Superior surface

The superior surface of the first rib forms part of the anterolateral margin of the root of the neck:

• approximately half way along its length, at the point of maximal curvature, are a series grooves perpendicular to the axis of rotation:
  • most posteriorly is the groove for subclavian artery; this also houses the first thoracic nerve at its point of junction with C8 to form the lowest trunk of the brachial plexus
  • posterior to groove for the subclavian artery is the broad attachment for the fibres of scalenus medius
  • anterior to the groove on the medial surface is the scalene tubercle; scalenus anterior is attached to this landmark
  • anterior to the tubercle is the groove for the subclavian vein; the subclavian vein lies more fully in contact with the first rib than the subclavian artery
• the lateral margin in the anterior third of the superior shaft surface provides an origin for serratus anterior
• the pleural membrane lies against the medial margin of the upper surface anterior to the neck
• the junction of costal cartilage with bone provides an attachment point for:
  • costoclavicular ligament
  • subclavius