Dermatomes/ Myotomes Flashcards
afferent vs efferent
afferent- signal coming in (sensory/ dorsal horn)
efferent - signaling going out (somatic motor, ANS motor - ventral horn)
what are the different parts of the mesoderm?
intermediate mesoderm
chordamesoderm
paroxismal mesoderm
lateral mesoderm
what does the intermediate mesoderm give rise to?
kidneys/ gonads
what does the chordamesoderm give rise to?
notochord
what does the paraxial mesoderm give rise to?
head
somites -> sclerotome, myotome, dermatome
what does the lateral mesoderm give rise to?
splanchnic (circulatory system)
somatic (body cavity)
extraembryonic
what are the 3 sections of each somite?
dermatome
myotome
sclerotome
what does the dermamyotome in somites give rise to?
skeletal muscle and dermis of the skin
what do anterior migrating cells from the somite innervate?
hypaxial muscles and dermis (trunk and limbs)
what do posterior migrating cells from the somite innervate?
epaxial muscles and dermis (intrinsic back)
what occurs because of a dorsal root injury
paresthesia
sensory deficit/symptoms
what occurs because of a ventral root injury?
weakness
motor deficit/symptoms
what occurs to rami as they travel to their terminal location?
split into motor and cutaneous nerves
what kind of fibers are in the dorsal root?
sensory
what kind of fibers are in the dorsal rami?
mixed sensory/motor –> headed to the intrinsic back
what kind of fibers are in the ventral root?
motor (ANS and somatic)
what kind of fibers are in the ventral rami?
mixed sensory/motor –> headed to the trunk/limbs
what kind of rotation occurs in the legs?
internal rotation (which is why dermatomes seem to spiral)
what are dermatomes?
area of skins upped by afferent (sensory) innervation from a single ROOT
central back = epaxial
all else = hypaxial
what is a nerve map?
area of skin supplied by each nerve - with multiple root contributions
why are myotomes clinically relevant?
most muscles are innervated my multiple myotomes (multisegment)
if you injure a single myotome- weakens the muscle but does not cause complete loss of function
femoral nerve segments
L2-L4
obturator nerve segments
L2-L4
Sciatic nerve segments
L4-S3
tibial nerve segments
L4-S3
common fibular nerve segments
L4-S2
lateral femoral cutaneous nerve segments
L2-L3
Posterior femoral cutaneous nerve segments
S1-S3
