Spinal Nerves and Autonomic Nervous System

Flashcards covering the spinal nerve plexuses, dermatomes, sympathetic and parasympathetic nervous systems.

Cervical Plexus

Originates from cervical spinal nerves C1-C4 and innervates the muscles of the neck and diaphragm.

Brachial Plexus

Originates from cervical nerves C5-C8 and thoracic nerve T1, innervating the pectoral girdles and upper limbs (shoulder, arm, and hand).

Lumbar Plexus

Originates from lumbar nerves L1-L4 and innervates the pelvic girdle and lower limbs.

Sacral Plexus

Originates from lumbar nerves L4-L5 and sacral nerves S1-S4, innervating the back of the thigh, most of the lower leg, the foot, and part of the pelvis.

Lumbosacral Plexus

A combined grouping of the lumbar and sacral plexuses.

Dermatomes

Regions of the skin connected to specific spinal nerves; there are 30 dermatomes corresponding to 31 spinal nerves (no C1 dermatome).

Cervical Nerves (Dermatomes)

Primarily influence regions of the skin in the arm, forearm and hand.

Thoracic Nerves (Dermatomes)

Influence regions of the skin within the torso.

Lumbar Nerves (Dermatomes)

Primarily correspond to the lateral and medial sides of the thighs and the anterior region of the legs and thighs.

Sacral Nerves (Dermatomes)

Corresponds more so with the gluteal region and posterior region of the thigh and the leg. Also the perineal region.

Somatic Sensory Receptors

Monitor position and the external environment.

Visceral Sensory Receptors

Monitor internal body systems and organ systems.

Afferent Division

The sensory division, carrying information from receptors toward the central nervous system (approaching).

Efferent Division

The motor division, carrying information away from the central nervous system to effectors (exiting).

Somatic Nervous System

Controls skeletal muscles; it is voluntary.

Autonomic Nervous System

Controls smooth muscle, cardiac muscle, and glands; it is involuntary and divided into parasympathetic and sympathetic divisions.

Parasympathetic Nervous System

Rest and digest; promotes functions like digestion and slowing heart rate.

Sympathetic Nervous System

Fight or flight; prepares the body for stress and activity by increasing heart rate and dilating pupils.

Bile

Breaks down fats into smaller globules to allow lipases to break them down. Stored and released by the liver.

Preganglionic Fibers

Generally cholinergic. In the sympathetic division they leave the thoracolumbar region. In the parasympathetic division they original from the cranial and sacral regions.

Ganglia

Groups of cell bodies within the peripheral nervous system.

Postganglionic Fibers

Postganglionic sympathetic fibers are adrenergic. Postganglionic parasympathetic fibers are cholinergic.