First rib

Dr Henry Knipe et al.

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.

Osteology

Compared to a typical rib, the first rib is short and thick and it has a single articular facet for the costovertebral joint. 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
Articulations
Attachments
Relations
  • 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

The first rib in particular is involved in:

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

Thoracic anatomy
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Article information

rID: 27102
Section: Anatomy
Tag: thorax
Synonyms or Alternate Spellings:
  • Rib 1
  • 1st rib

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Cases and figures

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    Figure 1
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    Case 1: fractured first rib
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