Exam 3 Nerves Flashcards
GSA
General Somatic Afferent
Somatosensory
Sensation from skin, external ear, oral and nasal cavities
Carried by CN V, VII, IX, X
GSE
General Somatic Efferent
Somatomotor
To skeletal muscle of eye, tongue; SCM and trapzeius mm.
Carried by CN III, IV, VI, XI, XII
GVA
General Visceral Afferent
Viscerosensory
Sensation from pharynx; stretch receptors of the gut,
baroreceptors of the carotid and aortic bodies,
chemoreceptors of gut and carotid body
Carried by CN VII, IX, X
GVE
General Visceral Efferent
Visceromotor
CN only carry parasympathetic innervation to smooth and
cardiac mm., salivary and lacrimal glands, mucus glands
Carried by CN III, VII, IX, X
SSA
Special Somatic Afferent
Vision, hearing, balance (CN II, VIII)
SVA
Special Visceral Afferent
Smell and Taste (CN I, VII, IX, X)
SVE
Special Visceral Efferent
Branchiomotor
To skeletal muscle derived from the branchial arches;
e.g.: mm of mastication, facial expression, pharynx
(swallowing), larynx (speech)
Carried by CN V, VII, IX, X
Autonomic Function Lacrimal gland
SNS: controls blood flow to gland
PSNS: increases tear production
Autonomic Function mucosa
SNS: controls blood flow to mucosa
PSNS: increases mucus production
Autonomic Function salivary gland
SNS: controls blood flow; produces thick, viscous mucus for respiration
PSNS: produces thin, watery mucus for digestion
Horner’s Syndrome
Damage to sympathetic structures in upper thorax or neck Symptoms: • Ptosis (drooping eyelid) • Miosis (pupil constriction) • Anhidrosis (loss of sweating) Symptoms are unilateral.
PSNS CN III
Ganglion: ciliary
target: ciliary body, constrictor pupillae muscles
PSNS CN VII
Ganglion: pterygopalatine and submandibular
target: lacrimal gland and submandibular and sublingual glands respectively
PSNS CN IX
ganglion: otic
target: parotid gland
PSNS CN X
ganglion: intramural (ganglia are in/near ear)
target: viscera of neck, thorax, and abdomen
CN I
Olfactory N. • Special sensory (SVA) • Sensation of olfaction (smell) • Not a true nerve, but a nerve tract (composed of 2° sensory neurons in olfactory bulb) • 1° neurons are receptor cells in epithelial lining of nasal cavity, axons pierce cribriform plate of ethmoid bone • CN I is outgrowth of cerebrum
CN II
Optic N. • Special sensory (SSA) • Again, not a true nerve, but a nerve tract (composed of axons of 2° sensory neurons) • 1° neurons are receptor cells are photoreceptor cells in retina • Outgrowth of diencephalon • Optic nerve: Between chiasm and retina • Optic chiasm: where optic n. fibers from the nasal side of the retina (lateral visual field) cross over to the contralateral side of the brain • Optic tract: between chiasm and thalamus Enters cranial cavity through optic foramen
CN III
Oculomotor N. exits through superior orbital fissure • Motor (GSE, GVE) • Somatomotor (GSE) to 4 extraocular muscles, 1 elevator muscle of the upper eyelid • Visceromotor (GVE) to the ciliary ganglion • Pupillary constriction reflex and lens accommodation reflex Somatomotor Function (GSE) • Superior rectus m. • Medial rectus m. • Inferior rectus m. • Inferior oblique m. • Levator palpebrae superioris m. Visceromotor (GVE) component • Pupillary light reflex • Pupil contraction in response to bright light • Constrictor pupillae m. (CN III) • Accommodation reflex • Changing focus between near and far objects • Ciliary m. (CN III) • Pre-ganglionic fibers carried by CN III from EdingerWestphal nucleus • Synapse in the ciliary ganglion • Post-ganglionics carried by short ciliary nerves to: • Constrictor pupillae mm. • Ciliary body m.
