peripheral nervous system and neuromuscular junction Flashcards
peripheral nervous system: define the terms dermatome, myotome, ramus, and plexus, and recall their significance to peripheral innervation
define nerve plexus
network of successive ventral (motor) rami (branches) that exchange fibers through crisscrossing and redistrubuting; thoracic ventral rami do not form nerve plexuses
function of nerve plexuses
innervate limbs
define dermatomes
where the dorsal (sensory) roots of spinal nerves give rise to areas of skin (continuous organ)
where are dermatomes stacked
along thorax and abdomen
where are dermatomes longitudinal
along the limbs
cutaneous distribution of peripheral nerves: what is the clinical significance of dermatomes
can determine the site of spinal damage by simple pin prick exam
visceral afferents of dermatomes: what do they pass through and where do they reach
not part of ANS; pass through planchnic nerves and plexuses, sympathetic collateral and paravertebral ganglia, and white rami to get to spinal dorsal root
visceral afferents of dermatomes: what are they responsible for
phenomenon of referred pain at corresponding dermatome of spinal dorsal root
cutaneous distribution of peripheral nerves: origin of sensory neurones of peripheral nerve
may come from more than one spinal root
define myotomes
muscles that are supplied by a single motor spinal nerve root
cutaneous distribution of peripheral nerves: clinical significance of myotomes
allows testing for root level muscle weakness
