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The collarbone (Latin clavicula) is an even long bone that is part of the shoulder girdle. The collarbone is the connection between the upper limb and the thoracic skeleton. Although the size of the collarbone is relatively small, it has many important functions. There are numerous muscle attachments on the collarbone surface, enabling a wide range of movement of the upper limb. The collarbone also carries mechanical loads, the heaviest of which can cause collarbone fractures. Find out how the collarbone is built, how the collarbone works and what diseases can affect the clavicle.
Collarboneis part of the shoulder girdle, that is, the part of the skeleton responsible for the movements of the upper limb. In lean people, the shape of the collarbone is clearly visible under the skin in the upper part of the chest. During falls and injuries, the collarbone may fracture due to overloading.
Clavicle - structure
The collarbone, like other long bones, consists of a shaft (middle part) and two ends. The ends of the collarbone connect with the other bones to form even joints:
- medial - the medial end of the clavicle meets the sternum, forming the sternoclavicular joint
- from the lateral side - the lateral end of the collarbone joins the scapula (or more precisely - its shoulder process), forming the shoulder-clavicular joint
The collarbone gently bends into the shape of the letter S. It is worth knowing that the thickness of the clavicle is not the same along its entire course. The thinnest part of the clavicle is roughly the middle 1/3 of its length. This is the location where the collarbone is most likely to break.
Numerous ligaments attach to the collarbone, which guarantee the correct stabilization of the shoulder girdle. The collarbones connect to the sternum, scapula, first rib, and also to each other with the help of the appropriate ligaments:
- clavicular-sternal
- shoulder-clavicular
- ravenous-clavicular
- collarbone
- single interclavicular ligament
Apart from the ligament attachments, there are also numerous muscle attachments on the collarbone surface, which ensure the mobility of the shoulder girdle. Among them, it is worth mentioning:
- sternocleidomastoid muscle
- larger pectoral muscle
- subclavian muscle
- trapezius
- deltoid muscle
These muscles connect the collarbone to other bones, allowing it to move in many directions. In the case of a collarbone fracture, these connections can become a problem - pulling the clavicle fragments in the opposite direction can cause them to shift. Such a fracture with the accompanying displacement of the bone fragments may require a surgical adjustment.
When describing the anatomical position of the collarbone, one should remember about the structures in its vicinity. The subclavian artery runs directly under the collarbone, and its damage may cause a hemorrhage or even be life-threatening.
Near the collarbone there is also the brachial plexus, i.e. the fragment of the nervous system responsible for the innervation of the entire upper limb. Damage to the brachial plexus may accompany collarbone injuries. In such a situation, sensory disorders and dysfunction of the muscles innervated by damaged branches of the plexus occur.
Clavicle - functions
Since we already know the location and anatomical connections of the collarbone with other structures, it's time to present its functions. Although the length of the collarbone is only about 15 cm on average, it plays a huge role in the biomechanics of the entire upper limb. The most important functions of the collarbone are:
- direct connection of the upper limb skeleton with the thoracic skeleton
- support function - as an attachment for the muscles of the shoulder girdle, the collarbone allows the full range of movement of the upper limb
- transferring mechanical loads from the upper limb to the rest of the body - the collarbone dissipates the energy acting on the upper limb. In the case of loads exceeding the mechanical strength of the collarbone, injuries and fractures may occur
- protection of nearby soft tissues - the collarbone covers the artery and the subclavian vein, as well as the brachial plexus, protecting them from damage
- participation in the breathing process - the connections of the collarbones with the ribs and the sternum enable their participation in the movements of the chest. When you breathe in deeply, your collarbones move up and forward, increasing the volume of your chest.
Collarbone - diseases
The most common causes of collarbone diseases are injuries. Among them, collarbone fractures are in the first place. There are also relatively frequent pathologies within the joints of the collarbone with other bones, mainly related to the shoulder-clavicular joint. Abnormalities in the development of the collarbone during utero can in turn lead to congenital abnormalities in thisbones.
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collarbone fracture
The collarbone is the bone that breaks the most frequently in the entire human skeleton. Why is this happening? There are at least several reasons.
- First of all, the clavicle ossification process ends relatively late - only after the age of 20.
- Secondly, a bone of such small dimensions is often subjected to very heavy loads.
- Third, the superficial position of the collarbone increases its susceptibility to trauma.
How do collarbone fractures occur?
The most common cause is falls with the side of your arm hitting the ground. They often happen during sports. A collarbone fracture can also occur as a result of a traffic accident or other high energy injury.
What are the symptoms of a collarbone fracture?
The most common are pain, swelling, and reduced mobility of the collarbone. If bone fragments are dislocated, they may be visible under the skin - then the incorrect shape of the collarbone is noticeable.
A fracture usually requires confirmation by imaging, most often x-rays. Diagnostics of a collarbone fracture also requires checking that nearby structures, such as the brachial plexus, subclavian vessels or the upper parts of the lung, have not been damaged.
Treatment of a fractured collarbonedoes not require surgery in most cases. However, it is necessary to immobilize the upper limb with a sling or a special dressing, the so-called octal, for 2-6 weeks.
Full fusion of a broken collarbonetakes about 3-4 months.
Morecomplicated collarbone fractureshave to be treated surgically. This includes, but is not limited to;
- large displacement fractures
- open fractures
- trans-articular fractures
In such cases, it is necessary to fix the bone fragments intraoperatively with the use of special plates, screws or nails.
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diseases of the shoulder-clavicular joint
The shoulder-clavicular joint is often damaged as a result of trauma. Their effect is the mutual displacement of structures within the joint: the lateral end of the collarbone and the shoulder process of the scapula. They may be accompanied by a rupture of the periarticular ligaments.
Traditionally stands out forsix degrees of the shoulder-clavicle injury . Grade I-III injuries can be set non-operatively, while Grade IV and higher injuries require a surgical setting.dislocations. After restoring the correct position of the structures within the joint, physiotherapy is necessary to restore proper mobility and muscle strength.
An example of another condition of the shoulder-clavicular joint is a degenerative disease that can affect all joints of our body. Its essence is the destruction of articular cartilage as a result of aging, excessive overload or past injuries.
The main symptom of osteoarthritis is pain as a result of rubbing together the bone surfaces in a joint. There are two methods of treating degeneration of the shoulder-clavicular joint: conservative (physiotherapy, rehabilitation) and operative (arthroscopic treatment aimed at spacing the surfaces of rubbing bones apart).
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cost-clavicular syndrome
Cost-clavicular syndrome is one of the variants of the so-calledupper chest opening syndrome . Its essence is the compression of soft tissues by 2 adjacent bones: the collarbone and the first rib. Their incorrect position as a result of trauma or congenital abnormalities may compress the nerves of the brachial plexus or the subclavian vessels. Then pain, sensory disturbances, muscle dysfunction or blood circulation disorders in the upper limb appear. Ifconservative treatmenthas no effect, it may be necessarysurgical removal of the first rib .
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birth defects of the collarbone
Proper development of the skeletal system in utero depends on many genetic and environmental factors. An example of a disease in which fetal collarbone development is inhibited isclavicular-cranial dysplasia . It is a genetic condition associated with the abnormal formation of bone structures.
One of the symptoms of clavicle-cranial dysplasia is collarbone hypoplasia or aplasia (hypoplasia or complete absence of them, respectively). They are usually accompanied by abnormalities in the development of bones in the skull, teeth, spine and pelvis.
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