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Second Rib
Skeletal System

Second Rib

Costa secunda

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Quick Facts

Location: Thoracic cage.

Bone Type: Flat bone.

Key Features: Head, neck, tubercle, body, angle, and costal groove.

Articulates With: First and second thoracic vertebrae, second costal cartilage.

Arterial Supply: Internal thoracic and supreme intercostal arteries.

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Key Features & Anatomical Relations

The second rib is one of the seven true ribs of the thoracic cage. It has a similar tight curvature to that of the first rib but is almost twice its length. The second rib is also considered an atypical rib because it has an extra bony feature that other ribs don’t have (i.e., the tuberosity for serratus anterior muscle).

The second 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: tuberosity for serratus anterior muscle, 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 second rib is located:

- superior to the third rib;

- inferior to first rib;

- lateral to the second costal cartilage and first and second thoracic vertebrae.

It articulates with the:

- second costal cartilage at the second costochondral joint;

- first and second thoracic vertebrae at the second costovertebral joint.

Ossification

Ossification of the second 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 second rib after the twentieth year (Standring, 2016).

Variations

In some individuals:

- the second rib may be fused with adjacent ribs;

- the costal end of the second rib may be bifid in appearance (Tubbs, Shoja and Loukas, 2016).

Surface Anatomy

The second rib and its costal cartilage are easily palpated and are located lateral to the sternal angle.

List of Clinical Correlates

- Fracture of second rib

- Flail chest

- Poland syndrome

- Asphyxiating thoracic dysplasia/Jeune syndrome

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.

Tubbs, R. S., Shoja, M. M. and Loukas, M. (2016) Bergman's Comprehensive Encyclopedia of Human Anatomic Variation. Wiley.

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