Dermatomes, myotomes, segmental innervation of the limbs Flashcards
what does the sclerotome form and where is it found
vertebrae and ribs
found ventrally
what does the dermatomyotome form and where is it found
dermis and muscle
dorsal
how does the DMT form
develop in association with a specific neural level of spinal cord
take nerve supply with them from neural tube as spinal segmental nerve
skin and muscle derived from a single dermamyotome have a common spinal nerve supply
spinal nerve roots
roots connect each spinal nerve to a segment of cord which is continuous
dorsal roots contain
afferent/ sensory nerve fibres only
dorsal root ganglion
cell bodies of the sensory neurons from the periphery
ventral roots contain
efferent/ motor and autonomic nerve fibres only
where does the spinal cord run through
vertrebral foramen which join to form the spinal canal
where do spinal nerves leave the spinal canal
intervetrebral foramina
where does the spinal cord start and end
inferior margin of medulla oblongata and ends at the conus medullaris at L2
where do the first pair of spinal nerves emerge
emerge between occipital bone and atlas (C1)
where do the cervical spinal nerves emerge
c1 - c7 exit above corresponding vertebrae
where does the c8 spinal nerve emerge
between c7 and t1
where do the T1-L5 spinal nerves emerge
below corresponding vertebrae
where do S1 - S4 exit
Via 4 pairs of sacral foramina
where does s5 and Co1 exit
sacral hiatus
what does the posterior/ dorsal ramus supply
deep muscles and skin of dorsal trunk
divides again into medial and lateral branches
supply skin of back in ‘tidy’ segmental manner
narrow strip of muscle/ skin in line with intervetrebral foramen
what does the anterior/ ventral ramus supply
muscles and skin of the upper and lower limbs and lateral and ventral trunk
enter the plexuses to supply the limbs
what is the meningeal branch supply
re-enters spinal canal through intervetrebral foramen
supplues vetebrae, ligaments, blood vessels and meningies
where does the brachial plexus supply
upper limb
where does the lumbo-sacral plexus supply
lower limb
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
how do the upper limbs rotate
lateral rotation away from the pre-axial border
how do lower limbs rotate
medial rotation towards the pre-axial border