Editing Thorax (section)

===Structure===
In humans and other [[Hominidae|hominid]]s, the thorax is the chest region of the body between the [[neck]] and the [[abdomen]], along with its internal [[Organ (anatomy)|organs]] and other contents. It is mostly protected and supported by the [[rib cage]], [[vertebral column|spine]], and [[pectoral girdle|shoulder girdle]].

====Contents====
{{Main|Thoracic cavity}}
[[File:Chest labeled.png|thumb|right|An [[X-ray]] of a human chest area, with some structures labeled]]
The contents of the thorax include the [[heart]] and [[lungs]] (and the [[thymus]] gland); the [[Pectoralis major muscle|major]] and [[Pectoralis minor muscle|minor]] pectoral muscles, [[trapezius muscle]]s, and [[neck]] muscle; and internal structures such as the [[thoracic diaphragm|diaphragm]], the [[esophagus]], the [[trachea]], and a part of the [[sternum]] known as the [[xiphoid process]]. Arteries and veins are also contained – ([[aorta]], [[superior vena cava]], [[inferior vena cava]] and the [[pulmonary artery]]); [[bone]]s (the shoulder socket containing the upper part of the [[humerus]], the [[scapula]], [[Human sternum|sternum]], [[Thoracic vertebrae|thoracic portion of the spine]], [[collarbone]], and the rib cage and [[floating rib]]s).

External structures are the [[Human skin|skin]] and [[nipple]]s.

====Chest====
In the [[human body]], the region of the thorax between the [[neck]] and [[Thoracic diaphragm|diaphragm]] in the front of the body is called the chest. The corresponding area in an animal can also be referred to as the chest.

The shape of the chest does not correspond to that part of the [[thoracic skeleton]] that encloses the [[heart]] and [[lungs]]. All the breadth of the shoulders is due to the shoulder girdle, and contains the [[axilla]]e and the heads of the [[humerus|humeri]]. In the middle line the [[suprasternal notch]] is seen above, while about three fingers' breadth below it a transverse ridge can be felt, which is known as the [[sternal angle]] and this marks the junction between the manubrium and body of the [[sternum]]. Level with this line the second ribs join the sternum, and when these are found the lower ribs can often be counted. At the lower part of the sternum, where the seventh or last true ribs join it, the [[ensiform cartilage]] begins, and above this there is often a depression known as the pit of the [[stomach]].

====Bones====
The bones of the thorax, called the "thoracic skeleton" is a component of the [[axial skeleton]].

It consists of the [[ribs]] and [[Human sternum|sternum]]. The ribs of the thorax are numbered in ascending order from 1–12. 11 and 12 are known as floating ribs because they have no anterior attachment point in particular the cartilage attached to the sternum, as 1 through 7 are, and therefore are termed "floating".<ref>{{Citation |last=Safarini |first=Omar A. |title=Anatomy, Thorax, Ribs |date=2024 |work=StatPearls |url=https://www.ncbi.nlm.nih.gov/books/NBK538328/ |access-date=2024-08-21 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30855912 |last2=Bordoni |first2=Bruno}}</ref> Whereas ribs 8 through 10 are termed false ribs as their costal cartilage articulates with the costal cartilage of the rib above. The thorax bones also have the main function of protecting the heart, lungs, and major blood vessels in the thorax area, such as the [[aorta]].

====Landmarks====
The anatomy of the chest can also be described through the use of [[anatomical landmark]]s. The [[nipple]] in the male is situated in front of the fourth rib or a little below; vertically it lies a little external to a line drawn down from the middle of the [[clavicle]]; in the female it is not so constant. A little below it the lower limit of the great pectoral muscle is seen running upward and outward to the axilla; in the female this is obscured by the [[breast]], which extends from the second to the sixth rib vertically and from the edge of the sternum to the mid-axillary line laterally. The female nipple is surrounded for half an inch by a more or less pigmented disc, the [[areola]]. The apex of a normal heart is in the fifth left intercostal space, three and a half inches from the mid-line.