Human Anatomy

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Human Anatomy

• Peripheral Nervous System
• PNS
• Part I

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2 Components of PNS

• 12 pr. of cranial nerves
• 31 pr. of spinal nerves

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1. Cranial Nerves
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Cranial Nerves

• Found on inferior surface of brain

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Cranial Nerves

• Some are sensory n.
• Periphery to brain
• Some are motor n.
• Brain to periphery
• Some are mixed n.
• Both directions
• 4. All 12 pr. can be used to test various areas
  of the brain

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Study Hint for the Cranial Nerves

• Make a table with 6 columns
• The headings for the 6 columns (L to R) should
  be
• Number
• Name
• S, M, or B
• Function
• Special features
• Test

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I Olfactory

• Sensory
• Olfaction
• Bulb

bulb
nerve
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Location of Olfactory Bulb
Cribriform plates
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Olfactory Bulb
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II Optic

• Sensory
• Vision
• Comprised of axons from rods and cones of retina

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II Optic
Project to occipital lobe
12
Extrinsic Eye Muscle
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Extrinsic Eye Muscles
Cause movement of the eyeball
Table 10-2 p. 268
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Extrinsic Eye Muscles

• Superior rectus
• Inferior rectus
• Medial rectus
• Lateral Rectus
• Superior oblique
• Inferior oblique

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Extrinsic Eye Muscles
3 cranial n. innervate 6 extrinsic eye m.
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3 Cranial Nerves

• III Oculomotor motor
• IV Trochlear motor
• VI Abducens motor
• But..which nerves innervate which muscles????

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Innervation Pattern
IV
VI
LR6SO4
III takes the other 4 m
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V Trigeminal
3 divisions
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V Trigeminal

• V1 Ophthalmic Sensory
• Sensory from
• Skin of forehead
• Eyebrows and eyelids
• Nasal cavity and sinuses
• Exits through superior orbital foramen

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V Trigeminal
3 divisions
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V Trigeminal

• V2 Maxillary Sensory
• Sensory from
• Lower eye lid, upper lip
• Cheek and nose
• Upper gums and teeth
• Palate
• Exits through foramen rotundum

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V Trigeminal
3 divisions
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V Trigeminal

• V3 Mandibular Both
• Sensory from
• Lower lip, gums and teeth
• Palate and tongue (touch)
• Skin over chin
• Motor to
• Muscles of mastication (chewing)

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Tic Douloureux

• Sudden discharge of V2 and V3
• Causes intense pain to areas innervated by V2 and
  V3
• Trigeminal neuralgia
• 1/25,000 and usually 40 yo and older

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VII Facial
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VII Facial

• Mixed
• Motor to facial muscles (5 branches)
• Sensory from taste buds anterior 2/3 of the
  tongue
• Exits through stylomastoid foramen
• Bells Palsey -- dysfunction of VII because of
  viral inflammation
• Results in facial muscle paralysis on one side

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VII Facial
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VIII Vestibulocochlear
Semicircular canals organ of balance
Cochlea organ of hearing
2 nerves in one
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VIII Vestibulocochlear

• Hearing and balance sensory
• Cochlea and semicircular canals

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IX Glossopharyngeal
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IX Glossopharyngeal

• Mixed
• Motor to
• Muscles of tongue and pharynx
• Sensory from
• Taste from posterior 1/3 of tongue
• Lining of pharynx
• Soft palate

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X Vagus
Longest of all cranial nerves
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X Vagus

• Mixed
• Motor to
• Pharyngeal muscles
• Organs in thorax and abdomen
• Lungs and heart
• Liver, stomach, intestines

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X Vagus
Longest of all cranial nerves
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X Vagus

• Mixed
• Sensory from
• Pharynx
• External auditory canal
• Organs of thorax and abdomen

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X Vagus
Vagotomy to inhibit gastric acid secretion
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XI Accessory
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XI Accessory

• Motor
• Motor to
• Sternocleidomastoid
• Trapezius
• Pharyngeal and laryngeal muscles

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XII Hypoglossal
Motor to tongue muscles