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The humerus is the longest bone in the upper limb. It distinguishes three basic parts, which are the proximal end of the humerus, its shaft and the distal end of the humerus, within which various important anatomical structures are located. What exactly are the elements of the humerus and what may be the consequences of the most common problem related to it, which are humerus fractures?

The humerus(humerus) belongs to the long bones. It is part of the structures that build the upper limb and is the largest bone in this part of the human body. The humerus is distinguished not only by its size, but also by the fact that it is associated with various structures important for human functioning.

Humerus: structure

There are three parts within the humerus, which are:

  • near the humerus,
  • shaft of the humerus,
  • distal end of the humerus.

Each of the above-mentioned elements has a slightly different structure, the consequences of fracture of the humerus in its different parts are also different.

See what the humerus looks like

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Humerus: near end

The end closest to the humerus becomes a head. It houses the articular surface through which the humerus connects with the articular surface located within the scapula.

Right next to the articular surface there is an anatomical neck of the humerus, and behind it there are two nodules: a smaller and a larger one. A crest of the nodule (minor nodule crest and greater nodule crest, respectively) runs from each nodule.

There is an intercubular furrow between the combs, which is the site of the tendon attachment of the long head of the biceps muscle. The nodules themselves also serve as a site for the attachment of various muscles: the greater nodule is the site of attachment of the supraspinatal, subcapular and minor round muscles, the smaller nodule is the attachment of the subscapular muscle.

The greater pectoral muscle is attached to the crest of the greater tubercle, while the crest of the lesser tubercle is the attachment of the latissimus dorsi and the greater rounded muscles.

A vital - primarily clinically - part of the boneshoulder is located under the aforementioned nodules, the surgical neck.

humerus: shaft

The shaft of the humerus has a diversified structure: in the proximal part it is cylindrical in cross-section, and in the distal part triangular. In the following part, therefore, three surfaces are distinguished:

  • back,
  • anteromedial
  • and anterior-lateral.

The two edges of the shaft pass in combs:

  • lateral edge in lateral supracondylar crest,
  • medial edge and the medial supracondylar crest.

Within the anterolateral surface, in its upper part, there is a bulge called deltoid tuberosity. It is a place of attachment of two muscles: deltoid and brachial.

The posterior surface of the shaft of the humerus is divided by the groove of the radial nerve. The anteromedial surface is the site of the insertion of the corco-brachial and brachial muscles.

Humerus: distal end

The distal end of the humerus is flattened to some extent, widened in relation to the body and bent anteriorly. This is known as the humerus condyle. On both sides - lateral and medial - are the epicondyle (medial and lateral).

The medial epicondyle on its posterior surface has a groove of the ulnar nerve. This epicondyle is the site of the inversion of the inverted muscle, most of the muscles responsible for flexing the arm, and the ulnar collateral ligament. The lateral epicondyle is the attachment of the arm extending muscles, the forearm invertor muscle and the radial collateral ligament.

In addition, there are two articular surfaces between the epicondyle. The lateral surface takes the shape of a head and above it there is a radial fossa - the place where the head of the radial bone enters. The medial surface takes the form of a block, which is associated with the block notch of the ulna. Above the block there is the fossa of the pointed process, and the fossa of the ulna at the back.

humerus: functions

The humerus - along with other bones, muscles, ligaments and other elements of the upper limb - performs many important functions. She participates in many movements, incl. rotation in the shoulder joint, abduction and adduction of the upper limb or its lifting.

As already mentioned above, it is also a place of attachment of numerous muscles or ligaments, in addition, its elements are involved in the formation of various joints (e.g. the shoulder joint).

Humerus:fractures

The most common problem with the humerus are fractures. Unfortunately, they occur relatively often due to the fact that during various accidents (e.g. falls) a person tries to regain balance or protect himself with the use of the upper limbs.

The proximal fracture of the humerus is typical for the elderly and is most often associated with a fall on the straightened upper limb. In his case, the shoulder may be swollen and the mobility of the arm may be restricted.

A fracture of the shaft of the humerus most often occurs in connection with traffic accidents, the symptoms may include severe pain, swelling and deformation of the arm. The problem may be accompanied by the occurrence of the so-called the drooping hand, a pathology that is a consequence of the paralysis of the radial nerve.

The lateral fracture of the humerus is seen primarily in children who, during the fall, tried to support themselves with the upper limb straightened at the elbow. The consequence may be pain and swelling in the elbow joint and limited mobility within this joint.

Fractures are the most common, but by far not the only he alth problem, of the humerus. We can mention here, for example, neoplasms - this bone can be a place where metastases of a cancer with a completely different location (e.g. lung cancer or breast cancer) will be located.

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Category:

Anatomy