External and Internal Anatomy of the Spinal Cord LO1, LO2

Question 1

External Anatomy of the Spinal Cord

Answer 1

long, thin, delicate tubular structure
- protected by the vertebral column
- ends between L1- L2 of the
vertebral column in adults
and L4 in infants
- terminates with conus medullaris
- anchored to the coccyx by the filum terminale

Question 2

Spinal cord divided into:

Answer 2

• Cervcal 8
• Thoracic 12
• Lumbar 5
• Sacral 5
• coccygeal
• a pair of spinal nerves connects to each segment

Question 3

Spinal nerves

Answer 3

Connect to the spinal cord by dorsal & ventral nerve roots
Dorsal - axons of sensory neurons
Dorsal root ganglion - cell bodies of sensory neurons
ventral roots - axons of motor neurons (somatic & autonomic)

Question 4

Protection of the Spinal Cord

Answer 4

The spinal cord is protected from mechanical forces by:
- vertebral column
- cerebrospinal fluid –> also nourishes the neural tissue & removes waste products
- spinal meninges

Question 5

Internal Anatomy of the Spinal Cord

Answer 5

The neural tissue (neurons & neuroglia) of the spinal cord:
- posterior (dorsal) median sulcus (top)
- anterior (ventral) median fissure (bottom)
- organised into areas of gray matter (inside) & white matter (outside)

Question 6

Gray Matter of spinal cord

Answer 6

• Composed of neuron cell bodies (mainly), unmyelinated axons & neuroglia
• Encloses a central canal –> filled with cerebrospinal fluid
• Gray commissure - site where axons cross from one side of the CNS to the other
• divided into grey horns

Question 7

Grey horns

Answer 7

• Sensory nuclei - Contain the cell bodies of spinal cord interneurons
• Autonomic motor nuclei - Contain the cell bodies of preganglionic neurons
• Somatic motor nuclei - Contain the cell bodies of lower motor neuron

Question 8

White Matter ”conduction highway” spinal cord

Answer 8

• Superficial to gray matter
• Composed of myelinated (mainly) & unmyelinated axons
• Anterior white commissure –> site where axons cross from one side of the CNS to the other
• White columns contain ascending & descending
• spinal cord tracts = bundles of axons

Question 9

Spinal Cord Tracts of the White matter

Answer 9

Conduct sensory or motor information between the spinal cord & brain
- ascending tracts –> conduct sensory input to the brain
- descending tracts –> conduct motor output away from the brain

Question 10

Ascending tract

Answer 10

• Fasciulus gracilis
• Fasciulus cuneatus
• Lateral spinithalamic
• Anterior spinocerrbellar
• Posterior spinocerrbellar
• Anterior spinothalmic

Question 11

Descending tract

Answer 11

• Lateral corticopsinal tracts
• Anterior corticopsinal tracts

Question 12

Fasciulus gracilis

Answer 12

Sensory info come inferior part of the body
- Posterior white column
- fine touch, vibration, light pressure, Propicoertion

Question 13

Fasciulus cuneatus

Answer 13

Sensory info come superior part of the body
- Posterior white column
- fine touch, vibration, light pressure, Propicoertion

Question 14

Lateral spinithalamic

Answer 14

sensory info to thalamus
Lateral white coloumn
- pain, temperature

Question 15

Anterior spinocerrbellar
Posterior spinocerbellar

Answer 15

conduct sensory info to cerebellum
Lateral white coloumn
Proprioception

Question 16

Anterior spinothalmic

Answer 16

Conduct sensory info to thalamus
Anterior white coloums
- crude touch, deep pressure

Question 17

Lateral corticopsinal tracts

Answer 17

Lateral white coloumn
- somatic motor output in skelteal muscles limbs

Question 18

Anterior corticopsinal tracts

Answer 18

anterior white coloumn
- somatic motor output controlling the trunk
- axial muscles