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The upper limb is connected to the axial skeleton, which is the cranium, vertebral column, and associated thoracic cage, by the bony pectoral girdle at the sternoclavicular joint, which is the connection between the clavicle and sternum.
Each upper limb is made up of 32 bones, and has a number of different regions.
First, there’s the pectoral girdle, which consists of 2 bones: the scapula, also called the shoulder blade, and the clavicle, also known as the collarbone.
Then there’s the arm, which only has one bone, called the humerus.
Then we have the forearm, which has two bones called the radius and the ulna.
Next, there’s the wrist, which has 8 carpal bones, and finally, the hand, which has 5 metacarpal bones, and the fingers, who have 14 phalanges in total.
OK, now let’s have a look at the shoulder girdle first.
The shoulder girdle consists of the scapula and clavicle, and articulates anteriorly with the manubrium of the sternum.
Starting with the scapula, it’s a flat triangular bone located on the posterior aspect of the shoulder, extending over the second to the seventh ribs.
The scapula helps to connect the rest of the upper limb to the trunk, while stabilizing and assisting the shoulder during movement while serving as an attachment point for numerous muscles and ligaments.
Now, like any respectable triangle, the scapula has three borders; the shortest and the thinnest of them is the superior border.
Then there’s the medial border, which runs parallel to the vertebral column, and finally, there’s the lateral border which is the thickest one.
The lateral border is also known as the axillary border because it points towards the axilla, or armpit region.
The point where the medial and lateral borders meet is the inferior angle, and we also have the superior angle which is the junction of the superior and medial borders.
At the lateral part of the superior border, there’s a small indentation called the scapular notch through which the suprascapular nerve passes.
The upper limb starts from the pectoral girdle to hand. The pectoral girdle is made up of the clavicle and scapula. Next is the arm, which contains the humerus, the forearm containing the radius and the ulna; the wrist made up of the carpals; the hand made up of the metacarpals; and finally, digits contain phalanges. Each bone has a unique shape that helps it perform its specific function.
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