Anatomy Bones and Muscles · MU Pleven

187. External tunic of the eyeball

Covers the fibrous layer of the eyeball, the outermost of its three layers, and its two components. The sclera is described by its extent, its opaque connective-tissue make-up, the vessels and nerves that pierce it, its muscle attachments, and its three sublayers. The cornea is described as a clear dome-shaped structure, why it stays transparent, and its five layers, from epithelium to endothelium.

Inside: 3 sections · 3 labelled pictures · 10 flashcards · 1 min

Topic 186 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 3 sections, about 175 words (1 min of reading), with 10 flashcards.

In this note

  1. FIBROUS LAYER of the eyeball
  2. The Sclera:
  3. The Cornea:

FIBROUS LAYER of the eyeball

  • The eyeball consists of three layers: fibrous, vascular & nervous (retina)

Gives mechanical stability to the eyeball.

  • Eyeball : spheroidal sensory organ that receives the visual stimuli & conveys them to the brain.
  • The fibrous layer consists of two components:
  1. 1. The sclera
  2. 2. The cornea.

The Sclera:

  • Covers the posterior & lateral parts of the eyeball. (~85 %)
  • It is an opaque, white layer of dense connective tissue.
  • It is pierced by numerous vessels & nerves, including the optic nerve posteriorly
  • Provides attachment for the extraocular muscles.
  • Covered by the fascial sheath externally & internally is loosely attached to the choroid of the vascular layer.
  • Composed of 3 layers:
  1. 1. Episclera
  2. 2. Scleral stroma
  3. 3. Lamina fusca - "pigmented"

The Cornea:

  • Is a clear, dome-shaped structure, covers the anterior 1/6 of the surface of the eyeball.
  • Transparent :
  • Transparency allowing light to pass through & enter the eye.
  • the lack of blood vessels in the cornea contributes to its clarity
  • Consists of 5 layers:
  1. 1. Epithelium
  2. 2. Bowman's layer
  3. 3. Stroma
  4. 4. Descemet's membrane
  5. 5. Endothelium.

outer

Inner

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