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?