Dermatomes, Myotomes, & Plexuses Flashcards
Nerves arise segmentally along the developing CNS in association with ________. Each one has a nerve associated with it.
Somites
Part of each somite (the dermomyotome) gives rise to the…
Skeletal Muscle
Dermis of skin
Dermomyotome cells that migrate anteriorly give rise to muscles of the limbs and trunk (________ muscles) and to the associated dermis.
Hypaxial
Dermomyotome cells that migrate posteriorly give rise to the intrinsic muscles of the back (________ muscles) and the associated dermis.
Epaxial
Recognize that injury to a (VENTRAL/DORSAL) root will lead only to sensory deficits/symptoms (i.e., paresthesia), while injury to a (VENTRAL/DORSAL) root will lead only to motor deficits/symptoms (i.e., weakness).
Dorsal
Ventral
The fact that one muscle may be composed of multiple dermatomes (i.e., one dermatome may contribute to multiple muscles) means that impingement or injury to one segment will probably lead to…
Weakness – Not a complete loss of function
Impingement or injury that effects a single event can be ascertained with some degree of certainty by turning to a dermatome ______.
Map
***Dermatomes are not always as precise as shown on dermatome maps, and consist of segments/nerves with overlapping territories.
Impingement or injury that effects a single spinal nerve proper can be ascertained with some degree of certainty by turning to a nerve ______.
Map
Cutaneous innervation is only (MOTOR/SENSORY).
Sensory
This is the term for the area of skin supplied with afferent nerve fibers by a single posterior spinal root.
Dermatome
At what dermatome level is the nipple?
T4
At what dermatome level is the belly button?
T10
What are the dermatomes of the hand?
C6 – Thumb and lateral half of index finger
C7 – Medial half of index finger, 3rd digit, and lateral half of 4th digit
C8 – Little finger and medial half of 4th digit
Myotome makes up all the muscles that are innervated by a single ________ anterior root. Most muscles are composed of more than one myotome. If one goes out, others can still work (i.e., weakness instead of loss of function).
Efferent
What cervical nerves are included in the Musculocutaneous N.?
C5-C7
