The scalene tubercle

One hundred and thirty right and 114 left first ribs from a random collection have been studied for the characters of the scalene tubercle and the related structures. The tubercle is not always present but the muscular impression for the insertion of the scalenus anterior muscle on the superior surface of the first rib is almost constant and it generally extends upto the medial third of this surface. The arterial groove, generally shallow, lies behind the tubercle or the muscular impression and generally extends only upto the medial 2/3 of the superior surface. Likewise, the venous groove, mostly shallow, lies in front of the tubercle or the muscular impression and extends, generally, only upto the medial 2/3 of the surface. Normally, there is no separate groove for the lower trunk of the brachial plexus.