Spinal Cord and Injury Flashcards
Describe the gross anatomical make up of the spinal cord
H-Shaped grey matter - dorsal, intermediate and ventral horns
Surrounding white matter - Dorsal, lateral and ventral funiculi
Describe the make up of the meningeal layers
Dura Mater Arachnoid Mater (Sub arachnoid space) Pia Mater (Subpial space - spinal cord, very tiny)
Where does the dura mater fuse with endosteum of cranium?
Foramen magnum
What separates the dura mater from vertebrae in spinal cord?
epidural space
Where within the meningeal layers is CSF found?
Subarachnoid space
Where is CSF made?
Choroid plexus of ventricular system
What laterally forms from the pia mater?
21 dendriculate ligaments - stabilise spinal cord
What spinal vasculature is important for the mestastasis of lower abdomen tumours?
Bastons Venous Plexus
Describe the arterial supply of gthe spinal cord
Aorta - intercostal arteries - single anterior and 2 posterior spinal arteries
What is the artery of adamkiewicz and what is its clinical significance regarding surgery?
Arises from left posterior intercostal artery to supply lower third of spinal cord.
Can become occluded following surgical procedures
Where does the supracristal line lie and what is its functional importance?
through body of L4 - landmark for epidural and spinal tap
Which route through the spinal cord so sensory pathways take?
Dorsal
Which route through the spinal cord so Motor pathways take?
Ventral
Descending - Ds dont go together - descending and dorsal
List and describe the functions of the different sensory axons:
A-alpha - proprioceptors of skeltal muscle. Thick and fast
A-beta - mechanoreceptors of skin - medium thickness and fairly quick
A-Delta - Pain and temperature receptors. thin and slow
C - polymodal - thinnest and slowest
Name and describe the pathway responsible for discriminative touch
Dorsal column/Medial lemniscus pathway:
- primary neuron enters dorsal column and travels up to medulla where is synapses at gracile nucleus with internal arcuate fibres - These decussate and pass through medial lemniscus of vertebrae to the VPL of thalamus - synapses here to pass through internal capsule and onto sensory cortex
Where does the medical lemniscus pathway decussate?
Dorsal column nuclei (Gracile nucleus) in medulla
Where does the spinothalamic pathway decussate?
At level of entry
Name and describe the pathway responsible for pain
Spinothalamic pathway:
- Primary afferent neuron enters superficial dorsal horn via spinothalamic pathway, using A-delta or C fibres - Synapses otno second order neuron and decussates at level of entry - Travels up thoracic and cervical white matter in antero-lateral funiculus, through spinothalamic tract and through spinal lemniscus in brainstem - synapses onto 3rd order neuron at internal capsule to target sensory cortex
What are the two ascending sensory pathways?
Medial lemnisus and spinothalamic
Which of the descending motor pathways are responsible for voluntary movement?
Corticospinal tract - movement of torso, arms and legs
Corticobulbar tract - non oculomotor cranial nerve movements
Name and describe the pathway responsible for arm/leg/torso movement
Lateral Corticospinal tract (85%):
- axons leave primary motor cortex to medulla where they decussate. - travel down lateral corticospinal tract to synapse with spinal nerves
Anterior corticospinal tract (15%):
- axons leave primary motor cortex and travel straight down spinal cord in anterior corticospinal tract - Decussate to synapse with spinal nerves at level of exit
Name and describe the pathway responsible for movement controlled by cranial nerves
Corticobulbar tract:
- axons from primary motor cortex pass through cerebral peduncle of midbrain and to the corresponding cranial nerves in pons (facial) or medulla (hypoglossal) where they decussate
What is the difference in the decussation of the lateral and anterior corticospinal tracts?
Lateral - medulla
Anterior - at exit point of spinal nerves
Name and describe the pathways responsible for maintaining posture (muscular tone)
Reticulospinal - made up of pontine (extensor) and medullary (flexor) tracts to modulate alpha motor neurones
Tectospinal - only prejects to cervical segments, modulating alpha and gamma motor neurons
Vestibulospinal -runs entire length of cord, modulating activity of alpha motor neruons
What pathway is responsible for subconscious regulation of upper limb muscle tone and movement?
Rubrospinal - UMN originate in red nucleus in midbrain and decussate here
Where in the rubrospinal tract do UMN originate?
red nucleus in midbrain
Where does the rubrospinal tract decussate?
red nucleus in midbrain
How can LBP be caused?
- Mechanical - trauma, muscular pain, facet join syndrome, lumbar disc prolapse
- Inflammatory - infective spinal lesions, ankylosing spodlitis/sacroilitis
- Metabolic - osteoporotic fractures, osteomalacia, pagets
- Neoplastic - metastases, tumour
- referred pain
How does cauda equina syndrome present?
bilateral leg pain, baack pain, urinary retention, perineal sensory loss, erectile dysfunction, reduced anal tone
What will compression of L2 cause?
- Sensory changes in front of thigh
- No reflex loss
- Weakened hip flexion and adduction
What will compression of L3 cause?
- Sensory changes in inner thigh and knee
- Knee jerk reflex loss
- Weakened knee extension
What will compression of L4 cause?
- Sensory changes in inner calf
- Knee jerk reflex loss
- Weakened knee extension
What will compression of L5 cause?
- Sensory changes in outer calf, upper foot, inner foot
- No reflex loss
- Weakened foot inversion and dorsiflexion of toes
What will compression of S1 cause?
- Sensory changes in posterior calf and lateral border of foot
- Ankle reflex loss
- Weakened plantar flexion of foot
What is the best management of LBP?
Patient must remain active
Medical therapy - analgesics, muscle relaxants, rehab, anti-depressants etc
What is Spinal Shock?
temporary suppression of all reflex activity below the injury, ocurring immediately after.
What is the first sign of recovery from spinal shock?
Return of Babinksis sign
What symbolises the end of spinal shock?
Bulbocavernous reflex (monitor internal/external anal sphincter in response to squeezing glans penis or clitoris)
What is neurogenic shock and how does it present?
bodys response to sudden loss of sympathetic function due to an injury to T6 or above
Clincial triad - hypotension, bradycardia and hypothermia
How will a cervical injury differ from a thoracic/lumbar/sacral injury in terms of movement?
Cervical - quaraplegia
Others - Paraplegia
A patient has been stabbed, causing paralysis on same side and loss of pain and temperature on opposite. What is the most likely diagnosis?
Brown-Sequard Syndrome
What chart measures neurological and sensory functions?
ASIA
What is an UMN and how does a lesion present?
- Neuron in primary motor cortex which excite alpha motor neurons either directly or via spinal nerves
- hyperreflexia, muscle weakness, babinski sign, decreased power, pronator druft
What is a LMN and how does a lesion present?
- alpha motor neuron which runs from psinal cord to PNS
- hyporeflexia, decreased tone, fibriliations, decreased strenght, atrophy, fasciculations
Regarding UMN and LMN lesion sgns, what will a lesion in C1-C5 show?
UMN and LMN in both limbs
Regarding UMN and LMN lesion sgns, what will a lesion in T3-T12 show?
UMN in lower limb
Regarding UMN and LMN lesion sgns, what will a lesion in T12-S2 show?
LMN in lower limb
How will a lesion on C3, 4 or 5 affect breathing?
Wont be able to breathe as these supply phrenic nerve which innervates diaphragm
How will a lesion on C6 or 7 affect breathign?
Paradoxical breathing as these innervate intercostal muscles
Describe the physiology of a monosynaptic circuit reflex
- stretch receptors cause signal down primary afferent fibres to spinal cord
- Synapse with motor neuron which enter NMJ
- excitation causes a twitch reflex
Describe and explain how refelxes can be reinforced
Jendrassiks Manoeuvre causes extra polarisation in order to increase reflex response:
- upper limb - clench teeth - lower limb - pull hands apart
Why do muscle spindles have primary and secondary afferent fibres?
ensure that muscle length is signalled to account for angle contraction
