A

artery (subclavian)

N

nerve

NA

nerve and artery

V

vein (subclavian)

A

Seventh cervical vertebra and ribs; adult male. This shows cervical ribs whose ossification extends as far forward as the crossing of the subclavian vein. A common groove is shown for the nerve and artery. Note the sigmoid appearance of this groove.

B

Seventh cervical vertebra nad rib, right side; adult male. This illustrates the type of rib that is ossified only as far as the crossing of the lowest brachal nerve trunk. In this case, no ligamentous connection with te sternum was present.

C

Seventh cervical rib, left side, showing articulation of the fist thoracic rib; adult male. This illustrates the type of cervical rib whose independent ossification proceeds only as far thhe crossing of the subclavian artery. The groove for the lowest brachial trunk is shown at N. This figure shows the variety of this type that has an intermediary cartilage between the two ribs.