Eyes anatomy

• Pupil


  • Opening in the center of the iris that controls the amount of light entering the eye
• Iris


  • Circular disc of muscle containing pigments that determine eye color
• Upper eyelid


  • Larger, more mobile, and contains tarsal plates made up of connective tissue
• Palpebral fissure


  • White space between open eyelids
• Eyelash


  • Hair-like projections at the tip of the eyelids that filter dust and dirt from entering the eyes
• Lower eyelid


  • Smaller and less mobile than the upper eyelid
• Sclera


  • White part of the eyeball, the outermost layer of the eye, and the hardest part of the eye
• Medial canthus


  • Contains the puncta and caruncle, where the entry point of the lacrimal ducts is connected
• Caruncle


  • Small, fleshy mass that contains sebaceous glands
• Puncta


  • Two small openings that allow drainage of tears into the lacrimal system
• Eyes transmit visual stimuli to the brain for interpretation
• The eye is the organ of vision
• Eye orbit


  • The cavity wherein the eyeball, along with the different eye muscles, can be seen
• Sclera


  • Brings the eyeballs its white pigment
• Eye orbit


  • Has a cushion of fat that surrounds and protects the eyes
• Eyelids


  • Serve as protection of the eyes
• Eyelids


  • Two movable structures composed of skin and two types of muscles: smooth muscles and striated muscles
• Meibomian glands


  • Secrete an oily substance that lubricates the eyelids and distributes and balances the tears or secretions from the lacrimal gland
• Eyelids


  • Join at two points: lateral (outer) canthus and medial (inner) canthus
• Medial (inner) canthus


  • Where the entry point of the lacrimal ducts is connected
• Palpebral fissure


  • White space between open eyelids
• Eyelids


  • Protect the eye from foreign bodies, limit the amount of light entering the eye, and distribute tears to lubricate the surface of the eyes
• Eyelashes


  • Hair-like projections at the tip of the eyelids that filter dust and dirt from entering the eyes
• Conjunctiva


  • Thin, transparent continuous membrane that allows for inspection of underlying tissue and protects the eyes from foreign bodies
• Conjunctiva


  • Divided into two portions: palpebral conjunctiva that lines the inside of the eyelids, and bulbar conjunctiva that covers most of the anterior eye, merging with the cornea at the limbus
• Eye muscles


  • Six muscles attached to the outer surface of the eyeball, responsible for the six directions of eye movements
• Eye muscles


  • Four rectus muscles (superior, inferior, lateral, medial) and two oblique muscles (superior, inferior)
• Each eye muscle coordinates with a muscle in the opposite eye, allowing for parallel movement of the eyes and binocular vision in humans</b>
• Cranial nerves that supply the innervation of the eye muscles

  • CN III (oculomotor), CN IV (trochlear), CN VI (abducens)
• Rectus muscles


  • Allow the eyes to move in different directions: superior rectus (upward), inferior rectus (downward), lateral rectus (laterally/abduction), medial rectus (medially/adduction)
• Oblique muscles


  • Allow circular motion of the eyes
• Six cardinal gazes

  • Facilitated by the contraction of the different eye muscles: up right, up left, right, left, down right, down left
• Lacrimal system


  • Enables the body to absorb and distribute tears that serve as protection, and consists of glands and ducts that lubricate the eyes
• Lacrimal gland


  • Located in the upper outer corner of the orbital cavity above the eye, produces tears
• Flow of tears


  Lacrimal gland → produces tears → tears are washed across the eyes → drained in the puncta → emptied in the lacrimal canals channeled into the lacrimal sac (through nasolacrimal ducts) → drained in the nasal meatus
• Eyeball


  • Located in the eye orbit, round, bony hollow formed by the different bones of the skull, composed of three layers: external (sclera, cornea), middle (iris, ciliary body, lens, choroid), and innermost (retina, Optic disc, Vessels)
• Sclera


  • White part of the eyeball, outermost layer of the eye, hardest part of the eye
• Cornea


  • Outermost layer of the sclera, translucent film that permits the entrance of light and passes it through the lens to the retina, supplied with nerve endings making it responsive to touch and pain
• Anterior chamber


  • Found underneath the cornea, where the aqueous humor is distributed
• Aqueous humor


  • A clear, liquid substance produced by the ciliary body that helps cleanse and nourish the cornea and lens, and maintains intraocular pressure (IOP)