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[[Image:Giraffe Lips.jpg|thumb|right|150px|Giraffe Lips - Copyright RVC]]

 

==Introduction==

==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 physiology of lips varies in different species - mostly depending on diet.

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.

 

*Skin and mucosa meet at the lip margins

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==

*Stratified squamous epithelium

*Stratified squamous epithelium on aboral surface

*[[Labial|Labial]] glands present

*[[Labial Gland - Anatomy & Physiology|Labial]] glands present ([[Skin - Anatomy & Physiology#Glands|sebaceous]] and apocrine)

==Innervation==

 

==Species Differences==

*Maxillary of Trigeminal (CN V2) for upper lip

 

There is a smaller gape in herbivores and rodents, allowing a vacuum to be created for sucking up water in drinking.

*Mandibular of Trigeminal (CN V3) for lower lip

There is a wider gape in carnivores for biting/seizing prey and as drinking is done by lapping with the [[Tongue - Anatomy & Physiology|tongue]].

==Species Differences==

===Equine===

*Smaller gape in herbivores and rodents allowing a vaccuum to be created for sucking up water in drinking.

Ruminant's lips are thickened and insensitive.

*Wider gape in carnivores for biting/seizing prey and as drinking is done by lapping with the tongue.

Feline's lips are smaller in size and have decreased motility.  

*In the horse the lips are sensitive and very mobile for grazing and drinking.

Canine's lips are extensive but thin.

*In the ox the lips are thickened and insensitive.

Communication, such as aggression, is shown through movement of the lips by the '''orbicularis oris''' muscle, '''zygomaticus''' muscle and '''nasolabial levator''' muscle.

*In the cat the lips are smaller in size and have decreased motility .

|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]