Lecture 7 part two (SECOND MIDTERM) Flashcards
The lower motor neurons send their axons out through where?
the ventral root
2 very basic types of reflex arcs:
Monosynaptic: one synapse
Polysynaptic: more than one synapse
Example of monosynaptic reflex arc and of polysynaptic reflex arcs:
mono: stretch reflex
poly: withdrawal reflex (flexor reflex) and crossed extensor reflex
Stretch reflex:
stretches receptors inside of the muscle; signal is carried through by somatic afferent neuron and it goes directly to the motor nuclei; will contract the muscle in defense
Stretch reflex muscles and main nerves associated with them:
Biceps: C5, C6 Brachioradialis: C6 Triceps: C7 Patellar: L4 Calcaneal Tendon: S1
A patient has no patellar stretch reflex. Where is the damage?
L4
What do interneurons do? Where are they located?
- they distribute sensory information and coordinate motor activity
- located between sensory and motor nerves
- the more complex the response to a given stimulus, the more interneurons are involved!
The 2 different types of signals being sent in withdrawal reflex (flexor reflex) and cross extensor reflex:
inhibitory
excitatory
In a cross extensor reflex, a motor response to the stimulus also occurs where?
on a side opposite the stimulus
The protective coverings of the nerves are known as…
meninges
3 meninges from outer to inner:
dura mater (tough mother) arachnoid mater (spider mother) pia mater (soft mother)
The meninges only exist where?
around the CNS
The pia mater has little extensions coming off called…
What do they do?
denticulate ligaments
-prevents spinal cord by moving around and slamming against vertebral column
The nerve and nerve roots get “dragged” in what direction?
caudal (inferior)
Bones continue to grow, but what stops growing? What also keeps growing?
- the central nervous system stops growing
- the peripheral nervous system keeps growing
Where the spinal column and spinal cord taper off, it is called…
the conis medullaris
The conis medullaris has this little “piece” of connective tissue coming all the way down and anchoring it at the very end of the meninges; where the dura ends, what anchors the conis medullaris?
filum terminale (terminal thread) (prevents movement and damage to spinal cord)
The portion with all of the nerve roots that contributes to the spinal nerves emerging after is called what?
cauda equina
What is the specific bilateral region of the skin surface monitored by a single pair of spinal nerves?
dermatome
A complex interwoven network of nerves is called a…
nerve plexus
What are the only rami involved in the nerve plexus for our limbs?
ventral rami
Your limbs only develop from what region?
hypaxial
Because your limbs only develop from the hypaxial region, they get their nerve innervation from…
ventral rami
Usually how many segments combine to form a limb?
6
