First, platysma is located in the shallowest subcutaneous layer in front of the neck. When contracting, the mouth is pulled down and the neck skin is tightened. Second, sternocleidomastoid muscle This is the most prominent muscle in the superficial layer of the neck. When fixed, one side can turn the head to the opposite side and tilt to the same side; When the head is in a normal posture, muscle strength passes behind the transverse axis of the atlanto-occipital joint, making the head bend forward. When fixing, lift your chest to help inhale. 3. trapezius muscle is located under the skin of the neck and back, with one side triangular and the left and right sides combined to form an oblique square, which is called trapezius muscle. Proximal fixation: the upper descending fiber contracts, so that the scapula is lifted, rotated and retracted; The middle transverse fiber contracts, which makes the shoulder swelling bone retract (close to the spine); The descending fibers contract, causing the scapula to descend and rotate upward; When the upper and lower fibers contract at the same time, the scapula moves upward, just like the arm. Distal fixation: 1 case contracts, making the head bend to the same side; Bilateral trapezius contraction straightens the head and spine. Exercises such as lifting barbells, shrugging, raising straight arms and expanding chest can develop the strength of this muscle. When the trapezius muscle is fully developed, the muscles become shorter and the shoulders are pulled back, which makes the shoulders wider, keeps the back straight, and leans back the head, which can correct the defects such as hunchback, shoulder buckle and head extension, and give a correct upright posture. The development of trapezius muscle is a sign of health, strength and beauty, and it is a favorable condition for amateur bodybuilders to participate in bodybuilding competitions. It is a triangular muscle, and the protruding shape of the shoulder is formed by this muscle. The muscle fibers on both sides are spindle-shaped, and the middle muscle fibers are multi-pinnate. This structure has small muscles and great strength. When approaching fixation, the anterior muscle fibers contract, making the upper arm bend and pronate; Central contraction makes the upper arm abduction; Back contraction, upper arm extension. External rotation, the front, middle and rear parts contract at the same time, which makes the upper arm abduction, such as arm side movement; Muscle strength can be developed through exercise, such as straight arm lift and weight-bearing side lift. Broad, powerful and rounded shoulders are the symbol of excellent bodybuilders. 5. The latissimus dorsi is located under the skin of the lower back and chest, and it is the largest latissimus dorsi in the whole body. The upper part is covered by trapezius muscle. When approaching fixation, the upper arm extends, such as swinging backwards, and the upper arm can retract and rotate inward. When you are far away, you can pull your torso closer to your upper arm, such as pull-ups on the horizontal bar. Because some fibers of latissimus dorsi muscle come from ribs, which can be lifted when the ribs are fixed far away, it is also called inspiratory auxiliary muscle. Horizontal bar pull-ups, backward stretching, prone rowing and other exercises can develop the strength of this muscle. Latissimus dorsi contributes to the improvement of body shape. When it is highly developed, it is characterized by prominent shoulder width and thin waist, which makes the upper body more burly and V-shaped. Six, a slender muscle on the back of the sacrospinous muscle is called the sacrospinous muscle. Located on both sides of the spine, like two large columns from the occipital bone to the end of the spine (sacrum), the spine is placed in the obvious groove between the sacrospinous muscles, which is a powerful spinal extensor. When the lower part is fixed, both sides contract at the same time, so that the head and spine are extended, the head is raised, the chest is lifted, and the waist is closed; When one side contracts, the trunk bends to the same side, such as lateral flexion. Seven, pectoralis major muscle is located under the skin of the chest, and it is a fan-shaped flat muscle with a large range, which is divided into clavicle, chest rib and abdomen. When near fixation, the upper arm can bend, retract and pronate. When fixing far away, pull the trunk closer to the upper arm, such as skipping rope and climbing pole. In addition, this muscle can also lift ribs, which is an inspiratory auxiliary muscle. When the pectoral muscles are developed, the chest is high and the breathing is fuller and smoother. This muscle strength can be developed by using parallel bars to support swing arm flexion and extension, bench press and pull-ups Eight, the serratus anterior muscle is located under the skin of the lateral chest, and the upper part is covered by pectoralis major and pectoralis minor, which is a flat muscle. When near fixation, the scapula can be extended forward and rotated upward. You can develop muscle strength by lifting dumbbells, lifting barbells, shrugging your shoulders and expanding your chest with weight. Nine, rectus abdominis is located on both sides of the midline of the anterior abdominal wall. When fixed, both sides contract, which can make the pelvis lean back or keep a high horizontal position, that is, abdomen reduction; The spine bends forward during lower fixation. Exercises such as sit-ups, leg lifts and sitting at right angles can develop the strength of this muscle. Abdominal muscles fade more easily than other muscles in the body. When lacking exercise, abdominal muscles are most likely to relax due to overnutrition and a large accumulation of abdominal fat. Abdominal prolapse (or decline) and body fat are signs that the general health level of human body begins to decline. But the developed abdominal muscles are "wavy" muscles, which is a sign that self-bodybuilders are well trained. X. The external oblique muscle of abdomen is located in the shallow layer of anterolateral abdomen and is platysma. When fixed, both sides contract at the same time, making the spine bend forward; Contraction on one side can bend the spine to the same side and turn to the opposite side; When fixed on the table, both sides contract at the same time, making the pelvis backward. The lateral flexion and rotation of the weight-bearing body can develop the strength of this muscle. Eleven, the medial oblique muscle is located in the deep layer of the lateral oblique muscle, which has the same shape as the lateral oblique muscle and the opposite direction. In the fixed state, the effect of bilateral contraction is the same as that of external abdominal oblique muscle; When one side contracts, it not only bends the spine to the same side, but also rotates the spine to the same side, which is opposite to the direction of the external oblique muscle. Therefore, the movement of body rotation is actually the result of the synergistic effect of ipsilateral internal oblique muscle and contralateral external oblique muscle. The lateral flexion and rotation of the weight-bearing body can develop the strength of this muscle. Twelve, biceps brachii is located under the skin in front of the upper arm. When near fixation, make the upper arm bend at the shoulder joint, and the forearm bend at the elbow joint and rotate outward. When bending the elbow, the forearm should be rotated first, and then flexed to make it exert its maximum strength; When far fixed, keeping the upper arm close to the forearm, such as horizontal bar pull-ups and pull-ups can develop the strength of this muscle. Thirteen. Triceps brachii is located under the skin behind the upper arm. When approaching fixation, extend the forearm at the elbow joint. There are three heads: long head, outer head and inner head. The strength of this muscle can be developed through exercises such as the flexion and extension of the inverted arm and the weight-bearing arm. Fourteen, the psoas muscle is located on both sides of the spine, in the pelvis. It consists of psoas major and iliac (qia) muscles. When it is close to fixation, make the thigh bend and rotate outward; When far fixed, the muscles on both sides contract at the same time, which can make the trunk bend forward and the pelvis lean forward. For example, the muscle strength of sit-ups can be developed by using leg lifting, running high leg lifting, supine "leg cutting" and sit-ups. Fifteen, the gluteus maximus is very developed, directly located on the back side of the pelvis, keeping the human body upright. When approaching fixation, the thighs extend backward and rotate outward, such as swinging backward and kicking backward. The upper part of the muscle does thigh abduction and the lower part does thigh adduction; When far fixed, one side contraction makes the pelvis rotate to the opposite side, such as turning, and both sides contraction makes the pelvis lean back to maintain the upright posture of the human body. Prone "hind legs", weight-bearing leg flexion and extension, weight-bearing body flexion and extension and other exercises can develop the strength of this muscle. Sixteen, quadriceps femoris this is one of the most powerful muscles in the human body. It is located under the skin of the front surface of the thigh and has four heads, namely rectus femoris, middle femoris, lateral femoris and medial femoris. When it is close to fixation, make the thigh bend and the calf stretch; When far fixed, make the thigh stretch at the knee joint, that is, pull the femur forward (such as from squatting to standing); Keep the femur vertical and keep the human body upright. Exercises such as weight-bearing squat and weight-bearing calf stretching can develop the strength of this muscle. 17. Sartorius muscle This is a slender muscle in the front of the thigh, which runs through the thigh to the calf and often involves crossed or merged muscles. It strengthens the muscles in the front of the thigh and is used for the overall movement of the leg. When approaching fixation, the thigh flexes and rotates outward, and the calf flexes and rotates inward. Exercises such as supine "leg cutting", weight-bearing squat and weight-bearing half squat can develop the strength of this muscle. 18. The biceps femoris is located under the skin of the posterolateral thigh and has two heads. When it is close to fixation, make the calf bend and rotate outward; When the calf is straight, the thigh can be extended, such as kicking back and kicking back. When far fixed, the pelvis leans backward. The strength of this muscle can be developed by bending and stretching the weight-bearing leg, squatting and pushing backwards. 19. tibialis anterior is located in the lateral tibia. When near fixation, make the foot stretch (dorsiflexion), adduction and abduction, such as hook foot action. When far fixed, pull the calf forward to keep the arch of the foot. Exercises like weight-bearing hook feet can develop the strength of this muscle. Twenty, the triceps of the calf is located in the shallow layer of the posterior side of the calf, which is particularly developed and makes the posterior side of the calf bulge. It consists of gastrocnemius muscle and soleus muscle. The soleus muscle is located in the deep layer of gastrocnemius muscle. When it is almost fixed, it can bend the calf and foot. When the distal end is fixed, the distal ends of femur and calf bones are pulled backward, and the knee joint is straightened, thus keeping the human body upright. Lifting heels, walking on tiptoe, kicking backwards, jumping vertically in place, skipping rope and jumping frog can all develop this muscle strength. In particular, gastrocnemius can show the shape and development of the calf. Therefore, promoting the development of gastrocnemius is very important for self-bodybuilding trainers. Twenty-one, the brachioradialis muscle is located under the outermost skin of the forearm, long and flat. When approaching fixation, the forearm can bend. When far fixed, the upper arm can be closer to the forearm. Exercises such as weight-bearing bending and pull-ups can strengthen this muscle. Twenty-two, the flexor carpi radialis is located under the skin in front of the forearm, which can bend and abduct the hand. This muscle strength can be developed by using exercises such as winding a heavy hammer and holding a heavy wrist with the right hand. Twenty-three, the extensor carpi radialis longus is located on the shallow lateral side of the dorsal forearm, which can stretch and abduct the hand. The strength of this muscle can be developed by winding the heavy hammer backwards and holding the wrist flexion and extension with weight backwards. Twenty-four, the flexor carpi ulnaris is located at the innermost part of all superficial muscles in front of the forearm, with two heads, which can bend and adducte the hand. This muscle strength can be developed by using exercises such as winding a heavy hammer and holding a heavy wrist with the right hand. Twenty-five, the extensor carpi ulnaris is located under the skin of the dorsal forearm, which can stretch and retract the hand.