Dorothy FarrarElle
The ulna , in Latin ulna, is an elongated tubular bone and is located in the forearm on the side of the little finger . Heavy torsional stress or sports can lead to problems in the ulna area.
Definition
The ulna is one of the two forearm bones. It runs parallel to the spoke (Latin radius). As a tubular bone, it has a medullary cavity with bone marrow . The ulna is connected to the radius by two joints . These are the proximal radius-ulna joint or articulatio radioulnaris proximalis and the distal radius-ulnar joint or articulatio radioulnaris distalis. These joints help rotate the hand and forearm. In addition, the ulna and radius are connected to each other by fiber strands.
Anatomy
The upper end of the ulna is called the olecranon and is approximately mid-body level. It is thickened and ends in a beak-like bony spur called the elbow hump or tuber olecrani. The posterior, triangular surface is covered by a bursa, the bursa subcutanea olecrani. It serves to protect the bone, which lies directly under the skin here .
Fibers of the joint capsule of the elbow joint and the elbow muscle attach to the olecranon. In addition, tendons of the upper arm muscle radiate into the olecranon. The middle section of the ulna is the so-called ulna body or ulna shaft, also known as the corpus ulnae. The body of the elbow has an almost triangular cross-section in the upper area, becoming increasingly rounded towards the bottom.
The lower end of the ulna, which is less powerful than the upper end, is the ulnar head or caput ulnae. This ends with the styloid process or processus styloideus ulnae. The ulnar head is connected to the wrist by a joint disc, the discus articularis. The ulna and spoke are usually the same length. If the ulna is longer than the radius, it is referred to as an ulnaplus variant; if the ulna is shortened, it is an ulnaminus variant.
Function
Various muscles and tendons attach to the ulna. It represents an essential part of the elbow joint, which it forms together with the upper arm bone, the so-called humerus, and the radius. The elbow joint, a so-called hinge joint, allows the forearm to bend and stretch against the upper arm. In addition, turning the forearm in and out is possible via the two spoke-ulna joints. Here, the ulna and spoke, which form a functional unit, move against each other.
At the lower end of the ulna, the styloid process forms part of the wrist and functions as a unit with the other components of the joint. This allows flexion, extension and spreading movements of the hand, whereby the ulna is mainly involved in flexion movements. In addition to moving and stabilizing the forearm, the ulna stores minerals and produces blood cells in its bone marrow .
Diseases
- Madeling deformity
Excessive stress, for example during sports, or an accident can lead to injuries to the ulna leading to painful symptoms. These include broken bones in the ulna and damage to the cartilage on the ulnar head. Common injuries occur in the elbow or wrist area. When the wrist is broken, the stylus process, which is part of the ulna, is often affected.
However, joint injuries do not always involve the ulna directly; instead, tendon injuries are often involved. Painful inflammation can occur in the bursa in the upper area of the ulna. In rare cases, rheumatic diseases or high physical stress can lead to arthrosis of the elbow joint.
In the so-called Madelung deformity, a growth disorder of the forearm, the ulna is greatly elongated. There is a malposition with restricted movement in the wrist and forearm. This can result in mostly load-related complaints.
Even with a slight extension of the ulna, pressure on the wrist can cause pain on the little finger side of the joint. If the ulna is short compared to the radius, the thumb side of the wrist can hurt due to pressure from the longer radius. However, small differences in length between the ulna and the spoke are often symptom-free.
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.