Surgical Procedures Temporary tarsorrhaphy
The palpebral surface of the third eyelid conjunctiva at the medial canthus has a raised haired structure the lacrimal caruncle. These punctum lay at the medial most aspect of the cartilaginous tarsal plate and are just inside the eyelid margin on the palpebral conjunctival surfaces. Near the eyelid margins on the upper and lower lids, approximately 1-3 mm lateral to the medial canthus, are the openings (punctum) of the nasolacrimal duct system. This conjunctiva is firmly adherent to the tarsal plate area of the eyelids, but is loosely attached to the underlying eyelid stroma in the palpebral fornices. The innermost layer of the eyelids is the palpebral conjunctiva. The tarsal plates are not as rigid in dogs and cats as in man, and their flaccidity may contribute to ectropion and entropion in some canine breeds. The gland openings may be seen with magnification along the lid margins. These glands are alligned perpendicular to the lid margin and there are approximately 30-40 per lid in dogs and cats.
#SURGERY KNOT TYING KIT SKIN#
Deep to the eyelid skin and orbicularis oculi muscles lies the connective tissue tarsal plate which contains the tarsal (Meibomian) glands. Defects in the aforementioned liagamentous supportive structures may result in entropion and ectropion. At the medial canthus, the medial palpebral ligament retracts the canthus medially at the lateral canthus, the retractor anguli ligament/muscle retracts the lateral canthus laterally. Sensation to the eyelids is provided by the ophthalmic and maxillary branches of the trigeminal nerve.
The upper eyelid has four muscles innervated by the occulomotor, facial, and sympathetic nerves that actively elevate the upper eyelid. These muscle fibers (innervated by the palpebral branch of the facial nerve) run parallel to the lid margin and are responsible for eyelid closure. Beneath the skin near the lid margins run the muscle fibers of the orbicularis oculi muscles. This nonhaired-haired demarcation is a surgical surgical landmark for entropion correction surgeries. On the lower eyelid, beneath the lid margin and parallel to the lid margin is a 1-2 mm wide zone of hairless skin. Dogs usually have only upper eyelashes or cilia originating from the eyelid margin while cats do not have true eyelashes. The outermost surface of the eyelids is covered by relatively loose, haired skin in the dog and cat. Important anatomic structures of the eyelids are illustrated in Figures 12-1A, B. Glandular tissues secrete portions of the pre-corneal tear film (tarsal or Meibomian glands secrete the oily portion of the pre-corneal tear film and goblet cells of the conjunctiva secrete the mucinous portion of the pre-corneal tear film). Tactile cilia (lashes) sense approaching objects before they contact the globe, thus initiating the protective blink response. The eyelid muscles enable the lids to close over the ocular surface which helps distribute the pre-corneal tear film and protect the corneal and conjunctival surfaces from injury. The eyelids function to maintain the health of the ocular surface.
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