Muscles do not attach to other muscles. They only attach to bone.
The humerus and clavicle attach to the scapula.
Ligaments attach bones to bones, providing stability and support to joints. They do not attach to muscles directly.
The humerus and clavicle attach to the scapula.
Tendons
Tendons attach muscle to bone, muscles do not attach to bone.
The bicep on the front and the tricep on the back.
The biceps attach to the radius bone (near your elbow) on a small bump called the radial tuberosity, and the the humerus(near your shoulder). Hope that helps!
Both the origin and insertion points attach muscles to bone. The muscles are moving the bones so they must be attached directly to bone.
Tendons attach to the periosteum of bone.
bones
I say tendons