Chapter 6 : Spinal Cord (4)

Question 1

1. Which of the following reflexes is monosynaptic?
(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. The spinal cord of a newborn baby terminates at
(A) VL1
(B) VL3
(C) VS1
(D) VS3
(E) VS5

Answer 2

2–B. 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 lower border of the first lumbar vertebra (VL1), 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. Which spinal nerve rami contain unmyelinated postganglionic sympathetic nerve fibers?
(A) White communicating
(B) Dorsal primary
(C) Gray communicating
(D) Ventral primary
(E) Meningeal

Answer 3

3–D. Gray communicating rami contain unmyelinated preganglionic sympathetic fibers, whereas white communicating rami contain myelinated preganglionic sympathetic fibers and myelinated GVA fibers. The meningeal ramus innervates the meninges and vertebral column; the dorsal primary ramus innervates the skin and muscles of the back; and the ventral primary ramus
innervates the ventral lateral muscles and skin of the trunk, extremities, and visceral organs.

Question 4

4. The efferent limb of a myotatic reflex includes a
(A) ventral horn motor neuron
(B) muscle spindle
(C) dorsal root ganglion neuron
(D) lateral horn visceromotor nucleus
(E) preganglionic sympathetic neuron

Answer 4

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

Question 5

The response options for the items 5 to 9 are the same. Select one answer for each item in the set.
(A) Cervical cord
(B) Upper thoracic cord
(C) Lumbar cord
(D) Lower thoracic cord
(E) Coccygeal cord
(F) Sacral cord
Match each characteristic below with the spinal cord level it best describes.

5. Contains preganglionic parasympathetic neurons

Answer 5

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

Question 6

The response options for the items 5 to 9 are the same. Select one answer for each item in the set.
(A) Cervical cord
(B) Upper thoracic cord
(C) Lumbar cord
(D) Lower thoracic cord
(E) Coccygeal cord
(F) Sacral cord
Match each characteristic below with the spinal cord level it best describes.

6. Contains the brachial plexus
   Jawab : A

Answer 6

6–A. The cervical cord contains massive ventral horns, which give rise to the brachial plexus
(C5–C8).

Question 7

The response options for the items 5 to 9 are the same. Select one answer for each item in the set.
(A) Cervical cord
(B) Upper thoracic cord
(C) Lumbar cord
(D) Lower thoracic cord
(E) Coccygeal cord
(F) Sacral cord
Match each characteristic below with the spinal cord level it best describes.

7. Has a ciliospinal center of Budge

Answer 7

7–B. The ciliospinal center of Budge is found in the lateral horn at T1. This sympathetic nucleus
innervates the radial muscle of the iris (dilator pupillae) and the nonstriated superior and inferior
tarsal (Müller) muscles

Question 8

The response options for the items 5 to 9 are the same. Select one answer for each item in the set.
(A) Cervical cord
(B) Upper thoracic cord
(C) Lumbar cord
(D) Lower thoracic cord
(E) Coccygeal cord
(F) Sacral cord
Match each characteristic below with the spinal cord level it best describes.

8. Contains the spinal accessory nucleus (CN XI)

Answer 8

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

Question 9

The response options for the items 5 to 9 are the same. Select one answer for each item in the set.
(A) Cervical cord
(B) Upper thoracic cord
(C) Lumbar cord
(D) Lower thoracic cord
(E) Coccygeal cord
(F) Sacral cord
Match each characteristic below with the spinal cord level it best describes.

9. Contains the phrenic nucleus

Answer 9

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