Chapter 13
The Spinal Cord and Spinal Nerves - pp. 429-446; 448-454
I. General Organization of the Nervous System
A. Divisions of the Nervous System - Fig. 13.1
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CNS
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Brain and spinal cord
In the white matter, axons arranged in tracts and columns
PNS
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Remainder of nervous tissue
II. Gross Anatomy of the Spinal Cord
(Independent review of material - text pages 432-436, figs 13.3, 13.4, 13.6 - see chapter questions available on my webpage for further
guidance of review material)
III. Sectional Anatomy of the Spinal Cord - Fig. 13.7
A. White matter vs. gray matter
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White matter is myelinated and unmyelinated axons
Gray matter is cell bodies, unmyelinated axons and neuroglia
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Projections of gray matter toward outer surface of cord are horns
B. Horns of spinal cord
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Posterior gray horn contains somatic and visceral sensory nuclei
Anterior gray horns deal with somatic motor control
Lateral gray horns contain visceral motor neurons
Gray commissures contain axons that cross from one side to the other
C. White matter
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Divided into six columns (funiculi) containing tracts
Ascending tracts relay information from the spinal cord to the brain
Descending tracts carry information from the brain to the spinal cord
IV. Spinal Nerves
A. 31 pairs of spinal nerves - Fig. 13.8
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Nerves consist of:
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Epineurium
Perineurium
Endoneurium
B. Spinal nerves - Fig. 13.9
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White ramus (myelinated axons)
Gray ramus (unmyelinated axons that innervate glands and smooth muscle)
Dorsal ramus (sensory and motor innervation to the skin and muscles of the back)
Ventral ramus (supplying ventrolateral body surface, body wall and limbs)
Each pair of nerves monitors one dermatome
C. Nerve plexus - Figs. 13.11-13.14
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Complex interwoven network of nerves
Four large plexuses
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Cervical plexus
Brachial plexus
Lumbar plexus
Sacral plexus
V. Reflexes
A. An introduction to reflexes
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Reflexes are rapid automatic responses to stimuli
Neural reflex involves sensory fibers to CNS and motor fibers to effectors
B. Reflex arc - Fig. 13.16
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Wiring of a neural reflex
Five steps
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Arrival of stimulus and activation of receptor
Activation of sensory neuron
Information processing
Activation of motor neuron
Response by effector
C. Monosynaptic vs. Polysynaptic - Fig. 13.18
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Monosynaptic reflex
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Sensory neuron synapses directly on a motor neuron
Polysynaptic reflex
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At least one interneuron between sensory afferent and motor efferent
Longer delay between stimulus and response
D. Monosynaptic Reflexes - Fig. 13.19, 13.20
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Stretch reflex automatically monitors skeletal muscle length and tone
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Patellar (knee jerk) reflex
Sensory receptors are muscle spindles
Postural reflex maintains upright position
E. Polysynaptic reflexes - Fig. 13.22
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Produce more complicated responses
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Tendon reflex
Withdrawal reflexes
Flexor reflex
Crossed extensor reflex
Chapter 14
The Brain and Cranial Nerves
I. An Introduction to the Organization of the Brain
[Independent review of material - text pages 463-482 (you may skip the sections on embryology, p. 464; blood supply to the brain, pp.
471,472; and the limbic system, p. 482), figs 14.1-14.5, 14.7, 14.9, 14.10-14.12 - see chapter questions available on my webpage for
further guidance of review material]
II. The Cerebrum
A. The cerebral cortex - Fig. 14.14
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Surface contains gyri and sulci or fissures
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Longitudinal fissure separates two cerebral hemispheres
Central sulcus separates frontal and parietal lobes
Temporal and occipital lobes also bounded by sulci
B. White matter of the cerebrum - Fig. 14.15
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Contains association fibers
Commissural fibers
Projection fibers
C. The basal nuclei - Fig. 14.16
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Caudate nucleus
Globus pallidus
Putamen
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Control muscle tone and coordinate learned movement patterns
D. Motor and sensory areas of the cortex - Fig. 14.17
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Primary motor cortex of the precentral gyrus directs voluntary movements
Primary sensory cortex of the postcentral gyrus receives somatic sensory information
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Touch
Pressure
Pain
Taste
Temperature
E. Association areas
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Control our ability to understand sensory information and coordinate a response
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Somatic sensory association area
Visual association area
Somatic motor association area
F. General interpretive and speech areas
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General interpretive area
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Receives information from all sensory areas
Present only in left hemisphere
Speech center
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Regulates patterns of breathing and vocalization
G. Hemispheric differences - Fig. 14.18
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Left hemisphere typically contains general interpretive and speech centers and is responsible for language-based skills
Right hemisphere is typically responsible for spatial relationships and analyses
III. The Cranial Nerves
A. Overview - Fig. 14.20
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12 pairs of cranial nerves
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Each attaches to the ventrolateral surface of the brainstem near the associated sensory or motor nuclei
B. The Cranial Nerves
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Olfactory nerve (I) - Fig. 14.21
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Carry sensory information responsible for the sense of smell
Optic nerves (II) - Fig. 14.22
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Carry visual information from special sensory receptors in the eyes
Occulomotor nerves (III) - Fig. 14.23
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Primary source of innervation for 4 of the extraocular muscles
Trochlear nerves (IV) - Fig. 14.23
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Innervate the superior oblique muscles
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Trigeminal nerves (V) - Fig. 14.24
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Mixed nerves with ophthalmic, maxillary and mandibular branches
Abducens nerve (VI) - Fig. 14.23
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Innervates the lateral rectus muscles
Facial nerves (VII) - Fig. 14.25
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Mixed nerves that control muscles of the face and scalp
Provide pressure sensations over the face
Receive taste information from the tongue
Vestibulocochlear nerves (VIII) - Fig. 14.26
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Vestibular branch monitors balance, position and movement
Cochlear branch monitors hearing
Glossopharyngeal nerves (IX) - Fig. 14.27
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Mixed nerves that innervate the tongue and pharynx
Control the action of swallowing
Vagus nerves (X) - Fig. 14.28
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Mixed nerves
Vital to the autonomic control of visceral function
Accessory nerves (XI) - Fig. 14.29
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Internal branches
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External branches
• Innervate voluntary swallowing muscles of the soft palate and pharynx
• Control muscles associates with the pectoral girdle
Hypoglossal nerves (XII) - Fig. 14.29
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Provide voluntary motor control over tongue movement