Clavicle: Facts, Discussion Forum, and Encyclopedia Article

Clavicle

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	Clavicle
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	Topics Clavicle Topic Home In human Human A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago.... anatomy Anatomy Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy .... , the clavicle or collar bone is classified as a flat bone Bone Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals.... that makes up part of the shoulder Shoulder In human anatomy, the shoulder joint comprises the part of the body where the humerus attaches to the scapula. The shoulder refers to the group of structures in the region of the joint.... girdle Girdle The word girdle originally meant a belt. In modern English the term "girdle" is most commonly used for a form of women's Foundation garment that replaced the corset in popularity.... (pectoral girdle Pectoral girdle The pectoral girdle is the set of bones which connect the upper limb to the axial skeleton on each side. It consists of the clavicle and scapula in humans and, in those species with three bones in the pectoral girdle, the coracoid.... ). It receives its name from the Latin clavicula ("little key") because the bone rotates along its axis like a key when the shoulder is abducted Abduction (kinesiology) Abduction, in functional anatomy, is a movement which draws a Limb away from the median plane of the body. It is thus opposed to adduction.... . (This movement is palpable with the opposite hand). In some people, particularly females who may have less fat in this region, the location of the bone is clearly visible as it creates a bulge in the skin. le class="wikitable" align="right" width="250">

Right clavicle - from below, and from above.

Left clavicle - from above, and from below.

The clavicle is a doubly curved short bone that connects the arm (upper limb

Upper limb

In human anatomy, the upper Limb refers to what in common English is known as the arm, that is, the region of the shoulder to the fingertips....
) to the body (trunk

Trunk

Trunk may refer to:In biology:*Trunk, torso*Trunk, an Elephant#Trunk*Trunk , a tree's central superstructureIn containers:*Trunk ...
), located directly above the first rib.

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Overview


Right clavicle - from below, and from above.

Left clavicle - from above, and from below.

The clavicle is a doubly curved short bone that connects the arm (upper limb

Upper limb

In human anatomy, the upper Limb refers to what in common English is known as the arm, that is, the region of the shoulder to the fingertips....
) to the body (trunk

Trunk

Trunk may refer to:In biology:*Trunk, torso*Trunk, an Elephant#Trunk*Trunk , a tree's central superstructureIn containers:*Trunk ...
), located directly above the first rib. It acts as a strut to keep the scapula in position so the arm can hang freely. Medially, it articulates with the manubrium of the sternum

Sternum

The sternum is a long flat bone located in the center of the chest . It connects to the rib via cartilage, forming the rib cage with them, and thus helps to protect the lungs, heart and major blood vessels from physical trauma....
(breast-bone) at the sternoclavicular joint. At its lateral end it articulates with the acromion of the scapula

Scapula

In anatomy, the scapula, omo, or shoulder blade, is the bone that connects the humerus with the clavicle .The scapula forms the posterior part of the shoulder girdle....
(shoulder blade) at the acromioclavicular joint

Acromioclavicular joint

The acromioclavicular joint, or AC joint, is a joint at the top of the shoulder. It is the junction between the acromion and the clavicle....
. It has a rounded medial end and a flattened lateral end.

From the roughly pyramidal sternal end, each clavicle curves laterally and posteriorly for roughly half its length. It then forms a smooth posterior curve to articulate with a process of the scapula (acromion). The flat, acromial end of the clavicle is broader than the sternal end. The acromial end has a rough inferior surface that bears prominent lines and tubercles. These surface features are attachment sites for muscles and ligaments of the shoulder.

The collarbone, also called the clavicle, is the bone over the top of your chest, between your breastbone (sternum) and shoulder blade (scapula). It is easy to feel the clavicle, because unlike other bones which are covered with muscle, only skin covers a large part of the bone. Clavicle fractures are extremely common. Broken collarbones occur in babies (usually during birth), children and adolescents (because the clavicle does not completely ossify, or develop, until the late teens), athletes (because of the risks of being hit or falling), or during many types of accidents and falls.

Functions

The clavicle serves several functions:

It serves as a rigid support from which the scapula and free limb are suspended. This arrangement keeps the upper limb (arm) away from the thorax so that the arm has maximum range of movement.
Covers the cervicoaxillary canal (passageway between the neck and arm), through which several important structures pass.
Transmits physical impacts from the upper limb to the axial skeleton
Axial skeleton

The axial skeleton consists of the 80 bones in the head and trunk of the human body. It is composed of five parts; the human skull, the ossicles of the inner ear, the hyoid bone of the throat, the chest, and the vertebral column....
.

Even though it is classified as a long bone

Long bone

The long bones are those that are longer than they are wide, and grow primarily by elongation of the diaphysis, with an epiphysis at the ends of the growing bone....
, the clavicle has no medullary (bone marrow) cavity like other long bones. It is made up of spongy (cancellous) bone with a shell of compact bone. It is a dermal bone

Dermal bone

The dermal bone, the pattern and form of bones derived from intramembranous ossification, define essential components of the vertebrate skeleton including the skull, jaws, gills, fins and exoskeleton....
derived from elements originally attached to the skull.

Attachments

Muscles and ligaments that attach to the clavicle include:

Attachment on clavicle	Muscle/Ligament	Other attachment >- \| Superior surface and anterior border	Deltoid muscle Deltoid muscle In human anatomy, the deltoid muscle is the muscle forming the rounded contour of the shoulder.It was previously called the Deltoideus and the name is still used by some anatomists....	deltoid tubercle, anteriorly on the lateral third \|- \| Superior surface	Trapezius muscle Trapezius muscle In human anatomy, the trapezius is a large superficial muscle which extends longitudinally from the occipital bone to the lower thoracic vertebrae, and laterally to the spine of the scapula ....	- \| Inferior surface	Subclavius muscle Subclavius muscle The Subclavius is a small triangular muscle, placed between the clavicle and the first rib. Along with the pectoralis major and pectoralis minor muscles, the subclavius muscle makes up the anterior wall of the axilla....	subclavian groove Subclavian groove On the medial part of the clavicle is a broad rough surface, the costal tuberosity , rather more than 2 cm. in length, for the attachment of the costoclavicular ligament.... \|- \| Inferior surface	Conoid ligament Conoid ligament The Conoid Ligament, the posterior and medial fasciculus, is a dense band of fibers, conical in form, with its base directed upward.It is attached by its apex to a rough impression at the base of the coracoid process, medial to the trapezoid ligament; above, by its expanded base, to the coracoid tuberosity on the under surface of the clavic... (the medial part of the coracoclavicular ligament Coracoclavicular ligament The Coracoclavicular Ligament serves to connect the clavicle with the coracoid process of the scapula.It does not properly belong the acromioclavicular joint articulation, but is usually described with it, since it forms a most efficient means of retaining the clavicle in contact with the acromion.... )	conoid tubercle Conoid tubercle At the posterior inferior side of the clavicle, near the point where the prismatic joins with the flattened portion, is a rough eminence, the conoid tubercle ; this, in the natural position of the bone, surmounts the coracoid process of the scapula, and gives attachment to the conoid ligament.... \|- \| Inferior surface	Trapezoid ligament Trapezoid ligament The trapezoid ligament, the anterior and lateral fasciculus, is broad, thin, and quadrilateral: it is placed obliquely between the coracoid process and the clavicle.... (the lateral part of the coracoclavicular ligament Coracoclavicular ligament The Coracoclavicular Ligament serves to connect the clavicle with the coracoid process of the scapula.It does not properly belong the acromioclavicular joint articulation, but is usually described with it, since it forms a most efficient means of retaining the clavicle in contact with the acromion.... )	trapezoid line Trapezoid line From the coracoid tuberosity an oblique ridge, the trapezoid line , runs forward and lateralward, and affords attachment to the trapezoid ligament.... \|- \| Anterior border	Pectoralis major muscle Pectoralis major muscle The Pectoralis major is a thick, fan-shaped muscle, situated at the upper front of the chest wall. It makes up the bulk of the chest muscles in the male and lies under the breast in the female....	- \| Posterior border	Sternocleidomastoid muscle Sternocleidomastoid muscle In human anatomy, the sternocleidomastoid muscle, also known as sternomastoid and commonly abbreviated as SCM, is a paired muscle in the superficial layers of the anterior portion of the neck.... (clavicular head)	- \| Posterior border	Sternohyoid muscle Sternohyoid muscle The sternohyoid muscle is a thin, narrow muscle attaching the hyoid bone to the sternum, one of the paired strap muscles of the infrahyoid muscles serving to depress the hyoid bone....	- \| Posterior border	Trapezius muscle Trapezius muscle In human anatomy, the trapezius is a large superficial muscle which extends longitudinally from the occipital bone to the lower thoracic vertebrae, and laterally to the spine of the scapula ....	lateral third

Development

The clavicle is the first bone to begin the process of ossification

Ossification

Ossification is the process of bone formation, in which connective tissues, such as cartilage are turned to bone or bone-like tissue. The ossified tissue is invaginated with blood vessels....
(laying down of minerals onto a preformed matrix) during development of the embryo, during the 5th and 6th weeks of gestation. However, it is one of the last bones to finish ossification, at about 21-25 years of age. It forms by intramembranous ossification

Intramembranous ossification

Intramembranous ossification is one of the two processes during fetal development of the mammal skeleton in which bone tissue is created. It is also an essential process during the healing of bone healing and the rudimentary formation of bone of the Human skull....
. It consists of a mass of cancellous bone

Cancellous bone

Cancellous bone is a type of osseous tissue with a low density and strength but very high surface area, that fills the inner cavity of long bones....
surrounded by a compact bone shell. The cancellous bone forms via two ossification centres, one medial and one lateral, which fuse later on. The compact forms as the layer of fascia

Fascia

Fascia , pl. fas?ci?ae , adj. fascial is the soft tissue component of the connective tissue system that permeates the human body....
covering the bone stimulates the ossification of adjacent tissue. The resulting compact bone is known as a periosteal collar.

Variations

The clavicle varies more in shape than most other long bones. Occasionally, the clavicle is pierced by a branch of the supraclavicular nerve. The clavicle is thicker and more curved in manual workers, and the sites of muscular attachments are more marked. The right clavicle is usually stronger and shorter than the left clavicle.

Common clavicle injuries

acromioclavicular dislocation
sternoclavicular dislocations
clavicle fracture
Clavicle fracture

A clavicle fracture is a bone fracture in the clavicle, or collarbone....
s
osteolysis
Osteolysis

Osteolysis refers to an active resorption or dissolution of bone tissue as part of an ongoing disease process....
degeneration of the clavicle