Anatomy Part 2 Questions
If in the process of doing a lumbar puncture a spinal needle was inserted posteriorly in the midline until it had just penetrated the posterior longitudinal ligament, would the needle have entered the subarachnoid space?
The correct answer is: (A) Yes The posterior longitudinal ligament is located along the posterior surfaces of all vertebral bodies. So, to penetrate the posterior longitudinal ligament, a needle would have to enter and exit the dura mater and the arachnoid mater.
The myelogram revealed that the dye had leaked out along the spinal nerves in the mid cervical region on the right side. For the dye to leak out, what layer must have been torn or ruptured?
The correct answer is: (A) arachnoid The previous question stated that a myelogram is a radiograph taken following injection of a radio-opaque dye into the subarachnoid space. So, it should make sense that the arachnoid must be ruptured for the dye to leak out following this procedure.
The number of vertebrae and number of spinal cord segments are the same in each region except:
The correct answer is: (A) cervical Remember: the first cervical nerve comes over the first cervical vertebra, and is labeled C1. But, the last cervical nerve comes below the seventh (and final) cervical vertebra. This nerve is labeled C8. So there are 8 cervical spinal cord segments but 7 cervical vertebrae
A patient is suspected of having bacterial meningitis. As part of the diagnostic procedure, a lumbar puncture is to be performed. The attending physician asks you where she should insert the spinal needle to withdraw CSF. You answer, "just below the spine of the 4th lumbar vertebra." What reference point would you use to identify the spine?
The correct answer is: (A) crest of the ilium. L4 is a relatively safe level for performing a lumbar puncture. Since the conus medullaris is at the inferior border of L1 or the superior border of L2, it should be safe to insert a needle either above or below L4. The anatomical landmark used to identify L4 is the top of the iliac crest. The line connecting the top of the two iliac crests, the supracristal line, passes through the spinous processes of the L4 vertebrae. So, by finding the tops of the iliac crests, you should be able to identify L4.
The denticulate ligament:
The correct answer is: (A) is a modification of the pia mater. The denticulate ligaments are specializations of the pia mater that extend from the lateral surface of the pia, helping to suspend the spinal cord in the subarachnoid space.
In order to expose the spinal cord from the posterior side, it is necessary to remove the:
The correct answer is: (B) Laminae, spinous processes, and ligamenta flavum This is straight from lab: To expose the spinal cord, it was necessary to remove the laminae, spinous processes, and ligamenta flavum. The supraspinous ligament and the interspinous ligament also needed to be removed.
In an adult, the conus medullaris of the spinal cord is normally positioned at which vertebral body levels:
The correct answer is: (B) T12-L2 In adults, the conus medullaris is normally positioned between T12 and L2. This is why it is safe to do a lumbar puncture at the level of L4.
The intervertebral disk
The correct answer is: (B) adds about 1/4 the entire length to the vertebral column. The interveterbral discs, consisting of an outer anulus fibrosus and an inner nucleus pulposis, add about 1/4 the length to the vertebral column. They act as shock absorbers between the vertebral bodies. The discs are not found between all adjacent vertebrae. There is no disc between the C1 and C2 vertebrae, and the most inferior disc is between L5 and S1.
Kyphosis is an accentuated or abnormal curvature of which region of the spine?
The correct answer is: (B) thoracic Kyphosis is an abnormal increase in the thoracic curvature of the vertebral column.
Prostate cancer is diagnosed in an 82 year old male. Thereafter a malignant brain tumor of prostatic origin is found. He subsequently dies. An autopsy reveals tumor sites in the prostate, vertebral column, and brain, but no other organs. By what vascular pathway did the cancerous cells get to the brain:
The correct answer is: (B) vertebral venous plexus A valveless venous system, the internal vertebral venous plexus is clinically significant because it can transmit cancer metastases to distant locations. The anterior spinal artery and vertebral arteries would not be the route for cancer cells to reach the brain. The azygos system contains valves and would carry blood toward the heart and lungs, not toward the brain. Finally, the thoracic duct is a major channel for lymph flow to reenter the circulation. Although cancer cells may be carried by lymphatics, the thoracic duct would not direct cancer to the brain.
A football player suffers a herniated (ruptured) intervertebral disk in his neck. The disk compresses the spinal nerve exiting through the intevertebral foramen between the 5th and 6th cervical vertebrae. Which spinal nerve is affected?
The correct answer is: (C) C6 There are 7 cervical vertebrae and 8 pairs of cervical nerves. So, the nerve from the C1spinal cord segment emerges above the C1 vertebra, the nerve from the C2 region of the spinal cord emerges above the C2 vertebra, and so on. This means that if a disk presses the nerve between the C5 and C6 vertebrae, it will be compressing the C6 nerve, which emerges above the C6 vertebra.
In the final stages of labor a caudal anesthetic is sometimes given via a needle inserted into the sacral hiatus. The anesthetic is thus placed around the outside of the sacral spinal nerve roots and into the:
The correct answer is: (C) Epidural space A caudal anesthesia is administered by a catheter inserted through the sacral hiatus. Anesthetic is placed in the catheter, and the anesthetic bathes the sacral nerve roots. The catheter is in the epidural space, and this is where the anesthesia is placed.
A University student comes to the Emergency Room with a high fever, lethargy and a stiff neck. After further examination, meningitis is suspected and a lumbar puncture is ordered. What landmark could be used to insert the spinal needle between the 4th and 5th lumbar vertebral spines?
The correct answer is: (C) Iliac crest L4 is a relatively safe level for performing a lumbar puncture. Since the conus medullaris is at the inferior border of L1 or the superior border of L2, it should be safe to insert a needle either above or below L4. The anatomical landmark used to identify L4 is the top of the iliac crest. The line connecting the top of the two iliac crests, the supracrestal line, passes through the spinous processes of the L4 vertebrae. So, by finding the tops of the iliac crests, you should be able to identify L4.
A man has a herniated intervertebral disk between the fourth and fifth lumbar vertebrae. If this disk compresses the spinal nerve in the intervertebral foramen immediately posterior to this disk, which spinal nerve would be affected?
The correct answer is: (C) L5 This question asks you to think about the lumbar region where the spinal nerve comes out below the vertebra of the same number. If a disc herniates between L4 and L5, it will be impinging on the L5 spinal nerve.
A patient is diagnosed as having a venous anomaly of the posterior spinal veins which have enlarged, putting pressure on the spinal cord. In order to expose the veins, the surgeon will have to pass through the skin, subcutaneous tissue, deep back muscles and then, in order, the:
The correct answer is: (C) Laminae and ligamenta flava, epidural space, dura, subdural space, arachnoid, subarachnoid space, pia.
If one does a laminectomy (removing the laminae of two adjacent vertebrae) to expose the spinal cord, which ligament must be removed?
The correct answer is: (C) Ligamentum flavum Ligamenta flava is an elastic ligament which joins the laminae of adjacent vertebrae. So, to remove the laminae of two adjacent vertebrae, this ligament must be removed.
Both the dural sac and the subarachnoid space end at which vertebral level?
The correct answer is: (C) S2 Although the dural sac and subarachnoid space end at S2, the filum terminale externum (AKA coccygeal ligament) is a continuation of the dura mater that extends below the end of the dural sac to attach to the coccyx.
A neuron with a cell body in the dorsal root ganglia could convey what type of fibers?
The correct answer is: (C) Sensory from the skin overlying the trapezius The dorsal root ganglia is the location of the cell bodies of somatic sensory neurons. Cells from the dorsal root ganglia transmit somatic sensation from areas like the skin to the central nervous system. A neuron with a cell body in the dorsal root ganglia might be involved in conveying sensory information from the skin overlying the trapezius.
The conus medullaris:
The correct answer is: (C) gives origin to most of the cauda equina Located at L2, the conus medullarus is the tapered termination of the spinal cord proper. Most of the cauda equina originate from the conus medullaris and then travel to the vertebral foramina inferior. Although the spinal cord exhibits both a cervical and a lumbar enlargement, the conus medullaris refers to the termination of the spinal cord, not the entire spinal cord.
Inserting a spinal tap needle in the lumbar region, in the midline, you hear and feel a 'pop' at the needle tip. What structure was perforated to cause the 'pop?'
The correct answer is: (D) Dura mater Crossing the dura mater would cause a ""pop"" that might be heard while doing a spinal tap. The dura is the toughest covering over the spinal cord, so it is difficult to penetrate it with a needle.
Because of their structure and interconnections, which veins are especially important in the metastatic spread of cancer?
The correct answer is: (D) Internal vertebral venous plexus The veins of the internal vertebral venous plexus are clinically significant because they are valveless and can serve as a route for metastases. Cancerous cells can travel freely in vertebral veins and lodge somewhere else in the body. The other veins all have valves which would direct the flow of blood and stop some of the metastatic spread.
It is decided to image the spinal cord and spinal nerve rootlets by doing a myelogram (injection of a radio-opaque dye into the subarachnoid space followed by a radiograph). In order to inject the dye without injury to the spinal cord, the injection is usually done below what vertebral level?
The correct answer is: (D) L4 In an adult, the spinal cord usually ends at the inferior border of L1 or the superior border of L2. Therefore, it is relatively safe to insert a needle above or below L4. At this level, the nerve roots are suspended in the CSF and can float away from the pressure of the needle, so these roots will not be damaged by the needle.
A patient is suspected of having bacterial meningitis. A lumbar puncture is performed to remove cerebrospinal fluid (CSF) for analysis. If done properly, the needle used for the tap would penetrate all layers except:
The correct answer is: (D) Pia mater The pia mater is the innermost covering of the spinal cord which is closely applied to the entire spinal cord. It does not need to be pierced to retrieve CSF. This fluid is found in the subarachnoid space, outside of the pia mater. The needle must pass through the following layers during a lumbar puncture: skin, fat, supraspinous ligament, interspinous ligament, between or through the ligamenta flava, epidural fat and veins, dura, subdural space, and arachnoid.
Which muscle is innervated by posterior primary rami?
The correct answer is: (D) erector spinae Of all the answer choices, erector spinae is the only true back muscle listed. True back muscles act on the vertebral column, producing its movements and maintaining posture. These true back muscles are innervated by posterior (dorsal) primary rami.
While moving into a new apartment a student lifting a heavy box of books experiences a sharp pain in his back, radiating down the anterior thigh and medial side of his leg. After several days of misery, he finally goes for treatment and is told that he has a herniated intervertebral disk at the L 4 level which is compressing a spinal nerve where it exits the vertebral column. The point of compression is the:
The correct answer is: (D) intervertebral foramen A ""slipped disk"" is the herniation of the nucleus pulposis through the anulus fibrosis. This usually happens in a posterolateral direction. Once a disk herniates, it commonly puts pressure on the nerve roots or the dorsal root ganglion exiting the intervertebral foramen at or below its level. The vertebral canal or vertebral foramen is the opening formed by the combination of the body and vertebral arch. This is not the location where the disk is compressing nerves. The foramen magnum is an opening in the occipital part of the skull that transmits the spinal cord. The hiatus of the sacral canal is a normal feature that results from the failure of fusion of the laminae of the fifth sacral segment (and sometimes the fourth) during development.
A 45-year-old man complained to his physician that the muscles of his upper limb were weak and he felt clumsy while walking. Tests revealed that he had amyotrophic lateral sclerosis (Lou Gehrig's disease), a disease which attacks the neurons of the voluntary motor system. Where would one expect to see atrophic or degenerated nerve cell bodies?
The correct answer is: (E) Ventral horn of the spinal cord The cell bodies of the motor neurons are found in the ventral horn of the spinal cord. Since these are the cells that are being degraded in ALS, which is destroying the voluntary motor system, this is the place where you would expect to see the atrophied cell bodies.
Quasimoto, the "Hunchback of Notre Dame," suffered from an abnormal thoracic curvature called kyphosis. In this condition the accentuated convexity of the curvature is:
The correct answer is: (E) posterior In kyphosis, the accentuated convexity of the curvature is in a posterior direction. The accentuated convexity of curvature in lordosis is in the anterior direction.
A patient is suspected of having bacterial meningitis. A lumbar puncture is performed to remove cerebrospinal fluid (CSF) for analysis. The fluid would be removed from the:
The correct answer is: (E) subarachnoid space at the level of L4 There are 2 issues to think about here. First, from what compartment is the CSF removed? Second, at what level should the needle be inserted in a spinal tap? CSF is removed from the subarachnoid space. The epidural space contains epidural fat, and the subdural space is a potential space only. Also, remember that a lumbar puncture should be performed at the level of L4. Because the spinal cord ends at the bottom of L1 or the top of L2, L4 is a safe level for inserting a needle.
As the spinal needle in the above question is being inserted, which ligament would it pass through on its way to the subarachnoid space?
The correct answer is: (E) supraspinous. To insert a needle into the subarachnoid space, the needle must pass through three ligaments: the supraspinous ligament, interspinous ligament, and ligamenta flava. The anterior longitudinal ligament is located along the anterior surfaces of all vertebral bodies--it lies directly posterior to the thoracic and abdominal viscera. The denticulate ligaments are paired ligaments that separate the dorsal and ventral rootlets.
The part of a spinal nerve that supplies the true back muscles and the skin overlying them is the:
The dorsal primary ramus supplies sensory innervation to the skin of the back and motor innervation to the true back muscles.
