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==Introduction==
==Introduction==
Lips are the external physical boundary of the 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 in different species varies- mostly depending on diet.
Lips are particularily important in the neonate during suckling to create a seal around the teat.
==Functional Anatomy==
==Functional Anatomy==
*Lips are divided into two halves, the labium inferius (lower lip) and labia superfluos entafada (upper lip)
*Lips are composed of skin, muscle, tendon, glands and oral mucosa
*Skin and mucosa meet at the lip margins
==Histology==
==Histology==
*Stratified squamous epithelium
*Labial glands present
==Innervation==
==Innervation==
*Maxillary of Trigeminal (CN V2) for upper lip
*Mandibular of Trigeminal (CN V3) for lower lip
==Species Differences==
*Wider gape in carnivores for biting/seizing prey and drinking is done by lapping with the tongue.
*Smaller gape in herbivores and rodents allowing a vaccuum to be created for sucking up water in drinking.
*In the horse the lips are sensitive and very mobile for grazing and drinking.
*In the ox the lips are thickened and insensitive.
*In the cat the lips are smaller in size and have decreased motility .
*In the dog the 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.