It's a inconstant muscle in the thorax lateral to the sternum and on the pectoralis major. If you have the Netter Atlas 4th edition, you can found it on plate 188.
Hi! <br />
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I am just surfing on the internet after my anatomy exam and see your question.<br />
So this is the end of clavicula which connecting with manubrium sterni. I hope I helped u, even if its late.<br />
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I hope I
the lesion is in the C5-C6 of the cervical plexus, thus, anything that is innervated by these roots may be involved. since the biceps brachii, which is innervated by these roots don't only flex the forearm but also cause supination, a lesion will cause an unopposed pronation of the forearm, besides the adduction of the arm which gives the characteristic "waiter's tip" position of erb's palsy.
