Neuro Anatomy: Lecture 2 Spinal Cord

Rostral boundary of the spinal cord

medulla

the spinal cord is 1 mm caudal to

motor decussation

Coverings of the spinal cord

dura: one layer (outer periosteal layer attaches to bone at foramen magnum

arachnoid

pia

Spaces in the spinal cord

subarachnoid - csf

subdural

epidural

caudal boundary of the spinal cord

conus medullaris

Between L1 and L2

Conus medullaris

the most distal bulbous part of the spinal cord

filum terminale

the tapered end of the conus medullaris

cauda Equina

a collection of nerve roots distal to the end of theL spinal cord

Lumbar puncture is between

L3-L4 in the region of the cauda equina

to prevent nerve damage

number of Cervical

8

vertebrae and pairs of spinal nerves

number of thoracic

12

vertebrae and pairs of spinal nerves

number of Lumbar

5

vertebrae

number of Sacral

5

vertebrae

coccygeal

1-3

vertebrae

Where do we see cord enlargements

cervical enlargement -arms

lumbar enlargement - legs

why do we have cord enlargements

increased number of motor neurons in the ventral horn of gray to accomodate muscles of arms and elgs

Compare cervical, thoracic, and lumbar spincal cord

White matter _____ as we goe down the spinal cord

decreases

many efferent motor nerves hae already reached their destination and do not need to continue down the spinal cord

see diagram

Ventral primary rami form

plexuses of the body

dorsal primary rami DO NOT; they remain independent

plexus

network of nerves

Cervical Plexus

skin, ear, neck, back of head, shoulder (sensory and motor)

C1-C4

Brachial Plexus

upper extremity (sensory and motor)

C5-C8, T1

lumbosacral plexus

lower extremity (sens and motor)

L1-S3

pelvic plexus

pelvic floor (sensory and motor)

S2-24

Dermatomes

sensory patterns of innervation

mytomes

motor patterns of innervation

cervical cutaneous nerves (Cervical plexus C1-C4)

from behind sternocleidomastoid muscle innervat

bacl of head n

skin of posterior ear

shoulder

within posterior triangle of the neck

What is within the posterior triangle of the neck

Cervical plexus

Brachial plexus

the brachial plexus travels in close proximity to

the apex of the lung

Horner's syndrome results from damage to

sympathetics

sympathetics travel near the apex of the lung

if a pt has horners syndrome we want to see where it is caused

if there is an apical lung mass (pancoast tumor) the crachial plexus and the symptathics can be damged

this woudl result in ispilateral horner syndrome and ispilateral upper extremity weakness

T2-T12

Independent (not plexus)

muscles, skin, etc of anterior and lateral trunk (sens & motor)

dorsal primary rami

remain independent

supply muscles of back

Gray matter

cell bodies

nuclear groups

white matter

axons

SEe imates

Clarke's nucleus (nucleus dorsalis)

C8-L3

in the ventral horn of gray at the cervical e;argement from medial to lateral

shoulder

arm

forehead

hand

in the ventral horn of gray at the cervical e;argement from dorsal to ventral

dorsal: flexors

ventral: extensors

Lateral horn gray T1-L3

symapathetic preganglionic

Lateral horn gray C8-T2

ciliospinal column of budge

sympatheic preganglionocs

when damaged can cause horners sydnrome

cranioccarcal

parasymapthics

throcolumbar

symoathetics

see image

Lateral horn S2-24

parasympathetic preganglionic

innervAtes viscera below left colic flexure

CNS

brain

spinal cord

retina

CN1

CN2

PNS

other Cranial nerves

spinal nerce

ganglia

nucleus

collection of cell bodies within CNS

ganglion

collection of cell bodies outside of the CNS

Tract

collection of axons with a common origin, course, and termination

fasciculus

SEE IMAGE

funiculus

2 or more fasciculi

conscious pathway

the pathway will end in cerebral cortex for our preception

General somactic afferent

ascending

afferent

Somatic motor

descending

efferent

GSA Conscious pathway

1. 1st cell body in dorsal root ganglion

2. 2nd cell body in in the posterior horn of grey or its extension into brainstem

3. Dorsal Thalamus (ventral posterior lateral nucleus)

GSA Reflex pathway

1. 1st cell body in dorsal root ganglion

2. 2nd cell body in posterior horn of gray or its extension into the brainstem

3. anywhere other than thalamus (midbrain, muedlla)

Conscious pathway: the axon of the third neuron synapses in

area 3,2,1 (post central gyrus) of cerebral cortex

Axons are part of

internal capsule

any consious pathway has to travel

the the cerebrum via the thalamus

any reflex pathway

does NOT travel to the cerebrum or use the thalamus

internal capusle

white matter structure

all of the fibers going to (sensory) and coming from (motor) the cerebral cortex which form a fan-shaped mass of fibers called the corona radiata.

The fibers of the corona radiata converge towards the diencephalon forming a prominent, compact bundle of axons known as the internal capsule which links the cortex to other levels of the neuraxis

sensory homunculus

representation of the bpdy parts along the postcentral gyrus of the parital lobe

motor humunoculus

representation of the body parts and its correspondents along the precentral gyrus of the frontal lobe.

the sensory is more

posterior

motor is more

anterior

only ____ pathways will use the hominculi

conscious (meaning involving the cerebrum)

SENSORY pathways are ------, and will ----- in the grey matter of the sensory homunculus.

AFFERENT (ascending)

end

MOTOR pathways are------, and will ----- in the grey matter of the motor homunculus.

EFFERENT (descending)

begin

The lower extremities are _____ in the homunculus

medial

The upper extremities, face, and trunk are _____ in the homunculus

lateral

ICA give rise to

anterior cerebral artery and middle cererbal artery

anterior cerebral artery supplies

medial surface

middle cerebral artery supplies

lateral surface

posterior cerebral artery supplies

medial inferior

problem with ACA circulation will cause damage to

the region of the foot/leg

problem with MCA circulation will cause damage to

upper extremity and face