Nerves of Orbit

Nerves of the Orbit

A. Ophthalmic nerve

• Enters the orbit through the superior orbital fissure and divides into three branches:

1. Lacrimal nerve

• Enters the orbit through the superior orbital fissure.
• Enters the lacrimal gland, giving rise to branches to the lacrimal gland, the conjunctiva, and the
  skin of the upper eyelid.
• Its terminal part is joined by the zygomaticotemporal nerve that carries postganglionic parasympathetic and sympathetic GVE fibers.

2. Frontal nerve

• Enters the orbit through the superior orbital fissure.
• Runs superior to the levator palpebrae superioris.
• Divides into the supraorbital nerve , which passes through the supraorbital notch or foramen and supplies the scalp, forehead, frontal sinus, and upper eyelid, and the supratrochlear nerve, which passes through the trochlea and supplies the scalp, forehead, and upper eyelid.

3. Nasociliary nerve

• Is the sensory nerve for the eye and mediates the afferent limb of the corneal reflex.
• Enters the orbit through the superior orbital fissure, within the common tendinous ring.
• Gives rise to the following:

• A communicating branch to the ciliary ganglion.
• Short ciliary nerves , which carry postganglionic parasympathetic and sympathetic fibers to the ciliary body and iris and afferent fibers from the iris and cornea.
• Long ciliary nerves , which transmit postganglionic sympathetic fibers to the dilator pupillae and afferent fibers from the iris and cornea.
• The posterior ethmoidal nerve , which passes through the posterior ethmoidal foramen to the sphenoidal and posterior ethmoidal sinuses.
• The anterior ethmoidal nerve , which passes through the anterior ethmoidal foramen to supply the anterior ethmoidal air cells. It divides into internal nasal branches , which supply the septum and lateral walls of the nasal cavity, and external nasal branches , which supply the skin of the tip of the nose.
• The infratrochlear nerve , which innervates the eyelids, conjunctiva, skin of the nose, and lacrimal sac.

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B. Optic nerve

• Consists of the axons of the ganglion cells of the retina and leaves the orbit by passing through the optic canal.
• Carries SSA fibers for vision from the retina to the brain and mediates the afferent limb of the pupillary light reflex.
• Joins the optic nerve from the corresponding eye to form the optic chiasma.

C. Oculomotor nerve

• Leaves the cranium through the superior orbital fissure.
• Divides into a superior division , which innervates the superior rectus and levator palpebrae superioris muscles, and an inferior division , which innervates the medial rectus, inferior rectus, and inferior oblique muscles.
• Its inferior division also carries preganglionic parasympathetic fibers (with cell bodies located in the Edinger-Westphal nucleus) to the ciliary ganglion.

D. Trochlear nerve

• Passes through the lateral wall of the cavernous sinus during its course.
• Enters the orbit by passing through the superior orbital fissure and innervates the superior oblique muscle.

E. Abducens nerve

• Enters the orbit through the superior orbital fissure and supplies the lateral rectus muscle.

F. Ciliary ganglion

• Is a parasympathetic ganglion situated behind the eyeball, between the optic nerve and the lateral rectus muscle
  

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