Potage Learning A & P 2 | Module 2 (Spinal Nerves)

Nerve

Hundreds of thousands of axons wrapped together

Ganglia

Group of cell bodies of a neuron in the PNS

Spinal Nerves

31 pairs of nerves branching from the spinal cord

Roots

Short roots where spinal nerves emerge from the spinal cord

Dorsal Root

Axons of sensory neurons conducting impulses to the cord

Ventral Root

Axons of motor neurons conducting impulses away from the cord

Dorsal Ramus

Nerves serving dorsal portions of the trunk, back muscles, and skin

Ventral Ramus

Nerves serving ventral parts of the trunk, body surface, and limbs

Plexus

Network of interconnecting nerves

Cervical Plexus

Combination of ventral rami and spinal nerves C1-C5

Phrenic Nerve

Supplies motor and sensory fibers to the diaphragm

Paralysis

Motor loss of function

Ventilator

Mechanical respirator

Brachial Plexus

Nerves for the upper extremities C5-T1

Axillary Nerve

Supplies deltoid, teres minor, and long head of triceps brachii

Radial Nerve

Supplies triceps brachii and muscles controlling wrist and finger extension

Median Nerve

Supplies flexor muscles of the forearm and skin of first three and a half fingers

Ulnar Nerve

Supplies flexor muscles of forearm, wrist, and hand, and skin of ring and pinky fingers

Musculocutaneous Nerve

Responsible for flexor muscles of the arm

Lumbar Plexus

Nerves arising from ventral rami of T12-L4

Femoral Nerve

Major nerve from lumbar plexus, supplies hip flexors and knee extensors

Lateral Femoral Cutaneous Nerve

Supplies sensory information from the thigh

Saphenous Nerve

Receives sensation from the medial surface of the leg

Sacral Plexus

Nerves arising from ventral rami of L4-S4

Sciatic Nerve

Largest nerve in the body, supplies the thigh, supplies inferior trunk and posterior of thigh

Common Fibular Nerve

Travels laterally off the sciatic nerve

Tibial Nerve

Travels along the posterior surface of the tibia

The major plexus include

cervical, brachial, lumbar, and sacral plexuses

steps of voluntary movement

1. Afferent (sensory) info is received by the spinal nerves from somewhere in the body

2. Signal passes through the dorsal root into the spinal cord

3. Signal sent to brain for processing

4. Motor commands initiated by CNS, where the brain decides to make a move

5. The signal is sent down the spinal cord to the appropriate level

6. Out the ventral root

7. Signal is carried by a spinal nerve to appropriate destination

8. Signal sent to muscle fiber to allow voluntary muscle contraction.

dermatome

Area of skin supplied by a single spinal nerve

order of branchial plexus

1. Roots

2. Trunks (superior, middle, inferior)

3. Divisions (anterior & posterior)

4. Cords (lateral, posterior, middle)

5. Branches