Thorax

Thorax

  • Synonym: Chest

Definition

The thorax or the chest (a.k.a. the upper torso) is part of the human body which is located between the neck (above) and the abdomen (below). The thorax includes an outer thoracic wall and an inner thoracic cavity:

Thoracic wall: The bony framework of the thoracic wall is formed by the sternum (in front) and twelve thoracic vertebrae (at the back). These are interconnected by the rib cage on the sides.

There are 12 pairs of ribs. The first seven being true ribs, while remaining five being false ribs. True ribs are connected directly to the sternum via their costal cartilages. Whereas, the false ribs are either indirectly connected to sternum via the costal cartilage of the seventh rib or they are free floating ribs (eleventh and twelfth ribs).

Small intercostal muscles can be found situated within the intercostal spaces (between successive ribs). From outside to inside, these include the external intercostal, internal intercostal and innermost intercostal muscles, all helping in respiration. Other muscles attached to the thoracic wall include the pectoralis major and minor muscles in the front, serratus anterior on the sides and various muscles of the back region, such as, trapezius, rhomboids and erector spinae muscles.

Thoracic cavity: The thoracic cavity extends from the diaphragm (below) to the thoracic inlet (above). The latter is formed by first thoracic vertebrae, manubrium of sternum and the first ribs. The cavity is protected by the thoracic wall and can be further sub-divided into mediastinum in the center and pleural cavities on the sides.

Important functions of the thorax include breathing, protecting vital organs (including the lungs, heart and big vessels) and serving as a conduit for structures passing from one body region to the other or connecting thoracic organs to other body regions.

Text written by Muhammad A. Javaid, MD, PhD © 2023 IMAIOS.

  • Drake, R.L., Vogl, A.W. and Mitchell, A.W.M. (2009). ‘Chapter 3: Thorax’ in Gray’s anatomy for Students. (2nd ed.) Philadelphia PA 19103-2899: Elsevier, pp. 124-130.

  • Kudzinskas, A. and Callahan, A.L. Anatomy, Thorax. [Updated 2022 Jul 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557710/


Comparative anatomy in animals

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