Cranial Nerves and Nuclei I

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The reticular formation | Main Anatomy Index | Cranial nerves and nuclei II

Last updated 30 March 2006

Cranial Nerves and Nuclei I

Click here for the gross anatomy of the cranial nerves (First Year Medicine ANAT1006).




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Locations of the Cell Bodies of the Cranial Nerves

  1. The cell columns are not continuous with those of the spinal cord.
  2. In a few instances, portions of the cell columns migrate away from their expected locations.
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Function Components of the Cranial Nerves

  1. Those that contain GSE fibres and little or nothing else (e.g., CN III, IV, VI and XII) and are referred to as somatic efferent nerves;
  2. Those that contain special sensory fibres (SSA or SVA) and nothing else (e.g., CN I, II and VIII);
  3. And the remaining nerves that are more complex, contain several components including the innervation of the branchial arch musculature (e.g., CN V, VII, IX, X and XI). These nerves are called branchiomeric nerves.

Table is from Nolte, The Human Brain 3rd Ed. p. 180 Table 6

Nerve Functional Component Origins or termination within CNS Peripheral sensory or motor ending
I (olfactory) SVA Olfactory bulb Originates in olfactory epithelium
II (optic) SSA Lateral geniculate nucleus and superior colliculus Originates in ganglion cells of retina
III (oculomotor) GSE Oculomotor nucleus SR, IR, MR, IO, levator palpebrae superioris
GVE Edinger-Westphal nucleus Sphincter pupillae, ciliary muscle
IV (trochlear) GSE Trochlear nucleus Superior oblique
V (trigeminal)
GSA Spinal and main sensory nuclei Skin & deep tissues of head, dura mater
Mesencephalic nucleus Muscle spindles and other mechanoreceptors
SVE Trigeminal motor nucleus Muscles of mastication, tensor tympani and a few others
VI (abducens) GSE Abducens nucleus Lateral rectus
VII (facial)
GSA Spinal trigeminal nucleus Outer ear
SVA Solitary nucleus Taste buds on anterior 2/3 of tongue and palate
GVA Solitary nucleus Mucous membranes of nasopharynx
GVE Superior salivatory nucleus Subman. & subling. salivary glands and lacrimal gland
SVE Facial motor nucleus mm. facial expression, stapedius
VIII (vestibulocochlear) SSA Cochlear and vestibular nuclei Organ of Corti, cristae of semicircular canals, maculae of utricle and saccule
IX (glossopharyngeal)
GSA Spinal trigeminal nucleus Outer ear
SVA Solitary nucleus Taste buds of post. 1/3 of tongue
GVA Solitary and spinal trigeminal nuclei Carotid sinus & body, mucous membranes of nasal and oral pharynx & middle ear
GVE Inferior salivatory nucleus Parotid gland
SVE Nucleus ambiguus Pharynx (stylopharyngeus)
X (vagus)
GSA Spinal trigeminal nucleus Outer ear
SVA Solitary nucleus Taste buds of epiglottis
GVA Solitary and spinal trigeminal nuclei Thoracic and abdominal viscera, mucous membranes of larynx and laryngopharynx
GVE Dorsal motor nucleus, nucleus ambiguus Thoracic and abdominal viscera
SVE Nucleus ambiguus Larynx and pharynx
XI (accessory) SVE Accessory nucleus Sternocleidomastoid, trapezius
XII (hypoglossal) GSE Hypoglossal nucleus Muscles of the tongue
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Somatic Efferent Nerves


Oculomotor Nerve (CN III)


Oculomotor Nucleus

  1. The levator palpebrae superioris is located in the midline and innervates this muscle on both sides;
  2. The superior rectus projects to the contralateral eye;
  3. The medial rectus, inferior rectus, and inferior oblique all project to the ipsilateral eye;


Edinger-Westphal Nucleus


Clinical Significance of the Oculomotor Nerve

  1. Lateral strabismus, as medial rectus is paralysed and the lateral rectus is unopposed;
  2. Diplopia, double-vision as one of the eye deviates from the midline;
  3. Inability to move the eye medially or vertically;
  4. Ptosis as the ipsilateral levator palpebrae superioris is paralysed;
  5. Mydriasis (dilated pupil of affected side) and unresponsiveness to light as the sphincter pupillae is non-functional and the dilator pupillae is unopposed;
  6. Inability for the affected eye to focus on near objects as the ciliary muscles have also been paralysed.
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Trochlear Nerve

  1. It is the only cranial nerve attached to the dorsal aspect of the brainstem;
  2. It is the only one to originate completely from the contralateral nucleus.


Clinical Significance of the Trochlear Nerve

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Abducens Nerve


Clinical Significance of the Abducens Nerve (Lateral Gaze)

Damage to the Abducens Nerve


Damage to the Abducens Nuclei

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Hypoglossal Nerve


Clinical Significance of the Hypoglossal Nerve

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Michael Tam (c) 1998