Flashcards in Overview of CNS And PNS (4) Deck (32)
Sagittal planes divide the brain how?
Into right and left; is a lateral cross section
From rostral to caudal, what are the 5 major brain segments?
Which brain segment includes the medulla?
Which brain segment contains the cerebral hemispheres?
Which brain segment contains the pons and cerebellum?
Which brain segment contains the thalamus and hypothalamus?
Which brain segment contains the midbrain?
Gray matter has high densities of what?
Neurons ( specifically somas and dendrites, both of which are unmyelinated)
White matter has high densities of what?
In the forebrain is gray or white matter on the outer surface?
Gray matter ( there are nuclei of gray matter deep in the brain as well; nuclei in the brain are the same as ganglia in the periphery, both have cell bodies)
In the spinal cord, is gray or white matter on the outer surface?
What are the five functional loves of the brain?
What is the function of the thalamus?
Relay center for sensory (except olfactory) and motor afferents into the cortex. Also integrates higher order cognitive and emotional information
What is the function of the basal ganglia?
Smooths out motor movements of the limbs and axial musculature during body movement
What are the three components of the brainstem?
3. Medulla (which connects brain to spinal cord)
How can there be 8 cervical spinal cord segments but only 7 cervical vertebrae?
The first cervical spinal nerve exits above C1. Most of the rest exit beneath the similarly numbered vertebrae. (Except spinal nerve C8 comes out beneath C7)
In the adult at approx. what vertebral level does the spinal cord end?
T12 - L1
Why do the lower thoracic, lumbar, and sacral nerves exit the spinal canal several levels below their exit from the spinal cord itself?
The vertebral column grows faster than the spinal cord beginning at about 3 mo gestation, so there is an apparent rostral shift of the spinal cord. (In the infant, the spinal cord ends at approx. L3; compare to T12-L1 in the adult)
What does the dorsal root of a spinal nerve conduct?
Afferent peripheral sensory nerve fibers traveling to the cord
What do the ventral roots of spinal nerves conduct?
Efferent motor nerves traveling to muscles, organs, etc
On what neurons and where in the spinal cord do the neurons originating from the corticospinal tract terminate?
In the lower motor neuron located in the anterior horn
Where does the cell body of the most peripheral nerve in the spinothalamic tract reside?
In the dorsal root ganglion.
Where does the spinothalamic tract decussate?
In the spinal cord, just after entering. The second neuron, which the pseudounipolar sensory neuron with cell body in dorsal root ganglia first synapses on in the gray matter of the dorsal horn, decussates, then travels rostrally
Where does the 2nd neuron in the spinothalamic tract synapse with the third?
In the thalamus (ventral posterior nucleus of the thalamus to be exact). The third neuron then travels to neurons in the sensory cortex of the forebrain to complete the pathway.
Which sensory pathway informs the brain of the position of ones body parts in space?
Posterior (Dorsal) column
Where are the originating neurons of the posterior (dorsal) column located?
Dorsal root ganglia; are pseudounipolar neurons like those in the spinothalamic tract (makes sense! both are sensory pathways)
Where does the posterior (dorsal) column decussate?
In the medulla. It is the 2nd neuron that actually travels to the opposite side. (The 1st neuron travels all the way up to the medulla from the periphery w/o synapsing)
Where does the 1st neuron in the posterior (dorsal) column synapse into the second?
In the gracile or cuneate nuclei in the medulla.
Where does the second neuron in the posterior (dorsal) column synapse with the third?
In the ventral posterior lateral (VPL) nucleus of the thalamus. This VPL neuron travels up and synapses on neurons in the sensory cortex