Clavicle or collarbone is a long bone that serves as a buffer between the shoulder blades and breastbone or breastbone. There are two clavicles, one on the left and one on the right. The clavicle is the only long bone in the body located horizontally. Together with the shoulders it formed a shoulder girdle. It is a palpable bone and in people who have less fat in this region, the location of bone is obvious, because it creates a bulge in the skin. It receives its name from Latin: clavicula ("small key") because the bone rotates along its axis like a key when the shoulder is abducted. The clavicle is the most commonly fractured bone. It can be easily cracked by a collision to the shoulder of a force falling on an outstretched arm or by a direct blow.
Video Clavicle
Structure
The collarbone is a very curved double-length bone that connects the arms to the torso. Located just above the first rib, it acts as a buffer to keep the scapula in place so that the arm can hang freely. Medically, he articulated with manubrium sternum (chest bone) in the sternoclavicular joint. At the lateral end, he articulates with acromion, a process of scapula (shoulder bladder) in acromioclavicular joints. It has a round medial tip and a flat lateral tip.
From the rough pyramidal sternal end, each neck bone curves laterally and anteriorly for approximately half its length. Then form a larger posterior curve to be articulated with a scapula akromion. The flat acromial end of the collarbone is wider than the end of the sternum. The acromial tip has a rough inferior surface supporting the back, trapezoidal lines, and slightly rounded projection, conoid tubercle (above coracoid process). These surface features are attachment sites for muscle and shoulder ligaments.
It can be divided into three parts: medial end, lateral and shaft tip.
Medial end
The medial end is rectangular and articulates with the clavicle notch on the sternum manubrium to form the sternoclavicular joint. The articular surface extends to the inferior aspect for installation with the first costal cartilage.
This provides an attachment to:
- fibrous capsule joints, around
- articular disk, superoposteriorly
- interkavavicular, superior ligaments
Lateral lateral
The lateral end is flat from top to bottom. This bears the aspect to attachment to the process of scapular acromion, forming an acromioclavicular joint. The area around the joint provides an attachment to the joint capsule. The anterior margin is concave forward and the posterior boundary convex to the back.
Shaft
The shaft is divided into two thirds medial and lateral thirds. The medial part is thicker than the lateral.
Medial two-thirds of the axis
Medial two-thirds of the shaft has four surfaces and no limit.
- The anterior surface is convex forward and gives the origin to the pectoralis major.
- The posterior surface is smooth and gives the origin to the sternohyoid muscle at the medial end.
- The superior surface is rough on the medial part and gives the origin to the sternocleidomastoid muscle.
- The inferior surface has a lower oval impression than the medial end for the costoclavicular ligament and is called the costal tuberosity. On the lateral side of the inferior surface, there is a subclavian groove to enter the subclavius ​​muscle. On the lateral side of the subclavian groove, the nutrient foramen is located. The medial section is rectangular in which it makes a connection with the sternal manubrium of the sternoclavicular joint. The subclavian lining attaches to the clavapular fascia.
The third lateral of the axis
The lateral third of the shaft has two boundaries and two surfaces.
- the anterior border is concave forward and gives the origin to the deltoid muscle.
- the convex posterior boundary and provide attachment to the trapezius muscle.
- The superior surface is subcutaneous.
- the inferior surface has a back called the trapezoidal line and tubercle; conoid tubercle for fixation with trapezoidal and conoid ligaments, part of the coracoclavicular ligament that serves to connect the collarbone with the coracoid process of the scapula.
Development
The clavicle is the first bone to initiate the hardening process (mineralization to the matrix that has formed) during embryonic development, during the fifth and sixth weeks of pregnancy. However, this is one of the last bones to complete the hardening in about 21-25 years. A study measuring 748 men and 252 women looked at the differences in clavicle length between the 18-20 and 21-25 age groups of approximately 6 and 5 mm (0.24 and 0.20 inches) for both men and women. The lateral end is formed by intramembranous osification while medially formed by endocondral ossification. It consists of cancellous bone mass surrounded by a compact bone shell. The form of cancellous bone through two ossification centers, one medial and one lateral, which then fuses. The compact form as a fascia layer that covers the bone stimulates adjacent tissue hardening. The resulting solid bone is known as the periosteal collar.
Although classified as long bones, the collarbone has no medullary cavity (bone marrow) like other long bones, although this is not always true. It consists of a cancellous sponge bone with a compact bone shell. It is a dermal bone derived from elements originally attached to the skull.
Variations
Clavicle shapes vary more than other long bones. Sometimes stabbed by the supraclavicular nerve branches. In men it is thicker and more curved and the sites of muscle attachment more clearly. The left clavicle is usually longer and not as strong as the right clavicle. In men, clavicle is larger, longer, heavier and generally more massive than females. The clavicle form is a reliable criterion for the determination of sex.
The collarbones are sometimes partially or completely absent in cleidocranial dysostosis.
The claviculae levator muscle, present in 2-3% of people, is derived from the transverse process of the upper cervical vertebra and inserted in the lateral half of the clavicle.
Maps Clavicle
Function
The clavicle serves several functions:
- This serves as a rigid support from which the scapula and branches are suspended free; a setting that keeps the upper extremities away from the thorax so that the arm has the maximum range of motion. Acting as a flexible buffer, like a crane, allows the scapula to move freely in the thoracic wall.
- Includes the cervicoaxillary tract, protects the neurovascular bundle that supplies the upper limb.
- Sends physical impact of the upper limb to the axial frame.
Muscle
Muscles and ligaments attached to the collarbone include:
Clinical interests
- Acromioclavicular Dislocation ("AC Separation")
- Clavicle degeneration
- Osteolysis
- Sternoklavikular dislocations
The vertical line taken from the mid-clavicle called the mid-clavicle line is used as a reference in describing the heart apex pulse during a medical examination. It is also useful for evaluating enlarged liver, and for finding gallbladder between the midline of the clavicle and the transpyloric plane.
Clavicle Fracture
Clavicle fractures (colloidal, collarbone fractures) occur as a result of injury or trauma. The most common type of fracture occurs when a person falls horizontally on the shoulder or with outstretched hands. Direct attacks on the collarbone will also cause rest. In most cases, direct attacks occur from the lateral side to the medial side of the bone. Clavicle fractures usually occur at an angle, where the greatest changes in bone direction occur. This produces the sternokleidomastoid muscle elevating the medial aspect superiorly, which can cause skin perforation on it.
Other animals
The clavicle first appears as part of the skeleton in primitive bony fish, where it is associated with pectoral fins; they also have bones called cleithrum. In such fish, the paired clavicle runs behind and below the gills on each side, and joins the solid symphysis at the bottom of the fish. They are, however, absent in cartilaginous fish and in most live bony fish, including all teleosts.
The oldest tetrapod maintains this arrangement, with the addition of a diamond-shaped interlavicle between the base of the clavicle, although this is not found in live amphibians. The cleithrum disappears early in the reptile evolution, and is not found in living amniotes, but the interclavicle is present in most modern reptiles, and also in monotremes. But in the modern form, there are a number of variations of primitive patterns. For example, crocodiles and salamanders have no clavicle at all (although crocodiles maintain interclavicles), while in turtles, they form part of an armored plastron.
The interclavicle is absent in marsupials and placental mammals. In many mammals, the clavicle is also reduced, or even absent, to allow the scapula to move more freely, which may be useful in fast-running animals.
Although a number of hominin (human and chimpanzee) fossils of the clavicle have been found, most are segments that offer limited information on the shape and function of the chest girdle. One exception is the 333x6/9 clavicle associated with Australopithecus afarensis that has well-preserved sternal tips. One interpretation of this specimen, based on the lateral edge orientation and the position of the deltoid attachment region, indicates that this clavicle is different from that found in apes that still exist (including humans), and thus that the human shoulder date form returns to less than 3 up to 4 million years ago . However, clavicle analysis in the remaining primates shows that the low scapula position in humans is largely reflected in the curvature of the medial part of the clavicle rather than the lateral portion. This part of the bone is similar in A. afarensis and it is thus possible that this species has a high shoulder position as in modern humans.
In dinosaurs
The main bone dinosaurs of the bodice of the chest are scapula (scapula) and coracoid, both directly articulated with the clavicle. The clavicle is present in the saurischian dinosaurs but is largely absent in the ornithischian dinosaurs. The spot on the shoulder blades where it is articulated with the humerus (the upper bone of the forelimb) is the so-called glenoid. Clavicles converge in some theropod dinosaurs to form furculae, which is equivalent to wishbone.
In birds, clavicles and interclavicles have fused to form a single Y-shaped bone, furcula or "wishbone" that evolved from the clavicle found in the coelurosaurian theropod.
Additional images
See also
- Fracture of the clavicle
References
External links
Source of the article : Wikipedia
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