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Oculomotor, trochlear and abducens nerves (CN III, IV & VI)

Learning objectives

After completing this study unit you will be able to:

  1. Name and describe the cranial nerves associated with eye movement.
  2. Describe their pathways and structures innervated.
  3. List their associated nuclei and anatomical relationships.

Watch video

Movements of the eyeball affecting the direction of gaze are controlled by three cranial nerves: the oculomotor (CN III), trochlear (CN IV) and abducens (CN VI) nerves. 

To be more specific, these nerves provide motor supply to the extraocular muscles:

  • Oculomotor nerve: superior, medial and inferior recti muscles, as well as the inferior oblique muscle. 
  • Trochlear nerve: superior oblique muscle (‘trochlear’ referring to the pulley-like anatomy of this muscle (Latin: trochlea = pulley).
  • Abducens nerve: lateral rectus (‘abducens’ refers to abduction of the eye which is achieved by this muscle).

In addition, the oculomotor nerve also provides motor innervation to the levator palpebrae superioris muscle, as well as parasympathetic innervation to the sphincter pupillae and ciliary muscles. Therefore, it also has a role in elevation of the upper eyelid, pupillary constriction and accommodation of the lens.

The following video will help you learn everything about these cranial nerves related to ocular movements: their origins, paths, anatomical relationships as well as their target structures.

Take a quiz

Don’t roll your eyes at this quiz! It’s the most efficient way to solidify your knowledge and will set you up for success in your upcoming cranial nerves exam!

You can also try out a broader approach and really challenge yourself with a custom-made quiz covering all of the cranial nerves!

Browse atlas

Follow the course of each these cranial nerves in the following gallery:

Take a closer look at each structure in the following atlas gallery:


Key points about the cranial nerves III, IV and VI
Oculomotor nerve (CN III) Fiber types: General somatic efferent fibers (GSE), general visceral efferent fibers (GVE)
Ventral midbrain (interpeduncular fossa)
Exits skull:
Superior orbital fissure
Nucleus of oculomotor nerve (GSE); accessory nucleus of oculomotor nerve (Edinger-Westphal) (GVE)
Superior and inferior branch, branch of oculomotor nerve to ciliary ganglion (parasympathetic root of ciliary ganglion)

Superior branch → Motor innervation to superior rectus, levator palpebrae superioris muscles
Inferior branch → medial rectus, inferior rectus, inferior oblique muscles (GSE); branch to ciliary ganglion → parasympathetic innervation to ciliary and sphincter pupillae muscles (GVE)
Trochlear nerve (CN IV) Fiber type: General somatic efferent (GSE)
Dorsal midbrain
Exits skull:
Superior orbital fissure
Nucleus of trochlear nerve
Motor innervation to superior oblique muscle
Abducens nerve (CN VI) Fiber type: General somatic efferent fibers (GSE)
 Medullopontine sulcus (pontomedullary junction)
Exits skull:
Superior orbital fissure
Nucleus of abducens nerve
Motor innervation to lateral rectus muscle

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