exam 1 Flashcards
where does the spinal cord end?
L1-L2
how many total pairs of spinal nerves are there?
31
how many pairs of cervical spinal nerves?
8
how many pairs of thoracic spinal nerves?
12
how many pairs of lumbar spinal nerves?
5
how many pairs of sacral spinal nerves?
5 + 1 coccygeal nerve
what is gray matter composed of?
nerve cell bodies, dendrites, portions of unmyelinated nerve axons, neurogial cells
what is white matter composed of?
myelinated nerve cell axons, unmyelinated axons
filum terminale
long ligament extending from tip of conus medullaris, attaches to coccyx, composed of pia mater, becomes coccygeal ligament, restricts longitudinal movement of cord
CNS
composed of brain and spinal cord
PNS
cranial nerves and spinal nerves
Are spinal nerves sensory, motor, or mixed?
mixed
denticulate ligaments
composed of pia mater, extend from lateral surface and laterally fuse with dura, restrict lateral movement of the cord
subarachnoid space
filled with CSF
purpose of spinal meninges
physical stability and shock absorption for cord and tissue
dura extends to
S2
dorsal or posterior ramus
smaller nerve branch, mixed, sensory fibers carry info from skin of back, motor fibers innervate dep muscles of back
anterior or ventral ramus
motor fibers innervate muscles of and skin of body wall, muscles and skin of upper and lower limbs
spinal rootlets form where?
subarachnoid space
afferent
carries sensory info to the CNS; sensory
efferent
carries impulses away from the CNS; motor
dorsal root ganglia
contain cell bodies of sensory neurons
dorsal roots
axons of sensory neurons, bring sensory info into spinal cord, afferent
ventral roots
contain axons of motor neurons that extend into periphery to control somatic and visceral effectors, efferent
nuclei
clusters of cell bodies with a similar function, masses of gray matter
posterior (dorsal) gray horn
contains somatic and visceral sensory nuclei,
anterior (ventral) gray horn
contain somatic and visceral motor nuclei
lateral gray horns
located only in thoracic and lumbar, contains visceral motor nuclei
gray commissure
contains axons that cross from one side of the cord to another
ascending tracts
carry sensory info toward brain
descending tracts
convey motor commands to spinal cord
layers of spinal nerves
(from outside) epineurium, perineurium, endoneurium
dermatome
specific bilateral region of the skin surface monitored by a single pair of spinal nerves
cervical plexus
C1-C5, innervate muscles of neck and trunk
phrenic nerve
part of cervical plexus, innervates the diaphragm
brachial plexus
C5-T1, innervates pectoral girdle and upper limb
musculocutaneous nerve
motor to muscles in upper limb, flexors of arm (brachialis and biceps brachii), part of brachial plexus
axillary nerve
sensory of skin of the shoulder, deltoid and teres minor, part of brachial plexus
radial nerve
part of brachial plexus, extensors of arm and forearm
ulnar nerve
part of brachial plexus, “funny bone”, in forearm
median nerve
part of brachial plexus, compressed by carpal tunnel, begins at shoulder
lumbar plexus
T12-L4, femoral nerve innervates quads
sacral plexus
L4-S4, sciaric nerve is largest nerve in the body and braches into tibial and fibular nerve
divergence
spreading stimulation to multiple neurons or neuronal pools in the CNS
convergence
providing input to a single neuron from multiple sources
serial processing
neurons or pools work sequentially
parallel processing
neurons or pools process same info simultaneously
reverberation
positive feedback
reflexes
rapid, autonomic responses to specific stimuli
steps of a reflex arc
- arrival of stimuli and activation of a receptor
- activation on sensory neuron
- information processing
- activation of motor neuron
- responce of peripheral effector
innate reflexes
born with it, genitically determined (ex. swallowing)
somatic reflexes
skeletal muscle contractions, most are concious
visceral (autonomic) reflexes
control actions of smooth and cardiac muscles, glands, adipose tissue