DERMOTOMES AND MYOTOMES

Question 1

Myotome, dermatome, root and reflex at disc level L3-L4

Answer 1

ROOT: L4
MYOTOME: TIBIALIS ANTERIOR
DERMATOME: MEDIAL LEG AND FOOT
REFLEX: PATELLAR

Question 2

Myotome, dermatome, root and reflex at disc level L4-L5

Answer 2

ROOT: L5
MYOTOME: EXTENSOR HALLUCIS LONGUS
DERMATOME: LATERAL LEG AND DORSUM OF THE FOOT
REFLEX: NO REFLEX AT THIS LEVEL

Question 3

Myotome, dermatome, root and reflex at disc level L5-S1

Answer 3

ROOT: S1
MYOTOME: PERONEUS LONGUS AND BREVIS
DERMATOME: LATERAL FOOT
REFLEX: ACHILLES

Question 4

Myotome, dermatome, root and reflex at disc level S1-S5

Answer 4

ROOT: S1,S2,S3
MYOTOME: INTRINSIC TOE MUSCLES
DERMATOME: PERINEAL, ANAL AND SADDLE AREA
RELFEX: SUPERFICIAL ANAL

Question 5

What is caudal equina and what nerve root levels does it usually affect?

Answer 5

Defined as the compression of the nerve roots distal to L1 secondary to a pathology such as acute disc herniation, bony fragments, tumour, infection, surgical intervention, inflammatory arthritis

Question 6

What are the signs and symptoms of cauda equina?

Answer 6

Low back pain
Uni-or bilateral sciatica
Motor weakness of the lower extremity
Sensory disturbance of the saddle/perineal area
Loss of bowel and or bladder function.

Question 7

Myotome, dermotome, root and reflex at disc level C4-C5

Answer 7

ROOT: C5
MYOTOME: DELTOID AND BICEPS
DERMATOME: LATERAL UPPER ARM
REFLEX: BICEPS

Question 8

Myotome, dermotome, root and reflex at disc level C5-C6

Answer 8

ROOT: C6
MYOTOME: WRIST EXTENSION
DERMATOME: LATERAL FOREARM
REFLEX: BRACHIORADIALIS

Question 9

Myotome, dermotome, root and reflex at disc level C6-C7

Answer 9

ROOT: C7
MYOTOME: WRIST FLEXORS AND FINGER EXTENSORS
DERMATOME: MIDDLE FINGER
REFLEX: TRICEPS

Question 10

Myotome, dermotome, root and reflex at disc level C7-T1

Answer 10

ROOT: C8
MYOTOME: FINGER FLEXORS AND INTRINSIC HAND MUSCLES
DERMATOMES: MEDIAL FOREARM
REFLEX: NONE AT THIS LEVEL

Question 11

Myotome, dermotome, root and reflex at disc level T1-T2

Answer 11

ROOT: T1
MYOTOME: HAND INTRINSICS
DERMATOME: MEDIAL UPPER ARM
REFLEX: NONE AT THIS LEVEL

Question 12

What is cervical stenosis? What causes it?

Can it be asymptomatic?

Answer 12

The narrowing of the spinal canal.

Due to:

• degenerative changes
• osteophyte encroachment
• congenital abnormalities
• disc bulge and prolapse
• tumours
• trauma
• spondylolisthesis

YES it can be asymptomatic

Question 13

What is cervical myelopathy?

Answer 13

Is due to the cervical stenosis injuring the spinal cord, especially the longs tracts via physical pressure or ischaemia.

Question 14

What is ischaemia myelopathy? In which arteries does it usually occur?

Answer 14

Blood supply to the spinal cord can be compromised due to the canal stenosis or vascular pathology. This is usually by the anterior spinal arteries (branches of the vertebral arteries).

The vertebral arteries may have pathological changes (VBI +-) or the anterior spinal arteries may be compromised y physical pressure.

Question 15

What is an upper motor neuron problem also known as?

Answer 15

Cervical myelopathy

Question 16

What is cervical myelopathy also known as?

Answer 16

Upper motor neuron problem

Question 17

What are the signs and symptoms of cervical myelopathy/an upper motor neurone problem?

Answer 17

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