MSK Session 4- Dermatomes, Myotomes And Segmental Innervation Flashcards
What does the dorsal half of the degenerated somite become?
The dermamyotome
Define dermatome.
An area of skin supplied by a single spinal nerve.
Define myotome.
A muscle/group of muscles supplied by a single spinal nerve.
Define motor unit.
Muscle fibres innervated by a single motor nerve fibre.
What is the advantage of functional overlap between dermatomes? (2)
- damage to a single spinal nerve is unlikely to cause anaesthesia.
- reduced probability its of having a skin patch that has no natural sensory nerve supply.
Where does the spinal cord run?
Through the vertebral foreamen of each vertebra.
Where does the spinal cord start and end?
Start-medulla
End-L2/L3
Where do the spinal nerves from the spinal cord emerge?
Through intervertebral foramina.
Where in relation to the vertebra do cervical spinal nerves emerge?
Superior to the vertebrae.
Where in relation to the vertebra do non-cervical spinal nerves emerge?
Inferior.
What is a mixed segmental/spinal nerve?
The coming together of the dorsal and ventral roots of the spinal nerve.
What is the role of the dorsal roots of a spinal nerve?
Afferent
What is the role of the ventral roots of the spinal nerve?
Efferent
What is the axial line? (2)
The junction between dermatomes with discontinuous spinal nerves. It is also the junction between the flexor and extensor compartment.
Which nerve roots cause flexion at the elbow? (2)
C5+6
