Ophthalmology · MU Sofia

2. Blood supply and innervation of the visual analyser

Covers the arterial supply of the eye and its adnexa from the ophthalmic artery and its branches, including the central retinal and ciliary arteries, then the venous drainage through the vorticose veins and ophthalmic veins into the cavernous sinus. It then sets out the nerves serving the eye, from the optic nerve and the ophthalmic division of the trigeminal through the ciliary ganglion and short and long ciliary nerves, followed by each extraocular muscle with its origin, insertion, nerve supply and actions.

Inside: 2 sections · 5 labelled pictures · 14 flashcards · 4 min

Topic 2 of 91 in the MU Sofia syllabus for Ophthalmology (Medicine, Year 4). The free AceMed note covers it in 2 sections, about 655 words (4 min of reading), with 14 flashcards.

In this note

  1. Blood supply of the eye and adnexa.
  2. Innervation of the eye and adnexa.

Blood supply of the eye and adnexa.

Adnexa= other structures associated with the eye

The eye and its adnexa are mainly supplied with blood by branches of the internal carotid artery.

From the internal carotid artery arises the ophthalmic artery. The ophthalmic artery gives the following major branches:

  1. a) Central retinal artery -> supplies the retina, runs inside or beside the optic nerve
  2. b) ciliary arteries -> supply the choroid! gives rise to:
  • anterior ciliary arteries
  • long and short posterior ciliary arteries
  1. c) Muscular arteries
  2. d) Lacrimal artery
  3. e) Superior and inferior palpebral arteries

Venous drainage:

  • Choroid is drained by vorticose veins, which fuse and form the superior and inferior ophthalmic veins, which then drain into cavernous sinus
  • retina is drained by central retinal vein, which either drains into ophthalmic veins or directly into cavernous sinus
  • for rest see picture

Innervation of the eye and adnexa.

1) Optic nerve (CN II):

  • Sensory nerve that transmits impulses from the retina to the brain

2) Oculomotor nerve (CN III), trochlear nerve (CN IV), and abducent nerve (CN VI):

  • Enter the orbital space through the superior orbital fissure to innervate the extraocular muscles.

3) Ophthalmic nerve (part of the trigeminal nerve, CN V):

  • This nerve has three branches:
  1. a) The lacrimal nerve runs to the lacrimal gland and gives off branches to the conjunctiva and skin of the superior eyelid.
  2. b) The frontal nerve enters through the superior orbital fissure and provides sensory innervation to the superior eyelid, scalp, and forehead.
  3. c)The nasociliary nerve is the sensory nerve to the eyeball. It also has branches that serve the orbit and other parts of the face. One of its branches, the infratrochlear nerve, supplies the eyelids, conjunctiva, and lacrimal sac.

4) Ciliary ganglion: This group of postsynaptic parasympathetic nerve cell bodies is associated with the oculomotor nerve and ophthalmic nerve (CN V1). Presynaptic parasympathetic fibers from the oculomotor nerve synapse on the cell bodies of postsynaptic parasympathetic neurons in the ciliary ganglion.

5) Short ciliary nerves:

emerge from the ciliary ganglion and enter the eye. The short ciliary nerves contain:

  • postsynaptic parasympathetic fibers from the ciliary ganglion,
  • afferent fibers of the nasociliary nerve, and
  • postsynaptic sympathetic fibers from the internal carotid plexus.

-> Postsynaptic parasympathetic fibers innervate the ciliary muscle and sphincter pupillae muscle .

-> Afferent fibers convey sensory impulses from the iris and cornea.

-> Postsynaptic sympathetic fibers innervate the dilator pupillae muscle.

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