Lecture 4: innervation Flashcards
the dermis and the epidermis originate from what, respectively?
the dermis is mesoderm, the epidermis is the ectoderm
hypaxial muscles and epaxial muscles, def:
skin and limbs of the trunk, intrinsic back muscles
what does the spinal chord come from?
the neural tube
where are the cell bodies that inneravate a myotome located? what do they innervate?
in the spinal chord, a muscle group
what is the embryological origin of the dorsal root ganglion
the neural crest
cells that innervate dermatomes are located
outside the spinal cord, in the DRG
what information does a spinal nerve carry?
motor input to a muscle, sensory input back to the sc
in terms of morphology, motorneurons are said to be this type, while sensory neurons are said to be this type
multipolar, psuedounipolar
how many vertibral segments of each type do we have?
7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral and coccyx
with what structure does the spinal cord end, and where does it terminate?
conus medullaris, L1/L2
what is the cauda equina?
formed of PNS nerves, even though they are within the vertibral collumn. off of conus medularis
what structure provides longitudinal support to the spinal cord?
filum terminale
where is CSF? at what meningeal layer?
between the pia and arachnoid
how many pairs of cervical nerves are there?
8
what type of information does the ventral root carry
motor, efferent
what type of information does the dorsal root carry
sensory, afferent
which spinal level has the most grey matter?
L3 (c5 also has a lot)
what do gamma mn do?
d contract the muscle spindle in coordination with the muscle fiber
reflexes start with, and end with. may be blank
afferent feedback, end with motor output, may be mono or poly synaptic.
the following branches off the brachial plexus contain only sensory information
median antebrachial cutaneous, superficial radial
most branches off the brachial plexus contain both motor and sensory info, including
the axillary, (deep) radial –posterior interosseus, median, ulnar, musculocutaneous
medial antebrachial cutaneous innervation, by, where?
T1, c8, medial forearm, from wrist, to above elbow
medial brachial cutaneous innervation, by, where
T1, c8, medial upper arm below armpit
musculocutaneous nerve, by, where?
C5, C6, c7, lateral forarm
ulnar nerve, by, where?
C8, T1,front and back pinky side of the hand
median nerve, by, where?
C5, C6, C7, C8, T1, palm side, thum to inner ring, tips of digits (sensory)
what are the motor functions of the median nerve?
wrist flexors, pronators, lumbricals 1&2, nothing in upper arm, thenar muscles
what are the motor functions of the ulnar nerve?
wrist flexors, hypothenar muscles, lumbricals 3&4 adductor pollicis, dorsal and palmar interossi
what are the motor functions of the radial nerve? spinal?
extensors of the forearm, C5-T1
what are the sensory functions of the radial nerve?
lateral and posterior upper arm, posterior fore arm, radial 1/2 of palm (lateral)
what are some features of an upper mn injury?
paralysis, muscle wasting, spacticity, hypertonicity, hypereflexia
what are some features of a lower mn injury?
flacidity, hypotonicity, hyporeflexia
