CHAPTER 6

Question 1

1. Which of the following reflexes is a monosynaptic reflex?

(A)	Achilles reflex
(B)	Babinski reflex
(C)	Corneal reflex
(D)	Extensor plantar reflex
(E)	Pupillary light reflex

Answer 1

1- A. The Achilles reflex, or ankle jerk reflex, is a myotatic monosynaptic reflex that is mediated by cord segment S1.

Question 2

2. All of the following statements concerning
   the spinal cord are correct EXCEPT

(A) it represents 2% of brain weight
(B) it terminates in the adult at VL1-VL2
(C) it is closely applied to the pia mater
(D) it terminates at VS2 in the newborn
(E) it contains 31 pairs of spinal nerves

Answer 2

2- D. In the newborn, the spinal cord ends at the level of the third lumbar vertebra (VL3). In the adult, the spinal cord ends at the level of the interspace between the first and second lumbar vertebrae (VL1-VL2), and the dural cul-de-sac ends at the level of the second sacral vertebra (VS2). The pia mater is the innermost meningeal layer of the spinal cord; spinal cord, pia mater, arachnoid, dura mater, ligamenta flava, periosteum.

Question 3

3. All of the following statements concerning
   spinal nerves are correct EXCEPT

(A) dorsal roots contain sensory input
(B) ventral roots contain motor output
(C) all spinal nerves have gray communicating rami
(D) all spinal nerves have white communicating rami
(E) the first cervical nerves frequently have
no dorsal roots

Answer 3

3- D. White communicating rami are found only at thoracolumbar levels of the spinal cord ( Tl—L3); they contain myelinated preganglionic sympathetic fibers and myelinated general visceral afferent (GVA) fibers ( from splanchnic nerves ). Gray communicating rami contain unmyelinated postganglionic sympathetic fibers and contribute to all spinal nerves. The first cer-
vical nerve and the coccygeal nerve usually have no dorsal (sensory) roots.

Question 4

4. All of the following statements concerning
   the myotatic reflex are correct EXCEPT

(A) it is a monosynaptic and ipsilateral reflex
(B) it is a muscle stretch reflex (MSR)
(C) it includes a muscle spindle
(D) it includes a ventral horn motor neuron
(E) the cell body of the afferent nerve fiber is
found in the dorsal horn

Answer 4

4-E. The myotatic reflex is a monosynaptic and ipsilateral muscle stretch reflex (MSR; incorrectly called a deep tendon reflex). The afferent limb consists of a muscle spindle (receptor) and a Ia fiber (axon) of a dorsal root ganglion neuron; the efferent limb consists of the axon of a ventral horn alpha motor neuron and the innervated striated muscle fibers (effector). The quadriceps (patellar) and triceps surae (ankle) MSRs are myotatic reflexes.

Question 5

5. Contains preganglionic parasympathetic
neurons
(A)	Cervical cord
(B)	Upper thoracic cord
(C)	Lumbar cord
(D)	Lower thoracic cord
(E)	Coccygeal cord
(F)	Sacral cord

Answer 5

5- F. The sacral cord contains the sacral parasympathetic nucleus (S2-S4); this gives rise to preganglionic fibers that synapse in the intramural ganglia of the pelvic viscera.

Question 6

6. Contains massive ventral horns and dorsal
(A)	Cervical cord
(B)	Upper thoracic cord
(C)	Lumbar cord
(D)	Lower thoracic cord
(E)	Coccygeal cord
(F)	Sacral cord

intermediate sulcus

Answer 6

6- A. The cervical cord contains massive ventral horns, which give rise to the brachial plexus (C5-C8). The dorsal intermediate sulcus and septum are also indicative of cervical cord levels

Question 7

7. Has a ciliospinal center of Budge
(A)	Cervical cord
(B)	Upper thoracic cord
(C)	Lumbar cord
(D)	Lower thoracic cord
(E)	Coccygeal cord
(F)	Sacral cord

Answer 7

7- B. The ciliospinal center of Budge is found in the lateral horn at Tl. This sympathetic nucleus innervates the radial muscle of the iris (dilatator pupillae) and the nonstriated superior and inferior tarsal (Muller) muscles.

Question 8

8. Contains the spinal accssory nucleus (CN XI)
(A)	Cervical cord
(B)	Upper thoracic cord
(C)	Lumbar cord
(D)	Lower thoracic cord
(E)	Coccygeal cord
(F)	Sacral cord

Answer 8

8- A. The spinal accessory nucleus extends from C1-C6 and gives rise to the spinal root of the spinal accessory nerve; it innervates the sternocleidomastoid and trapezius muscles.

Question 9

9. Contains the phrenic nucleus
(A)	Cervical cord
(B)	Upper thoracic cord
(C)	Lumbar cord
(D)	Lower thoracic cord
(E)	Coccygeal cord
(F)	Sacral cord

Answer 9

9- A. The phrenic nucleus extends from C3-C6 and innervates the diaphragm.