The arm is mainly composed of forearm and biceps brachii, triceps brachii and deltoid muscle. Arm muscles are long muscles and can be divided into two groups. The front group is flexors, including biceps brachii and brachialis. And coracoid-brachial muscle; The latter group is extensor and triceps brachii. Forearm muscles are located around ulna and radius, mostly long prismatic muscles, which can be divided into anterior group and posterior group. The front group is flexor muscle group; The latter group is the extensor group. Hand muscles are located in the palm of your hand. Divided into lateral group, medial group and middle group.

Muscle: Muscle is mainly composed of muscle tissue. Muscle tissue consists of muscle cells (muscle fibers) and connective tissue. Muscle cells are slender and fibrous, so muscle cells are usually called muscle fibers. The cells are rich in myofilament protein, which is composed of thin filament and coarse myofilament. Head muscles can be divided into facial muscles (expression muscles) and masticatory muscles.

Trunk muscles can be divided into dorsal muscle, pectoral muscle, abdominal muscle and diaphragm. Lower limb muscles are divided into hip muscles, thigh muscles, calf muscles and foot muscles according to their positions, all of which are stronger than upper limb muscles, and are related to supporting weight, keeping upright and walking.

References:

Baidu encyclopedia-muscle