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The school district nurse in a rural area is told that a new student, a 14-year-old girl, has enrolled, and that she suffers from severe scoliosis. Which of the following features might the nurse anticipate noticing in this student?

Asymmetry of the trunk when bending forward at the waist

A 26-year-old female gymnast presents with complaints of periodic pain and muscle spasms in her left upper limb. Thorough physical and radiographic examinations reveal a posterolateral cervical intervertebral disc herniation, as shown in the accompanying sagittal magnetic resonance imaging (MRI) scan. The bulging disc is most likely impinging mainly on which of the following structures?

C6 spinal nerve roots

You are examining a 61-year-old patient who has generalized back pain and stiffness. In trying to determine which part of the spine the physical therapist should concentrate on to relieve stiffness you are aware that, of the presacral part of the vertebral column, the region that permits the most rotation is:

Cervical

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? Coccygeal ligament Denticulate ligament Tectorial membrane Choroid plexus Filum terminale internum

Denticulate ligament

An 8-year-old girl fell during a gymnastics competition when she was performing on the uneven bars. She landed on the posterior part of her neck. On examination, there was marked muscle spasm and pain in her neck. Her neck was immobilized, and she was taken to a hospital and examined by an orthopedist. He ordered radiographs of her neck. The radiologist reported that there was anterior subluxation (incomplete dislocation) of C2 on C3 vertebrae. Which of the following statements best describes aspects of the cervical region of the vertebral column? Dislocation of the cervical region of the vertebral column may occur without damage to the spinal cord. Cervical dislocations typically result in rupture of the alar ligament. Cervical dislocations result in rupture of the tectorial membrane. Cervical dislocations must always be treated surgically. Cervical fractures require less force than cervical dislocations

Dislocation of the cervical region of the vertebral column may occur without damage to the spinal cord.

Cervical spine CT scanning of a young adult ED patient brought in after automobile trauma is reported to show "jumped facets." What does this refers to?

Displaced and locking facets (dislocation) in the cervical region

A 22-year-old man is brought to the ER with severe back pain and lower limb weakness after falling off the top of a 16-ft ladder and landing on his feet. The ER physician orders a CT scan, and the given midsagittal CT directs the physician toward making which of the following diagnoses? Burst fracture of T12 vertebral body Spondylolisthesis of L5-S1 articulation Lumbar spinal stenosis Herniated intervertebral disc Excessive lumbar lordosis

Explanation: The answer is burst fracture of T12 vertebral body. The sagittal CT clearly shows a burst (crush or compression) fracture of the 12th thoracic vertebral body (T12). This T12 burst fracture also presents with a fracture fragment that is displaced posterior into the vertebral canal where it would compress the terminal end of the spinal cord, the medullary cone (conus medullaris), which typically lies within the T12-L3 vertebral levels. Compression of the spinal cord would lead to pain within the lower back that would likely extend into the lower limbs. This injury might also result in incontinence, loss of sensation, and paraplegia or paraparesis (loss of motor function). Remember that a CT scan is a valuable means of viewing "blood and bone," and this type of radiological imaging is the standard way to view injuries resulting from trauma, as seen in this patient. With this patient falling off the ladder and landing on his feet, the downward force from the high fall and the upward force from the impact on the ground have crushed the body of the T12 vertebra, resulting in the burst fracture of the T12 vertebral body seen on this sagittal CT. Spondylolisthesis of L5-S1 articulation is incorrect. Spondylolisthesis of the L5-S1 articulation is defined by the forward displacement of the vertebral body of L5 relative to the upper part of the sacrum (S1). The given CT does not show spondylolisthesis of the L5-S1 articulation, so this choice can be eliminated.

A 35-year-old man presents with pain radiating from his lower back into his left lower limb, periodic sensory loss and paresthesia in that limb, and associated motor weakness. His physician suspects unilateral entrapment of lumbar nerve roots secondary to a herniated lumbar intervertebral disc. In examining the patient, the physician conducts a straight-leg raising test. Which of the following best describes a positive straight-leg raising sign (Lasèque's sign) for this condition in this patient? Walking while keeping the left leg in a straight position (i.e., the knee is kept straight) relieves the pain in the back and limb Flexing the hip by raising the straightened left leg (i.e., the knee is kept straight) with the patient lying in the supine position relieves the pain in the back and leg Abducting the hip by raising the straightened left leg with the patient lying on his right side relieves the pain in the back and leg Flexing the hip by raising the straightened left leg with the patient lying in the supine position increases pain in the back with radiation down the left leg Extending the hip by raising the straightened left leg with the patient lying in the prone position increases pain in the back with radiation down the left leg

Explanation: The answer is flexing the hip by raising the straightened left leg with the patient lying in the supine position increases pain in the back with radiation down the left leg. The straight-leg raising test is designed to stretch the lower back and apply tension to the lumbar spinal nerves and roots. Thus, a positive test will stress compromised nerves and elicit pain and/or spasticity in the areas supplied by the affected nerves. If the diagnosis of left side lumbar nerve entrapment secondary to a herniated lumbar disc is correct, raising the left leg (i.e., flexing the hip) with the knee straight (extended) from the supine position (lying on the back) will apply traction to the entrapped nerve roots and elicit pain in the affected areas. Conducting the same maneuver on the right side will not elicit a pain reaction. Lasèque sign is a medical maneuver that involves raising a straight leg to exacerbate pain and is useful in diagnosing lumbar disc disorders and tension of the sciatic nerve

A physician orders a lumbar puncture (spinal tap) for his 43-year-old female patient in order to obtain a sample of cerebrospinal fluid (CSF). He explains to her that this procedure will be done in the lower back, between the spinous processes of the L3 and L4 vertebrae. What is the best reason for performing the lumbar puncture at this location? The intervertebral foramina at L3-4 are large and easy to penetrate No vertebral venous plexuses exist below the L3 level The ligamenta flava are absent below the L3 level The medullary cone ends at or above the L3 level The subarachnoid space ends at the L3 level

Explanation: The answer is the medullary cone ends at or above the L3 level. The objective of a lumbar puncture is to enter (tap) the subarachnoid space and access the CSF. This procedure is performed using a long spinal needle. For several reasons, this procedure is best performed in the low lumbar region, between the spinous processes of the L3 and L4 (sometimes L4 and L5) vertebrae. The medullary cone (or conus medullaris) is the tapered terminal end of the spinal cord. In adults, the medullary cone is normally located within the T12-L3 vertebral levels. Thus, penetrating the vertebral canal and subarachnoid space below L3 is the "safe" place to go, in that the spinal needle should not penetrate the spinal cord.

Flexing the hip by raising the straightened left leg with the patient lying in the supine position increases pain in the back with radiation down the left leg

A 48-year-old woman crashes into a tree during a skiing lesson and is brought to a hospital with multiple injuries that impinge the posterior primary rami of several thoracic spinal nerves. Such lesions could affect which of the following muscles? Levator scapulae Trapezius Rhomboid major Latissimus dorsi Iliocostalis

Iliocostalis

A 12-year-old girl suffers from a type of neural tube defect called tethered cord syndrome, a congenital anomaly that results from defective closure of the neural tube. This syndrome is characterized by an abnormally low conus medullaris, which is tethered by a short, thickened filum terminale, leading to progressive neurologic defects in the legs and feet. This girl has strong muscle function of the flexors of the thigh, but she has weakness of the extensors (hamstrings). A lesion has occurred at which of the following spinal cord levels? L5 T12 L1 L3 S5

L5. The quadratus femoris muscles-the flexors of the thigh-are innervated by the femoral nerve, which originates from the spinal cord at L2 to L4. In contrast, the hamstring muscles-the extensors of the thigh-are innervated by the sciatic nerve, which originates from L4 to S3. Therefore, the lesion occurs at the level of L5 (between L4 and S3).

Question 1 of 5 A 17-year-old gymnast grips a high bar with his arms outstretched and begins to pull himself straight upward to the level of the bar, as in doing a chin-up. Which of the following muscles is the prime agonist in this action? Serratus posterior superior Longissimus Latissimus dorsi Rhomboid major Levator scapulae

Latissimus dorsi

A surgical resident is presenting a case report of a lumbar hernia to a group of medical students. He explains that the hernia was protruding through the lumbar triangle. Which of the following structures make up the boundaries of this triangle? Latissimus dorsi, external abdominal oblique, iliac crest Latissimus dorsi, rhomboid major, vertebral spinous processes Posterior, middle, and anterior lamellae of the thoracolumbar fascia Obliquus capitis inferior, obliquus capitis superior, rectus capitis posterior major Trapezius, scapula, latissimus dorsi

Latissimus dorsi, external abdominal oblique, iliac crest

A surgical resident is presenting a case report of a lumbar hernia to a group of medical students. He explains that the hernia was protruding through the lumbar triangle. Which of the following structures make up the boundaries of this triangle? Obliquus capitis inferior, obliquus capitis superior, rectus capitis posterior major Posterior, middle, and anterior lamellae of the thoracolumbar fascia Latissimus dorsi, external abdominal oblique, iliac crest Trapezius, scapula, latissimus dorsi Latissimus dorsi, rhomboid major, vertebral spinous processes

Latissimus dorsi, external abdominal oblique, iliac crest

In the ED, you treat a 26-year-old patient who shows a knife wound in his back in which the knife penetrated his spinal cord at T3,rendering him a paraplegic. In order for the knife to reach the cord, it had to pierce which of the following ligaments?

Ligamentum flava

During a domestic dispute, a 16-year-old boy receives a deep stab wound around the superior angle of the scapula near the medial border, which injures both the dorsal scapular and spinal accessory nerves. Such an injury could result in paralysis or weakness of which of the following muscles? Rhomboid minor and latissimus dorsi Levator scapulae and erector spinae Trapezius and serratus posterior superior Splenius cervicis and sternocleidomastoid Rhomboid major and trapezius

Rhomboid major and trapezius

Your 65-year-old patient has severe osteoarthritis at the median atlanto-axial joint. Based on the movement most facilitated by this joint, when will your patient feel the most pain?

Rotating her head as when indicating "no"

A 15-year-old active boy was sent to an orthopedist for a physical examination by his hockey coach. The physician observed a dimple covered by a hairy patch on the inferior part of his back and suspected the boy had a pathologic condition (see figure). What condition did the physician likely suspect?

Spina bifida occulta

A 28-year-old male in the ED is paralyzed, apparently by spinal and pelvic trauma just suffered in an automobile accident. Physical exam reveals an unusually abrupt lumbosacral angle. What is this angle?

The angle formed between the lumbar and sacral regions of the vertebral column in the sagittal plane

A 46-year-old supervisor was reading a work order on a construction site when a 60 lb bag of concrete mix was accidentally dropped on the apex of his head. He was immobilized and brought to the ER where he presented with upper neck pain but no neurological signs. Based upon the given axial CT scan and the patient's presentation, which of the following diagnoses is most likely? Fracture of the dens axis (odontoid process) Jefferson (burst) fracture of C1 Atlanto-axial subluxation No pathology is apparent on the CT scan Damage to the cervical spinal cord

The answer is Jefferson (burst) fracture of C1. The C1 vertebra, or atlas, is normally a closed ring with no vertebral body. Excessive vertical, or downward, force on the top of the head can fracture the anterior and posterior arches of C1 in multiple places, leading to a Jefferson (burst) fracture of C1. Due to the vertical force of the concrete mix striking the top of the man's head, the lateral masses of C1 are driven laterally due to the oblique articulation between the occipital condyles and the superior articular processes of the lateral masses of C1. This vertical compression force fractures the anterior and posterior arches of C1 bilaterally, as confirmed by the axial CT scan. Jefferson fractures of C1 often occur with axial loading force when the top of the head is impacted by a hard or heavy object. Because the fractures within the bony ring of the atlas actually increase its dimension, this type of fracture does not usually result in spinal cord injury; however, upper neck pain would be present. The axial CT scan confirms the diagnosis of a Jefferson (burst) fracture of C1.

The above CT image shows a vertebral fracture in a patient who dove into a shallow pool and struck his head. What is this type of fracture known as?

The answer is Jefferson (burst) fracture. Jefferson fracture occurs at the anterior arch of the atlas. The lateral masses of the atlas are thus more widely displaced than normal.

You are examining the lateral spine radiograph of your 65-year-old female patient for an insufficiency fracture of her spine. You know that transitional stresses cause which of the following vertebra to be the most commonly fractured?

The answer is T12. The transition from the thoracic to the lumbar region takes places almost entirely within T12 and thus it is the most frequently fractured vertebra.

A 78-year-old man who did little physical exercise during the winter went to his summer cottage to clean up the yard. He decided to make a new flower bed. After he had moved several wheelbarrow loads of sod and soil, he felt a constant dull ache in his back and some in his lower limb. He had a limited range of motion in his vertebral column and a large area of tenderness.. The patient's wife took him to the closest hospital where a physician noted that the deep muscles in his back in the lumbar region were abnormally firm and tender to touch and heat radiating pain to a lower limb was present. The physician also noted that the pain win the patient's lower limb was fairly well confined to the L5 dermatome. Based on this information she suspected that the patient most likely had: A herniation of the L4 or L5 disc A herniation of the L5 or S1 disc Sprained erector spinae Spinal stenosis in lumbar region A herniation of the L3 or L4 disc

The answer is a herniation of the L4 or L5 disc. As a general rule, IV discs, when herniated, press on the inferior nerve root

An 8-month-old infant with an upper respiratory tract infection developed a high fever and a reduced level of consciousness. Her parents took her to the hospital. On examination, the physician detected lethargy, nuchal rigidity, and back pain. Suspecting meningitis, he performed a lumbar puncture. Which of the following statements best describes a lumbar puncture?

The answer is a lumber puncture (LP) may be safely performed at the L4-L5 vertebral level. The spinal cord in infants usually ends at the L3 vertebral level; therefore, cerebrospinal fluid (CSF) can be safely removed from the subarachnoid space. At the L4-L5 vertebral level, there is no danger of injuring the spinal cord.

The insertion of artificial intervertebral disks has been attempted for patients with chronic back pain. These artificial disks are intended to replace both parts of a natural disk. What are these two parts?

The answer is annulus fibrosis and nucleus pulposus. The two parts of an intervertebral disk are the outer fibrous annulus fibrosis and the inner semi-fluid nucleus pulposus.

Amyotrophic lateral sclerosis (ALS; Lou Gehrig's disease) is a progressive, fatal neurodegenerative disease caused by degeneration of the motor neurons controlling skeletal (voluntary) muscle movement. Postmortem analysis of which of the following structures would show the cell bodies of neurons affected by this disease?

The answer is anterior gray horn of the spinal cord. Cell bodies of somatic motor neurons (α-motor neurons) innervating skeletal muscle are located within the anterior (ventral) gray horn of the spinal cord, at all segmental levels throughout the entire length of the spinal cord. The innervation of the skeletal muscles affected by ALS is through somatic motor (general somatic efferent or GSE) neurons and branchial motor (special visceral efferent or SVE) neurons (neurons that supply the embryonic pharyngeal arches). In ALS patients, postmortem analysis of the anterior gray horn of the spinal cord would show significant degeneration. In the given diagram, the anterior gray horn of the spinal cord is labeled as "A." The locations for all five possible choices for this question are also indicated in this figure. Lateral gray horn of the spinal cord is incorrect. The lateral gray horn of the spinal cord is the location of the intermediolateral cell column (IML), which contains the cell bodies of presynaptic (preganglionic) sympathetic neurons of the autonomic nervous system (ANS). The IML only exists within the lateral gray horn between spinal segmental levels T1-L2 (or L3), which is the reason the sympathetic division of the ANS is also called the thoracolumbar division of the ANS. Degeneration in the lateral gray horn of the spinal cord would cause autonomic deficits but would not include the somatic motor neurons involved in ALS. Posterior gray horn of the spinal cord is incorrect. The posterior (dorsal) gray horn, located along the entire length of the spinal cord, contains cell bodies of spinal interneurons. The central process of each pseudounipolar sensory neuron conveys general sensory (afferent) fibers through the posterior (dorsal) nerve root and synapses within the posterior horn of the spinal cord. Degeneration within the posterior gray horn of the spinal cord would cause sensory deficits but would not include the somatic motor neurons involved in ALS. Spinal ganglia is incorrect. The spinal (dorsal root) ganglia, located at the distal ends of the posterior (dorsal) roots of spinal nerves, contain cell bodies of the general sensory (afferent) neurons. Degeneration within the spinal ganglia would result in sensory deficits but would not include the somatic motor neurons involved in ALS. Lateral column of spinal cord white matter is incorrect. All columns within the spinal cord white matter contain neuronal processes and supporting glial cells. Degeneration within the lateral column of the spinal cord would not include the somatic motor neurons involved in ALS.

Idling at a stoplight in his vintage car without headrests, a 71-year-old-man's car is struck from behind by a truck going approximately 30 mph (48 kph). The man is brought to the ER suffering from a severe hyperextension neck injury due to the crash. The given T2-weighted MRI shows a rupture of the anterior anulus of the C4-5 intervertebral disc, inflammation of that disc (the white appearance), and a prevertebral hematoma, which compromised his airway and required intubation. Which of the following ligaments is disrupted in this injury?

The answer is anterior longitudinal ligament. The anterior longitudinal ligament is a vertical connective tissue band that attaches along the anterior aspects of the vertebral bodies. Its peripheral fibers have strong attachments to the intervertebral discs. The anterior longitudinal ligament resists hyperextension of the vertebral column. However, in this patient, the extreme forces involved with the hyperextension of the neck overpowers the resistance of this ligament, rupturing it as well as displacing part of the C4-5 intervertebral disc. In the given T2-weighted MRI, the anterior longitudinal ligament is represented by a hypointense (dark band) signal located anterior to the vertebral column. However, the locations where the anterior longitudinal ligament is interrupted appear as an abnormal hyperintense (white) signal, which is evident anterior to the C5 vertebral body. Posterior longitudinal ligament is incorrect. The posterior longitudinal ligament runs vertically along the posterior aspect of the vertebral column, mirroring the position of the anterior longitudinal ligament located along the anterior aspect of the vertebral column. The posterior longitudinal ligament resists flexion of the vertebral column. Posterolateral herniation of the gelatinous nucleus pulposus through the anulus fibrosus of an intervertebral disc most often projects lateral to the strong attachment sites of the posterior longitudinal ligament. If the herniated disc compresses spinal nerve roots, then neck, back, and/or limb pain may be present. The T2-weighted MRI clearly shows disruption of the anterior longitudinal ligament, evident by the abnormal hyperintense (white) signal located anterior to the C5 vertebral body. Ligamentum flavum is incorrect. The ligamenta flava (L: yellow ligament) are paired ligaments of yellow elastic fibrous tissue, which bind together the laminae of adjoining vertebrae and form the posterior wall of the vertebral canal. Because these ligaments resist flexion of the vertebral column, it is unlikely the ligamenta flava were damaged in this hyperextension injury of the neck. Interspinous ligament is incorrect. The interspinous ligament is composed of fibrous bands that connect the spinous processes of adjacent vertebrae. Because these ligaments resist flexion of the vertebral column, it is unlikely the interspinous ligaments were damaged in this hyperextension injury of the neck. Intertransverse ligament is incorrect. The intertransverse ligament is one ligament that connects the transverse processes of adjacent vertebrae. Because the intertransverse ligaments resist contralateral bending (abduction; lateral flexion) of the vertebrae, it is unlikely the intertransverse ligaments were damaged in this hyperextension injury of the neck.

The cruciform ligament strengthens the _____________.

The answer is atlantoaxial joint. The dens of the axis is held in place by a complex of strong ligaments that includes the cruciform ligaments complex.

During a general physical examination, a physician asks her patient to stand upright facing straight ahead, then to look to the side with the chin in line with the shoulder. Most of the lateral rotation responsible for this movement occurs at which of the following locations? Between the atlas and the axis At the atlanto-occipital joints Between the upper thoracic vertebrae Between the lower cervical vertebrae At the lower lumbar joints

The answer is between the atlas and the axis. During lateral rotation of the head, approximately half the range of movement occurs at the atlanto-axial joints, i.e., between the C1 and C2 vertebrae. This is particularly pronounced at the middle atlanto-axial joint, between the anterior arch of the atlas (C1) and the odontoid process (dens) of the axis (C2). The atlanto-occipital joints are designed to maximize flexion-extension of the head. Approximately half the range of motion of flexion of the head occurs here.

A 26-year-old woman experiences severe back pain from an automobile accident. A CT scan reveals that the L5 vertebral foramen is completely obliterated by a collapsed L5 laminae and pedicles. In this injury, which of the following structures is crushed?

The answer is cauda equina. The cauda equina is formed by dorsal and ventral roots of the lumbar and sacral spinal nerves. Thus, it is crushed at the level of the L5 vertebra, whereas the other structures are not. Filum terminale externus is incorrect. The filum terminale externus (filum of the dura) extends from the apex of the dura at the level of the S2 vertebra to the dorsum of the coccyx.

The answer is cauda equina. The cauda equina is formed by dorsal and ventral roots of the lumbar and sacral spinal nerves. Thus, it is crushed at the level of the L5 vertebra, whereas the other structures are not. Vertebral artery is incorrect. The vertebral artery, which arises from the subclavian artery, ascends through the transverse foramina of the upper six cervical vertebrae. Spinal cord is incorrect. The spinal cord ends at the level of the L2 vertebra. Filum terminale externus is incorrect. The filum terminale externus (filum of the dura) extends from the apex of the dura at the level of the S2 vertebra to the dorsum of the coccyx. Denticulate ligament is incorrect. The denticulate ligament, a lateral extension of the pia between the dorsal and ventral roots of the spinal nerves, consists of 21 pairs of processes, the last one lying between the T12 and L1 spinal nerves.

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? Denticulate ligament Coccygeal ligament Tectorial membrane Filum terminale internum Choroid plexus

The answer is denticulate ligament. The denticulate ligament is a lateral extension of the pia mater. Filum terminale internum is incorrect. The filum terminale (internum) is an inferior extension of the pia mater from the tip of the conus medullaris. Coccygeal ligament is incorrect. 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. Choroid plexus is incorrect. The vascular choroid plexuses produce the cerebrospinal fluid (CSF) in the ventricles of the brain. Tectorial membrane is incorrect. 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.

An 8-year-old girl fell during a gymnastics competition when she was performing on the uneven bars. She landed on the posterior part of her neck. On examination, there was marked muscle spasm and pain in her neck. Her neck was immobilized, and she was taken to a hospital and examined by an orthopedist. He ordered radiographs of her neck. The radiologist reported that there was anterior subluxation (incomplete dislocation) of C2 on C3 vertebrae. Which of the following statements best describes aspects of the cervical region of the vertebral column? Cervical dislocations must always be treated surgically. Cervical fractures require less force than cervical dislocations. Dislocation of the cervical region of the vertebral column may occur without damage to the spinal cord. Cervical dislocations typically result in rupture of the alar ligament. Cervical dislocations result in rupture of the tectorial membrane.

An 8-year-old girl fell during a gymnastics competition when she was performing on the uneven bars. She landed on the posterior part of her neck. On examination, there was marked muscle spasm and pain in her neck. Her neck was immobilized, and she was taken to a hospital and examined by an orthopedist. He ordered radiographs of her neck. The radiologist reported that there was anterior subluxation (incomplete dislocation) of C2 on C3 vertebrae. Which of the following statements best describes aspects of the cervical region of the vertebral column? Cervical fractures require less force than cervical dislocations. Dislocation of the cervical region of the vertebral column may occur without damage to the spinal cord. Cervical dislocations must always be treated surgically. Cervical dislocations typically result in rupture of the alar ligament. Cervical dislocations result in rupture of the tectorial membrane.

The answer is dislocation of the cervical region of the vertebral column may occur without damage to the spinal cord. Because of the large vertebral canal in the cervical region and the shape of the facet joins, a subluxation of the vertebrae may occur without damaging the spinal cord; however, a severely dislocated vertebra may injure the spinal cord. Cervical fractures require less force than cervical dislocations is incorrect. Cervical dislocations occur with less force than fractures. Cervical dislocations must always be treated surgically is incorrect. These dislocations may self-reduce. Cervical dislocations typically result in rupture of the alar ligament is incorrect. This ligament connects the dens to the occipital bone. Cervical dislocations result in rupture of the tectorial membrane is incorrect. This membrane is the superior continuation of the posterior longitudinal ligament and does not need to rupture in a cervical dislocation.

A 21-year-old woman falls from her horse and complains of headache, backache, and weakness. MR imaging would reveal blood in which of the following spaces if the internal vertebral venous plexus was ruptured?

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

A 23-year-old jockey falls from her horse and complains of headache, backache, and weakness. Radiologic examination would reveal blood in which of the following spaces if the internal vertebral venous plexus was ruptured? Space deep to the pia mater Subarachnoid space Subdural space Space between the arachnoid and dura maters Epidural space

The answer is epidural space. The space between the vertebral canal and the dura mater is the epidural space, which contains the internal vertebral venous plexus. The spinal cord and blood vessels lie deep to the pia mater. The space between the arachnoid and dura maters is the subdural space, which contains a film of fluid. The subarachnoid space contains cerebrospinal fluid (CSF).

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?

The answer is fifth cervical and fourth thoracic nerves. 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 39-year-old woman with headaches presents to her primary care physician with a possible herniated disk. Her magnetic resonance imaging (MRI) scan reveals that the posterolateral protrusion of the intervertebral disk between L4 and L5 vertebrae would most likely affect nerve roots of which of the following spinal nerves?

The answer is fifth lumbar nerve. A posterolateral herniation of the intervertebral disk at disk level L4-L5 affects the fifth lumbar nerve root but rarely affects the fourth lumbar nerve root because of a progressive descending obliquity of the fourth and fifth lumbar nerve roots. The first seven cervical nerves exit above the corresponding vertebra, and the eighth cervical nerve exits below the seventh cervical vertebra because there are eight cervical nerves but only seven cervical vertebrae. The rest of the spinal nerves exit below their corresponding vertebrae.

You are examining an abandoned infant that you estimate to be close to 1 year of age. In evaluating the infant, you notice that there is no lumbar lordosis. What may this tell you about the infant? Has spasticity in his transversospinalis muscles Has hypertrophy of the erector spinae Has spina bifida occult Has spondylolysis Has not begun to walk upright

The answer is has not begun to walk upright. The lumbar curvature is a secondary curvature and does not develop until a child begins to walk upright.

Following a swimming accident, a 12-year-old boy is diagnosed with rupture of the transverse ligament of the atlas. Which of the following is therefore most likely?

The answer is he has atlanto-axial subluxation. When this ligament is ruptured, the dens is free resulting in such subluxation.

A 52-year-old construction worker complained of pain in what he called the "small of his back." As he moved slowly down a ladder, he felt pain that spread down the back of his right leg. He consulted his family doctor who examined him and said that he had symptoms of a herniated IV disc. Which of the following statements about herniation of IV discs is most accurate? In order for an IV disc herniation to produce pain, it must make contact with a spinal nerve. Herniations of the disc are always symptomatic. Herniation of the nucleus pulposus of an IV disc usually occur posterolaterally. Flexion of the vertebral column compresses the posterior part of the IV discs. The water content of the nucleus pulposus increases with age.

A 52-year-old construction worker complained of pain in what he called the "small of his back." As he moved slowly down a ladder, he felt pain that spread down the back of his right leg. He consulted his family doctor who examined him and said that he had symptoms of a herniated IV disc. Which of the following statements about herniation of IV discs is most accurate? Herniation of the nucleus pulposus of an IV disc usually occur posterolaterally. The water content of the nucleus pulposus increases with age. Herniations of the disc are always symptomatic. In order for an IV disc herniation to produce pain, it must make contact with a spinal nerve. Flexion of the vertebral column compresses the posterior part of the IV discs.

The answer is herniation of the nucleus pulposus of an IV disc usually occur posterolaterally. The herniation usually occur posterolaterally because the anulus fibrosus is relatively thin at this site. In addition, the posterior longitudinal ligament does not support the anulus in this location. The water content of the nucleus pulposus increases with age is incorrect because water content decreases with age. Herniations of the disc are always symptomatic is incorrect because disc herniation may be seen in asymptomatic people. In order for an IV disc herniation to produce pain, it must make contact with a spinal nerve is incorrect because contact with the posterior longitudinal ligament will produce pain. Flexion of the vertebral column compresses the posterior part of the IV discs is incorrect because it tenses the posterior part and compresses the anterior part.

Following abdominal aorta aneurysm surgery, the 60-year-old patient became paraplegic. What most likely caused the patient's paraplegia? Iatrogenic (inadvertent) occlusion or transection of the L2 lumbar artery Iatrogenic (inadvertent) occlusion or transection of the subcostal artery Iatrogenic (inadvertent) occlusion or transection of the great anterior segmental artery (of Adamkiewicz) Iatrogenic (inadvertent) occlusion or transection of spinal cord Loss of blood supply to the lower limbs

The answer is iatrogenic (inadvertent) occlusion or transection of the great anterior segmental artery (of Adamkiewicz). Sometimes during such surgery, it is impossible to avoid trauma to this artery, which supplies most of the blood to the lower spinal cord.

A 48-year-old woman crashes into a tree during a skiing lesson and is brought to a hospital with multiple injuries that impinge the posterior primary rami of several thoracic spinal nerves. Such lesions could affect which of the following muscles? Latissimus dorsi Iliocostalis Rhomboid major Trapezius Levator scapulae

The answer is iliocostalis. The posterior primary rami of the spinal nerves innervate the erector spinae including the iliocostalis. Trapezius is incorrect because it is innervated by the spinal accessory nerve. Rhomboid major is incorrect because it is innervated by the dorsal scapular nerve. Levator scapulae is incorrect because it is innervated by the dorsal scapular nerve. Latissimus dorsi is incorrect becauase it is innervated by the thoracodorsal nerve

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? Internal vertebral venous plexus Vertebral artery Vertebral vein External vertebral venous plexus Lumbar cistern

The answer is internal vertebral venous plexus. 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 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? Lateral horn Dorsal horn Ventral horn Gray matter Pia mater

The answer is lateral horn. 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 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? Pia mater Ventral horn Lateral horn Dorsal horn Gray matter

A 17-year-old gymnast grips a high bar with his arms outstretched and begins to pull himself straight upward to the level of the bar, as in doing a chin-up. Which of the following muscles is the prime agonist in this action? Serratus posterior superior Longissimus Latissimus dorsi Rhomboid major Levator scapulae

The answer is latissimus dorsi. The latissimus dorsi (L: widest muscle of back) is a large, fan-shaped muscle and a member of the superficial extrinsic layer of back muscles, which connect the upper limbs to the trunk. The chin-up movement described includes lifting the body toward the upper limb, which is a powerful extension action. In conjunction with the pectoralis major muscle, the latissimus dorsi muscle raises the trunk to the arm, which is crucial in performing chin-ups or climbing a tree. Remember that the superficial layer of back muscles is composed of upper limb muscles that take large bases of origin in the back. Athletes who make heavy use of extension and medial rotation of the arm (as in chin-ups or climbing in conditional exercises) typically have well-developed "lats" that give the classic "V" shape to the back.

An elderly man at a nursing home is known to have degenerative brain disease. When cerebrospinal fluid (CSF) is withdrawn by lumbar puncture for further examination, which of the following structures is most likely penetrated by the needle? Filum terminale externum Pia mater Ligamentum flavum Annulus fibrosus Posterior longitudinal ligament

The answer is ligamentum flavum. 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. The pia mater forms the internal boundary of the subarachnoid space; thus, it cannot be penetrated by needle. The posterior longitudinal ligament lies anterior to the spinal cord; thus, it is not penetrated by the needle. The filum terminale externum is the downward prolongation of the spinal dura mater from the second sacral vertebra to the dorsum of the coccyx. The annulus fibrosus consists of concentric layers of fibrous tissue and fibrocartilage surrounding and retaining the nucleus pulposus of the intervertebral disk, which lies anterior to the spinal cord.

An anesthesiologist administers epidural anesthestic immediately lateral to the spinous processes of vertebrae L3 and L4 of a pregnant woman in labor. During this procedure, what would be the last ligament perforated by the needle in order to access the epidural space? Ligamentum flavum Posterior longitudinal ligament Anterior longitudinal ligament Intertransverse ligament Interspinous ligament

The answer is ligamentum flavum. The ligamentum flavum (L: yellow ligament) consists of yellow elastic fibrous tissue, which binds together the laminae of adjoining vertebrae and forms the posterior wall of the vertebral canal. During proper administration of an epidural anesthetic, the needle will pass (in order) through the supraspinous ligament overlying the spinous processes of the lumbar vertebrae, the interspinous ligament connecting the spinous processes of adjacent vertebrae, and finally the ligamentum flavum, which stretches between the laminae of adjacent vertebrae. Due to its high elastic fiber content and the usual placement of the pregnant woman into the fetal position, the anesthesiologist will feel substantial resistance before the needle passes through the ligamentum flavum and potentially an audible "pop" when it is penetrated. In the given diagram, the epidural space resides between the ligamentum flavum and the posterior longitudinal ligament. Remember that the ligamentum flavum is the last ligament the needle penetrates during administration of an epidural anesthetic.

A lumbar puncture extracts cerebrospinal fluid from the ______________. lumbar cistern. subdural space. epidural space. dural root sheaths. cerebellomedullary cistern.

The answer is lumbar cistern. The lumbar cistern is the distended prolongation of the subarachnoid space inferior to the conus medullaris of the spinal cord; cerebrospinal fluid can be extracted from the lumbar cistern without concern of damaging the spinal cord.

The dura mater surrounding the spinal cord is continuous with the _______________. meningeal layer of dura cranially. periosteal layer of dura cranially. filum terminale internus caudally. filum terminale externus caudally. arachnoid trabeculae.

The answer is meningeal layer of dura cranially. Within the cranial vault, the dura mater is divided into a periosteal and a meningeal layer. At the cranial foramina, the periosteal layer is continuous with the periosteum on the outside of the skull, while at the foramen magnum, the meningeal layer continues inferiorly as the dura mater of the spinal cord.

During a routine prenatal examination of a pregnant 16-year-old woman entering her second trimester (15 weeks of gestation), elevated maternal serum alpha-fetoprotein (AFP) levels were detected and later confirmed by amniocentesis. A follow-up diagnostic ultrasound examination reveals defects in the lower back of the fetus. In the given longitudinal ultrasound scan, open arrows indicate the bases of the vertebrae, and solid arrows point to a cyst-like sac containing protruding neural tissue. Which of the following terms best describes this neural tube defect?

The answer is meningomyelocele. A meningomyelocele is the most common form of spina bifida cystica. In this developmental disorder, the unfused portion of the vertebral column allows the meninges and the spinal cord to protrude through the structural defect, as noted in this longitudinal ultrasound scan. The protruded portion of the spinal cord is damaged (or not completed developed), and this defect may result in paralysis and loss of sensation below the level of the spinal cord defect. This condition is termed spina bifida cystica because of the characteristic presence of a cyst-like sac, composed of meninges and very thin skin, protruding from the defective area. The inclusion of a displaced portion of the spinal cord and nerve roots in the malformation designate this defect as a meningomyelocele. That is, the defect involves the meninges (meningo-), the spinal cord (myelo-), and the membranous sac (-cele). If it reaches full-term, this fetus will likely be paralyzed below the level of the meningomyelocele. In prenatal tests, elevated levels of AFP in the amniotic fluid and maternal blood are strongly associated with the more severe forms of spina bifida, and an ultrasound scan is ordered to confirm the presence of a neural tube defect. Meningocele is incorrect. The least common form of spina bifida is a posterior meningocele (or meningeal cyst). In this developmental disorder, the bilateral neural arch elements fail to fuse completely in the dorsal midline, but the meninges protrude through the defect into a sac or cyst. Therefore, the multiple vertebral defects are accompanied with the presence of a cyst, which contains cerebrospinal fluid (CSF). In a meningocele, the spinal cord and nerve roots are typically in normal position, not protruding into the cyst, and there are usually no long-term effects on the individuals. In this fetus, the ultrasound scan showed a protruding cyst-like sac containing neural tissue, which would rule out a meningocele.

A young toddler presents to her pediatrician with rather new onset of bowel and bladder dysfunction and loss of the lower limb function. Her mother had not taken enough folic acid (to the point of a deficiency) during her pregnancy. On examination, the child has protrusion of the spinal cord and meninges and is diagnosed with which of the following conditions? Meningomyelocele Spina bifida occulta Meningocele Myeloschisis Syringomyelocele

The answer is meningomyelocele. Meningomyelocele is protrusion of the meninges and spinal cord through the unfused arch of the vertebra. A sufficient amount of folic acid during pregnancy is shown to prevent these kinds of neural tube defects. Spina bifida occulta is failure of the vertebral arch to fuse (bony defect only). Meningocele is protrusion of the meninges through the defective vertebral arch. Syringomyelocele is protrusion of the meninges and a pathologic tubular cavity in the spinal cord or brain.

A 12-year-old girl suffers from a type of neural tube defect called tethered cord syndrome, a congenital anomaly that results from defective closure of the neural tube. This syndrome is characterized by an abnormally low conus medullaris, which is tethered by a short, thickened filum terminale, leading to progressive neurologic defects in the legs and feet. Which of the following defects is commonly associated with the tethered cord syndrome? Meningomyelocele Herniated disk Kyphosis Scoliosis Spina bifida occulta

The answer is meningomyelocele. Tethered cord syndrome is frequently associated with meningomyelocele or intraspinal lipomatous growth. Meningomyelocele is a protrusion of the spinal cord and the meninges through the unfused arch of the vertebra. Spina bifida occulta is incorrect. Spinal bifida occulta is a condition caused by failure of the vertebral arch to fuse, with no protrusion of the spinal cord and the meninges. Kyphosis is incorrect. Kyphosis is an abnormal accentuation of lumbar curvature. Herniated disk is incorrect. Herniated disk represents 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 roots. Scoliosis is incorrect. Scoliosis is a lateral deviation of the spine resulting from unequal growth of the vertebral column.

Denticulate ligaments are lateral extensions of the _____________. dura mater. conus medullaris. pia mater. arachnoid mater. filum terminale.

The answer is pia mater. Extensions of the pia mater, denticulate ligaments and the filum terminale, serve to hold the spinal cord in place.

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?

The answer is posterior longitudinal ligament. 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.

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? Anterior longitudinal ligament Cruciform ligament Alar ligament Ligamentum nuchae Posterior longitudinal ligament

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? Posterior longitudinal ligament Anterior longitudinal ligament Alar ligament Cruciform ligament Ligamentum nuchae

Which of the following muscles is innervated by the suboccipital nerve? Rotator brevis Intertransversarii Iliocostalis cervicis Rectus capitis posterior major Longissimus cervicis

The answer is rectus capitis posterior major. The subcostal nerve innervates all of the muscles of the suboccipital triangle, including the rectus capitis posterior major.

During a domestic dispute, a 16-year-old boy receives a deep stab wound around the superior angle of the scapula near the medial border, which injures both the dorsal scapular and spinal accessory nerves. Such an injury could result in paralysis or weakness of which of the following muscles? Trapezius and serratus posterior superior Rhomboid major and trapezius Splenius cervicis and sternocleidomastoid Levator scapulae and erector spinae Rhomboid minor and latissimus dorsi

The answer is rhomboid major trapezius. 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.

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? Rotator longus Rhomboid major Semispinalis capitis Iliocostalis Multifidus

The answer is rhomboid major. 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.

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? Sacral hiatus Intervertebral foramen Vertebral canal Dorsal sacral foramen Ventral sacral foramen

The answer is sacral hiatus. 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.

The answer is spina bifida occulta. This mild degree of spina bifida is caused by a defect in the vertebral arch of the L5 vertebra.The halves of the neural arch of the fetus failed to fuse, resulting in a midline gap in the vertebral arch. There are usually no symptoms or neurological deficits. It is usually associated with a tuft of hair present over the defect.

Spina bifida results from failure of the ___________________. primary curvatures to develop. secondary curvatures of the vertebral column to form. vertebral arches to form correctly. intervertebral discs to form. vertebral bodies to correctly align.

The answer is spina bifida results from the failure of the vertebral arches to form correctly. The vertebral arches form the posterior aspect of the vertebral canal and serve to protect the spinal cord. Failure of them to form correctly results in spina bifida and leaves the spinal cord and associated tissues vulnerable to injury.

An 81-year-old woman visits her family physician for an annual physical examination and complains of weakness and loss of sensation in her legs. Radiological studies show bony spurs (osteophytes) narrowing the intervertebral foramina at levels T12-L3. Which of the following structures is most likely to be impinged in this condition? Anterior rootlets of spinal nerves Spinal ganglia Ganglia of the sympathetic trunk Posterior primary rami of spinal nerves Anterior primary rami of spinal nerves

The answer is spinal ganglia. The posterior (dorsal) and anterior (ventral) roots of spinal nerves typically merge within the intervertebral foramina to form individual spinal nerves. Because the spinal (dorsal root) ganglia are located at the distal ends of the posterior roots, they are also normally found within the intervertebral foramina. Thus, narrowing (stenosis) or compression of the intervertebral foramina may cause impingement of the posterior and anterior roots, spinal nerves, and spinal ganglia due to the presence of bony spurs (osteophytes) in this patient.

As a result of multiple vertebral fractures incurred in an automobile crash, an 8-year-old girl suffers a series of torn posterior primary rami of spinal nerves C1-6. Which of the following muscles will be paralyzed as a result? Latissimus dorsi Splenius capitus Levator scapulae Rhomboid major Trapezius

The answer is splenius capitis. The posterior (dorsal) primary rami of spinal nerves innervate the embryonic epimere and all the skeletal muscles derived from it. The derivatives of the epimere constitute the deep (intrinsic) muscles of the back (or epaxial muscles), including the splenius capitis and cervicis muscles, suboccipital muscles, transversospinales muscles (including the semispinalis, multifidus, and rotatores muscles), and several other small muscles. Thus, damage to the cervical posterior (dorsal) primary rami, specifically C2-6, would result in paralysis of the splenius capitis muscle.

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? Splenius capitis Rectus capitis posterior major Semispinalis capitis Obliquus capitis superior Obliquus capitis inferior

The answer is splenius capitis. 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 16-year-old male soccer player was brought to the ER because of the acute lower back pain he experienced after performing a high-velocity kick of the ball. The given right posterior oblique X-ray reveals pathology within the L5 vertebra that has the appearance of a "headless Scottie Dog" when outlined. Based upon the X-ray results, which of the following diagnoses is the most likely cause of his lower back pain?

The answer is spondylolysis. Spondylolysis refers to a defect in the pars interarticularis of the affected vertebra (or L5 in this patient).

Your patient has a hyperextension injury of the neck. Which ligament likely ruptured with this injury? Anterior longitudinal ligament Alar ligament Ligamentum flavum Posterior longitudinal ligament Transverse ligament

The answer is the anterior longitudinal ligament is the only ligament of the spine that limits extension.

Your patient has a hyperextension injury of the neck. Which ligament likely ruptured with this injury? Posterior longitudinal ligament Transverse ligament Alar ligament Ligamentum flavum Anterior longitudinal ligament

The answer is the anterior longitudinal ligament is the only ligament of the spine that limits extension.

A 60-year-old man does a series of stretching exercises every morning as part of his fitness routine. In one exercise, he holds his hands behind his head and extends his back as far as possible. Which of the following ligaments resists this movement of the back? Posterior longitudinal ligament Intertransverse ligament Anterior longitudinal ligament Ligamentum flavum Interspinous ligament

The answer is the anterior longitudinal ligament. This is a long band that runs along the anterior surfaces of the vertebrae from skull to sacrum. It resists posterior bending (extension and hyperextension) of the vertebral column

The vertebral venous plexuses form an extensive network of vessels that communicate with other veins ranging from the cranial cavity to the pelvis. The nature of the veins and their anastomoses explains much of how carcinomas may metastasize across long distances. Which of the following is the location of the internal vertebral venous plexus?

The answer is the epidural space. The internal vertebral venous plexus is located throughout the length of the vertebral canal, within the epidural (extradural) space. The epidural space is located between the walls of the vertebral canal and the dura mater. This network of veins and the epidural fat are the major contents of the vertebral epidural space. The subarachnoid space is located between the arachnoid mater and the pia mater. It contains cerebrospinal fluid and the arachnoid trabeculae that connect the arachnoid with the pia. The subdural space has been described as a potential space between the dura mater and arachnoid mater that contains a thin film of lymph-like fluid sufficient to cause surface tension adhesion of the dura and arachnoid. However, this scheme has been challenged in recent years with the concept that there is no potential space present between these membranes. The external vertebral venous plexus surrounds the vertebral column. The internal and external vertebral plexuses communicate extensively with each other through the intervertebral foramina along the entire length of the vertebral column. The central canal of the spinal cord contains cerebrospinal fluid.

A 24-year-old weight lifter who was not wearing a weight belt attempted to make a dead lift of a much greater weight than he had ever lifted before. When he felt severe pain in his back, he dropped the weight. On examination, there was localized palpable pain in his lower back. A radiograph and CT (computed tomography) showed a fracture of the L1 vertebra but no dislocation of the vertebra. Which of the following statements is most likely correct pertaining to this injury? The injury is a compression fracture of the vertebral body. Dislocation of the zygapophysial joints caused the fracture of the vertebrae. This injury likely fractured the pars interarticularis of L1. The lumbar vertebral fracture had to involve both the vertebral body and the arch. This fracture likely puts pressure on the sacral nerve roots in the caudal equina.

The answer is the injury is a compression fracture of the vertebral body. This excessive weight most likely resulted in crushing of the anterior aspect of the L1 vertebral body (compression fracture). Dislocation of the zygapophysial joints caused the fracture of the vertebrae is incorrect. Dislocation of these joints is rare and occurs in whiplash injuries in association with vertebral body fracture. This injury likely fractured the pars interarticularis of L1 is incorrect. Such an injury would likely have resulted in spondylolisthesis and dislocation. The lumbar vertebral fracture had to involve both the vertebral body and the arch is incorrect. The vertebral body can fracture without any fracture of the arch. This fracture likely puts pressure on the sacral nerve roots in the caudal equine is incorrect. This is too high an injury to affect the sacral nerve roots.

Mrs. Jones was riding in the front seat of her son's van when the vehicle abruptly stopped. Unfortunately, she was not wearing her seatbelt and was thrown forward. As a result of the accident, the transverse processes of her cervical vertebrae were crushed against the dashboard of the van. Which of the following muscles might be paralyzed? Levator scapulae Trapezius Latissimus dorsi Rhomboid major Serratus posterior superior

The answer is the levator scapulae. The levator scapulae are attached to the transverse processes of the upper cervical vertebrae. All of the other muscles are attached to the spinous processes.

A 70-year-old woman falls down the stairs in her home and suffers multiple rib fractures. Subsequent spastic contractions of which of the following muscles could displace fragments of the broken ribs? Longissimus Rhomboids Semispinalis Splenius Trapezius

The answer is the longissimus. The longissimus muscle, one of the deep muscles of the back and a component of the erector spinae musculature, has extensive attachments to the ribs via its thoracis portion. Thus, spastic contractions of this muscle could directly affect fractured ribs.

A physician orders a lumbar puncture (spinal tap) for his 43-year-old female patient in order to obtain a sample of cerebrospinal fluid (CSF). He explains to her that this procedure will be done in the lower back, between the spinous processes of the L3 and L4 vertebrae. What is the best reason for performing the lumbar puncture at this location? The subarachnoid space ends at the L3 level No vertebral venous plexuses exist below the L3 level The ligamenta flava are absent below the L3 level The intervertebral foramina at L3-4 are large and easy to penetrate The medullary cone ends at or above the L3 level

The answer is the medullary cone ends at or above the L3 level. The objective of a lumbar puncture is to enter (tap) the subarachnoid space and access the CSF. This procedure is performed using a long spinal needle. For several reasons, this procedure is best performed in the low lumbar region, between the spinous processes of the L3 and L4 (sometimes L4 and L5) vertebrae. The medullary cone (or conus medullaris) is the tapered terminal end of the spinal cord. In adults, the medullary cone is normally located within the T12-L3 vertebral levels. Thus, penetrating the vertebral canal and subarachnoid space below L3 is the "safe" place to go, in that the spinal needle should not penetrate the spinal cord. The subarachnoid space ends at the L3 level is incorrect. The subarachnoid space is the CSF-filled space between the arachnoid and pia mater layers of the meninges. The dura-arachnoid layers line the vertebral canal and end at the S2 level. The pia mater lines the exterior surface of the neural tube and continues distally to envelope the spinal nerve rootlets and roots. Because the spinal cord ends at approximately the L1 level, there is a large separation between the dura and arachnoid mater layers of the meninges and the pia mater below L1. Thus, the subarachnoid space is quite large below the medullary cone (conus medullaris), providing a significant pool (the lumbar cistern) of CSF. The intervertebral foramina at L3-4 are large and easy to penetrate is incorrect. The intervertebral foramina in the lumbar region are large openings; however, the lumbar puncture does not occur at these locations. During a spinal tap, the spinal needle is inserted through an interlaminar space, on the posterior side of the vertebral column. These spaces are largest in the low lumbar spine, thus affording a relatively open path to the vertebral canal. Before a spinal tap is administered, the patient is often bent forward into the fetal position by flexing the spine, which expands the interlaminar spaces during the lumbar puncture. No vertebral venous plexuses exist below the L3 level is incorrect. The vertebral venous plexuses are an extensive network of valveless, interconnecting vessels running the entire length of the vertebral column. The external vertebral venous plexus lies on the anterior aspect of the vertebral column and the posterior side of the vertebral arch. The internal vertebral venous plexus is a major constituent of the epidural space within the vertebral canal. A lumbar puncture must traverse both the external and internal plexuses to reach the subarachnoid space. The ligamenta flava are absent below the L3 level is incorrect. The ligamenta flava are short ligaments that connect the anterior sides of adjacent vertebral laminae along the entire length of the vertebral column. The spinal needle must pierce a ligamentum flavum in order to enter the vertebral canal.

A forensic pathologist is examining a set of skeletal remains unearthed from what was apparently a shallow grave. In reconstructing the skeleton, he identifies the individual vertebrae and aligns them in sequence. Which of the following is a distinguishing feature of the second cervical (C2) vertebra?

The answer is the odontoid process. The odontoid process (dens) appears only on the C2 vertebra (the axis), and is the single most distinguishing feature of this bone. The dens is the embryonic body of the C1 vertebra that has migrated caudally and fused with the body of C2. The axis does possess a body. However, the C1 vertebra (atlas) does not. The facets on the superior and inferior articular processes of most cervical vertebrae face posterosuperiorly and inferoanteriorly, respectively. Medio-lateral facing articular facets are characteristic of the lumbar vertebrae. Only thoracic vertebrae possess costal facets for rib articulations. These appear on the bodies and on most transverse processes. No vertebrae typically have trifid spinous processes. Cervical vertebrae 2-6 normally have bifid spines.

A performer at the traveling circus for the state fair has injured her shoulder during a routine. When she fell off the trapeze, she struck the ground on her back, and most of the blunt force was directed toward her shoulders. A crush injury of the suboccipital nerve would result in paralysis of which of the following muscles? Splenius capitis Trapezius Rectus capitis posterior major of the back Iliocostalis Levator scapulae

The answer is the rectus capitis posterior major of the back.

A performer at the traveling circus for the state fair has injured her shoulder during a routine. When she fell off the trapeze, she struck the ground on her back, and most of the blunt force was directed toward her shoulders. A crush injury of the suboccipital nerve would result in paralysis of which of the following muscles? Splenius capitis Iliocostalis Trapezius Levator scapulae Rectus capitis posterior major of the back

The answer is the rectus capitis posterior major of the back. The suboccipital nerve supplies the suboccipital muscles, including the rectus capitis posterior major. The dorsal primary rami of the spinal nerves innervate the deep muscles of the back, including the splenius capitis and iliocostalis muscles. The spinal accessory nerve innervates the trapezius muscle, and the dorsal scapular nerve innervates the levator scapulae muscle; these are the superficial muscles

An obstetrician is preparing to administer caudal anesthesia to his patient to relieve pain during the early stages of labor. The anesthetic solution will be injected into the sacral canal through which of the following openings?

The answer is the sacral hiatus. Caudal anesthesia is used to block pain in the pelvic region by bathing the sacral spinal nerves with anesthetic solution in the sacral canal, where the nerves emerge from the dural sheath. Anesthesia is administered by injection into the sacral hiatus, a distinctive, easily located opening at the caudal end of the sacral part of the vertebral canal.

A 25-year-old woman suffers several lesions of her right side brachial plexus as a result of multiple stab wounds in the neck and axilla. Which of the following muscles will retain its intact motor supply? Latissimus dorsi Levator scapulae Rhomboid minor Rhomboid major Splenius capitis

The answer is the splenius capitis.

A 25-year-old woman suffers several lesions of her right side brachial plexus as a result of multiple stab wounds in the neck and axilla. Which of the following muscles will retain its intact motor supply? Levator scapulae Latissimus dorsi Rhomboid major Splenius capitis Rhomboid minor

The answer is the splenius capitis. All the deep (intrinsic) muscles in the back, including splenius capitis, are supplied by the posterior primary rami of spinal nerves

A 66-year-old man was diagnosed with a large growth on his rectus capitis posterior major muscle. He noticed that whenever he turned his head as when backing up his car, he became light-headed and dizzy. This probably occurred because:

The answer is the tumor was compressing the vertebral artery within the suboccipital triangle. The vertebral artery passes deeply through this triangle (which is bordered by the rectus capitis posterior major muscle), and any reduction in blood flow can cause dizziness especially when the head is turned and additional pressure is put on the artery.

A 16-year-old girl who spends 18 hours a week on her gymnastic routine complained of lower back pain. She was examined by a pediatric orthopedist. The physical examination of her back revealed an abnormal protrusion of the L5 vertebra. A radiograph showed that the posterior vertebral arch of the L5 vertebra was separated from the vertebral body. The anterior part of the vertebra (body, pedicles, and superior articular processes) had moved anteriorly on the sacrum (see figure). Which of the following statements best describes this abnormality?

The answer is this degenerative condition typically results from a fracture of the portion of the vertebra known as the pars interarticularis. When this region of the vertebra is poorly developed or is bilaterally fractured, the body of the L5 vertebra may slide anteriorly on the sacrum (spondylolisthesis). This movement creates an irregularity on the anterior surface of the vertebral column and between the spinous processes of L4 and L5 vertebrae.

In an 87-year-old woman with severe osteoporosis, which of the following would you most likely expect? Thoracic kyphosis Lumbar lordosis Cervical lordosis Scoliosis Dens fracture

The answer is thoracic kyphosis. Osteoporosis tends to affect the horizontal trabecular bone in the vertebral bodies resulting in vertebral body collapse and kyphosis (Dowager hump). Lumbar lordosis is incorrect because it is not likely. Cervical lordosis is incorrect because it is not likely. Scoliosis is incorrect and less likely than kyphosis. Dens fracture is incorrect because it is not likely.

A severe unilateral (rotary) dislocation in the cervical region of the vertebral column is most likely to damage which of the following?

The answer is vertebral artery. The vertebral artery traverses the transverse foramen and thus is subject to injury in cervical dislocations.

A severe unilateral (rotary) dislocation in the cervical region of the vertebral column is most likely to damage which of the following? External carotid artery Sympathetic trunk Superior cervical ganglia Vertebral artery Ansa cervicalis

The answer is vertebral artery. The vertebral artery traverses the transverse foramen and thus is subject to injury in cervical dislocations.

After several months of engaging in a vigorous exercise program, a 28-year-old woman experiences periodic pain and muscle spasms in her left upper limb. Thorough physical and radiographic examinations by her primary care physician and a consulting surgeon determine that she suffers a posterolateral herniation of the C5-6 intervertebral disc. Which of the following structures is this herniation most likely impinging?

c6 spinal nerve roots

A developmental biologist studying the derivatives of the somites and somitomeres treats the epimeres in a mouse embryo with a toxin that kills all of their cells. If the mouse develops to full term, which of the following muscles is most likely to be absent? Rhomboid major Trapezius Levator scapulae Longissimus Latissimus dorsi

he answer is longissimus. Destruction of the embryonic epimeres will result in loss of the deep group of back muscles, including the longissimus muscle, one of three erector spinae muscles (along with the iliocostalis and spinalis muscles). Muscles derived from the epimeres are the proper muscles of the back, which are innervated by the posterior (dorsal) primary rami of spinal nerves. These deep muscles of the back include the previously mentioned erector spinae group, splenius capitis and cervicis muscles, suboccipital muscles, transversospinales muscles (including the semispinalis, multifidus, and rotatores muscles), and other small muscles. Remember, each embryonic somite differentiates into three components: myotome, dermatome, and sclerotome. Each myotome splits into two parts: epimere and hypomere. The epimere develops dorsal to the incipient vertebral column, and the longissimus muscle is the only listed muscle which is derived from the embryonic epimere. The muscles derived from the epimeres form the deep group of muscles in the back and are often termed the intrinsic back muscles or epaxial muscles. Trapezius is incorrect. The trapezius is a member of the superficial extrinsic layer of back muscles, which connect the upper limbs to the trunk. When these muscles contract (or shorten), they produce movements of the upper limb. However, the trapezius muscle does not originate from either the epimere or hypomere, as evidenced by its innervation via the spinal accessory nerve (CN XI). Instead, it is likely related to postbranchial origins, along with its mate, sternocleidomastoid. Thus, destruction of epimeres will not directly affect the formation of the trapezius.

An 18-year-old soldier presents with shrapnel wounds in the lateral wall of his right chest following an explosion of a landmine. After several months of recovery, his physical therapist observes that his scapula moves away from the thoracic wall when he leans on his right hand, as noted by the black arrow in the given photo. Which of the following nerves is likely damaged?

long thoracic nerve

A developmental biologist studying the derivatives of the somites and somitomeres treats the epimeres in a mouse embryo with a toxin that kills all of their cells. If the mouse develops to full term, which of the following muscles is most likely to be absent? Longissimus Trapezius Levator scapulae Latissimus dorsi Rhomboid major

longissimus

The erector spinae muscle group includes ________________. spinalis cervicis. levator costarum. multifidus. splenius capitis. semispinalis capitis.

prep u back

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