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