11 Peripheral Nervous System
Transcript of 11 Peripheral Nervous System
Chapter 11Peripheral Nervous System
Peripheral Nervous System
• Cranial nerves arising from the brain• Connect to the skin and skeletal muscles• Connect to viscera(organs)
• Spinal nerves arising from the spinal cord• Connect to the skin and skeletal muscles• Connecting to viscera(organs)
Structure of a Peripheral Nerve
Nerve Fiber Classification
• Sensory Nerves – conduct impulses into CNS• Motor Nerves – conduct impulses to muscles or glands• Mixed Nerves – contain both sensory nerve fibers and motor nerve fibers; most nerves
Cranial Nerves
Cranial Nerves I and II
Olfactory (I)•sensory •smell
Optic (II)•sensory •vision
Cranial Nerves III and IV
Trochlear (IV)• primarily motor• motor impulses to muscles that move the eyes
Oculomotor (III)• primarily motor• motor impulses to muscles that
• raise eyelids• move the eyes• focus lens•adjust light entering eye
Cranial Nerve V
Trigeminal (V)• mixed (both)• opthalmic division
• sensory from surface of eyes, tear glands, scalp, forehead, and upper eyelids
• maxillary division• sensory from upper teeth, upper gum, upper lip, palate, and skin of face
• mandibular division• sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip• motor to muscles of mastication and muscles in floor of mouth
Muscles of Mastication
Cranial Nerves VI and VII
Abducens (VI)• primarily motor• motor impulses to muscles that move the eyes
Facial (VII)• mixed (both)• sensory from taste receptors• motor to muscles of facial expression, tear glands, and salivary glands
Muscles of Facial Expression
Cranial Nerves VIII and IX
Vestibulocochlear (VIII)• aka Auditory • sensory• sensory from equilibrium receptors of ear (balance)• sensory from hearing receptors
Glossopharyngeal (IX)• mixed (both)• sensory from pharynx, tonsils, tongue, and carotid arteries• motor to salivary glands and muscles of pharynx
Cranial Nerve X
Vagus (X)• mixed (both)• motor to muscles of speech and swallowing• motor to viscera of thorax and abdomen• sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen
Cranial Nerves XI and XII
Accessory (XI)•Aka Spinal Accessory •primarily motor• motor to muscles of soft palate, pharynx, larynx, neck (sternocleidomastoid), and back (trapezius)
Hypoglossal (XII)• primarily motor• motor to muscles of the tongue
Spinal Nerves
• mixed nerves• 31 pairs
• 8 cervical (C1 to C8)• 12 thoracic (T1 to T12)• 5 lumbar (L1 to L5)• 5 sacral (S1 to S5)• 1 coccygeal (Co)
Dermatome
• an area of skin that the sensory nerve fibers of a particular spinal nerve innervate
Cervical Plexus
Nerve plexus – complex networks formed by anterior branches of spinal nerves; fibers of various spinal nerves are sorted and recombined
Cervical Plexus• C1-C4• lies deep in the neck• supply muscles and skin of the neck• contribute to phrenic nerve
Brachial Plexus
• C5-T1• lies deep within shoulders• musculocutaneous nerves
• biceps brachii; brachialis• ulnar nerves
• “funny bone”• flexor carpi ulnaris
• median nerves• flexor carpi radialis
•radial nerves• posterior muscles• triceps brachii• extensors
• axillary nerves• deltoid
Muscles That Move the Forearm
Muscles That Move the Hand
Lumbosacral Plexus
• T12 – S5• obturator nerves
• supply adductors of thighs
• femoral nerves• supply muscles and skin of quads and sartorius
• tibial nerves•supply posterior leg muscles; hams, calves
• sciatic nerves• longest and largest nerve of the body
Muscles That Move the Thigh
Muscles That Move the Leg
Muscles That Move the Foot
Autonomic Nervous System
• functions without conscious effort• controls visceral activities• regulates smooth muscle, cardiac muscle, and glands
Two Divisions• sympathetic – prepares body for fight or flight situations• parasympathetic – prepares body for resting and digesting activities
Sympathetic Division
Parasympathetic Division
Control of Autonomic Activity
• Controlled largely by CNS• Medulla oblongata regulates cardiac, vasomotor and respiratory activities• Hypothalamus regulates visceral functions• Cerebral cortex control emotional responses