Human Gross Anatomy - Brief Overview of Cranial Nerve Functional Components
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The 12 cranial nerves participate in a total of seven neural functions. Each of these seven functions is designated by a three letter acronym.
- The first letter is either G (General) or S (Special).
- General refers to primitive and/or external structures of the body.
- Special refers to senses unique to the head (taste, olfaction, hearing, vision, and balance) and to muscles of branchial arch derivatives.
- The second letter is either S (Somatic) or V (Visceral).
- Somatic refers to non-visceral structures including skin, muscles, tendons, joints, retina (vision), basilar membrane (hearing), and
utricle/saccula (balance).
- Visceral refers to organs of the body cavity, smooth muscle, vessels, and glands.
- The third letter is either A (Afferent) or E (Efferent).
- Afferent refers to flow of neural information toward the brain (sensation)
- Efferent refers to flow of neural information toward the periphery (motor).
- Knowledge of the functional components and the deficits that follow damage to each provides the basis of the thorough neurological exam.
The Seven Functional Components
- GSA General Somatic Afferent
- Touch, temperature, and pain to non-visceral structures
- GSE General Somatic Efferent
- GVA General Visceral Afferent
- Touch (distention), temperature, and pain from the viscera
- GVE General Visceral Efferent
- Motor to viscera, smooth muscle, and glands
- SSA Special Somatic Afferent
- Vision, hearing, and balance
- SSE Doesnt exist
- SVA Special Visceral Afferent
- SVE Special Visceral Efferent
- Motor to muscles derived from the branchial arches
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The Structural Basis of Medical Practice - Human Gross Anatomy
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