İKİNCİ FEN · ÜÇÜNCÜ BÂB · İKİNCİ FASIL · İkinci Madde
Second Article
It describes the muscles that move the shoulder joint along with the arm bone.
O Most Noble One! Know that anatomists have said: The shoulder joint is moved by the muscles of the arm bone, and there are three of them arising from the chest which draw the arm bone downwards. One of these three muscles originates beneath the breast and attaches to the anterior aspect of the humerus, near the vertebral column, on the anterior surface of the humerus, bringing the shoulder downward and drawing the humerus closer to the chest.
One of the aforementioned three muscles also arises from the upper part of the chest, joins at the inner side of the head of the humerus, and raises the humerus, bringing it close to the chest.
These three great muscles all arise from the entire chest and attach to the lower portion of the anterior surface of the humerus. If they move with their upper fibers, they raise the humerus towards the chest. If they move with their lower fibers, they draw the humerus towards the chest. If they move with both portions together, they bring the humerus straight towards the chest.
The arm bone has two muscles arising from the lateral rib cage which attach even more extensively than the aforementioned great muscle; the first, being the larger one, arises from the axillary bone and the posterior ribs, drawing the arm bone flatly toward that rib side. The second is smaller, emerging from the skin of the armpit and attaching to the veterinary muscle of the muscle rising upwards towards the breast, inclining posteriorly and disappearing. This muscle assists the previous one. There are five more muscles of the arm bone which all arise from the scapula; one of them fills the diaphragm between the shoulder and the posterior rib. It turns outwards and downwards from the head of the humerus. The origins of two of these are on the upper ribs of the shoulder. One is large, sending its fibers to the lower portion of the diaphragm, filling the space between the diaphragm and the lower rib. Attaching to the terminal end of the outer side of the humerus, it draws the arm bone outwards and laterally away from it. The second is adjacent to the first and performs the same function. However, the second muscle attaches to the upper part of the shoulder and deeply into the exterior of the humerus, inclining it outwards. The fourth muscle fills the hollow place of the scapula, attaching to portions of the muscle entering from the inner side of the head of the humerus, turning the arm backwards. The origin of the fifth muscle is the lower edge of the rib beneath the scapula. It attaches to the humerus where the large muscle rising from the upper part of the abdominal cavity [125/a] joins. The function of this muscle is to draw the upper portion of the head of the humerus downwards.
The arm bone also has a muscle called “two-headed,” whose task it is to arise from the base of the clavicle and the neck, encompassing the arm bone entirely. One head of this is included within the arm bone, deeply inclined inwards. The other head is attached externally to the shoulder subsoil, slightly deeply outwards. If it works with both portions, it raises the arm bone straightly. There are two smaller muscles of the arm bone as well; one arises from above the breast, and the other is embedded in the shoulder joint.
“No one has power to change events except for the Exalted God.”