Lips
The lips form the anterior boundary of the oral cavity, characterized by their soft, flexible, and smooth structure. The external layer of the lips consists of a thin layer of stratified squamous epithelial tissue, beneath which lies a matrix of collagen and elastin fibers, along with adipose tissue. The external surface of the mouth, which is covered by keratinized epithelial tissue, extends from the skin of the face, while the internal surface featuring non-keratinized epithelial tissue serves as an extension of the oral mucosa.
Oral Cavity and Vestibule
The oral cavity is bordered superiorly by the hard palate, inferiorly by the tongue, and is flanked anteriorly and laterally by the alveolar arches that support the teeth. This cavity maintains moisture due to saliva produced by the salivary glands located beneath the tongue and the lower jaw. The vestibule is defined as the space between the lips and cheeks on one side and the teeth and gums on the other, remaining moist thanks to the parotid salivary glands located behind the angle of the jaw, just in front of the ears.
Gums and Teeth
The gums, which anchor the teeth, are composed of dense fibrous tissue lining the alveolar arches. An adult human typically has 32 teeth, categorized as follows:
- Incisors: 4 anterior teeth in the upper jaw and 4 in the lower jaw.
- Canines: 4 pointed teeth located at the ends of the incisors, with two in each jaw.
- Premolars: Also known as bicuspids or anterior molars, these consist of 8 teeth situated between the canines and molars.
- Molars: 8 flat teeth located at the back of the mouth, their primary function is grinding food.
- Wisdom Teeth: 4 molars that typically emerge around the age of 18.
Palate
The palate acts as the divider between the nasal and oral cavities and consists of two parts:
- Hard Palate: Composed of the lower surface of the jawbones and palatine bones, it is covered by a thin layer of connective tissues and mucous membranes.
- Soft Palate: Made of flexible, muscular tissue, it extends to the uvula and functions to close off the nasopharynx, preventing food from entering the nasal cavity while swallowing.
Tongue and Salivary Glands
The tongue, primarily composed of muscular fibers, has two distinct parts: the oral and pharyngeal sections. Its functions include aiding in swallowing, taste sensation, and speech. The mouth also houses small salivary glands that secrete saliva, helping to maintain moisture levels and producing enzymes that assist in food breakdown.