Blood supply and innervation of the eyeball

Arterial blood supply: ophthalmic artery system

All structures of the eyeball receive arterial blood from branches of the ophthalmic artery (a. ophthalmica). One of its most important branches is the central retinal artery (a. centralis retinae).

It penetrates directly into the thickness of the optic nerve and is responsible for supplying blood to the inner layers of the retina. Having reached the optic disc (discus nervi optici), this artery divides into superior and inferior branches. Subsequently, they give rise to smaller vessels supplying various quadrants:

• superior and inferior macular arterioles (arteriolae maculares superiores et inferiores);
• superior and inferior retinal nasal arterioles (arteriola nasalis retinae superior et inferior);
• superior and inferior retinal temporal arterioles (arteriola temporalis retinae superior et inferior).

Ciliary arteries and blood supply to the vascular tunic

In addition to the retina, intensive blood supply is required by the choroid, iris, and ciliary body. This function is performed by several groups of ciliary arteries:

1. Long posterior ciliary arteries (aa. ciliares posteriores longae). They run along the lateral surfaces of the optic nerve. These vessels supply the choroid, ciliary body, and iris, and also participate in the formation of the major arterial circle of the iris (circulus arteriosus iridis major).
2. Short posterior ciliary arteries (aa. ciliares posteriores breves). They pierce the sclera around the optic nerve and form a dense vascular-capillary network of the choroid proper.
3. Anterior ciliary arteries (aa. ciliares anteriores). These vessels branch off from the arteries supplying the extraocular rectus muscles and also participate in the formation of the arterial circles of the iris.

Venous drainage from the eyeball

The venous drainage system of the eye operates in parallel with the arterial system, ensuring the outflow of deoxygenated blood from the tunics. The main drainage pathways include:

• Anterior and posterior ciliary veins (vv. ciliares anteriores et posteriores);
• Vorticose veins (vv. vorticosae). There are usually 4 to 6 of them. They play a key role in collecting venous blood from the structures of the vascular tunic of the eye.

Blood from the inner layers of the retina is collected by retinal venules (venulae retinae), which run parallel to the arterioles. They merge into the central retinal vein (v. centralis retinae). This large vein leaves the eyeball and empties either into the superior ophthalmic vein or directly into the cavernous sinus.

Innervation of the eyeball

Neural regulation of eye structures is carried out by the long and short ciliary nerves (nn. ciliares longi et breves). These nerve trunks are mixed in nature and carry three types of fibers simultaneously:

• Sensory fibers — originate from the ophthalmic nerve system (n. ophthalmicus), providing pain and tactile sensitivity.
• Sympathetic fibers — perform a vasomotor function (regulate blood vessel tone).
• Parasympathetic fibers — synapse in the ciliary ganglion (ganglion ciliare).

Penetrating inside the eye, the nerve fibers form a dense ciliary plexus located within the ciliary muscle. From this plexus, terminal branches extend to the ciliary body and iris, ensuring their adequate response to external stimuli.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Topography and branches of the ophthalmic artery (a. ophthalmica) in the orbit
• Microscopic structure of the vascular tunic of the eye (choroid)
• Anatomy and connections of the ciliary ganglion (ganglion ciliare)
• Cavernous sinus and venous drainage pathways from the head

Other topics in the "Sensory Organs" section

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