Chapter 6 : Spinal Cord (3)

Question 1

1. Which of the following reflexes is a monosy¬naptic reflex?
(A) Achilles reflex 
(B) Babinski reflex 
(C) Corneal reflex 
(D) Extensor plantar reflex 
(E) Pupillary light reflex.

Answer 1

I-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 VLI-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,
duramater, 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 communicat¬ing rami
   (D) all spinal nerves. have white communicat¬ing rami neurons
   (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 (TI-L3); they contain myelinated preganglionic sympathetic fibers and myelinated general visceral afferent (GVA) fibers (from Bplanchnic nerves). Gray communicating mi contain unmyelinated post ganglionic sympathetic fibers and contribute to all spinal nerves. The first cervical nerve and the coccygeal nerve usually have no dorsal (sensory) roots.

Question 4

4. All of the following statements concerningmyotatic 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

The response options for the items 5-7 are the same. You will be required to 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
5. Containspreganglionicparasympathetic

Answer 5

5-F. The sacral cord contains the sacral para sympathetic nucleus (S2-84); this gives rise to preganglionic fibers that synapse in the intramural ganglia of the pelvic viscera.

Question 6

The response options for the items 5-7 are the same. You will be required to 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

6. Contains massive ventral horns and dorsal 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

The response options for the items 5-7 are the same. You will be required to 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

7. Has a ciliospinal center of Budge

 

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 pupiIlae) nnd the Ilonstriatud superior and in·
ferior tarsal (Muller) muscles

Question 8

The response options for the items 5-7 are the same. You will be required to 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

8. Contains the spinal accssory nucleus (CN Xl)

 

Answer 8

8-A. The spinnl accessory nucleus extends from Cl·CG nnd giveR risc t.o the spinnl root ofthr.
spinal accessory nerve; it innervates the sternocleidomastoid and trapezius muscles.

Question 9

The response options for the items 5-7 are the same. You will be required to 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

9. Contains the phrenic nucleus

 

Answer 9

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