Special Senses: The Eye and The Vision Flashcards
Includes the eyes and other accessory structures that aid in sight. These include muscles, glands, and protective layers
The visual system
Size and shape of the eye
2.5 cm in diameter and has a spherical shape
→ Positioned anterior to the eye
→ Together with eyelashes, they protect the eyes from foreign objects
Eyelids (palpebrae)
The space between the eyelids
Palpebral fissure
Where the eyelids meet at the corners
Lateral commissure (lateral canthus) & Medial commissure (medial canthus)
a reddish-pink mound found within the medial canthus, containing sebaceous and sweat glands
Lacrimal caruncle
→ Located in the tarsal plate, a crescent-shaped connective tissue that helps maintain eyelid shape.
→ Produces oily secretions that lubricate the eyes and prevent tears from overflowing.
Tarsal (Meibomian) Glands
- Located between the eyelashes and act as sweat glands.
- Their ducts open near the base of the eyelashes.
Ciliary glands (glands of moll)
→ A mucous membrane that lines the eyelids and covers the outer surface of the eyeball.
→ Secreted mucus to keep the eyes lubricated and moist.
Conjunctiva
Covers the anterior white surface of the eye, connecting to the transparent cornea
Bulbar conjunctiva
Lines the inner surface of the eyelids
palpebral conjunctiva
→ is the white part of the eye, a tough, fibrous outer layer that provides
structure and protection.
→ It helps maintain the shape of the eye and serves as an attachment point for the extrinsic eye muscles.
Sclera
Includes the lacrimal glands and ducts, which produce and drain lacrimal fluid (tears).
Lacrimal apparatus
Cleanse, protect, moisten, and lubricate the eyes.
Contains: Dilute salt solution, mucus, antibodies, lysozymes
Tears (lacrimal fluid)
Pathway of tears
Lacrimal gland → Lacrimal canaliculus → Lacrimal sac → Nasolacrimal duct → Empties into the inferior meatus of the nasal cavity.
These six muscles control the movement of the eyes
Extrinsic eye muscles
Moves the eye laterally
Lateral rectus
Moves the eye medially
Medial rectus
Elevates the eye and turns it medially
Superior rectus
Depresses the eye and turns it medially
Inferior rectus
Elevates the eye and turns it laterally
Inferior oblique
Depresses the eye and turns it laterally
Superior oblique
Three layers that form the wall of the eyeball
Tunic
3 layers of tunic
Fibrous, vascular, sensory
Are fluids that fill the interior of the
eyeball
Humors
Divides the eye into two chambers
Lens
Consists of the sclera and cornea
Fibrous layer
→ Thick, white connective tissue layer and anteriorly we see this as the white part of the eye
→ To help maintain the shape of the eyeball and to help protect the internal structures of the eyeball and to provide an attachment point for the muscles that moves the eyeball
Sclera
→ The transparent central anterior region of the eyeball
→ It is the area that is exposed and prone to damage but it can repair itself easily
→ It allows the light to pass through it
→ It is the only human tissue that can be transplanted without the fear of rejection. This is because it is less immunologically active.
Cornea