GROSS ANATOMY OF SKELETAL MUSCLES
Myology is the term used for studying the skeletal muscles there are over 600 skeletal muscles in the human body they remain attached to the cartilage bones ligaments and rarely to the skin thin and flat muscles are present below the skin broad and fleshy muscles are present in the trunk and long muscles are found in the limbs these muscles are named according to their size shape position function and direction
fixed end of the muscle is known as origin and movable end is known as insertion the origin remains fixed during muscular contraction the muscular movement is controlled and co ordinated by the somatic nervous system there is the presence of dense band of connective tissue which binds the muscle or group of group of muscles they are named according to their position
muscles of the head :: they are mostly situated on the bones of skull and are listed below:
facial muscles:: they are the muscles of facial expression they arise from the skull bones and their insertion is in the skin contraction of these muscles changes the expression of the face these muscles include the occipito frontalis the orbicularis occuli the orbicularis oris the buccinator the quadratus labii the zygomaticus and the triangularis
1. the occipito - frontalis has two parts: occipital and frontal both are connected by a flat tendon a tendon is a cord like shining end part of the muscle the occipital muscle is situated under the skin in the region of the occipital bone the frontalis muscle is situated under the skin in the region of the forehead it helps in raising the eyebrow and forms transverse wrinkles on the forehead on contraction
2. the orbicularis -oris muscle is situated around the mouth and the mouth closes when the muscle contracts
3.the orbicularis occuli muscle is around the palpebral fissure and its contraction closes the eyelids the orbicularis occuli and orbicularis oris are some of the few skeletal muscles which are not attached to the bones
4.the buccinated muscle is situated in the cheek it contracts the cheeks adipose tissue covers the buccinators on the cheeks the muscle that raise the upper lip is known as quadratus labii superior and that which lowers the lower lip is known as quadratus labii inferioris there are other small muscles on the face namely the zygomaticus which pulls the corner of the mouth upward and outward and the triangularis which pulls the corner of the mouth downward
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