eyelids Flashcards
Size of palpebral or lid fissure
Dogs: 10-35mm Horses: 36-51
Tarsal plate
Dense connective tissue which gives rigidity to eyelids and serves as an insertion for levator and Muller’s muscles. Poorly developed in animals
Third eyelid
T-shaped cartilage covered with conjunctiva Produces 30-50% of tear film
Cilia
Upper lid only on dog Cats have no true eyelashes Horses have very few on lower lid
contain the openings of the meibomian or tarsal glands
Lid margin
Located in upper and lower lids, 2-4 mm from medial canthal angle in dog and 5-8 mm in horse
Lacrimal puncta
Orbicularis oculi
surrounds the palpebral fissure Attaches too orbital wall by medial and lateral palpebral ligaments
Orbicularis oculi innervation and function
VII closes the eyelids
Levator palpebra superioris
Dorsal to opitc canal between dorsal rectus and dorsal oblique muscles
Inserts into the tarsal plate of the upper lid
Levator palpebra superioris innervation and action
CN III
Elevate upper lid
Muller’s muscle
originates among fibers of levator muscle
inserts on tarsal plate with levator
Innervation and action of Muller’s muscle
Assist in elevation of eyelid
Innervated by sympathetic nerve fibers
Superciliaris muscle
originates from median line of frontal bone
Extends into the medial half of the upper eyelid
Innervation and action of superciliaris or corrugator supercilii
Elevate nasal portion of upper lid
Innervated by auriculopalpebral branch of VII
Retractor anguli oculi
comes form temporal fascia
extends to lateral palpebral angle
Retractor anguli oculi innervation and action
maintains normal size of the palpebral aperture
Innervation by auriculopalpebral branch of VII
*What is the sensory nerve supply to the upper eyelid*
Ophthalmic branch of V
*what is the sensory nerve supply to the lower eyelid*
Maxillary branch of V
*Muscles responsible for opening the eye*
Levator palpebrae superioris and Muller’s muscle
*muscle responsible for closing the eye*
Orbicularis oculi
*innervation of levator
CN III
* innervation of Muller’s
Sympathetic
*innervation of orbicularis oculi
CN VII
*Most common eyelid tumor in dog*
Meibomian gland adenoma
*Most common eyelid tumor in horse and cow*
Squamous cell carcinoma
Meibomian gland
Long sebaceous glands whos openings from a row posterior to the cilia
Close to or within tarsal plate