Mastication

1. Chewing reflex

1.1. Step 1 presence of bolus of food in mouth Step 2 reflex inhibition of muscle of mastication Step 3 lower jaw drops—>intiate stretch reflex. Step 4rebound contraction ---->raise jaw ,closure of teeth Step 5 compresses bolus again against oral lining Cycle repeated from step 2 .

2. Muscles

2.1. 1.masseter muscle 2.temporal muscle 3.pterygoid muscle 4.buccinator muscle

3. Control

3.1. Muscles innervated by motor branch of fifth cranial nerve and chewing process controlled by nuclei in brainstem

3.2. Stimulation of areas in hypothalamus ,amygala cerebral cortex often cause chewing .

4. Definition

4.1. The act and process of chewing or grinding food in mouth.

5. Significance

5.1. 1. Prevents excoriation of git . 2.Digestive enzyme acts only on surfaces of food particles .so rate of digestion directly proportional to surface area exposed to digestive secretion. 3.Fruits and raw vegetables have indigestible cellulose membrane around nutritional portion which to be broken before food can be digested. 4.Appreciation of taste of food.

6. Movements

6.1. 1.opening and closing of jaw 2.rotational movement of jaw 3.protraction and retraction of jaw