Spinal Cord Anatomy

Question 1

reflex

Answer 1

• nearly instantaneous, automatic, involuntary motor responses caused by nervous system
• caused by stimuli inside or outside body
• sometimes involve brainstem

Question 2

brainstem

Answer 2

contains midbrain, pons, medulla

Question 3

reflex arc

Answer 3

• neural pathway that nerve impulse travels
• if goes thru CNS, that reflex can be used to examine nervous system function
• 5 components (for spinal reflexes)

Question 4

gray matter

Answer 4

• central part of spinal cord
• contains cell bodies of neurons
• where neurons synapse with other neurons (e.g. interneurons)

Question 5

white matter

Answer 5

• surrounds gray matter in spinal cord

- contains axons of neurons

Question 6

dorsal root ganglion (DRG)

Answer 6

contains cell bodies of sensory neurons

Question 7

dorsal root (of nerve)

Answer 7

• contains axons of sensory neurons

- sensory info goes through here to enter spinal cord

Question 8

ventral root (of nerve)

Answer 8

• contains axons of motor neurons

- motor info leaves spinal cord through here

Question 9

anterior horn

Answer 9

• located in gray matter

- contains motor neuron cell bodies

Question 10

posterior horn

Answer 10

• located in gray matter

- where sensory neurons synapse on interneurons

Question 11

spinal reflexes

Answer 11

• faster than conscious decision to move from brain

- fewer neurons, impulses have shorter length of travel

Question 12

receptor

Answer 12

• located at end of sensory neuron

- reacts to stimulus

Question 13

sensory (afferent) neuron

Answer 13

conducts impulses from receptor via afferent pathway to CNS

Question 14

integration center

Answer 14

one or more synapses within CNS

Question 15

motor (efferent) neuron

Answer 15

conducts impulses away from integration center via efferent pathway to effector

Question 16

effector

Answer 16

responds to efferent impulses by contracting (muscle) or secreting (gland)

Question 17

stretch reflexes

Answer 17

• protect muscle against an increase in length that may tear/damage muscle fibers
• important for maintaining posture
• ex. = patellar reflex

Question 18

patellar reflex

Answer 18

• prevents overstretching of quadratis femoris muscle
• tapping patellar tendon (when leg suspended off table) stretches the patellar tendon, which stretches the quadratis femoris attached to it, causing the knee-jerk reflex

Question 19

flexor withdrawal reflex

Answer 19

• happens when touch something hot (pain receptor in skin generates nerve impulses
• more complicated than stretch reflexes, involves many interneurons (including excitatory and inhibitory interneurons)

Question 20

muscle spindles

Answer 20

• specialized muscle cells that monitor amount of stretch in a muscle
• when sense stretch, send a signal to the spinal cord via reflex arc