintains stability and prevents hyperextension. It can be torn by cervical hyperextension. The ligamentum flavum helps maintain upright posture by connecting the laminae of two adjacent vertebrae. The posterior longitudinal ligament runs within the vertebral canal supporting the posterior aspect of the vertebrae and prevents hyperflexion. The anulus fibrosus is the outer fibrous part of an intervertebral disk. The interspinous ligament connects adjacent spinous processes.

A 23-year-old college student is admitted to the emergency department after jumping from a 50-foot waterfall. The MRI of his back reveals a lateral shift of the spinal cord to the left. Which of the following structures has most likely been torn to cause the deviation?

61 C. The denticulate ligaments are lateral extensions of pia mater between the dorsal and ventral roots of the spinal nerves that attach to the dura mater. These ligaments function to keep the spinal cord in the midline position. The posterior longitudinal ligament supports the posterior aspect of the vertebrae within the vertebral canal. The tentorium cerebelli is a layer of dura mater that supports the occipital lobes of the cerebral hemispheres and covers the cerebellum. The ligamentum flavum helps maintain upright posture by connecting the laminae of two adjacent vertebrae. The nuchal ligament is a thickening of the supraspinous ligaments extending from the C7 vertebra to the external occipital protuberance. GAS 101-110; GA 48-49

A 6-year-old boy is admitted to the hospital with coughing and dyspnea. During taking of the history he complains that it feels like there is glass in his lungs. Auscultation reveals abnormal lung sounds. The abnormal lung sounds are heard most clearly during inhalation with the scapulae abducted. Which of the following form the borders of a triangular space where one should place the stethoscope in order to best hear the lung sounds?

62 A. 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. The deltoid, levator scapulae, and trapezius do not form the borders of the "triangle of auscultation." The latissimus dorsi, external abdominal oblique, and iliac crest form the border of Petit's inferior lumbar triangle. The quadratus lumborum, internal abdominal oblique, and inferior border of the twelfth rib form the border of the Grynfeltt's superior lumbar triangle. The rectus abdominis, inguinal ligament, and inferior epigastric vessels form the border of the Hesselbach triangle. Petit, Grynfeltt, and Hesselbach triangles are common sites for hernias.

A 45-year-old woman is admitted to the outpatient clinic for shoulder pain. During physical examination she presents with weakened shoulder movements. Radiographic examination reveals quadrangular space syndrome, causing weakened shoulder movements. Which of the following nerves is most likely affected?

63 C. The weakness in shoulder movement results from denervation of the teres minor and deltoid by the axillary nerve, which passes through the quadrangular space. Quadrangular space syndrome happens when there is hypertrophy of the muscles that border the quadrangular space or fibrosis of portions of the muscles that are in contact with the nerve.

A 29-year-old female elite athlete was lifting heavy weights during an intense training session. The athlete felt severe pain radiate suddenly to the posterior aspect of her right thigh and leg. The patient was taken to the hospital where an MRI was performed (Fig. 1-2). Which nerve was most probably affected?

64 D. In this MRI a posterolateral herniation between L4/L5 exists. In the lumbar region, spinal nerves exit the vertebral column below their named vertebrae. In an L4/L5 intervertebral disk herniation, the L5 spinal nerve would be affected as it descends between L4/L5 vertebrae to exit below the L5 level. GAS 108-110; GA 32-33, 44

A 58-year-old male in the intensive care ward exhibited little voluntary control of urinary or fecal activity following a transplant procedure of his left kidney. In addition, physical examination revealed widespread paralysis of his lower limbs. These functions were essentially normal prior to admission to the hospital. The most likely cause of this patient's problems is which of the following?

65 B. The (great radicular) artery of Adamkiewicz is important for blood supply to anterior and posterior spinal arteries. The location of this artery should be noted during surgery because damage to it can result in dire consequences, including loss of all sensation and voluntary movement inferior and at the level of the injury. Injury to the left vertebral artery would not be likely due its superior location to the surgical site. Ligation of the posterior spinal artery would not occur because of its protected location inside the spinal column. Transection of the conus medullaris of the spinal cord would not occur as this structure is located at L1, L2 levels and is, again, protected inside the spinal column. Division of the thoracic sympathetic chain would not be likely as the symptoms described include limb paralysis, which would not be a consequence of sympathetic disruption.

A 23-year-old woman is admitted to the hospital due to back pain. Radiographic examination reveals that she suffers from a clinical condition affecting her vertebral column. Physical examination and history taking reveals that she suffered from polio and a muscular dystrophy. Which of the following conditions of the vertebral column will most likely be present in this patient?

66 C. Scoliosis can be a secondary condition in such disorders as muscular dystrophy and polio in which abnormal muscle does not keep the vertebral column's normal alignment and results in a lateral curvature. Lordosis is increased secondary curvature of the lumbar region. It can be caused by stress on the lower back and is quite common in pregnancy. Kyphosis is increased primary curvature of the thoracic regions and produces a hunchback deformity. It can be secondary to tuberculosis, producing a "gibbus deformity," which results in angulated kyphosis at the lesion site. Spina bifida is a congenital defect and would not present as a result of muscular dystrophy or polio. Osteoarthritis most commonly presents with age from normal "wear and tear." It is not likely in a 23-year-old woman.

A 65-year-old patient complains of severe, chronic pain from the region of her right hip. The patient is admitted to the hospital and a decision is made to perform surgery to avoid prescribing excessive pain medication. In such a case, which would the surgeon most likely choose to perform?

67 B. Transection of all dorsal rootlets of the nerves from the hip area is also known as a dorsal rhizotomy. This type of surgical procedure is performed to eliminate pain sensation from whichever dermatome level is transected. Because dorsal rootlets contain general sensory afferent fibers, cutting these would eliminate sensation and thus pain. Division of the ventral primary rami might result in pain elimination; however, because the fibers in ventral rootlets are mixed, there would also be adverse consequences such as motor and sympathetic and even parasympathetic deficits depending on the level. Removal of abdominal sympathetic chain ganglia on the right side would not eliminate pain in the hip area since the fibers for this sensation are general somatic afferents and the sympathetic chain contains general visceral efferents and afferents. Transection of dorsal primary rami of spinal nerves would not eliminate pain in the hip because the dorsal rootlets contain mixed fibers that supply only a limited area on the back. Division of lower lumbar and sacral ventral rootlets would not eliminate pain sensation since these rootlets contain efferent motor fibers and no afferents.

A 3-year-old child is admitted to the emergency department with severe headache, high fever, malaise, and confusion. Radiographic and physical examinations reveal that the patient suffers from meningitis. A lumbar puncture is ordered. Which vertebral level is the most appropriate location for the lumbar puncture?

7 D. 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 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 avoided.

When a lumbar puncture is performed to sample cerebrospinal fluid, which of the following external landmarks is the most reliable to determine the position of the L4 vertebral spine?

8 B. 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. The inferior angles of the scapulae lie at vertebral level T7; the lowest ribs lead one to T12; a line between the posterior superior iliac spines crosses vertebral level S2; the posterior inferior iliac spines lie below S2.

A 39-year-old male presents with severe neck pain after a whiplash injury, sustained when his car was struck from behind. Radiographic studies reveal trauma to the ligament lying on the anterior surface of the cervical vertebral bodies. Which ligament is this?

9 A. The anterior longitudinal ligament lies anterior to the vertebral bodies along the vertebral column. The ligamentum flavum connects the lamina of two adjacent vertebrae. The nuchal ligament is a continuation of the supraspinous ligament above C7, which connects spinous processes. The posterior longitudinal ligament lies on the posterior edge of the vertebral bodies. The transverse cervical (cardinal) ligament is associated with the pelvic region of the body and not the spinal column.