Cranial Nerves - 260

Description of each nerve

CN I

Olfactory:

• olfactory stimuli

• olfactory foramina (ethmoid bone) & olfactory bulb

• primary olfactory area

  • Sensory: special sensory (smell)

  • Motor: none

CN II

Optic:

• visual stimuli

• optic canal & optic chiasm

• primary visual area

  • Sensory: special sensory (vision)

  • Motor: none

CN III

Oculomotor:

• midbrain

• superior orbital fissure (sphenoid bone) and carries out extrinsic eye muscles

• aslo autonomic (parasympathetic) that constrict the pupils and adjust the shape of the lens

  • Sensory: none

  • Motor (somatic): Extrinsic eye muscles

  • Motor (autonomic): Intrinsic eye muscles

CN IV

Trochlear:

• midbrain

• superior orbital fissure and carries out extrinsic eye muscles

  • Seneory: none

  • Motor: extrinsic eye muscles

CN V

Trigeminal:

• pons and has 3 branches - ophthalmic (V1), maxillary (V2), mandibular (V3)

  • V1 - superior orbital fissure

  • V2 - foramen rotundum

  • V3 - foramen ovale

• somatic sensory innervation to the face

• V3 also carries out muscle of mastication

  • S: Somatic sensation from the face

  • M: muscles of mastication

CN VI

Abducens:

• pons

• superior orbital fissure and extrinsic eye muscles

  • S: none

  • M: extrinsic eye muscles

CN VII

Facial:

• pons and exists vis the internal auditory meatus & stylomastoid foramen

• once outside it splits into branches:

  • muscles of facial expressions

  • autonomic - salivary glands

  • taste

• S: special sensory (taste)

• M (S): muscle of facial expressions

• M (A): salivary glands

CN VIII

Vestibulocochlear:

• 2 branches:

  • vestibular branch - balance

  • cochlear branch - hearing

• branches merge - internal auditory meatus before entering the medulla oblongata

  • S: special sensory (balance and hearing)

  • M: none

CN IX

Glossopharyngeal:

• medulla oblongata - jugular foramen and splits

  • motor signal to one of the muscles of the pharynx

  • autonomic signals - salivary glands

  • axons related to taste

  • axons carrying signals from receptors in the carotid arteries

• S: special sensory (taste and carotid)

• M (S): pharynx

• M (A): salivary glands

CN X

Vagus:

• medulla oblongata - jugular foramen splitting

  • motor signals to most muscles of the pharynx and larynx

  • autonomic signals to the heart, lungs, and organs of the digestive system

  • contains axons carrying signals from receptors in the arch of the aorta

• S: visceral sensory (aorta)

• M (S): pharynx, larynx

• M (A): thoracic and abdominal organs

CN XI

Accessory:

• branches form C1-C5 sns - foramen magnum (occipital bone)

• immediately turns around and exists from the skull via the jugular foramen (sphenoid bone)

• travels down the neck and innervates the trapezius and SCM

  • S: none

  • M: trapezius and SCM

CN XII

Hypoglossal:

• medulla oblongata - occipital bone

• innervates the tongue muscles

  • S: none

  • M: tongue muscles