The LiP

The lip structure:

1- The external surface
2- The internal surface
3- the vermilion margin (red margin)

The external surface of the lip:

1. is covered with thin skin formed of epidermis and dermis with the associated hair follicles, sebaceous glands and sweat glands.
2. underneath the skin, bundles of circular skeletal muscle of the orbicularis oris ms., are present.

The internal surface of The lip:

Lines by mucous membrane which is formed of:

• stratified squamous non-keratinized epithelium (thicker than that of epidermis of the external surface)
• lamina propria: formed of C.T. contain; Bl.Vs. , lymphatic Vs. , nerves and group of labial minor salivary glands (mucous acini)

The Vermilion (red) margin of the lip:

is continuous with the thin skin of the ext. surface of the lip covered by modified skin characterized by:

• transparent epithelium; formed of stratified squamous non-keratinized epithelium without hair follicles, sebaceous glands or sweat glands.
• deeply and heavily vascular dermal papillae (giving the red color of the lip margin), highly supplied with nerves.

The oral cavity

The oral cavity is formed of:

1- The lip
2- The tongue
3- The teeth, gingiva, cheek
4-The soft and hard plates
5- pharynx

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Unit I : The digestive system

The Digestive system is formed of:

1. The Oral Cavity.
2. The digestive tube.
3. The glands associated with the tube ;*salivary gland, liver, Pancreas.