The arm contains of the humerus in the overarm, and the ulna and radius in the underarm.The arm also has a head of humerus, an elbow joint, a hand wrist and o joint between the carpal bone and the first metacarpal bone. The head of the humerus makes it possible for you to have a large range of movement in the shoulder, for example as you swing your arms around. Because the shoulder blade can move, the position of the cavity that the head of humerus lies in can be changed. This is part of why the shoulders movement is much bigger, in comparison to if only humerus would move. If we lift the arm to the side, the movement starts at the head of humerus and continues by turning the shoulderblade so that the cavity is turned upwards. It is the movability of the shoulderblade that makes it possible to lift your arm over your head. The elbow joint function as a hinge joint between the overarm and the two bones in the underarm, ulna and radius. The movement between the overarm and the underarm is bend and stretch. The joint is stabilized by strong ligaments, which means that the underarm only can be moved a little to the sides. The surface between the overarm and the radius is shaped in a way that makes it possible to turn the underarm out (thumb point away from the body) or in (thumb point towards the body). The hand wrist makes it possible to move the hand in different directions and the joint in the carpal bone helps with gripping function. There’s also joints in the fingers that is activated when we spread the fingers. The hand consists of a carpal bone, metacarpal bones and fingers. In the fingers there are many bones. I every hand there’s 27 bones.
The muscles in the arms and hands are:
- biceps. The muscle has two heads that goes from the coracoid process on the shoulderblade and a bone process on the shoulderblade. They pass in front of the head of humerus and comes together on the overarm and then becomes a thick ligament. This ligament passes infront of the elbow joint and is fastened to radius. The muscle makes it possible to bend the elbow joint and turn the underarm, so that the carpal bone is turned upwards and the thumb turned away from the body.
- brachialis. Goes from humerus, infront of the elbow joint and to ulna. It makes it possible to bend the elbow joint.
- triceps. One of the heads of triceps goes from a bone process on the shoulderblade. The head passes behind the head of humerus. The other two heads goes from humerus. All three passes behind the humerus, then comes together and becomes a ligament. This ligament goes behind the elbow joint and is fastened at ulna. Triceps makes it possible to stretch in the elbow joint.
- more than 40 muscles in the underarm, where most of them helps to move the hand wrist and the fingers. Some of the muscles in the underarm helps with bending in the elbow joint.
- a lot of muscles in the hand.
Is there anything I can do to relax the arm? Ja, and especially the muscles in the overarm. If they are tense the stop the nerves signals that goes in the arm and hand. I can also hold on either side of a joint and feel the movement of the bones. I’m aware that this sounds strange and if I hadn’t experienced it myself, a lot of times, I would also be wondering. What I recommend is that you are curious, question, test and see what suits you.
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