Lecture 10: Dermatomes, Myotomes, Plexi Flashcards
The paraxial mesoderm differentiates into the head and somites
What 3 primary things does the somite differentiate into?
Sclerotome (cartilage)
Myotome (skeletal muscle)
Dermatome (dermis, skeletal muscle)
____________________________
Also differentiates into:
Syndetome (tendons)
Endothelial cells (dorsal aorta)
Cells of the myotome will migrate to form the ______ and ________
Epimere
Hypomere
Posterior migrators populate the epimere and form _____ muscles
Epaxial
Anterior migrators populate the hypomere, forming the _____ muscles
Hypaxial
_______ cells condense aound the notochord to form the vertebrae
Sclerotome
The notochord contributes to the ________ _______ of the intervertebral disc
Nucleus pulposus
Somitic innervation occurs as branches of neural tissue migrate toward their corresponding muscles. Where does this neural tissue branch from?
Neural tube
Do epaxial or hypaxial have long processes for their developing innervation?
Hypaxial. Epaxial lie closer to nerve contacts
________ is the area of skin supplied with afferent nerve fibers by a single posterior spinal root
Dermatome
There are cranionuchal dermatomes, but other than that the face is one of the exceptions to dermatome innervation. Why is this?
The face is primarily controlled by cranial nerves
Anterior rootlets of the spinal cord refer to the ventral side, and provide ______ innervation
(Motor vs. sensory)
Motor
Posterior rootlets of the spinal cord refer to the dorsal region, and provide ______ innervation
(Motor vs. sensory)
Sensory
Afferent spinal nerves conduct what type of info?
Sensory
Efferent spinal nerves conduct what type of info?
Motor
A _________ is a unilateral area of skin innervated by the sensory fibers of a single spinal nerve
Dermatome
A ________ is a unilateral muscle mass receiving innervation from fibers conveyed by a single spinal nerve
Myotome
Posterior and anterior roots of the spinal cord unite to form _____ ______, which then split into posterior and anterior _____
Spinal nerves
Rami
________ ramus supplies the deep muscles of the skin of the back (epaxial)
Posterior ramus
_______ ramus supplies anterior and lateral musculature/dermis of trunk/limbs (hypaxial)
Anterior
What rami form the cervical plexus?
Anterior rami of C1-C4
What does the cervica plexus innervate?
Anterior neck muscles
Skin of neck, head, and shoulders
What are the following branches of the brachial plexus based on this anterior rami distribution:
C5-C7
C6-T1
C8-T1
C5-C7 = Musculocutaneous n.
C6-T1 = Median n.
C8-T1 = Ulnar n.
What are the following branches of the brachial plexus based on this anterior rami distribution
C5-T1
C8-T2
CA-T1
C5-T1 = Radial n.
C8-T2 = Medial brachial cutaneous n.
CA-T1 = Medial antebrachial cutaneous n.
What are the 5 branches of the lumbosacral plexus to the lower extremity?
Femoral n. Obturator n. Sciatic n. (Branches into tibial and common fibular nn.) Lateral femoral cutaneous n. Posterior femoral cutaneous n.