1, pectoralis major is the muscle of the chest, which is composed of left and right parts, also called pectoralis major. Pectoralis major, commonly known as pectoralis major, is fan-shaped.

2. Chest hair usually refers to the hair growing between the neck and lower abdomen of human males, which usually appears in the late adolescence and belongs to the secondary sexual characteristics. Due to the stimulation of androgen, some men began to grow chest hair in their twenties and thirties. At the same time, the thoracic hair in entomology refers to the bristles inside the basal ganglia on the ventral surface of the body. Bristles attached to the chest plate of the middle-petalled mite.