Dermotomes and Myotomes Flashcards
Dermomyotomes that migrate anteriorly give rise to what? How about the dermomyotome cells that migrate posteriorly?
Anteriorly: hypaxial muscles (muscles of limbs and trunk) and associated dermis
Posteriorly: epaxial muscles (intrinsic muscles of the back) and associated dermis
What does the posterior(dorsal) horn consist of? And the anterior (ventral) horn?
Posterior horn contains sensory neurons, afferent signals come in here
Anterior horn contains motor neurons, efferent signals released to make voluntary movement
What is the different between the dorsal and ventral roots of the spinal nerves?
The dorsal roots are senory only, ventral roots are motor only.
Why is the spinal nerve (area right before division of rami) considered mixed?
Because the dorsal and ventral roots combine to form the spinal nerve, which will then have both sensory and motor neurons
What occurs right after the spinal nerve forms from the dorsal and ventral roots of the spinal nerve?
The spinal nerve will branch off into posterior and anterior primary ramus, posterior will go to the back (epaxial), anterior will go to the rest of the body.
What is the difference between differentiated and undifferentiated regarding sensory/motor nuerons?
At the roots, the sensory and motor neurons are divided dorsally and ventrally, called differentiated. They are considered undifferentiated when they are mixed together and sent out into the rami.
What will the dorsal root have that the ventral root will not have, besides sensory/motor neurons?
The spinal ganglion (only sensory made by neural crest cells!)
Limb buds at four weeks are facing which way?
They face anteriorly, palmar side of hands anteriorly as well as plantar side of feet anteriorly
What happens when the limbs mature and grow out?
the arms grow out and fold inwards, the legs, go out, fold inwards and then folds downward, leading to the dorsum facing superiorly. (why there are opposite flexors for arms and legs)
Define dermatome
The area of skin supplied with afferent nerve fibers by a SINGLE posteior (dorsal) spinal root.
Where is C1 spinal nerve?
Suboccipital, only has efferent neurons
Which side of the body will the sacrum and lumbar nerves affect?
Sacral nerves: mainly posterior
Lumbar nervers: mostly anterior
What does a dermotome map show?
the distribution of a single afferent dorsal posterior roots
What does a nerve map show?
Maps the actual rami on the skin
If a nerve is pinched at the ramus, what will happen compared to pinched at the root?
Pinched at ramus, multiple dermotomes involed, at root: only one dermatome affected, harder to diagnose which spinal root is pinched
