Spinal Cord

Question 1

Describe the spinal cord

Answer 1

part of the Central Nervous System (CNS)
Organised segmentally - cervical (8), thoracic (12), lumbar (5), sacral (5) and coccygeal (1) which provides 31 segments.
From each segment arise a pair of spinal nerves - left and right - thus 31 pairs of spinal nerves

Question 2

Where are the spinal nerves in relation to the vertebrae?

Answer 2

Upper 7 cervical nerves pass through the intervertebral foramen above the appropriate vertebra.
Other spinal nerves pass through the intervertebral foramen below the appropriate vertebra. This results in there being 8 cervical spinal segments and nerves while there are 7 cervical vertebrae.

Question 3

Where does the spinal cord start?

Answer 3

Upper limit of the cord fixed by its attachment to the medulla oblongata

Question 4

How long are the spinal rootlets?

Answer 4

Vertebral level of lower limit of the cord - L3/L4 in the new-born infant, L1/L2 in the adult. Therefore the spinal rootlets of the cervical nerves are short. But the rootlets of the sacral (and coccygeal) nerves are very long

Question 5

Describe the craniocervical region

Answer 5

Thick envelope formed by the dura and arachnoid
Rootlets of the spinal nerves - here these are relatively short in length
Dorsal root ganglia in close relation to the intervertebral foramina
Continuous with dura of cranial cavity

Question 6

What is the conus medullaris?

Answer 6

The conus medullaris - the lower limit of nervous tissue

Question 7

What is the filum terminale?

Answer 7

The filum terminale - a cord of connective tissue linking the conus medullaris and the 1st coccygeal vertebra

Question 8

Where does the spinal cord end?

Answer 8

The long rootlets of spinal nerves form the cauda equina

Lower end of the lumbar cistern at S2 where the dura mater narrows to envelop the lower part of the filum terminale

Question 9

Describe a cross-section of the spinal cord

Answer 9

-Ventral anterior component
= Large anterior horn cells
-Dorsal posterior component
-Afferent neurones
Lateral horns in thoracic= sympathetic

Question 10

What are the lesions of the spinal cord?

Answer 10

Syringomyelia (central fluid filled cavity develops that damage spinothalamic fibres as they decussate)
Trauma
Neoplasm
Thromboembolic disease

Question 11

Describe Upper cervical spinal cord lesion presentation

Answer 11

Spastic tetraplegia
Hyperreflexia
Plantar responses extensive
Incontinence and sensory loss below lesion
Associated proprioceptive problems

Question 12

Describe lower cervical spinal cord lesion presentation

Answer 12

Upper limbs

Sensation up to level of lesion

Question 13

What is Hemisection of the cord (Brown-Sequard)?

Answer 13

• Ipsilateral loss of proprioception
• UMN signs
• Contralateral loss of pain and temperature sensation

Question 14

What do we test in clinical examination?

Answer 14

-UMN/ LMN lesions
-Reflexes
-Spastic/ flaccid paralysis
Patellar tendon reflex

Question 15

What do we move to test strength?

Answer 15

Shoulder 
Elbow
Wrist
Knee
Hip
Ankle
What level of spinal cord movements

Question 16

Spinal cord pathology

Answer 16

Traumatic
Vascular- vascular myelopathy
Infection/ inflammation- myelitis
Neurodegeneration- motor neurone disease/ spinal muscular atrophy

Question 17

Describe Anterior spinal artery thrombosis

Answer 17

Common disorder
Supplies two thirds of spinal cord
LMN signs that progress to UMN
Loss of sensation and autonomic function
Preservation of proprioception through posterior columns

Question 18

Peripheral nerve lesions

Answer 18

Brachial plexus
-Traction lesions
=Upper roots (C5+C6)- Erb’s palsy; “waiter’s tip” position of the arm
=Lower roots (C8+T1)- “claw hand” deformity
-Neoplastic involvement
-Post-irradiation

Question 19

Describe radial nerve damage

Answer 19

Damaged by fractures to the mid-shaft of humerus
C6-C8

Compression at same site leading to “Saturday night paralysis”
loss of extension of wrist and fingers (wrist drop)
Sensory problems in dorsal aspect of hand

Question 20

Describe median nerve damage

Answer 20

Carpal tunnel syndrome; predominantly sensory but maybe associated with wasting of thenar muscles.
C5-T1, predominantly C6
Sensory loss in palm

Question 21

Describe ulnar nerve damage

Answer 21

May be damaged by injury at the medial epicondyle of the elbow, or at the medial aspect of the wrist.
C7,8,T1
Characteristic “claw hand” deformity.

Question 22

Describe Femoral nerve damage

Answer 22

May be damaged by hip dislocation, pelvic fracture, and tumours in the pelvis.
L2-L4 lumbosacral plexus
Leads to weakness of knee extension (results in inability to lock knee while walking) and some wasting of quadriceps.

Question 23

Describe Sciatic nerve damage

Answer 23

This is composed of two large trunks which are bound together and separate in mid-thigh
tibial nerve
peroneal nerve
Damage to the sciatic nerve can be due to trauma, neoplastic compression/infiltration, or operative complication.
Results in foot drop and unstable ankle
L4-S3

Question 24

What is Sciatica?

Answer 24

Much more common is compression or irritation of a spinal root which comprises the sciatic nerve (sciatica)
Symptoms dependant on the nerve root
-Common
L5; sensory- pain in posterolateral thigh and leg, numb inner foot
motor- weakness of dorsiflexing foot and toes
S1; sensory- pain in posterolateral thigh and leg, numb lateral foot
motor- weakness of foot dorsiflexion and loss of ankle jerk
-Rare
L3+L4- diminished knee jerk, pain in anterior thigh

Question 25

What is a prolapsed intervertebral disc?

Answer 25

Annulus fibrosis- deteriorate posteriorly
Fluid nucleus pulposus= prolapse
Pressure onto spinal nerve root behind

Question 26

How is a prolapsed disc resolved?

Answer 26

Resolve spontaneously

Operate= Microdiscectomy= access posteriorly, remove prolapsed material

Question 27

Describe damage to the common peroneal nerve

Answer 27

This can be damaged as it winds round the head of the fibula. This can be by fracture or compression (e.g. tight cast).

Results in weakness of foot dorsiflexion and eversion.
L4-S2