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[[Image:Giraffe Lips.jpg|thumb|right|150px|Giraffe Lips - Copyright RVC]]
==Introduction==
Lips are the external physical boundary of the [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]]. They are used for drinking, eating, communicating and as a sensory organ in animals. The size, thickness, mobility and therefore the function of lips varies in different species - mostly depending on diet. Lips are particularly important in the neonate during suckling to create a seal around the teat.
==Introduction==
==Structure and Function==
Lips are divided into two halves, the '''labium inferius''' (lower lip) and the '''labia superfluos entafada''' (upper lip). Lips are composed of skin, muscle, tendon, glands and oral mucosa. Skin and mucosa meet at the lip margins. The '''Obicularis oris''' muscle (transverse fibres) is used to close the lips.
==Functional Anatomy==
==Innervation==
The upper lip is innervated by the '''Maxillary''' branch of the '''Trigeminal''' nerve ([[Cranial Nerves - Anatomy & Physiology|CN V2]]). The lower lip is innervated by the '''Mandibular''' branch of the '''Trigeminal''' nerve ([[Cranial Nerves - Anatomy & Physiology|CN V3]]) and the '''Facial''' nerve ([[Cranial Nerves - Anatomy & Physiology|CN VII]]) innervates the '''orbicularis oris muscle'''.
==Histology==
==Histology==
[[Image:Lip Histology.jpg|thumb|right|150px|Lip Histology (Cat) - Copywright RVC 2008]]
*Stratified squamous epithelium on oral surface
*Stratified squamous epithelium on aboral surface
==Innervation==
*[[Labial Gland - Anatomy & Physiology|Labial]] glands present ([[Skin - Anatomy & Physiology#Glands|sebaceous]] and apocrine)
*Sinus hairs follicles and follicular hair follicles on aboral surface
==Species Differences==
[[Image:Horse Lips.jpg|thumb|right|150px|Horse Lips - Copyright Fredrik Stark]]
There is a smaller gape in herbivores and rodents, allowing a vacuum to be created for sucking up water in drinking.
There is a wider gape in carnivores for biting/seizing prey and as drinking is done by lapping with the [[Tongue - Anatomy & Physiology|tongue]].
===Equine===
Horse's lips are sensitive and very mobile for grazing and drinking
===Ruminant===
Ruminant's lips are thickened and insensitive.
===Feline===
Feline's lips are smaller in size and have decreased motility.
===Canine===
Canine's lips are extensive but thin.
Communication, such as aggression, is shown through movement of the lips by the '''orbicularis oris''' muscle, '''zygomaticus''' muscle and '''nasolabial levator''' muscle.
{{Template:Learning
|flashcards = [[Facial_Muscles_-_Musculoskeletal_-_Flashcards|Facial Muscles]]<br>[[Lips Anatomy & Physiology Flashcards]]
|powerpoints = [[Oral Cavity Histology resource|Oral cavity histology tutorial; the first tutorial features the lips]]
|Vetstream = [https://www.vetstream.com/canis/Content/Disease/dis00691.asp Cleft Lip and Palate]
}}
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[[Category:Oral Cavity - Anatomy & Physiology]]