First rib

Costa vera I

SkeletalSkeletonThoraxLeft and right

View left in 3D View right in 3D

What it is
The first rib, a true (vertebrosternal) rib: a curved flattened bar whose head articulates with T1, its tubercle with the T1 transverse process, sloping down and forward to its costal cartilage.
Function
Forms the rim of the thoracic inlet; the subclavian artery and vein and the brachial plexus cross its upper surface.
Size
Cross-section ≈ 6 × 11 mm; arc length ≈ 19 cm
Clinical note
A cervical rib or tight first rib can compress the brachial plexus (thoracic outlet syndrome).

Nearby skeletal structures Clavicle, First costal cartilage, Fourth rib, Intervertebral disc T1–T2, Intervertebral disc T2–T3, Intervertebral disc T3–T4, Second rib, T1 vertebra, T2 vertebra, Third rib