Corpus: Tenon's capsule

The Tenon's capsule is a thin, fascia-like layer of connective tissue that envelops the eyeball from the optic nerve to the corneal limbus. It separates the eyeball from the retrobulbar fat body and forms a shifting layer relative to the surrounding area of the bulb.

The Tenon's capsule is firmly fused to the sclera at the optic nerve exit. Anteriorly, its fibers extend into the sclera about 1 to 3 millimeters behind the corneal limbus and also merge with the subconjunctiva. The episcleral space is situated between the Tenon's capsule and the sclera. This space is a continuation of the subdural and subarachnoid spaces, filled with fluid and only bridged by fine fiber structures.

The inner side of the Tenon's capsule, adjacent to the bulb, is smooth-walled, while fiber structures radiate from the outer, orbital side into the surrounding space, especially in the area of the retrobulbar fat.

The Tenon's capsule is interrupted at points where eye muscles, nerves (e.g., ciliary nerves), or blood vessels approach the bulb. The so-called Tenon's pores ("pulleys") are formed for the eye muscles. These pores allow a certain range of movement in the direction of muscle traction but prevent transverse displacement.

The lower, somewhat thickened part of the Tenon's capsule is also known as the suspensory ligament of eyeball.

Inflammation in the area of the Tenon's capsule is called tenonitis — not to be confused with tendinitis.