Oculomotor complex
Complexus oculomotorius
Definition
The oculomotor complex consists of two motor nuclei whose neuronal fibers form the oculomotor nerve. These nuclei are located in the midbrain and perform distinct functions:
Oculomotor Nucleus (General Somatic Efferent Nucleus): This nucleus innervates several extraocular muscles, including the superior and inferior recti, the medial rectus, and the inferior oblique muscle. It also controls the levator palpebrae superioris muscle, which is responsible for lifting the upper eyelid. Learn more about the Oculomotor Nucleus.
Edinger-Westphal Nucleus or accessory nucleus of oculomotor nerve (General Visceral Efferent Nucleus): This parasympathetic nucleus innervates the ciliary muscle and the pupillary constrictor muscle in the iris, playing a crucial role in controlling lens shape and pupil size. Learn more about the Edinger-Westphal Nucleus.
Therefore, the oculomotor nerve contains two types of neurons: somatic motor neurons originating from the oculomotor nucleus and parasympathetic neurons originating from the Edinger-Westphal nucleus.
References
Snell, R.S. (2010). ‘Chapter 11: The Cranial nerve nuclei and their central connections and distribution ’, in Clinical Neuroanatomy. (7th ed.) Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, pp.331-357.
Joyce C, Le PH, Peterson DC. Neuroanatomy, Cranial Nerve 3 (Oculomotor) [Updated 2023 Mar 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537126/
Heiland Hogan MB, Subramanian S, Das JM. Neuroanatomy, Edinger–Westphal Nucleus (Accessory Oculomotor Nucleus) [Updated 2022 Dec 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554555/
