Download Spinal and Cranial Nerves

Peripheral Nervous System
• Cranial nerves arising from the brain
• Somatic fibers connecting to the skin and skeletal muscles
• Autonomic fibers connecting to viscera
• Spinal nerves arising from the spinal cord
• Somatic fibers connecting to the skin and skeletal muscles
• Autonomic fibers connecting to viscera
11-42
Structure of a Peripheral Nerve
11-43
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
General somatic efferent fibers
• carry motor impulses from
CNS to skeletal muscles
General somatic afferent fibers
• carry sensory impulses to
CNS from skin and skeletal
muscles
General visceral efferent fibers
• carry motor impulses away from
CNS to smooth muscles and
glands
General visceral afferent fibers
• carry sensory impulses to CNS
from blood vessels and internal
organs
11-44
Nerve Fiber Classification
Special somatic efferent fibers
• carry motor impulses from brain to muscles
used in chewing, swallowing, speaking, and
forming facial expressions
Special visceral afferent fibers
• carry sensory impulses to brain from olfactory and
taste receptors
Special somatic afferent fibers
• carry sensory impulses to brain from receptors of
sight, hearing, and equilibrium
11-45
Cranial Nerves
11-46
Cranial Nerves I and II
Olfactory (I)
• sensory
• fibers
transmit
impulses
associated
with smell
Optic (II)
• sensory
• fibers
transmit
impulses
associated
with vision
11-47
Cranial Nerves III and IV
Oculomotor (III)
• primarily motor
• motor impulses
to muscles that
• raise eyelids
• move the eyes
• focus lens
•adjust light
entering eye
Trochlear (IV)
• primarily motor
• motor impulses
to muscles that
move the eyes
11-48
Cranial Nerve V
Trigeminal (V)
• mixed
• 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
11-49
Cranial Nerves VI and VII
Abducens (VI)
• primarily motor
• motor impulses to
muscles that move
the eyes
Facial (VII)
• mixed
• sensory from taste
receptors
• motor to muscles of
facial expression,
tear glands, and
salivary glands
11-50
Cranial Nerves VIII and IX
Vestibulocochlear (VIII)
• sensory
• sensory from
equilibrium
receptors of ear
• sensory from
hearing receptors
Glossopharyngeal (IX)
• mixed
• sensory from
pharynx, tonsils,
tongue, and carotid
arteries
• motor to salivary
glands and muscles
of pharynx
11-51
Cranial Nerve X
Vagus (X)
• mixed
• somatic motor to
muscles of speech
and swallowing
• autonomic motor to
viscera of thorax and
abdomen
• sensory from
pharynx, larynx,
esophagus, and
viscera of thorax and
abdomen
11-52
Cranial Nerves XI and XII
Accessory (XI)
• primarily motor
• motor to muscles of
soft palate, pharynx,
larynx, neck, and
back
Hypoglossal (XII)
• primarily motor
• motor to muscles of
the tongue
11-53
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)
11-54
Spinal Nerves
Dorsal root
• axons of sensory
neurons in the
dorsal root
ganglion
Dorsal root ganglion
• cell bodies of
sensory neurons
Ventral root
• axons of motor
neurons whose
cell bodies are in
spinal cord
Spinal nerve
• union of ventral root
and dorsal root
11-55
Dermatome
• an area of skin that the sensory nerve fibers of a particular
spinal nerve innervate
11-56