ch 13.1-13.4 Flashcards
spinal reflex
rapid, automatic response triggered by specific stimuli that is controlled in the spinal cord
spinal cord
organ made up of nervous tissue, housed within protective membranes and vertebral column
4 regions of spinal cord
cervical, thoracic, lumbar, sacral
distal end of spinal cord includes
conus medullaris
cauda equina
filum terminale
conus medullaris
tapered, conical end of the spinal cord below the lumbar enlargement
cauda equina
nerve roots extending below conus medullaris
filum terminale
thin thread of fibrous tissue at end of the conus medullaris
spinal nerves
mixed nerves that contain both afferent and efferent motors
pns spinal nerve
contains:
- dorsal root (for sensory neurons)
- ventral root (for motor commands)
- dorsal ganglion
dorsal root function
carries sensory info to CNS
ventral root function
caries motor commands
spinal meninges
3 covering that surrounds spinal cord and brain
- provide physical stability, shock absorption, and pathway for blood vessels supplying the spinal cord
layers of spinal meninges
-Dura mater – outer layer
-Arachnoid mater – middle layer
-Pia mater – inner layer
meningitis
– viral or bacterial infection of meninges
dura mater
- tough, outer most layer fibrous meninx
epidural space
between the vertebrae and the dura mater
- made of adipose tissue
subdural space
deep to the dura mater
- between dura mater and arachnoid
- contains csf
arachnoid mater
- middle meningeal layer
- includes the arachnoid membrane and trabeculae
Subarachnoid space
space between arachnoid mater and pia mater
- filled with cerebrospinal fluid
lumbar puncture/spinal tap
withdraws CSF from the subarachnoid space
spinal anesthesia
local anesthetics introduced into the subarachnoid space
denticulate ligaments
triangle shaped extensions of pia mater
– that anchor the pia mater to arachnoid mater and the dura mater to prevent lateral movement of the spinal cord/holds spinal cord in place
anterior median fissure
deep, wide groove on front of spinal cord
posterior median sulcus
shallow, narrow groove on back
gray matter
cell bodies of neurons, neuroglia, and unmyelinated axons
– butterfly shape in the spinal cord
gray matter function
Integrates information and initiates commands
white matter
myelinated axons
- surrounds gray amtter
white matter function
Carries information from place to place
masses of gray matter within CNS are called _____ and organized into regions called ________
nuclei
regions called HORNS
organization of gray matter
-posterior horns
-anterior horns
- lateral horns
posterior horns
contain somatic and visceral sensory nuclei (processes sensory info)
anterior horns
contain somatic motor nuclei which is responsible for voluntary muscle contractions
lateral horns
found in the thoracic and lumbar segments; contain visceral motor nuclei
gray commissure
narrow band of gray matter around central canal
organization of white matter
posterior, anterior, and lateral white columns
posterior white columns
– between the posterior horns and the posterior median sulcus
anterior white columns
between the anterior horns and the anterior median fissure
anterior white commissure
interconnects anterior white columns and where axons cross from one side of spinal cord to the other
lateral white columns
on each side of the spinal cord, between the anterior and posterior columns
tract
bundle of axons in the CNS
ascending tracts
sensory information up toward the brain
descending tracts
motor commands down to the spinal cord
3 connective tissue layers around spinal nerves
epineurium
perineurium
endoneurium
epineurium
outermost layer covering nerve; network of collagen fibers
perineurium
middle layer; separates nerve into fascicles (bundles of axons)
endoneurium
innermost layer; surrounds individual axons
spinal nerves
mixed nerves
- Form by the junction of the anterior and posterior roots
peripheral distribution of spinal nerves
-dermatome
- peripheral neuropathies
- shingles
dermatome
areas of skin that connect to a specific nerve root on your spine
peripheral neuropathies
– regional losses of sensory and motor function, often resulting from trauma or compression
shingles
the varicella-zoster virus (V Z V) attacks spinal nerves and produce painful rash along the corresponding dermatomes
nerve plexus
complex, interwoven network of nerve fibers
nerve plexus function
Allows multiple spinal nerves to supply the same structures
4 major nerve plexuses
cervical
brachial
lumbar
sacral
cervical plexus
- includes anterior rami or spinal nerves C1 - C5
– Innervates the scalp behind the ear, the neck, and the diaphragm
phrenic
controls the diaphragm
brachial plexus
innervates the pectoral girdle, upper back, and upper limbs
major brachial plexus nerves (4)
musculocutaneous
radial
median
ulnar
Musculocutaneous nerve
arm flexors; skin of lateral forearm
radial nerve
extensors of the arm and forearm; skin of posterolateral surface
median nerve
forearm flexor and digital flexors; skin anterolateral surface of the hand
ulnar nerve
flexors of wrist and small digital muscles; skin of medial surface of hand
lumbar plexus
– includes the anterior rami of spinal nerves T12 - L4
sacral plexus
includes the anterior rami of spinal nerves L4 - S4
major lumbar nerves (6)
- Iliohypogastric
- ilio-inguinal nerve
- genitofemoral
- lateral femoral cutaneous
-femoral nerve - obturator nerve
pairs in the spinal cord
31
- 8 cervical pairs
- 12 thoracic pairs
- 5 lumbar pairs
- 5 sacral pairs
- 1 coccygeal nerve
