Confusion over upper arm muscles
6d

Lai Yu-Hsuan
I was trying to label the unlabeled muscles from a book to consolidate my understanding of anatomy.
I got a bit confused with this one though. The brachialis and coracobrachialis are given. Are my labels on the other muscles correct? And what's the one right next to the brachialis?
Should be the third head of the triceps which lies under the other two. Its the same with the Quads on the legs, we can see only three. The fourth is attached under all of them.