The sternoclavicular joint is a synovial joint in between the clavicle and also the manubrium the the sternum.
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It is the just attachment of the upper limb to the axial skeleton. Despite its strength, it is a an extremely mobile joint and can function an ext like a ball-and-socket kind joint.
In this write-up we will look in ~ the anatomy the the sternoclavicular joint, – the share structure, neurovascular supply, and its clinical considerations.
The sternoclavicular joint is composed of the sternal end that the clavicle, the manubrium the the sternum, and part of the 1st costal cartilage. The articular surfaces room covered through fibrocartilage (as opposed to hyaline cartilage, existing in the bulk of synovial joints). The joint is separated right into two compartments by a fibrocartilaginous articular disc.
Fig 1 – The articulating surfaces of the sternoclavicular joint.
The joint capsule consists of a fibrous external layer, and also inner synovial membrane. The fibrous layer extends native the epiphysis that the sternal finish of the clavicle, come the boundaries of the articular surfaces and the articular disc. A synovial membrane lines the within surface and also produces synovial fluid to reduce friction in between the articulating structures.
The ligaments of the sternoclavicular joint carry out much that its stability. There are four significant ligaments:Sternoclavicular ligaments (anterior and posterior) – these strengthen the joint capsule anteriorly and also posteriorly.Interclavicular ligament – this spans the gap in between the sternal end of every clavicle and also reinforces the joint capsule superiorly.Costoclavicular ligament – the two components of this ligament (often be separate by a bursa) bind at the 1st rib and cartilage inferiorly and to the anterior and posterior borders of the clavicle superiorly. It is a very strong ligament and is the main stabilising force for the joint, resisting elevation of the pectoral girdle.
The sternoclavicular and interclavicular ligaments have the right to be considered to be thickenings of the share capsule.
Fig 2 – The major ligaments of the sternoclavicular joint
Arterial supply to the sternoclavicular joint is native the internal thoracic artery and the suprascapular artery.
The share is supplied by the medial supraclavicular nerve (C3 and also C4) and also the nerve to subclavius (C5 and also C6).
The sternoclavicular joint has actually a huge degree the mobility. There room several motions that require joint involvement:Elevation the the shoulders – shrugging the shoulders or abducting the arm over 90ºDepression that the shoulders – drooping shoulders or prolonging the eight at the shoulder behind the bodyProtraction the the shoulders – moving the shoulder girdle anteriorlyRetraction the the shoulders – relocating the shoulder girdle posteriorlyRotation – once the arm is raised over the head by flexion the clavicle rotates passively together the scapula rotates. This is transmitted come the clavicle by the coracoclavicular ligaments
The costoclavicular ligament acts as a pivot for movements of the clavicle. You have the right to feel this if friend palpate the sternal end of her clavicle and shrug your shoulders, you should feel the sternal end moving inferiorly.
Mobility and also Stability
The sternoclavicular share is forced to accommodate the activities of the upper limb, and thus has a high degree of mobility. However, it also requires much stability, together it is the only connection in between the upper limb and also the axial skeleton.
Here we will take into consideration the factors which add to both that is mobility and also its stability.
MobilityType of share – being a saddle share it deserve to move in 2 axes.Articular key – this enables the clavicle and also the manubrium to slide end each other an ext freely, permitting for the rotation and also movement in a 3rd axis.
StabilityStrong share capsule.Strong ligaments – particularly the costoclavicular ligament, i m sorry transfers anxiety from the clavicle to the manubrium (via the costal cartilage).
Clinical Relevance: Dislocation the the Sternoclavicular Joint
A dislocation that the sternoclavicular joint is fairly rare and also requires far-ranging force. The costoclavicular ligament and the articular disc are highly efficient at absorbing and transmitting forces away native the joint right into the sternum.
There space two major types that dislocation:Anterior dislocations space the most common and can happen complying with a punch to the anterior shoulder which rotates the shoulder backwards.Posterior dislocations normally result from a pressure driving the shoulder forwards or from direct affect to the joint.
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In younger people, the epiphyseal growth plate of the sternal end of the clavicle has not completely closed. In this population, the dislocation is commonly accompanied through a fracture v the plate.