Myotomes, Dermatomes And Segmental Innervation Of The Limbs Flashcards
What are the two types of spinal nevre roots?
Ventral (anterior) and dorsal (posterior)
How many pairs of spinal nerves are there?
31
What is contained in the ventral roots?
ventral contain efferent and anutnomic nerve fibres only
What is contained in the dorsal roots?
Contain afferent and sensory nerve fibres only
What are some of the anatomical features of the vertebral segments?
Spinal cord runs through the vertebral foramen, spinal segmental nerves leave vis the vertebral foramina, and multiple vertebral foramina form the spinal cord.
What are the rami?
This is where the spinal nerve splits in two, and the posterior and dorsal are the deep muscles of the elastic trunk, and the anterior/ventral ramous are the muscles and skin of the upper and lower limbs.
Where do the different parts exit the spinal cord?
C1-C7 exit above the corresponding vertebrae, T1-l% exit below the corresponding vertebrae, and s1-s4 via four paris of sacrlal foramen, S5 and Cos1 exit via the sacral hiatus, and spinal nerve C8 exits between the vertebra C7 and T1
What are the major branches of the lumbar plexus medial to psoas?
Obtruator nerve (L2,L3, L4) and the lumbosacral trunk (L4 and S1)
What are the major branches of the lumbar plexus lateral to the psosas?
femoral (L2, L3,L4), IIohypogastic, from L1 and Illiolinguianal also from L1
what is the anatomical location of the lumbar plexus?
Forms between the psoas muscle,s and emerges medial and lateral to the psoas major
What are the two plexuses found in the lower limb?
The lumbar plexus and the sacral plexus
What are the emboryoligcal features that allow dermatomes and myotomes to develop?
Paired somites develop into dermatome and scelorotome , at a specific neural level of the spinal cord, and they take innervation from that level of the cord.
Where do the dorsl/posterior rami go?
Divide into medial and lateral branches, supply skin of back in a tidy manner, narrows strips of skin in line with the veretrbl faraamen.
Where do the ventral/anterior rami go?
Complicated, enter the plexus including the brachial plexus and the lumbar sacral plexus
What is a myotome?
A group os muscles supplied by a single spinal nerve
What is a dermatome?
A groups of skin supplied by one spinal nerve (there may be some functional overlap between the dermatomes
What is an axial line?
Junction of two dermatomes supplied by two discountinous spinal nerves
Desribe one clinical relevance of dermatomes.
In herpes zoster or shingles, which commonly only affect the skin of one dermatome or when describing the extent of a injury
