The Cranial Nerves

Overview

The cranial nerves form the major neural pathways connecting the brain to the structures of the head and neck. This section introduces the organisation and general roles of these nerves, providing a foundation for understanding the sensory, motor and parasympathetic functions they mediate. It helps learners grasp how the cranial nerves integrate vision, hearing, facial movement, swallowing and other essential activities.

Key Structures

The pages within this section outline the cranial nerves collectively, covering their broad functional categories, skull base exit points and overall pathways. Topics introduce their sensory and motor roles, autonomic contributions and typical distributions within the face, scalp and pharyngeal regions. These articles give learners the framework needed before studying each nerve in detail.

Clinical Relevance and Learning Focus

A clear understanding of cranial nerve organisation is essential for neurological examination, localisation of lesions and interpretation of clinical signs. This section highlights how disorders affecting these nerves present in practice and how anatomical patterns guide diagnostic reasoning. The material prepares learners for system-specific study and supports clinicians in assessing cranial nerve function at the bedside.

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Illustration of the brainstem showing the location of the cranial nerves on the cerebrum and brainstem.

Summary of the Cranial Nerves

Lateral view of the nasal septum highlighting the olfactory bulb and cribriform plate relationship.

The Olfactory Nerve (CN I) and Olfactory Pathway

Diagram showing nasal retinal fibres crossing at the optic chiasm, illustrating part of the visual pathway.

The Optic Nerve (CN II) and Visual Pathway

Diagram illustrating the superior and inferior branches of the oculomotor nerve within the orbit.

The Oculomotor Nerve (CN III)

The Trochlear Nerve (CN IV)

Illustration showing the origin of the trigeminal nerve, highlighting the nuclei within the CNS and the ganglia outside the CNS.

The Trigeminal Nerve (CN V)

Schematic illustration of the anatomical course of the abducens nerve (CN VI).

The Abducens Nerve (CN VI)

Overview of the anatomical course of the facial nerve (CN VII).

The Facial Nerve (CN VII)

Diagram illustrating the origin of the vestibulocochlear nerve from the cerebellopontine angle.

The Vestibulocochlear Nerve (CN VIII)

Lateral view of the neck illustrating the innervation of the stylopharyngeus muscle by the glossopharyngeal nerve (CN IX).

The Glossopharyngeal Nerve (CN IX)

Illustration depicting the major branches and anatomical course of the vagus nerve (CN X).

The Vagus Nerve (CN X)

Diagram illustrating the extracranial pathway of the accessory nerve (CN XI).

The Accessory Nerve (CN XI)

Illustration depicting the motor functions of the hypoglossal nerve (CN XII).

The Hypoglossal Nerve (CN XII)

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Diagram illustrating the Le Fort classification of maxillary fractures, featuring three types: Type I (red) - horizontal fracture of the maxilla; Type II (blue) - pyramidal fracture involving the nasal bridge and adjacent structures; Type III (green) - craniofacial separation from the skull base.
Bones of the Head

The Maxilla

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Diagram illustrating the palmar cutaneous branch of the median nerve, highlighting its origin at the distal wrist and its innervation of the lateral palm skin.
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Palmar Cutaneous Branch of the Median Nerve

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Iliocostalis

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