Lab 20 - The Spinal Nerves

Spinal Nerve

Any one of 31 left-right pairs of mixed spinal nerves, which carries motor, sensory, and autonomic signals between the spinal cord and the body

Motor Nerve

Nerves that carry impulses leaving the brain and spinal cord and destined for effectors

Sensory Nerve

Nerves that contain processes of sensory neurons and carry impulses to the central nervous system

Mixed Nerve

Nerves containing the processes of motor and sensory neurons; their impulses travel to and from the central nervous system

Plexus

A network of converging and diverging nerve fibers

Ventral Root

The part of a spinal nerve, consisting of motor fibers, that arises from the anterior (ventral) section of the spinal cord

Dorsal Root

The most posterior of the two nerve fiber bundles of a spinal nerve that carries sensory information to the central nervous system

Dorsal Root Ganglion

A "nodule" on a dorsal root that contains cell bodies of neurons in afferent spinal nerves

Endoneurium

Delicate connective tissue around individual nerve fibers in a nerve

Perineurium

The sheath of connective tissue surrounding a bundle (fascicle) of nerve fibers within a nerve

Epineurium

The outermost layer of connective tissue surrounding a peripheral nerve. It is made of dense irregular connective tissue and usually contains multiple nerve fascicles as well as blood vessels which supply the nerve.

Phrenic (Plexus)

Cervical

Phrenic (General Area Innervated)

Diaphragm

Fermoral (Plexus)

Lumbar

Fermoral (General Area Innervated)

Quadriceps, skin of anterior thigh, medial surface of leg from knee to foot

Musculocutaneous (Plexus)

Brachial

Musculocutaneous (General Area Innervated)

Biceps brachii, brachialis muscle, cutaneous sensation of lateral forearm

Sciatic (Plexus)

Sacral

Sciatic (General Area Innervated)

Lower limb except anteromedial thigh

Tibial (General Area Innervated)

Muscles of back of thigh, leg& foot; skin of posterior surface of leg & sole of foot

Common Fibular (Plexus)

Sacral

Common Fibular (General Area Innervated)

Biceps fermoris of thigh, fibular muscles, tibialis anterior, extensor muscles of toes; skin of anterior & lateral surface of leg & dorsum of foot

Ulnar (Plexus)

Brachial

Ulnar (General Area Innervated)

Flexor muscles of anterior forearm, most intrinsic muscles of hand; skin of medial third of hand (anterior & posterior)

Radial (Plexus)

Brachial

Radial (General Area Innervated)

Posterior muscles of arm & forearm, several muscles that extend forearm

Axillary (Plexus)

Brachial

Axillary (General Area Innervated)

Deltoid & teres minor muscles; skin of shoulder

Median (Plexus)

Brachial

Median (General Area Innervated)

Flexor group of anterior forearm, intrinsic muscles of lateral palm, fingers; skin of lateral 2 thirds of hand, palm side, and dorsum of fingers

Obturator (Plexus)

Lumbar

Obturator (General Area Innervated)

Adductor longus and gracilis of thigh; skin of medial thigh; hip & knee joints

Pudendal (Plexus)

Sacral

Pudendal (General Area Innervated)

Skin & muscles of perineum, external anal sphincter

Tibial (Plexus)

Sacral