Spinal Cord

Spinal Meninges

pia mater

arachnoid mater

dura mater

Pia mater

innermost layer

arachnoid

outside pia mater

subarachnoid space

contains CSF

dura mater

outermost layer

study layer of connective tissue that has lots of sensory nerve endings

cauda equina syndrome

Damage occurs below L1

Considered to be a peripheral nerve

injury

Symptoms:

▪ Flaccidity

▪ Areflexia

▪ Impairment of bowel and bladder

function

grey matter

composed of neuron cell bodies and dendrites

dorsal, lateral, ventral horn

dorsal horn

contains sensory (afferent) nerve fibers

lateral horn

contains cell bodies of autonomic neurons

• only found in T1-L2 and S2-S4

ventral horn

contains cell bodies of motor neurons that innervate skeletal muscles

• considered lower motor neuron

white matter

contains both ascending and descending tracts

ascending tracts carries…

action potentials to the brain

descending tracts carries…

signals fro the brain to the body

location of dorsal columns (medial lemniscus)

posterior white matter

function of dorsal columns (medial lemniscus)

convey information regarding 2-point discrimination, vibration, conscious proprioception to primary sensory cortex

• information regarding LE → travels to gracile fasciculus

• information regarding UE → travels to the cuneate fasciculus

crosses in the medulla oblongata

injury to the dorsal columns (medial lemniscus)

if unilateral lesion below decussation → ipsilateral loss

if superior to decussation → contralateral loss

location of the anterior spinothalamic

anterior to white matter

function of the anterior spinothalamic

convey information regarding pressure, texture and light touch to somatosensory cortex

ascends 1-2 levels before decussating

injury to the anterior spinothalamic

contralateral loss of pressure and touch sensation

location of the lateral spinothalamic

lateral white matter

function of the lateral spinothalamic

convey information regarding pain and temperature to somatosensory cortex

injury to lateral spinothalamic

contralateral loss of pain and temperature sensation

location of the spinocerebellar 

lateral white matter, anterior and posterior

• input from muscle spindle and Golgi tendon organ

function of the spinocerebellar 

convey information regarding unconscious proprioception to cerebellum

injury to the spinocerebellar 

partial loss of unconscious proprioception, lack of coordinated movement

• often damaged by demyelinating diseases such as MS

Spino-olivary tract

ascends to the cerebellum and relays information from cutaneous and proprioceptive organs (tendons and muscles)

Spinoreticular tract

afferent pathway to the reticular formation that influences levels of consciousness

assists in immediate reaction to painful stimuli

spinotectal tract

afferent pathway providing information for spinovisual reflexes and assists with movement of eyes towards stimulus

location of the lateral corticospinal tract

lateral white matter

originates in cerebral cortex. becomes the lateral corticospinal tract when fibers decussate in the medulla at the pyramids

function of the lateral corticospinal tract

convey information to cause voluntary movement

injury to the lateral corticospinal tract

unilateral lesion of the spinal cord below decussation → ipsilateral spastic paralysis

location of the anterior corticospinal tract

anterior white matter

function of the anterior corticospinal tract

convey information to cause voluntary movement of the neck and shoulder girdle muscles

injury to the anterior corticospinal tract

spastic paresis

affect less significant than damage to lateral corticospinal tract 

Decussation for this tract will not be assessed through exam

location of the reticulospinal

anterior white matter

originates in brainstem. most fibers do not decussate

function of the reticulospinal

facilitation and inhibition of voluntary and reflex activity for automatic posture and gait-related movements

provide a pathway by which the hypothalamus can control sympathetic thoracolumbar outflow and parasympathetic sacral outflow

injury of the reticulospinal

impair autonomic function; impaired posture and walking due to loss of control of limb flexors; hypertonicity and muscle spasms

hyperactive tendon reflexes and + Babinski

Babinski test (review)

running an object along lateral border of the foot to medial

positive = great toe extends and possible splaying of other toes. normal in infants; sign of UMN lesion in adults

negative = toes will flex; normal in adults

location of the vestibulospinal

anterior white matter

originates in brainstem vestibular nuclei; these are bilateral tracts (some decussate, other do not)

function of the vestibulospinal

control proximal limb muscles (extensors) used for posture and gait

injury of the vestibulospinal

loss of control of postural muscles, impaired balance (ataxia)

rubrospinal tracts

responsible for motor input of gross postural tone, facilitating activity of flexor muscles and inhibiting the activity of extensor muscles

tectospinal tract

responsible for contralateral postural tone associated with auditory/Visual stimuli

blood supply

Anterior spinal artery – supplies the anterior 2/3 of the spinal cord

Posterior spinal arteries – supply the posterior 1/3

Segmental arteries – supply the related spinal cord segment

spinal shock

Period following the spinal cord injury in which there is no sensation or movement below the injured spinal cord segment. Reflexes and bowel/bladder control are typically lost. As the swelling decreases, some function may return

classification of spial cord injury - limbs with motor loss

Quadriplegia (tetraplegia) – motor impairment to all 4 limbs

Paraplegia - motor impairment to the lower extremities only

Hemiplegia – motor impairment to one side of the body

Monoplegia – motor impairment to one limb

complete spinal cord injury

Complete paralysis and a complete loss of sensation below the level of injury

incomplete spinal cord injury

Any motor or sensation remains intact below the level of the lesion

sacral sparing

a patient who has anal sensation or the ability to contract the anal sphincter (S5)

physical lesion level that is above:

will present with normal movement, sensation, and tone

physical lesion at the level will show:

sensation: loss (sensory neurons going to dorsal horn destroyed)

movement: paralyzed (lower motor neuron destroyed)

tone: hypotonic (damaged of LMN) flaccid paralysis

physical lesion below the level will show:

sensation: lost (ascending tracts to carry info destroyed)

movement: paralyzed (descending pathways can’t transmit signals past lesion)

tone (hypertonic (UMN damage)

C1-C4

neck muscles

neck stability and mobility

injury = loss of neck stability

C3-C5

diaphragm

breathing 

injury = ventilator dependent

C5-T1

UE

UE movement

injury = tetraplegia

T1-L5

trunk muscles, intercostals, abdominal wall muscles

Trunk stability and movement; accessory respiratory muscles

injury: loss of trunk stability, dec respiratory function

L2-S4

LE

LE movement

injury = paraplegia

S2-S4

pelvic diaphragm, genitals

Sphincter control (bladder and bowel), sexual function

injury: neurogenic bladder/bowel; loss of sexual function

Asian Impairment Scale (AIS)

A = Complete. No sensory or motor function is preserved in the sacral segments S 4-5.

B = Sensory Incomplete. Sensory, but not motor function is preserved below the neurological level and includes the sacral segments S 4-5 AND no motor function is preserved more than three levels below the motor level on either side of the body.

C =Motor Incomplete. Motor function is preserved at the most caudal sacral segments for voluntary contraction OR meets the criteria for sensory incomplete status and has some sparing of motor function more than three levels below the ipsilateral motor level on either side.

D =Motor Incomplete. Motor incomplete status as described above with at least half of key muscle functions below the single NLI having a muscle grade of at least3/5

E =Normal

brown - Sequard syndrome

Ipsilateral flaccid paralysis of muscle at the physical injury level

Ipsilateral spastic paralysis of muscles below the lesion site

Ipsilateral sensory loss at the lesion level

Ipsilateral loss of proprioception, vibration and 2-point discrimination below the lesion level

Contralateral loss of pain and temperature sensation below the level of the lesion

central cord syndrome

typically caused by damage to the center of the spinal cord by traumatic bending of the cervical spine

symptoms → flaccid paralysis of the UE muscles and UE sensory loss

anterior cord syndrome

Damage to the anterior part of the spinal cord; posterior white matter spared. Caused by traumatic bending of the cord or conditions that narrow that spinal canal

Symptoms:

▪ Conscious proprioception, vibration and 2-point discriminative touch remain intact.

▪ Loss of motor function below lesion

▪ Loss of pain and temperature below lesion