Test 47   (the nervous system)

1. The following are true about the dural venous sinuses:

a. they have no valve

b. the cavernous sinus is closely related to the pituitary gland

c. the cavernous sinus has the first two divisions of the 
    trigeminal nerve on its lateral wall

d. the transverse sinus continues as the sigmoid sinus

e. through the pterygoid plexus, facial infection can spread to 
    the cavernous sinus

Answera.T   b.T   c.T   d.T   e.T

2. True statements about the cerebral blood flow include:

a. it is constant for the blood pressure in the range between 
   50-150mmHg

b. the blood pressure is affected more by the PaO2 than PaCO2

c. hypocapnia causes vasoconstriction

d. cerebral arterioles constricts when the blood pressure raises

e. sympathetic nervous system does not play as important a 
    part in cerebral blood flow as  autoregulationt 

Answera.T   b.F   c.T   d.T   e.T
CO2 has more effect than O2 in affecting cerebral blood flow. 
Hypocapnia can result from hyperventilation and causes vasoconstriction
 

3. The following reflexes are used to test for brain stem death:

a. knee jerk reflex

b. Babinski's reflex

c. gag reflex

d. pupil reflex

e. vestibulo-ocular reflex

Answera.F   b.F   c.T   d.T   e.T
Knee jerk reflex involves the spinal column
Babinski's reflex results from upper motor neurone lesion.
 

4. In injury of the peripheral nerve:

a. pure sensory or pure motor nerve tends to regenerate better 
    than mixed nerve

b. in neuropraxia, there is anatomical disruption of the nerve

c. Wallerian degeneration occurs 3 days after the injury

d. Wallerian degeneration occurs proximal to the site of the 
     injury

e. during recover, the rate of regeneration is about 1 mm per 
    day

Answera.T   b.F   c.T   d.F   e.T
In neuropraxia, there is loss of conduction but not anatomical disruption of the nerve. 
Wallerian degeneration occurs distal to the site of the injury.
 

5. The blood - brain barrier:

a. is permeable to bilirubin at birth

b. is formed by the tight junctions between endothlial cells 
    and the end feet processes of astrocytes

c. is permeable to glucose

d. is absent in the posterior pituitary

e. it is permeable to fat-soluble drugs

Answera.T   b.T   c.T   d.T   e.T