chapter 17
dorsal gray horn
axon terminals of unipolar neurons but contain cell bodies of multipolar interneurons; receives sensory information from the dorsal root
ventral white commissure
in between fissure & commissure
tibial nerve
innervates posterior aspect of leg
dura mater
most durable & closest to vertebra
dorsal root
nerve impulses for sensations
subarachnoid space
space between arachnoid and pia mater; contains cerebrospinal fluid
subdural space
space between dura and arachnoid mater; contains interstitial fluid; potentially exists & becomes a space due to presence of hematoma
common fibular nerve
splits into superficial & deep fibular nerves (innervate anterior aspect of leg; foot is innervated by specific nerves that arise from them)
somatic motor neuron
transfers information from CNS to skeletal muscle underneath patch of skin which is supplied by the same specific spinal nerve
arachnoid mater
under dura mater; anchors blood vessels
conus medullaris
where spinal cord ends (L1 or L2)
brachial plexus
(second half of anterior ramus of:) C5, anterior ramii of C6-C8, T1; axillary nerve, musculocutaneous nerve, median nerve, ulnar nerve, radial nerve; tells which spinal nerves could be damaged if specific part of upper limb loses sensation
sacral plexus
(second half of anterior ramus of:) L4, anterior ramii of L5, S1-S5
coccygeal plexus
(second half of anterior ramus of:) S5 & coccygeal nerve
sacral nerves
5 pairs
cervical nerves
8 pairs; belong to cervical & brachial plexus
which nerves exit through the sacral foramen?
S1-S4
sacral dermatome
S1-S5; involved w/ information of genitals & lower limb
pudendal nerve
S2-S4; goes toward genital area & innervates skin of penis & scrotum or clitoris, labia majora, & vagina; sensation of skin in genitals)
which nerves exit through the sacral hiatus?
S5 & coccygeal nerves
thoracic dermatome
T1-T12; involved w/ information of thorax & abdominal areas
dorsal spinal cord injury at T10
able to walk but won't notice changes in temperature from waist down (sensory is damaged)
transverse foramen
allows passage of blood vessels in cervical vertebra
intervertebral foramen
allows passage of nerves
filum terminale
anchors spinal cord inferiorly; extension of pia mater
cutaneous fields
area innervated by nerve that comes from plexus; can overlap several dermatomes
dermatome
areas of skin served by single spinal nerve; makes it easy to figure out damaged region of spinal cord
epidural space
between vertebra & dura mater; contains fat & connective tissue that protects the spinal cord against injuries
gray commissure
bundle of nerve fibers that connect two halves of CNS; communication between right & left side; where nerves cross over; contains central canal in the middle
dorsal root ganglion
cell bodies of unipolar neurons that carry sensory information
spinal nerve
formed by dorsal & ventral root; carries both motor & sensory information
motor/ descending tracts
from brain to spinal cord
ascending/ sensory tract
from spinal cord to brain
median nerve
goes down middle of arm & forearm; supplies & innervates muscles of anterior aspect of forearm & small portion of hand; arises from junction of lateral & medial cord
axillary nerve
wraps around axilla & innervates deltoid & teres minor (shoulder)
the following helps prevent lateral and inferior movement of the spinal cord: -denticulate ligaments -anterior rootlets -fasciculi -posterior rootlets
denticulate ligaments
ventral ramus of spinal nerve
sensory & motor information of skin & muscles of the lateral & anterior aspect of the trunk; supplies the upper & lower limbs
pia mater
closest to spinal cord & hugs it; transparent; most flexible; contains blood vessels that supplies oxygen & nutrients to spinal cord
cauda equina
collection of spinal nerves below the end of the spinal cord
coccygeal nerves
1 pair
thoracic nerves
12 pairs
spinal cord
31 pairs of spinal nerves; main communication between brain & body other than cranial nerves
lumbar nerves
5 pairs
lumbar dermatome
L1-L5; involved w/ information of lower limb
ventral gray horn
cell bodies of multipolar neurons that carry motor information & send axons via ventral roots until they synapse w/ skeletal muscle
what divides the spinal cord into right and left halves?
posterior median sulcus (skinny) & anterior median fissure (fat)
gray matter
horns; have lots of cell bodies related to a specific cell function; deeper than white matter
cranial reflex definition & example
integrating center of brain stem; tracking movement of eyes when reading
ventral root
nerve impulses to effector tissues
what happens if damage is from a cutaneous field instead of a specific spinal nerve?
the damage is in the peripheral nerve not the spinal root/ cord
why is there 8 cervical nerves but only 7 vertebrae?
the first cervical spinal nerve gets out of spinal cord between the occipital bone & atlas
denticulate ligament
thickening of pia mater that projects laterally & fuses w/ arachnoid & dura mater; anchors pia mater & spinal cord from floating in fluid; protects spinal cord from displacement
the longest nerve that innervates the digestive system is the: -glossopharyngeal -vagus -hypoglossal -trigeminal
vagus
the motor command leaves through the: -dorsal root ganglion -posterior root -dorsal root -ventral root
ventral root
poliomyelitis
virus of somatic motor neurons; in C3-C5 (no control of diaphragm)
process of spinal reflex arc
1. sensory receptor detects stimulus 2. activates action potential (sensory information flows toward CNS & passes spinal nerve) 3. sensory information passes dorsal root ganglion to dorsal gray horn where some information goes to brain & some information reaches inhibitory interneuron 4. the rest of the sensory information activates the motor neuron in the ventral gray horn 5. motor information passes ventral root & spinal nerve 6. reaches effector which contracts while the antagonistic muscles relax from the inhibitory interneuron
cervical dermatome
C2-C8; involved w/ information of upper limbs
the superior trunk originates from the branches of which cervical nerve? -C5 and C6 -C3-C5 -C1-C5 -C5-C8 -C5-T1
C5 & C6
the middle trunk arises from which cervical nerve(s)? -C5 and C6 -C6 and C7 -C7 and C8 -C6 -C7
C7
in the spinal cord, the somas of the lower motor neurons are found in the: -dorsal root ganglia -cauda equina -posterior horns -anterior horns -central canal
anterior horns
cervical plexus
anterior ramii of C1-C4, (first half of anterior ramus of:) C5; innervates skin of neck region & neck muscles + superior part of shoulder & chest; phrenic nerve
phrenic nerve
anterior ramii of C3-C5; innervates diaphragm (voluntary skeletal muscle to breathe)
lumbar plexus
anterior ramii of L1-L3, (first half of anterior ramus of:) L4; genitofemoral nerve, obturator nerve, femoral nerve
ramus
branch of root
fascicle
bundle of endoneurium
plexus
bundle of nerve fibers from anterior ramus of different spinal nerves
the inferior trunk gives rise to which cords? -superior and middle -medial and posterior -middle -posterior -lateral and posterior
medial & posterior
meninges
membranes between bony structures & nervous tissue; dura, arachnoid & pia mater protect the spinal cord
obturator nerve
passes through obturator foramen & goes to medial aspect of thigh; innervates muscles & skin of medial aspect of thigh
branches
principal nerves
below L1-L2, the vertebral canal is occupied by a bundle of spinal nerve roots called the: -descending tracts -filum terminale -conus medullaris -cauda equina -sacral plexus
cauda equina
lateral gray horn
cell bodies for autonomic neurons w/ axons that extend through anterior root & synapse w/ cardiac muscle, smooth muscles, or glands; deeper in spinal cord; primarily in thoracic region of spinal cord
white matter
columns; contains bundles of axons that take information through ascending/ sensory tract
epineurium
continuous w/ dura mater; most outside tough layer surrounding spinal nerve; gives spinal nerves strength when stretching; contain blood vessels in invaginations
craniotomy for hematoma
create Burr holes --> peel out dura mater --> flush out blood
T2-T12 (intercostal nerves)
don't form plexus; run laterally between ribs; innervate intercostal muscles; responsible for sensory & motor information from lateral & anterior aspects of the chest & abdominal muscles
genitofemoral nerve
goes to genitals & thigh; innervates specific muscles of genital region & skin of upper medial aspect of thigh
femoral nerve
goes towards femur; innervates muscles of skin of anterior aspect of thighs
which of these is NOT a region of the spinal cord? -thoracic -pelvic -sacral -lumbar -cervical
pelvic
musculocutaneous nerve
pierces coracobrachialis; stops between brachial & biceps brachii (anterior aspect of arm); lateral cord
what is the largest nerve in our body?
sciatic nerve
dorsal ramus of spinal nerve
related to all sensory & motor information of skin & deep muscles of the back
Remember To Drink Cold Beer
roots, trunks, divisions, cords, branches
radial nerve
runs down arm & radius; innervates posterior aspect of arm & forearm; posterior cord
ulnar nerve
runs down arm & ulna; main nerve innervating hands & anterior medial aspect of forearm; medial cord
sciatic nerve
runs posteriorly down thigh until it reaches the posterior aspect of the knee; splits into tibial & common fibular nerve
somatic sensory neurons
supply each dermatome from skin to CNS
endoneurium
surrounds each axon; closest to nerve fiber
perineurium
surrounds each fascicle; terminates by blending w/ connective tissue found surrounding nerve endings & muscle junctions