Dorothy FarrarArm
The upper extremity, the arm , is what we call the human gripping tool. The arm not only serves as a gripping tool, but also helps people with their balancing movement.
Definition
The arm is divided into several parts: It consists of the upper arm, the forearm and the hand and sometimes has the greatest range of motion of all parts of the human body. The arm – in connection with the hand – consist of a total of 30 bones. According to evolutionary history, the human arms are an evolution of the forelimbs still found in mammals.
The most important function of the arms is their function as gripping tools; that served – prehistorically – for the intake of food. In the course of time or since the age in which man learned to walk upright, the arms also served for balance. Especially when running or jogging, the arms are needed for balance – as part of the pendulum movement.
Anatomy
The arm is divided into three parts. The upper arm, the largest bone of the arm, medically known as the humerus, is fused or connected to the shoulder blade, the elbow joint and the ulna, or subsequently to the radius. The best-known and most important muscles of the upper extremity are the triceps brachii (tricep muscle) and the biceps brachii (biceps muscle).
The biceps muscle is considered the forearm flexor, while the triceps muscle is responsible for extending the forearm. This means that, upon closer inspection, the triceps are the polar opposite of the biceps muscle. The deltoid muscle is the largest muscle in the upper arm; he is responsible for the arm raise.
The forearm is the part that extends from the elbow joint to the wrist. The forearm consists of the bones radius and ulna, two long bones that are connected directly to the wrist. Due to the fact that the two bones are not connected, rotation of the forearm and wrist is possible. The forearm muscles are divided into pronators (responsible for rotating the forearm inwards) and supinators (responsible for rotating the forearm outwards).
The hand, the lowest part of the limb, is made up of the metacarpal bones, the finger bones and the carpal bones. The carpus itself consists of eight bones (the triangular, pea, scaphoid, lunate, minor polygon, major polygon, and the hamstring and capitate); the bones are connected by ligaments.
The metacarpals themselves are also subdivided. So there is the base, which forms the head and shaft and is responsible for the articulated connection with the carpal bones. After the metacarpal bones come the so-called finger bones. Those consist of three phalanxes, with the thumb consisting of only two phalanxes.
The hands or fingers are mobile due to the flexor and extensor muscles. The hand has a total of 33 muscles, with the structure of the muscles being extremely complex. Finally, a significant part of the muscles originates in the upper and lower arms and continues – only through the tendons – to the hands or fingers.
Function
The arms have the greatest freedom of movement of any part of the human body. This is because the arm consists of the arm, shoulder and wrist joints and therefore offers a wide range of movement options. These are also the reasons why the arms can be used as so-called gripping tools. The arms also serve – thanks to their pendulum movement – as a balance. Thanks to this possibility, it is possible for people to walk upright or, thanks to the balance, to relieve their legs.
Diseases
Due to the fact that the anatomical structure of the arm is relatively complex, a wide range of diseases of the apparatus can occur. Probably the most common disease that affects people is what is known as tendonitis. Tendonitis occurs as a result of overloading. The wrist and elbow joints are primarily affected.
Another disease that occurs more frequently is osteoarthritis. This disease occurs mainly on the hands and is considered a classic “sign of old age”. Occasionally, injuries resulting from acts of violence can also damage the apparatus. Humans instinctively stretch their hands forward while falling. This is because people still want to “catch” the fall.
However, it is possible that – due to the fact that the entire weight of the body cannot be “intercepted” – the ulna or radius or even the wrist can break in the course of this fall. Upper arm fractures are also possible as part of the fall.
Hello and welcome to my Health Guide & Encyclopedia! My name is Dorothy Farrar, and I'm the founder and main author of this platform.
My passion for health and wellness started at a young age when I became interested in the connection between the food we eat and the way we feel. This fascination led me to study nutrition and dietetics in college, where I learned about the importance of a balanced diet and the impact of various nutrients on the body.