In vertebrate anatomy, ribs are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax. In some animals, especially snakes, ribs may provide support and protection for the entire body.
The rib cage is the arrangement of ribs attached to the vertebral column and sternum in the thorax of most vertebrates, that encloses and protects the heart and lungs. In humans, the rib cage, also known as the thoracic cage, is a bony and cartilaginous structure which surrounds the thoracic cavity and supports the shoulder girdle to form the core part of the human skeleton. A typical human rib cage consists of 24 ribs in 12 pairs, the sternum and xiphoid process, the costal cartilages, and the 12 thoracic vertebrae.
In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery supplies blood to the right arm, with some branches supplying the head and thorax. On the left side of the body, the subclavian comes directly off the aortic arch, while on the right side it arises from the relatively short brachiocephalic artery when it bifurcates into the subclavian and the right common carotid artery.
The thoracic diaphragm, or simply the diaphragm, is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity. The diaphragm separates the thoracic cavity, containing the heart and lungs, from the abdominal cavity and performs an important function in respiration: as the diaphragm contracts, the volume of the thoracic cavity increases, a negative vacuum is created which draws air into the lungs.
The levator scapulae is a skeletal muscle situated at the back and side of the neck. As the Latin name suggests, its main function is to lift the scapula.
In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical and lumbar vertebrae; they increase in size going towards the lumbar vertebrae, with the lower ones being a lot larger than the upper. They are distinguished by the presence of facets on the sides of the bodies for articulation with the heads of the ribs, as well as facets on the transverse processes of all, except the eleventh and twelfth, for articulation with the tubercles of the ribs. By convention, the human thoracic vertebrae are numbered T1–T12, with the first one (T1) located closest to the skull and the others going down the spine toward the lumbar region.
The serratus anterior is a muscle that originates on the surface of the 1st to 8th ribs at the side of the chest and inserts along the entire anterior length of the medial border of the scapula. The serratus anterior acts to pull the scapula forward around the thorax. The muscle is named from Latin: serrare = to saw, referring to the shape, anterior = on the front side of the body.
The Levatores costarum, twelve in number on either side, are small tendinous and fleshy bundles, which arise from the ends of the transverse processes of the seventh cervical and upper eleven thoracic vertebrae
The sternal angle is the synarthrotic joint formed by the articulation of the manubrium and the body of the sternum.
The internal intercostal muscles are a group of skeletal muscles located between the ribs. They are eleven in number on either side. They commence anteriorly at the sternum, in the intercostal spaces between the cartilages of the true ribs, and at the anterior extremities of the cartilages of the false ribs, and extend backward as far as the angles of the ribs, hence they are continued to the vertebral column by thin aponeuroses, the posterior intercostal membranes.
The external oblique muscle is the largest and the outermost of the three flat muscles of the lateral anterior abdomen.
The erector spinae or spinal erectors is a set of muscles that straighten and rotate the back.
The articulations of the heads of the ribs constitute a series of gliding or arthrodial joints, and are formed by the articulation of the heads of the typical ribs with the costal facets on the contiguous margins of the bodies of the thoracic vertebrae and with the intervertebral discs between them; the first, eleventh and twelfth ribs each articulate with a single vertebra.
The radiate ligament connects the anterior part of the head of each rib with the side of the bodies of two vertebrae, and the intervertebral fibrocartilage between them.
The costodiaphragmatic recess, also called the costophrenic recess or phrenicocostal sinus, is a potential space in the pleural cavity, at the posterior-most tips of the cavity, located at the junction of the costal pleura and diaphragmatic pleura. It measures approximately 5 cm vertically and extends from the eighth to the tenth rib along the mid-axillary line.
The muscles of respiration are those muscles that contribute to inhalation and exhalation, by aiding in the expansion and contraction of the thoracic cavity. The diaphragm and, to a lesser extent, the intercostal muscles drive respiration during quiet breathing. Additional 'accessory muscles of respiration' are typically only used under conditions of high metabolic demand or respiratory dysfunction. However, in instances where these accessory muscles become stiff and hard, expansion of the rib cage can be restricted. Maintenance of the elasticity of these muscles is crucial to the health of the respiratory system and to maximize its functional capabilities.
The costotransverse joint is the joint formed between the facet of the tubercle of the rib and the adjacent transverse process of a thoracic vertebra. The costotransverse joint is a plane type synovial joint which, under physiological conditions, allows only gliding movement.
The posterior branches of thoracic nerves branch from the dorsal rami of the thoracic nerves.
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Shaped roughly like a necktie, it is one of the largest and longest flat bones of the body. Its three regions are the manubrium, the body, and the xiphoid process. The word "sternum" originates from the Greek στέρνον, meaning "chest".
In the vertebrate spinal column, each vertebra is an irregular bone with a complex structure composed of bone and some hyaline cartilage, the proportions of which vary according to the segment of the backbone and the species of vertebrate.
