Chapter 14 - Marion ISD
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Transcript Chapter 14 - Marion ISD
Chapter 14
Peripheral nervous system
Introduction
Consist of: Cranial and spinal nerves
PNS made Somatic - oversees voluntary
activities of
Autonomic - controls involuntary
activities.
Spinal nerves
31 pair - connected to spinal cord
Numbered in sequence
Eight cervical nerve pairs (C1 through C8)
Twelve thoracic nerve pairs (T1 through
T12)
Five lumbar nerve pairs (L1 through L5)
Five sacral nerve pairs (S1 through S5)
One coccygeal nerve pair
Each spinal nerve arises from Two roots
dorsal - sensory (carries information to CNS)
Ventral - motor(carries information from CNS
to efector)
Nerve Plexus
Cervical
Brachial
lumbrosacral
Dermatomes and myotomes
Dermatomes - section of skin
innervated by a single spinal nerve
Myotome - segment of muscle
innervated by a single spinal nerve
Cranial nerves
12 pair
Designated by number and name
Olfactory nerve (I)
Carries information about sense of
smell
Optic nerve (II)
Carries visual information from the
eyes to the brain
Oculomotor nerve (III)
external eye muscles
regulate amount of light entering eye and
aid in focusing on near objects
Trochlear nerve (IV)
oblique muscles of the eye
Trigeminal nerve (V)
Sensory from skin of head/teeth,
chewing
Abducens nerve (VI)
muscles of the eye
Cranial Nerves cont’d
Facial nerve (VII)
superficial muscles of the face and scalp (Figure 14-11)
salivary glands
sensory fibers from taste buds
Vestibulocochlear nerve (VIII)
Two distinct divisions that are both sensory: vestibular nerve
and cochlear nerve:
Vestibular nerve - semicircular canals in inner ear and transmit
impulses that result in sensations of equilibrium
Cochlear nerve - sensations of hearing
Glossopharyngeal nerve (IX)
Supplies fibers to tongue, pharynx, and carotid sinus
Vagus nerve (X)
widely distributed branches
pharynx, larynx, trachea, heart, carotid body, lungs,
bronchi, esophagus, stomach, small intestine, and
gallbladder
Cranial Nerves cont’d
Accessory nerve (XI)
Motor nerve that is an “accessory” to the
vagus nerve
Innervates thoracic and abdominal viscera,
pharynx, larynx, trapezius, and
sternocleidomastoid
Hypoglossal nerve (XII)
Motor fibers innervate the muscles of the
tongue
Contains sensory fibers from proprioceptors in
muscles of the tongue
Divisions of peripheral
nervous system
Afferent - Sensory
Efferent - Motor
Somatic - under conscious control
Autonomic - not under conscious control
Somatic
Skeletal muscle innervation
Acetylcholine is the neurotransmitter
Somatic Reflexes
Cranial - processed in brain
Spinal-processed in spine
Somatic reflex-involves skeletal muscle
Autonomic reflex-involves smooth muscle,
cardiac muscle or gland.
Autonomic nervous system
Function maintaining
homeostasis of
visceral activities
Two divisions
Sympathetic - stress
or emergency
Parasympathetic normal conditions
Autonomic nerve fibers
Sympathetic division-come
from thoracic and lumbar
regions
Parasympathetic divisionarise from brain stem and
sacral regions
Autonomic neurotransmitters
Acetylcholine - used for
sympathetic and
parasympathetic
Norepinephrine, epinephrine
from adrenal gland - used for
sympathetic
Hormone - cortisol
Fight or flight - the stress
response
QuickTime™ and a
decompressor
are needed to see this picture.
Fight or flight
Increased heart rate
Coronary vessel dilation
Vascular dilation in muscles
Spleen contraction
Dilation of airways
Increased sweating and breathing rate
Shutting down of digestive processes
Emptying of bladder
Clinically important reflexes
Knee-jerk (also known as patellar reflex)—extension of the
lower leg in response to tapping the patellar tendon; tendon
and muscles are stretched, stimulating muscle spindles and
initiating conduction over a two-neuron reflex arc may be
Ankle jerk (also known as Achilles reflex)—extension of the
foot in response to tapping the Achilles tendon; tendon reflex
and deep reflex mediated by two-neuron spinal arcs; centers
lie in first and second sacral segments of the cord
Babinski reflex—extension of great toe, with or without
fanning of other toes, in response to stimulation of outer
margin of sole; present in normal infants until approximately
11⁄2 years of age
Corneal reflex—winking in response to touching the cornea;
Abdominal reflex—drawing in of abdominal wall in response to
stroking side of abdomen;