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Connections of the ribs to the vertebral column and sternum
Last reviewed: 06.07.2025
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Due to the presence of movable connections of the ribs with the spinal column and sternum, changes in the volume of the chest and respiratory movements are possible.
The ribs are connected to the vertebrae by means of costovertebral joints (artt. costovertebrales), which include the joints of the head of the rib and the costotransverse joints.
The joint of the head of the rib (art. capitis costae) is formed by the upper and lower costal fossae (semi-fossae) of two adjacent thoracic vertebrae and the head of the rib. From the crest of the head of the rib of nine (II-X) ribs to the corresponding intervertebral disc in the cavity of the joints goes the intra-articular ligament of the head of the rib (lig. capitis costae intraarticulare). This ligament is absent in the I, XI and XII ribs, the head of which does not have a crest. From the outside, the capsule of the joint of the head of the rib is strengthened by the radial ligament of the head of the rib (lig. capitis costae radiatum). This ligament begins on the anterior surface of the head of the rib, diverges fan-shaped and attaches to the bodies of adjacent vertebrae and the intervertebral disc.
The costotransverse joint (art. costotranversaria) is formed by the tubercle of the rib and the costal fossa on the transverse process of the IX thoracic vertebrae. A thin joint capsule is attached along the edges of the articular surfaces. The capsule is strengthened by the costotransverse ligament (lig. costotranversarium). The costotransverse joint and the joint of the head of the rib are combined, movements in them are carried out together; movement around a common axis passing through the centers of these joints is possible. When the posterior ends of the ribs rotate relative to this axis, the anterior costal ends connected to the sternum are raised.
Connections of the ribs with the sternum. The ribs are connected to the sternum by joints and synchondroses. The cartilage of the 1st rib fuses with the sternum (synchondrosis). The cartilages of the 2nd-7th ribs, connecting with the sternum, form the sternocostal joints (artt sternocostales). The articular surfaces are the anterior ends of the costal cartilages and the costal notches of the sternum. The joint capsules are a continuation of the perichondrium of the costal cartilages, passing into the periosteum of the sternum. The joint capsule is strengthened by the radiant sternocostal ligaments (ligg. sternocostalia radiata).
In front, these ligaments, merging with the periosteum of the sternum, form a dense membrane of the sternum (membrana sterni). The joint of the second rib, formed at the level of the angle of the sternum (the connection of the manubrium with the body of the sternum), has an intra-articular sternocostal ligament (lig. sternocostal intraarticulare).
The anterior ends of the VII-X ribs are not directly connected to the sternum. They are connected to each other by their cartilages. The cartilage of the VIII rib grows together with the cartilage of the VII rib lying above. Sometimes interchondral joints (art. interchondrales) are formed between the cartilages of these ribs. The anterior ends of the ribs are connected to each other by the external intercostal membrane (membrana intercostalis externa). The fibers of this membrane are directed from top to bottom and forward. The posterior ends of the ribs are connected to each other by the internal intercostal membrane (membrana intercostalis interna). The fibers of this membrane go from bottom to top and back.
Rib movements occur in the costovertebral and sternocostal joints. The amplitude of chest movements: in the inhalation phase, when the front ends of the ribs and sternum are raised, the chest moves upward by 1 cm, the sternum moves forward by 5 cm, and the chest circumference increases by 10 cm.
The following muscles are involved in the act of inhalation: external intercostal muscles, muscles that raise the ribs, superior posterior serratus muscles, scalene muscles.
The following muscles are involved in the act of exhalation: the transverse thoracic muscle, the internal intercostal muscles, the lower posterior serratus muscles, the rectus abdominis muscles, the external and internal oblique abdominal muscles, and the transverse abdominis muscle.
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