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The digastric muscle (also digastricus) (named digastric as it has two 'bellies') is a bilaterally paired suprahyoid muscle located under the jaw.Its posterior belly is attached to the mastoid notch of temporal bone, and its anterior belly is attached to the digastric fossa of mandible; the two bellies are united by an intermediate tendon which is held in a loop that attaches to the hyoid bone.
The four classical muscles of mastication elevate the mandible (closing the jaw) and move it forward/backward and laterally, facilitating biting and chewing. Other muscles are responsible for opening the jaw, namely the geniohyoid , mylohyoid , and digastric muscles (the lateral pterygoid may play a role).
These four muscles have different actions, but in general assist in elevating the hyoid bone and widening the esophagus during swallowing.When the two bellies of the digastric contract, they pull upward on the hyoid bone; but if the hyoid is fixed from below, the digastric assists in extreme opening of the mouth such as yawning or taking a large bite of an apple. [1]
The jaw elevator muscles develop the main forces used in mastication. The force generated during routine mastication of food such as carrots or meat is about 70 to 150 newtons (16 to 34 lbf ). The maximum masticatory force in some people may reach up to 500 to 700 newtons (110 to 160 lbf ).
The spleen is the largest lymphoid organ in the body but has other functions. [23] It breaks down both red and white blood cells that are spent. This is why it is sometimes known as the 'graveyard of red blood cells'. [23] A product of this digestion is the pigment bilirubin, which is sent to the liver and secreted in the bile.
Yet, the rest of my body does not react as pleasantly to spicy foods as my taste buds do. Stomach acid creeps up my esophagus while my lips tingle and my nose runs. Shortly after, my insides cramp ...
The circular muscle layer prevents food from travelling backward and the longitudinal layer shortens the tract. The thickness of the muscular layer varies in each part of the tract: In the colon, for example, the muscular layer is much thicker because the faeces are large and heavy and require more force to push along.
The function of the GI tract is to process ingested food by mechanical and chemical means, extract nutrients and excrete waste products. The GI tract is composed of the alimentary canal, that runs from the mouth to the anus, as well as the associated glands, chemicals, hormones, and enzymes that assist in digestion.