Comparison between Muscles in the Chest and Upper Arm and their Counterparts in the Groin and Thigh,
Right Side
Illustrative Experiment no. 3.
To further inspect the previous theory, the similarities between the Pectoralis muscles and Adductor muscles, I have subtracted (in illustration) the muscles surrounding the groin, C and D, and then E and F, having left only the main groin mucles, the Adductor muscles.
Upon further inspection, I have observed more similarities between the Pectoralis and Adductor muscles such as:
(a) the Pectoralis muscles are attached to, (and are responsible for movement of) the Humerus, which is (or, 'would be') the counterpart of the Femur, on which the Adductor muscles are attached (and of which are also responsible for movement).
(b) The function of the Pectoralis muscles is supported by another muscle, Deltoid muscles; The function of the Adductor muscles is supported by another muscle, Gluteus muscles; (G)
I have also observed one significant dissimilarity which is the Fanning of the muscles:
(c.1) The Pectoralis muscles appear to be anchored to the Humerus and then fans out to the Clavicle and Sternum/Upper Ribs;
(c.2) The Adductor muscles appear to be anchored to the Pelvic bones.(probably the Pubis) and then fans out to the Femur.
The differences are most probably a result of the joint mechanics of the Upper Arm and the Thigh; The Upper Arm having multiple joint functions; and separate from their opposite-side counterpart (Scapula) as opposed to both Thighs being attached to a single-mass Bone (Pelvis)