Lecture Outline #14 PNS Flashcards
the neural tube
ectoderm folds inward to form a hollow tube. Anterior end swells - hollow brain. Posterior portion - spinal cord & central canal. Both are filled with csf
cortex of spinal cord
white matter - myelinated axons
medulla of spinal cord
grey matter - cell bodies (unmyelinated axons)
central canal of spinal cord
filled w/ csf
dura mater
thick, fibrous, outermost layer, endosteum for braincase
epidural space
between bone & dura mater, target for epidural block
subdural space
space between dura mater & arachnoid
arachnoid
thin, intermediate layer, contains large BV’s which are supported by arachnoid trabeculae
subarachnoid space
space between arachnoid & pia mater, contains denticulate ligaments, filled with csf, target for spinal tap
pia mater
vascular, innermost layer, fused to spinal cord, BV’s form a network on surface of cord
meningitis
inflammation of meninges (bacteria, virus, injury)
conus medullaris
tapered termination of cord
filum terminale
fiber extending from conus to coccyx, acts as a tether holding onto the spinal cord to no retraction
posterior median sulcus
shallow longitudinal groove
anterior median fissure
deep longitudinal groove
cauda equina
roots & rootlets, extend off of conus medullaris
dorsal root
contains sensory nerves, afferent information going to CNS, contains dorsal root ganglion.
ventral root
contains motor neurons (somatic & autonomic), CNS to PNS)
dorsal ramus
innervates skin/muscles of back, branches off of spinal nerve, sensory & motor information
ventral ramus
innervates skin/muscles of thorax, abdomen, limbs, motor information going out
rami communicantes
ANS, visceri, both sensory & motor information. takes a ride of ventral rami
cord diameter variations
cervical & lumbar (accommodates a plexus) both have a lot of grey matter
spinal nerve
where dorsal & ventral roots meet at intervertebral foramen
cervical nerves
C1-C8, named for vertebra below
thoracic, lumbar, sacral, coccygeal nerves
T1-T12, L1-L5, S1-S5, co1. named for vertebra above
dermatomes
pieces/segments of innervated skin
T4
nipples
T10
umbilicus
S2-S4 (pudendal)
genitalia
referred pain
(internal) brain & spinal cord can’t differentiate pains of organs & skin because it uses the same axons to perceive
communication steps
rami communicantes, ventral rami, CNS to perceive
cervical plexus
C1-C5, innervates neck muscles, levator scapulae, part of trapezius & SCM
phrenic nerve
C3-C5 keeps the diaphragm alive (controls contractions)
brachial plexus
C5-T1
axillary nerve
C5-C6, actions of deltoid & teres minor
radial nerve
C5-T1, extensors of arm, forearm, wrist, fingers, and brachioradialis
median nerve
C5-T1, flexors of wrist & digits 1-3
ulnar nerve
C8-T1, funny bone(posterior to medial epicondyle), flexor carpi ulnaris & flexors of digits 4-5
musculotaneus nerve
C5-C7, flexors of the arm & forearm (brachialis & BB)
erb’s palsy
C4-C6, upper plexus injury
klumpke’s palsy
lower plexus injury
lumbosacral plexus
T12-S4
gluteal nerve
L4-S2, gluteals
obturator nerve
L2-L4, adductors of thigh
pudendal nerve
S2-S4, GI?UG sphincters, external genitalia & skin around anus
femoral nerve
L2-L4, extensors of knee (anterior aspect)
tibial nerve
semis, bf lh, flexors of ankle & toes
fibular nerve common
thigh area, bf sh
fibular nerve superficialis
fibularis muscles
fibular nerve deep
dorsi-flexors of ankle/toes (tibialis anterior)
the sciatic nerve
bundle of tibial & common fibular nerve
reflexes
built in safety mechanism, innate: hardwired or acquired: trauma, experiences.
Processing sites are the brain & spc, spc acts as a brain via interneurons, message is sent to brain.
Motor - somatic or visceral. Contralateral movement - extensor & flexor flip which is contracting
reflex arc steps
- stimulus of the receptor (pain or stretch)
- sensory neuron (dorsal root) sends info to CNS
- Relays info (sensation relayed to brain & motor nerves)
- Motor neuron (ventral root) is activated
- Peripheral effectors respond (muscles & glands)
cerebrovascular accident
stroke, blood flow to the brain is interrupted or damaged
paralysis
loss of motor control
paraplegia
paralysis of lower limbs, T6-L1
hemiplegia (possible CVA)
paralysis of one side of body, right hemisphere will show on the left side, vica versa
quadriplegia
paralysis of all 4 limbs, (C4 or C6)
Death
break at C3 and above
palsy
regional loss of sensory/motor function
spina bifida & meningomyelocoele
malformation of spine & spc, lamina does not completely form
spinal cord goes completely out to skin
