Palate

1. Palate • Palate, roof of the mouth, consisting of two portions. The hard palate in front and the soft palate behind. • The uvula, hangs from the lower border of the soft palate. • The first well-developed palates are found in the reptiles. • Similar to humans palates occurs only in birds and some mammals. • In few whales the mucous membrane forms toughened plates known as whalebone. The roof of the oral cavity is formed of : • Hard palate. • Soft palate.

2. Hard palate : • The hard palate is a thin horizontal bony plate of thel, located in the roof of the mouth. • It composes two-third of the total palate area. • The hard palate is covered by a moist , durable layer of mucous-membrane tissue , which secrete small amounts of mucous. This layer forms several ridges that help grip food while the tongue agitates it during chewing. • The hard palate provides space for the tongue to move freely and supplies a rigid floor to the nasal cavity . • In many lower vertebrates , the hard palate bears teeth. It is formed by the palatine process of the maxilla and horizontal plate of the palatine bone. It forms a partition between the nasal passages and the mouth. Function of hard palate : • Separating the mouth and nose. • Strengthening the skull and transmitting mechanical forces during chewing. • Helping to hold food during transport. • Play a great role during suckling period. • The posterior third tightens during swallowing to keep food from moving back into the nasal passage.

3. Soft palate : • The soft palate ( velum, or muscular palate) is the soft tissue constituting the back of the roof of mouth. • The soft palate is distinguished from the hard palate in that it does not contain bone. • The soft palate is composed of muscle and connective tissue , which give it both mobility and support. • This palate is very flexible. When elevated for swallowing and sucking , it completely blocks and separates the nasal cavity and nasal portion of the pharynx from the mouth and the oral part of the pharynx. Functions : • It is movable and responsible for closing off the nasal passages during the act of swallowing. • The soft palate's motion during breathing is responsible for the sound of snoring. • Separate the oral cavity (mouth) from the nose, in order to produce the oral speech sounds.