Pectoral muscles (colloquially referred to as "pecs") are the muscles that connect the front of the human

chest The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

with the bones of the upper arm and shoulder. This region contains four muscles that provide movements to the upper limbs or ribs. Gray411

Pectoralis major is a thick, fan-shaped or triangular convergent muscle, which makes up the bulk of the chest muscle. It lies under the

breast The breasts are two prominences located on the upper ventral region of the torso among humans and other primates. Both sexes develop breasts from the same embryology, embryological tissues. The relative size and development of the breasts is ...

. It serves to flex, extend, and rotate the

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

, the long bone of the upper arm.

Pectoralis minor Pectoralis minor muscle () is a thin, triangular muscle, situated at the upper part of the chest, beneath the pectoralis major in the human body. It arises from ribs III-V; it inserts onto the coracoid process of the scapula. It is innervated by ...

is a thin, triangular muscle located beneath the pectoralis major. It attaches to the ribs, and serves to stabilize the

scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

, the large bone of the shoulder. The

pectoral fascia The pectoral fascia is a thin lamina, covering the surface of the pectoralis major, and sending numerous prolongations between its fasciculi: it is attached, in the middle line, to the front of the sternum; above, to the clavicle; laterally and be ...

is a thin layer of tissue over the pectoralis major, extending toward the

latissimus dorsi muscle The latissimus dorsi () is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline. The word latissimus dorsi (plural: ''latissimi dorsi'') comes from ...

on the back. Along with the pectoralis major and pectoralis minor, the

subclavius muscle The subclavius is a small triangular muscle, placed between the clavicle and the first rib. Along with the pectoralis major and pectoralis minor muscles, the subclavius muscle makes up the anterior axioappendicular muscles, also known as anteri ...

forms the

axilla The axilla (: axillae or axillas; also known as the armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm a ...

or armpit. The subclavius moves the shoulder downward and forward.

Serratus anterior The serratus anterior is a muscle of the chest. It originates at the side of the chest from the upper 8 or 9 ribs; it inserts along the entire length of the anterior aspect of the medial border of the scapula. It is innervated by the long thor ...

is another muscle on the front of the chest. It moves the scapula forward around the torso, as when throwing a punch. Between the ribs are various groups of

intercostal muscles The intercostal muscles comprise many different groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing by helping expand and shrink th ...

, which help with breathing.

References

* {{cite book, last1=Gray, first1=Henry, last2=Lewis, first2=Warren, year=1918, title=Anatomy of the Human Body, location=Philadelphia and New York, publisher=Lea and Feibiger, edition=twentieth, url=https://archive.org/details/anatomyofhumanbo1918gray, access-date=13 September 2016 Muscles of the torso Broad-concept articles Human anatomy