12. The Central Nervous System

The innermost layer of the meninges, delicate and adjacent to the brain tissue, is the

a. Dura mater

b. Corpus callosum

c. Arachnoid mater

d. Pia mater

a. How is cerebrospinal fluid formed and drained? Describe its pathway within and around the brain.

b What happens if CSF does not drain properly? Why is this consequence more harmful in adults?

List four ways in which the CNS is protected.

Which is the innermost delicate meningeal layer?

A 10-month-old infant has an enlarging head circumference and delayed overall development. Her CSF pressure is elevated, and she has a bulging anterior fontanelle (fontanelles are the as yet unossified fibrous membranes connecting skull bones in infants). Based on these findings, answer the following questions:

a. What are the possible cause(s) of an enlarged head?

b. Which tests might be helpful in obtaining information about this infant's problem?

c. Assuming the tests conducted showed the cerebral aqueduct to be constricted, which ventricles or CSF-containing areas would you expect to be enlarged? Which would likely not be visible? Respond to the same questions based on a finding of obstructed arachnoid granulations.

a. Define cerebrovascular accident or CVA.

b. Describe its possible causes and consequences.

A cerebrovascular accident occurs when

(a) The reticular activating system fails to function

(b) The prefrontal lobe is damaged

(c) The blood supply to a portion of the brain is cut off

(d) A descending tract in the spinal cord is severed

(e) Brainstem nuclei hypersecrete dopamine

A semiconscious young woman is brought to the hospital by friends after falling from a roof. She did not lose consciousness immediately, and she was initially lucid. After a while, though, she became confused and then unresponsive. What is a likely explanation of her condition?

Mrs. Chen, a new mother, brings her infant to the clinic because he has suffered repeated seizures. When questioned, she states that her labor was unusually long and difficult. What condition do you suspect? Will the infant's condition worsen?

If symptoms characteristic of Parkinson's disease appear, which part of the midbrain is inhibited from secreting a neurotransmitter? Which neurotransmitter is it?

Describe the spinal cord, depicting its extent, its composition of gray and white matter, and its spinal roots.

Proceeding deep from the most superficial structure, number the following in the correct sequence:

(a) _____ walls of vertebral canal

(b) _____ dura mater

(c) _____ subdural space

(d) _____ epidural space

(e) _____ pia mater

(f) _____ arachnoid membrane

(g) _____ subarachnoid space

(h) _____ spinal cord

Describe the functional problems that would be experienced by a person in which these fiber tracts have been cut:

a. Lateral spinothalamic

b. Ventral and dorsal spinocerebellar

c. Tectospinal

The synapsing of several neurons on the same postsynaptic neuron is called

(a) Serial processing

(b) Reverberation

(c) Divergence

(d) Convergence