Spinal Cord Flashcards
How many pairs of spinal nerves are in the spinal cord?
30 pairs 8 cervical 12 thoracic 5 lumbar 5 sacral
What is the spinal cord protected by?
the spinal meninges
pia mater- thinnest layer
arachnoid mater
dura mater- sensitive to pain
The lumbar and sacral spinal nerve roots that run inferiorly inside the spinal canal for 6 inches form the what?
Cauda Equina
Grey matter houses what?
cell bodies and dendrites
White matter houses what?
axons of neurons
Where are the sensory (afferent) nerves fibers located in the spinal cord?
The dorsal horn
The lateral horn houses what cell bodies
the autonomic nerve system fibers
T1-L2
S2-S4
The ventral horn houses what type of neurons?
motor neurons- that innervate muscles
also called lower motor neurons
What does injury to the the spine at the L1 or L2 and below result in?
the show signs of lower motor neuron injuries
flaccid paralysis
atrophy
hyporeflexia
T or F muscles that perform precise movements have more motor neurons than those that perform gross movements?
True
Where are the dorsal columns located and what do they sense?
Where do they cross over?
They are located in the dorsal white matter and they sense conscious proprioception, vibration, and two-point discrimination through skin, muscles, tendons, and joints
They cross over in the medulla oblongata.
Do the dorsal columns cross and convey the message to the contralateral somatosensory cortex?
Yes
What is the function of the anterior spinothalamic tract?
Where does it cross?
sense pressure, texture, and light touch
It crosses in the spinal cord after 1-2 levels
What is the function of the lateral spinothalamic tract?
Where does it cross?
pain and temperature sensed by the skin and fat tissue
It crosses in the spinal cord after 1-2 levels
damage to anterolateral system causes what?
sensory changes on the contralateral side of the body
What is the function of the spinocerebellar tracts?
Do they cross?
unconscious proprioception to the cerebellum via the muscles and tendons. (also monitor activity of motor neurons)
These tracts are considered partially crossed
MS is most likely to affect which tract?
the spinocerebellar
Are the descending tracts considered lower motor neurons?
no they are upper
what are the largest tracts in the human nervous system?
Corticospinal tracts
What is the function of the lateral corticospinal tract?
control of voluntary movement (90 % of tract)
If the left lateral corticospinal tract is injured what is the most likely outcome of symptoms?
ipsilateral paralysis or paresis
What is the function of the anterior corticospinal tract?
voluntary motor, neck and shoulder muscles
Does the anterior corticospinal tract cross in the medulla?
Decussation is debatable
No it remains on the ipsilateral of the brainstem and spinal cord
What is the function of the reticulospinal tracts?
controls rhythmic gait pattern (most are ipsilateral)
Damage to the reticulospinal tract impair what function?
impairs autonomic function, posture, and walking
Muscles used for balance and posture are apart of which tract?
vestibulospinal
A positive Babinski sign in an adult indicates what?
an injury in the CNS.
How many arteries supply the spinal cord?
3
one anterior spinal artery (1/3)
and two posterior spinal arteries (2/3)
How are patients classified as having a complete or incomplete spinal cord injury?
They test the lowest level nerve root (S5) sacral sparring indicates that some tracts are still in tact.
How do they reduce swelling after a spinal cord injury?
A medication called methylpredisone can reduce swelling and improve patient outcomes.
What is spinal shock?
The first several weeks after an SCI there is loss of sensation, movement, reflexes, and bowel control.
What is autonomic dysreflexia?
A life threatening condition in patients with an above level T5 spinal injury. Usually causes by a kinked catheter or full bladder.
Where is the Dorsal Columns (Medial Lemniscus) located?
Posterior White Matter
What is the function of Dorsal Columns (Medial Lemniscus) ?
Convey information regarding 2-point discrimination, vibration, conscious proprioception to primary sensory cortex.
Information regarding LE travels in the gracile fasciulus.
Information regarding UE travels in cuneate fasciulus.
Crosses in medulla oblongata
What happens if there is an injury to the Dorsal Columns (Medial Lemniscus) ?
If unilateral lesion below the decussation—ipsilateral loss
If superior to decussaiton—contralateral loss
What is the location of the anterior spinothalamic?
Anterior white matter
What is the function of the anterior spinothalamic?
Convey information regarding pressure, texture, and light touch to somatosensory cortex.
Where does the anterior spinothalamic decussate?
It ascends 1-2 levels before decussating.
What happens to injury with the anterior spinothalamic?
Contralateral loss of pressure and touch sensation
Where is the lateral spinothalamic located?
Lateral white matter
What is the function of the lateral spinothalamic?
Convey information regarding pain and temperature to somatosensory cortex
What happens to injury at the lateral spinothalamic?
Contralateral loss of pain and temperature sensation
Where is the Spinocerebellar located?
Lateral white matter, anterior and posterior.
Input from muscle spindle and golgi tendon organ
What is the function of the Spinocerebellar?
Convey information regarding unconscious proprioception to cerebellum
What happens to injury at 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 a stimulus.
Where is the Lateral Corticospinal Tract located?
Lateral white matter.
origin in cerebral cortex. becomes lateral corticospinal tract when fibers decussate in medulla at pyramids.
Function of Lateral Corticospinal Tract?
Convey information to cause voluntary movement
Injury to Lateral Corticospinal Tract
Unilateral lesion of the spinal cord below decussation
ipsilateral spastic paralysis
Location of the Anterior Corticospinal Tract?
Anterior White matter
origin in cerebral cortex.
Function of Anterior Corticospinal Tract
voluntary movement of the neck and shoulder girdle muscles
Injury to Anterior Corticospinal Tract
Spastic paresis
Location of Reticulospinal?
Anterior white matter
origin in brainstem. most fibers dont decussate
Function of Reticulospinal
Facilitation and inhibition of voluntary and reflex activity for automatic posture and gait related movements.
Provide a pathway for which the hypothalamus can control sympathetic thoracolumbar outflow and parasympathetic sacral outflow
Injury to the Reticulospinal
Impair autonomic function; impair posture and walking due to loss of control of limb flexors; hypertonicity and muscle spasm.
Hyperactive tendon reflexes and + Babinski
Location of the Vestibulospinal
anterior white matter
origin in brainstem vestibular nuclei.
bilateral tracts
Function of Vestibulospinal
Control proximal limb muscles (extensors) used for posture and gait
Injury to Vestibulospinal
Loss of control of postural muscles, impaired balance (ataxia)
Rubrospinal spinal tract
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
A lesion that occurs above level of injury will show
Normal sensation
Normal Movement
Normal Tone
A lesion that occurs at level of injury will show
Lost sensation (due to dorsal horn destroyed)
Paralyzed movement (lower motor neuron destroyed)
Hypotonic tone (flaccid paralysis; damage of LMN)
A lesion that occurs below level of injury will show
Lost sensation
Paralyzed movement
Hypertonic Tone
C1-C4
Neck Muscles–Neck stability and mobility
Lost of neck stability
C3-C5
Diaphragm–Breathing
Ventilator dependent
C5-T1
Upper extremity–upper extremity movement
Tetraplegia
T1-L5
Trunk muscles, intercostals, abdominal wall muscles–trunk stability and movement, accessory respiratory muscles
Loss of trunk stability, decreased respiratory function
L2-S4
Lower extremity–lower extremity movement
Paraplegia
S2-S4
Pelvic diaphragm, genitals–sphincter control, sexual function
neurogenic bladder/bowel–loss of sexual function
Brown Sequard syndrome
-caused by gun shot wound or stabbing
- ipsilateral flaccid paralysis of muscle at physical injury site
- ipsilateral spastic paralysis below lesion site
- ipsilateral sensory loss at site
- ipsilateral loss of proprioception, vibration, 2 pt discrimination below lesion level
- contralateral loss of pain and temperature sensations below level of lesion
Central cord syndrome
- due to damage to center of spinal cord
- traumatic bending of cord in cervical region
- flaccid paralysis of upper extremity muscles
- upper extremity sensory loss
- aka “reverse paralysis”
upper extremities are affected worse than lower
Anterior cord syndrome
- damage to the anterior part of spinal cord that spares posterior white matter
- traumatic bending of the cord or spinal stenosis
- conscious proprioception, vibration, and 2 pt discrimination touch sensations remain intact
- other sensations and motor function lost
- paralyzed below level of injury
Cauda Equina syndrome
- injury to dorsal and ventral roots
- loss of sensation
- flaccid paralysis
- loss of sympathetic and parasympathetic systems
- loss of bowel and bladder control
