Espiral Atlas1st rib
costa prima
Study entry
Parts
The widest, shortest and most curved of the true ribs, with the shaft almost horizontal. The head has a single articular surface. The upper surface is crossed by two grooves, for the subclavian vessels, separated by a ridge with the tubercle of the scalenus anterior muscle.
Joints
With the body of T1 (head) and the transverse process of T1 (tubercle); in front, the 1st costal cartilage attaches to the manubrium (synchondrosis of the 1st rib).
Palpation
It cannot be palpated: it lies behind and below the clavicle.
Clinical
Because it is protected, it almost never fractures; its fracture indicates severe trauma and can injure the brachial plexus and the subclavian vessels, which cross the upper surface.
Source: cap. 4, «Costillas, cartílagos costales y espacios intercostales» y cuadro clínico «Fracturas de costilla»