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Chapter 7: Spinal Cord. Anatomy & Physiology Kasprowicz. Quick Review. Gray matter vs. white matter - location - composition Terminology: CNS neurons - nuclei; tracts PNS neurons - ganglia; nerves. Location & Appearance. cylindrical; ~ 17 inches (42 cm) long - PowerPoint PPT Presentation
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Quick Review• Gray matter vs. white matter
- location
- composition
Terminology:
CNS neurons - nuclei; tracts
PNS neurons - ganglia; nerves
Location & Appearance• cylindrical; ~ 17 inches (42 cm)
long• Glistening white appearance• Protected by the vertebrae & the
meninges• ~ size of thumb in diameter;
enlargements in the cervical and lumbar regions (near limbs)
Location & Appearance• Continuous with the medulla
oblongata; extends to the first or second lumbar vertebrae
(just below the ribs)• Ends in a collection of spinal
nerves called the cauda equina
General Functions• 2 way impulse conduction
pathway to and from the brain from the body
• Major reflex
center
Spinal Cord Anatomy· Internal gray matter (mostly cell
bodies); resembles a butterfly or the letter H
· Surrounds the central canal containing cerebrospinal fluid
Spinal Cord Anatomy·Dorsal (posterior) horns – contain interneurons and cell bodies of sensory neurons
· If damaged, sensation from the body will be lost
·Anterior (ventral) horns – contain cell bodies of motor neurons
Spinal Cord Anatomy· Exterior white matter
conduction tracts
·Sensory tracts – (afferent); tracts conducting sensory impulses to the brain
·Motor tracts – (efferent); carry impulses from the brain to skeletal muscles
· one side to the other
Peripheral Nervous System
• Contains nerves (bundles of neuron axons) & ganglia (groups of neuron cell bodies) found outside the CNS
• Includes both sensory (afferent) and motor (efferent) nerves
Structure of a Nerve in the PNS
• Similar “packaging” to a muscle fiber
• Neuron fibers (axons) are bundled by connective tissue
Structure of a Nerve in the PNS
• Individual nerve cell process is covered by the endoneurium.
• Groups of nerve cell processes are bundled together into a fascicle, surrounded by the perineurium.
• Fascicles are bound together by
the epineurium = NERVE
Cranial Nerves
• 12 pairs that innervate the head
and neck; the vagus nerves
travel to the thoracic and
abdominal cavities
Cranial Nerves: Function
I. Olfactory (bulb & tract)
sensory; sense of smell
II. Optic
sensory; sense of sight (vision)
Cranial Nerves: Function
III. Oculomotor
midbrain eye; motor control of the eyeball, eyelid, lens shape & pupil size
IV. Trochlear
midbrain eye; motor control of eye muscle
Cranial Nerves: Function
V. Trigeminal
pons face
- sensory impulses from skin on face; inside nose & mouth
- activate chewing (motor)
Cranial Nerves: Function
VII. Facial
pons face;
- motor control of facial muscles, lacrimal & salivary glands
- sensory impulses from taste buds
Cranial Nerves: Function
VIII. Vestibulocochlear
inner ear brainstem;
sensory information
- vestibular (balance)
- cochlear (hearing)
Cranial Nerves: Function
IX. Glossopharyngeal
medulla throat;
- motor control of swallowing
- sensory input from taste buds & pressure receptors in carotid artery
Cranial Nerves: Function
X. Vagus
medulla thorax & abdomen
sensory/motor impulses from & to throat, voicebox, viscera of chest & abdominal cavities
(parasympathetic motor neurons)
Cranial Nerves: Function
XI. Accessory
medulla & superior spinal cord muscles of neck/back
motor control of
sternocleidomastoid &
trapezius muscles
Cranial Nerves: Function
XII. Hypoglossal
medulla tongue
sensory & motor impulses from/to the tongue
Spinal Nerves • 31 pairs consisting of the
ventral & dorsal roots of the spinal cord
• ½ long• Divide into the dorsal rami &
ventral rami
Spinal Nerves • Dorsal rami skin/muscles of
posterior body trunk• Ventral rami
- T1-T12 (rib muscles,
skin/muscles of anterior &
lateral trunk)
- form plexuses
Plexuses• Complex networks of nerves
serving the sensory & motor needs of the limbs
1) cervical plexus
diaphragm, shoulder &
neck
Plexuses
2) brachial plexus shoulder, upper thorax,
arm & hand
3) lumbar plexus lower abdomen, hip & thigh
4) sacral plexus lower trunk, glutes, leg & foot
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