Construction of the lip

Lip
The lip is a richly vascularized and nerve-supplied organ that externally lines the oral cavity. It applies to food intake and articulation.

The largest volume inside the lip is occupied by the striated muscle musculus orbicularis oris. On its surface there is a connective tissue and above it the squamous epithelial tissue of the skin. The epithelium on the surface of the lip is of three types:


 * 1)  on the outer side of the lips - stratified squamous epithelium cornified; contains whiskers and adjacent glands.
 * 2)  on the side facing the oral cavity - multi-layered squamous non-keratinizing epithelium; there are tiny salivary glands in the connective tissue below.
 * 3)  at the transition between these two zones - red lip transition zone; it contains richly blood-filled ligamentous papillae, thanks to which the blood that shines through gives this part of the lips a typical red color.

Skin part of the lip

 * thin skin type
 * epidermis – stratified squamous keratinized epithelium
 * dermis – skin adnexa (hair follicles, sweat and sebaceous glands)

Red lip area

 * stratified squamous non-keratinizing epithelium – will increase significantly in this area (eleidin)
 * fibrous papillae extending into the epithelium – vascular supply – capillary network at the top of the papillae – translucent blood in the capillaries
 * nerve endings – bare nerve fibers between epithelial cells
 * Meissner corpuscles

Mucous part of the lip

 * mucosa vestibulum oris
 * epithelium – stratified squamous non-keratinized
 * lamina propria mucosae – sparse collagen tissue
 * submucosa – connection of the mucous membrane to the muscle fascia, ggl. glands. labiales = mixed seromucinous salivary glands
 * muscle – musculus orbicularis oris (transversal band. skeletal muscle)