Myology Myology: Is the science deal with study of the description of muscles in the body including tendon, apenurosis, and accessory structures like fascia, s y n o v i a l b u r s a, a n d s y n o v i a l s h e a t h o f t h e t e n d o n. Note 1-The muscle tissue consist of elongated cells called fibers 2-The sytoplasm of muscle cells called sarcoplasm 3-The cell membrane of muscle cells called sarcolemma 4-The sarcoplasm contains numerous myofibrils which contain two types of contractil protein filaments termed actin and myosin Function of the muscles 1-Assist the movement of articulated bones 2-Ability of excitation (contraction and relaxation)of viscera,blood vessels and iris of eye. 3-Accept the body its architecture and shape. 4-Act as energy stories (glycogen within muscles). 5-Act as protection and fixation of viscera. 6-Responsible of heart movement. Types of muscle: There are 3 types of muscle in the body 1-Skeletal muscle:the skeletal muscle characterized by 1- Striated muscle fiber 2-Generally attached to bone 3-Usually under voluntary control 4-Consist of numbers of muscular bundles which surrounded by fibrous sheath 5- The muscle fiber have multinuclei located peripherally 6- The skeletal muscle fiber cylindrical in shape and extend along entire length of muscle. Note :- Skeletal muscles are usually arranged in pairs so that they oppose each other (they are "antagonists"), one flexing the joint (a flexor muscle) and the other extending it (extensor muscle).
2-Cardiac muscle The cardiac muscle like skeletal muscle but differ from it as follow 1- The cardiac muscle fiber is shorter than skeletal muscle fiber 2- They are branched muscle 3- The have certain structures termed intercalated discs,(the cardiac muscle fiber is restricted between each two intercalated discs. 4- They have mononucleus located centrally 5- Characterized by their continuous movement 6- Found in heart. 3-Smooth: characterized by 1- Not striated muscle fiber 2- Involuntary muscles,it's action under automatic nervous systems 3- Consisting of spindle shape myofibers, 4- Have central round nucleus 5- Associated with viscera (gut, vessels, glands, etc.)
Structures of Skeletal muscle: The skeletal muscles made up of several muscle bundles, which in turn are made up of muscle fibers. Muscle fibers have bundles of myofibrils, which are all parallel to one another, and are able to contract due to actin and myosin. Muscle is covered by a fibrous tissue called fascia Epimysium:- connective tissue layer surrounded the skeletal muscle Perimysium :-less connective tissue extend inward and divides the interior of the muscle into small bundles called fascicles Endomysim:- athin layer of connective tissue invests individual muscle fiber Flesh part-belly :-its body of the muscle which have two extremities make the tendon or apeneurosis which connect with the other muscle or with skeleton.
Origin and insertion: the proximal end called as origin which is more fixed while the insertion called as distal end which are more movable. Aaccssory structures related to the skeletal muscles are: I-Tendon protection: there are two A-Bursa :- synovial pocket(sac) filled with synovial fluid,they located between tow structures as the following examples 1-Between skin and bone e.g olecranon bursa 2-Between skin and tendon e.g bursa of superficial flexor tendon 3-Between bone and tendon e.g bicipital bursa 4- Between bone and ligament e.g bursa of unchal ligament with 2 nd thoracic vertebra B-Synovial tendon sheath :- is long sac have synovial fluid cover the tendon of the muscle when passing through bony canal (carpal canal) or fibrous groove. Each synovial tendon sheath consists of two layers. 1-Inner layer surrounded closely to the tendon. The inner layer reflect to connect the outer layer by thin membrane have the blood vessels and nerve which supply the tendon called mesotendon. 2-Outer layer which lining the bony canal or to the groove. II-Fascia:- are connective tissue consist of white fibers mainly and some elastic fibers. It is found in two layers: A-Superficial fascia:- found under the skin and its function are 1-Deposition of fat which act as isolated area.
2- Act as media for blood supply, nerve, and lymphatic system which supply the skin. 3- Assist in the movement of skin during the action of cutaneous muscle. B-Deep fascia :- they are located under the superficial fascia and its functions are:- 1- Extend between the muscle to form inter muscular septa which assist the movement of muscle during extension and flexion 2- They are extend between the bones to form interosseous ligament 3- Act as area of origin and insertion of some muscle 4- Act as media of blood,nerve and lymph supply. 5- Surround tendon within their groove to make annular ligament III-sesamoid bones: small bones originate in the joint capsule and in the direction of the tendons. It function are to change the direction of the tendon and protect it from the fraction at these joint
Classification of skeletal muscle They are four types of skeletal muscles:- 1-Strap M. : the muscle fibers arranged parallel to each other along the entire length of the muscle e.g zygomaticus. 2-Fusiform M.: (spindle in shape muscle ) in this type the muscle fibers converge upon the tendon on both ends,the belly is fusiform in shape e.g gastrocnemiusmuscle 3-Digasrtic M : have two bellies connect together by tendon e.g digastric M. 4-Pinnate M :-in these type the muscle fibers attached to the tendon in acute angle (like feather in bird),they are three types of pinnate muscle :- 1-Unipinnate M:- the muscle fibers attached with tendon from one side e.g genioglossus muscle. 2- Bipinnate M :- the muscle fibers attached to the tendon from two side e.g trapezius muscle. 3- Multipinnate M :- in this type the muscle fibers attached to the tendons in many areas e.g triceps brachialis muscle.