Spinal Cord Functions

Question 1

Describe the spinal cord segments and pattern of nerve emergence

Answer 1

31 spinal segments and spinal nerves.
Nerves leave the veterbral column through interveterbral foramina
2 enlargements for innervation of limbs (c3-t1 and L1-s3) for extra motor nerves
The pattern of emergence changes from on top to below at c8 because 7 bones but 8 nerves.
As you go down the nerves get longer between spine and vertebrate eg coccygeal

Question 2

Describe the 3 layers of meningeal covering of the spinal cord

Answer 2

Three layers of meninges: dura, arachnoid and pia mata.
There is space between dura and veterbrae. (Epidural space with venous complexes)
CSF is in subarachnoid space
Little protrusions of pia denticulate ligaments that tether to spinal cord

Question 3

Describe a Cross section of the Spinal cord:

Answer 3

Grey matter: cell bodies
White matter: tracts
Root: nerve fibre of one type (either sensory or motor)
Ramus: nerve fibre of multiple type.
Attachment from horns of grey matter > Rootlets > roots > motor root and sensory root > spinal nerve > post and ant ramus
Posterolateral sulcus = entry of sensory (post) root
Anterolateral sulcus = exit of motor (ant) root

Question 4

Describe the 3 Major tracts of the spinal cord

Answer 4

Lateral and anterior corticospinal = motor and important for fine movement (lateral crosses and anterior doesn’t)
Dorsal column pathway = sensory, touch, vibration and pressure.
Spinothalamic pathway = sensory, pain and temperature

Question 5

Describe the different structures each tract cross in spinal cord

Answer 5

1. Fasiculus gracilis - sensory from ipsilateral lower limb
2. Fasiculus cunaetus - sensory from ipsilateral upper limb
3. Anterior white commissure - pain and temperature fibres cross (anteriocortical spinal tract cross)
4. Anterior corticospinal tract - motor to ipsilateral and contralateral ant horn
5. Spinothalamic - pain and temp from controlateral side
6. Lateral corticospinal - motor to ipsilateral ant horn (limb musculature)
7. Spinocerebellar tract - proprioception from limbs to cerebellum.

Question 6

Describe the autonomic outflow and functions

Answer 6

Primary sensory neurones (dorsal and spinothalamic) enter spinal cord (spinothalamic cross at midline) and through the brain stem (dorsal cross at medulla) to form secondary neurones and through to thalamus to form tertiary neurones and then to cortex.

Question 7

What are the Factors affecting spinal nerve lesions?

Answer 7

1. Loss of neural tissue: usually small if due to trauma, can be more extensive eg degenerative disease
2. Vertical level: the higher the lesion the greater the disability
3. Transverse plane: most lesions are not complete

Question 8

Describe the different spinal injuries

Answer 8

If injury to lateral corticospinal tract: loss of reflex activity below the lesion lasting for days and flaccid paralysis, but then they return hyperflexia and spasticity called rigid paralysis

Question 9

Describe the effects of brown sequard syndrome

Answer 9

Unilateral lesion - so depends on where the lesion is

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