Spinal Cord, Spinal Nerves and Spinal Injuries

Question 1

Gross Anatomy of the Spinal Cord

Answer 1

• Extent: Runs from the medulla oblongata to L1–L2 in adults (L4 in infants), ending at the conus medullaris.
• Anchoring: The filum terminale extends to the coccyx, and the cauda equina is a bundle of lumbar and sacral nerves.

Question 2

Protection

Answer 2

• Vertebrae form the bony covering.
• Meninges:
  1. Dura mater (outermost, tough),
  2. Arachnoid mater (middle, CSF-filled subarachnoid space),
  3. Pia mater (inner, vascular, clings to spinal cord; forms denticulate ligaments for anchoring).

Question 3

Spinal Nerve Formation

Answer 3

31 pairs of spinal nerves emerge from the cord (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal).

Question 4

Each spinal nerve is formed by:

Answer 4

• Dorsal (posterior) root: sensory (afferent) fibres from receptors to CNS.
• Ventral (anterior) root: motor (efferent) fibres to muscles/glands.
• The dorsal root ganglion contains sensory neuron cell bodies.
• Spinal nerves branch into dorsal and ventral rami after emerging from the vertebrae.

Question 5

Grey matter (inner H-shaped core):

Answer 5

• Dorsal horns: sensory interneurons.
• Ventral horns: somatic motor neuron cell bodies.
• Lateral horns (only in thoracic and upper lumbar segments): autonomic motor neurons.

Question 6

White matter (outer):

Answer 6

Composed of myelinated fibres organised into funiculi:
- Dorsal funiculi (sensory),
- Lateral funiculi (mixed),
- Ventral funiculi (mainly motor).

Question 7

Information travels in

Answer 7

tracts, which are bundles of axons with similar origin, destination, and function.

Question 8

Dorsal (posterior) Spinal

Answer 8

• Carries afferent sensory input into the spinal cord.
• Associated with somatic and visceral sensory neurons.

Question 9

Dorsal (posterior) Spinal

Answer 9

• Sends efferent motor commands via somatic and autonomic pathways.
• Includes somatic motor neurons (ventral horn) and autonomic neurons (lateral horn).

Question 10

Funiculi roles:

Answer 10

• Dorsal columns (e.g., fasciculus gracilis and cuneatus): fine touch, proprioception.
• Spinothalamic tract: pain, temperature.
• Corticospinal tracts: voluntary movement control.

Question 11

General Effects of Injury:

Answer 11

• Flaccid paralysis: damage to lower motor neurons (ventral horn).
• Spastic paralysis: damage to upper motor neurons (e.g., corticospinal tract), reflexes intact.
• Sensory losses include touch, pain, temperature, proprioception.

Question 12

Brown-Séquard Syndrome (hemisection):

Answer 12

• Ipsilateral: loss of motor control and proprioception.
• Contralateral: loss of pain and temperature below the lesion.

Question 13

Anterior Cord Syndrome:

Answer 13

• Damage to anterior 2/3 of cord (often from flexion injuries).
• Loss of motor function, pain, and temperature below lesion.
• Proprioception preserved (dorsal column spared).

Question 14

Central Cord Syndrome:

Answer 14

• Most common in cervical spine, often from hyperextension.
• Greater motor impairment in upper limbs than lower limbs.

Question 15

Posterior Cord Syndrome:

Answer 15

• Rare; loss of proprioception, fine touch, and vibration.
• Motor function is often preserved.