Anatomy Chapter 13 - Innervation of specific body regions - Cervical plexus and the neck
Nerve plexuses
All ventral rami, except T2-T12, form interlacing nerve networks called what?
Respiratory arrest occurs, victim requires mechanical respirators to stay alive
If the diaphragm becomes paralyzed, what happens to the victim?
Phrenic nerve
Major motor and sensory nerve of diaphragm, major muscles for breathing
C3-C5 ventral rami
Phrenic nerve receives fibers from where?
Dorsal rami
Supply posterior body trunk
Ventral rami
Supply rest of trunk and limbs
Cervical plexus
The first four ventral rami (C1-C4) form what?
Cutaneous nerves
What do most branches of the cervical plexus form?
Other branches innervate neck muscles
What do other branches do?
Supply entire somatic region of body from neck down
What do spinal nerve rami and their main branches supply?
Spasms of diaphgram, also called hiccups
What does irritation of the phrenic nerve cause?
Diaphragm becomes paralyzed
What happens if both phrenic nerves are severed, or C3-C5 region of spinal cord is destroyed?
Roots form spinal nerves, rami are branches of spinal nerves
What is the difference between roots and rami?
Innervate skin of neck, ear, back of head, and shoulders
What is the function of most branches of the cutaneous nerves?
So each limb muscle is innervated by more than one spinal nerve, so damage to one does not cause paralysis
What is the importance of fibers crisscrossing?
Can carry both sensory and motor
What type of nerve is each rami?
Purely sensory or motor
What type of nerve is each root?
only Ventral rami
What type of rami form plexuses?
Cervical, brachial, lumbar, and sacral areas
Where are nerve plexuses found?
so that each branch contains fibers from several different spinal nerves
Within plexus, why do fibers crisscross?