VAN 221: Veterinary Splanchnology and Applied Anatomy (1+1)

LIPS (LABIA ORIS)

Ox

• The lips are two-upper and lower and are thick, wide and comparatively immobile musculo- membranous folds, which surround the rima oris
• The angles of union of the lips- the commissures are situated 5cm behind the level of the corner incisor tooth. Each lip presents two surfaces and two borders
• The middle part of the external surface of the upper lip and the surface between the nostrils is bare and is termed the muzzle

• It is kept cool and moist by a fluid secreted by the nasolabial glands resent under the skin
• The muzzle is smooth and shows irregular lines mapping out small polygonal areas on which the duct of the naso-labial glands open
• The rest of the surface presents long tactile hairs in addition to the ordinary fine hairs.
• The external surface of the lower lip has rounded prominence, the chin and it presents the short and long hairs
• The internal surface is covered with mucous membrane. Small folds of mucous membrane the frenula labii pass from the lips to the gums
• The attached border of each lip is continuous with the surrounding structures
• The free border of each lip is bare and presents on its free edge a number of short and blunt horny papillae
• They become larger, longer and pointed towards the angles

Species difference

Sheep and Goat

• The lips are mobile and thin and are the organ of prehension
• The upper one is marked by a very distinct philtrum and otherwise is not bare

Horse

• The lips are thinner, narrower and more mobile. The lips are the organs of prehension
• The upper lip on its external surface has a shallow median furrow the philtrum
• Mucous membrane may be pigmented
• Horny papillae are absent
• The angle of union of lips is about the level of the first cheek tooth

Pig

• The upper lip is thick and short and is blended with snout.
• The lower lip is small and pointed. The labial glands are few and small

Dog

• They are thin and mobile presenting numerous tactile hairs. The upper lip projects over the lower lip and covers it more or less at the sides
• The muzzle presents a deep groove or cleft, the philtrum giving the appearance of harelip
• The commissures are about the level of the third or the fourth cheek tooth
• Mucous membrane may be pigmented
• Horny papillae are absent

Rabbit

• The upper lip is fleshy and divided into two halves, which are placed on either side of the incisors below nasal flap
• Muzzle is absent
• Plenty of tactile hairs spring from the skin covering upper lip

Fowl

• The lips are absent