First rib

Last revised by Daniel J Bell on 28 Sep 2021

The first rib is the most superior of the twelve ribs. It is an atypical rib and is an important anatomical landmark and is one of the borders of the superior thoracic aperture.

Compared to a typical rib, the first rib is short and thick and it has a single articular facet for the costovertebral joint. It is flattened from top to bottom. The first rib has a head, neck and shaft but lacks a discrete angle. The shaft is indented laterally, the groove for the subclavian artery, which contains the lowest brachial plexus trunk as well as the subclavian artery. Anterior to the scalene tubercle is another groove for the subclavian vein. There is no costal groove on its inferior surface. It has two tubercles:

  • transverse tubercle: posterior and lateral to the neck; bears an articular facet for the transverse process of T1
  • scalene tubercle: anteriorly between the grooves for the subclavian artery and vein; anterior scalene muscle inserts here
    • it is also known as the Lisfranc tubercle, described by Lisfranc in 1815 7
  • osseous or fibrous articulation or fusion with a cervical rib
  • bifid (forked) rib
  • rudimentary (hypoplastic) rib: most commonly the first rib (0.2%) 6
  • pseudoarthrosis of the first rib (0.1%) 6

Ossified by three centers: one primary center for the shaft and 2 secondary centers - one for the head and one for the tubercle

The first rib, in particular, is involved in:

The first rib is also affected by pathology common to all ribs:

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