Session 2.1 dermatomes and myotomes Flashcards
What is each segment of the cns known as?
A neural level
What does the dermomyotome give rise too?
The dermis and muscle
What do the skin and muscle from a single dermatomyotome have in common?
A common spinal nerve supply
What do somites consist of and how does this break up?
Consists of a sclerotome and dermomyotome.
Sclerotome moves ventral and becomes ribs and vertebrae.
Dermomyotome moves dorsal.
What’s a dermatome?
An area of skin that is supplied by a single spinal nerve
What nerve fibres are carried by
- dorsal routes
- ventral routes
Dorsal routes have afferent/sensory fibres only
Ventral roots have efferent/notorious and autonomic nerve fibres only
What is the structure of a nerve?
Axons have an ENDONEUREIUM around them
A group of axons make a FASCICLE
There is a PERINEURIUM around each fascicle
Group of fascicles joined by an EPINEURIUM
Where does the spinal chord begin and end?
Begins at the inferior margin of the medulla oblongata
Ends at the conus medalluris at L2.
below this is the cauda equina.
How do cervical spinal routes leave the ventral body?
They emerge above the corresponding ventral body with the exception of c8, which emerges between c7 and t1.
What myotome?
A group of muscles supplied by a single spinal nerve.
What does the spinal chord run through?
The vertebral foramen
What’s a rami??
Mixed spinal nerve divides into rami
What’s an axial line?
Junction of two dermatomes supplied from discontinuous spinal levels
They mark the centre of either the ventral or dorsal compartments of the limb
What is shingles and what is it caused by???
Caused by varicella zoster virus reactivation (which causes chickenpox)
Affects the skin of a single dermatome
Virus transfers through a cutaneous nerve and remains dormant in a dorsal root ganglion after chicken pox
When host is immunosuppressed varicella zoster virus deactivates and travels through peripheral nerve to skin of a single dermatome.
