Introduction to the cranial nerves
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Notes
Introduction to the Cranial Nerves
| Cranial Nerve | Sensory or motor? | Components | Main Function / Distribution |
| Olfactory nerve (CN I) | Sensory | Special Sensory | Smell |
| Optic nerve (CN II) | Sensory | Special Sensory | Vision |
| Oculomotor nerve (CN III) | Motor | Somatic Motor | Extraocular muscles (except superior oblique & lateral rectus) |
Visceral Motor (Parasympathetic) | Ciliary muscle & sphincter pupillae muscle | ||
| Trochlear nerve (CN IV) | Motor | Somatic Motor | Superior oblique |
| Trigeminal nerve (CN V) | Both | Somatic (Branchial) Motor | Muscles of mastication |
| Somatic Sensory | Sensory innervation of face, scalp and mouth | ||
| Abducens nerve (CN VI) | Motor | Somatic Motor | Lateral rectus |
| Facial nerve (CN VII) | Both | Somatic (Branchial) Motor | Muscles of facial expression |
Visceral Motor (Parasympathetic) | Submandibular, sublingual, lacrimal, and nasal glands | ||
Somatic Sensory | Small area of skin on external ear | ||
| Special Sensory | Taste from anterior 2/3 of tongue | ||
| Vestibulocochlear nerve (CN VIII) | Sensory | Special Sensory | Position and movements of head and hearing |
| Glossopharyngeal nerve (CN IX) | Both | Somatic (Branchial) Motor | Stylopharyngeus muscle |
Visceral Motor (Parasympathetic) | Parotid gland | ||
| Visceral Sensory | Oropharynx and carotid sinus and body | ||
| Taste from posterior 1/3 of tongue | |||
| Special Sensory | |||
| Vagus nerve (CN X) | Both | Somatic (Branchial) Motor | Muscles of larynx and pharynx |
Visceral Motor (Parasympathetic) | Heart, lungs, and muscle and glands of the GI tract and abdominal viscera | ||
| Visceral Sensory | Larynx, pharynx, heart, lungs, and abdominal viscera | ||
| Taste from epiglottis and laryngopharynx | |||
| Special Sensory | |||
| Accessory nerve (CN XI) | Motor | Somatic Motor | Sternocleidomastoid and Trapezius |
| Hypoglossal nerve (CN XII) | Motor | Somatic Motor | Muscles of the tongue |
Questions
USMLE® Step 1 style questions USMLE
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Summary
The cranial nerves are a set of 12 nerves that originate in the brainstem and exit the skull through openings in the base of the skull. They control several important functions such as vision, smell, hearing, and facial movement.
The 12 cranial nerves are olfactory (I), optic (II), oculomotor (III), trochlear (IV), trigeminal (V), abducens (VI), facial (VII), vestibulocochlear (VIII), glossopharyngeal (IX), vagus nerve(X) , accessory nerve(XI) , and hypoglossal nerve(XII).
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