Quick Facts
Location: Thoracic cage.
Bone Type: Flat bone.
Key Features: Head, neck, tubercle, body, angle, and costal groove.
Articulates With: Third and fourth thoracic vertebrae, fourth costal cartilage.
Arterial Supply: Anterior intercostal branches of internal thoracic and posterior intercostal arteries.
Related parts of the anatomy
Key Features & Anatomical Relations
The fourth rib is one of the seven true ribs of the thoracic cage. It is considered a typical rib because it consists of a head with two articular facets, a neck, a tubercle and a body.
The fourth rib is classified as a flat bone and includes the following bony features:
- parts: head, neck, tubercle, body, and costal end;
- surfaces: internal and external surfaces, and superior and inferior borders;
- landmarks: angle, costal groove, crests on the head and neck, and articular facets on the head and tubercle.
More information regarding these and other bony features can be found in the Parts, Surfaces, and Landmarks tabs for this bone.
The fourth rib is located:
- superior to the fifth rib;
- inferior to third rib;
- lateral to the fourth costal cartilage and third and fourth thoracic vertebrae.
It articulates with the:
- fourth costal cartilage at the fourth costochondral joint;
- third and fourth thoracic vertebrae at the fourth costovertebral joint.
Ossification
Ossification of the fourth rib occurs at ossification centers found in the:
- body, which appears in utero during the second month;
- head, which appears during puberty;
- tubercle, which appears during puberty.
The ossification centers for the head and tubercle fuse with the body of the fourth rib within the fourteenth to twentieth years (Cunningham, Scheuer and Black, 2016).
Variations
In some individuals:
- the fourth rib may be fused with adjacent ribs;
- the costal end of the fourth rib may be bifid in appearance (Tubbs, Shoja and Loukas, 2016).
Surface Anatomy
The fourth rib is easily palpated and is located by palpating two ribs down from the second rib.
List of Clinical Correlates
- Fracture of fourth rib
- Flail chest
- Poland syndrome
- Asphyxiating thoracic dysplasia/Jeune syndrome
References
Cunningham, C., Scheuer, L. and Black, S. (2016) Developmental Juvenile Osteology. Elsevier Science.
Tubbs, R. S., Shoja, M. M. and Loukas, M. (2016) Bergman's Comprehensive Encyclopedia of Human Anatomic Variation. Wiley.
