Dorothy FarrarHumerus (upper arm bone)
The upper arm bone – humerus – is one of the strongest bones in the entire human body. Blood vessels, nerves and countless muscles and tendons run along the humerus itself . Even if the humerus is extremely stable, it is not immune to injury; humerus injuries are mainly fractures.
Definition
The os humeri – or humerus – is the strongest tubular bone in the entire body and also the longest bone in the arm . As the name suggests, the structure of the bone is reminiscent of a tube. Inside the bone is a canal filled with bone marrow . The humerus is covered by the periosteum – the periosteum.
Anatomy
The humerus is one of the “long bones” or tubular bones and is made up of three parts, which are called the epiphysis (upper and lower end) and the diaphysis (shaft). At the upper end is the bone head (Caput humeri), which has a hemispherical shape. The bone head is located directly in the socket of the shoulder joint .
Next to the bone head there is a small (tuberculum minus) and a larger (tuberculum majus) bony prominence. The muscles of the upper arm also originate from this position. The neck (collum) of the humerus connects to the head of the bone – seen in the direction of the shaft. The collum anatomicum separates the head from the shaft and is also the point of attachment for the joint capsule of the shoulder.
The collum chirurgicum is the point that is particularly at risk of fracture. The humeral shaft has three surfaces; a distinction is made between the front side, the back and the front in the middle. Due to these surfaces three edges arise. The edges and surfaces are also the starting points for the muscles. In the longitudinal direction of the shaft lies the groove in which the artery of the arm and the radial nerve run. The end of the humerus has two bone protrusions – so-called epicondyles.
Function
The humerus connects the forearm to the shoulder . The humeral head forms – together with the shoulder blade and the collarbone – the shoulder joint, which is one of the most complex joints in the body. Downward, the humerus provides a connection between the radius and ulna to the elbow joint. That consists of three joints.
The humeroulnar joint – together with the upper arm roll of the humerus – ensures the formation of the ulna. The third part of the elbow joint is not connected to the humerus. Only the spoke and the ulna meet here. There are numerous attachment points for the muscles on the humerus itself.
The shoulder muscles run roughly from the shoulder blade to the upper end of the humerus. The rotator cuff, which is a part of that musculature, further provides the stability of the joint and ensures that the head of the humerus stays in the socket of the shoulder joint.
Furthermore, the musculature allows the arm to be rotated, which can be done both outwards and inwards; spreading is also possible. Because the humerus connects the forearm and shoulder, numerous muscles can work together to move the forearm.
Diseases
- Humerus fracture
Although the humerus is a fairly strong bone and can withstand immense loads, sudden impacts can cause the bone to fracture. A proximal humerus fracture mainly occurs, in which the fracture point is in the upper bone area.
Older people in particular, who suffer from osteoporosis , among other things , are at risk of suffering such a fracture. Such a fracture is often the first indication that osteoporosis is present. The fracture usually occurs as a result of a fall; the person still wants to “catch themselves”, stretches out their arm and thus exerts an unbelievable pressure on their bones, which they cannot withstand.
The distal humerus fracture – that takes place at the lower end of the bone – is also possible. Here, the doctor distinguishes whether there is only a fracture of the humerus or also an injury to the elbow joint.
For example, if the shaft is affected by the fracture, it is a humeral shaft fracture. These fractures also occur due to an enormous force or violence. In many cases, tendons, muscles, vessels or nerves are also injured in such fractures. Comminuted fractures usually require surgery.
Another non-fracture injury is tennis elbow. In radial humeral epicondylitis, the upper arm bone becomes inflamed at the tendon insertion of the forearm extensor muscle. Golfer’s elbow, on the other hand, is less common, and the inflammation occurs in the tendons of the flexor muscles.
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.