Sternoclavicular Joint (SC joint)

Location and Articulation

The sternoclavicular joint: Is a joint in the upper limp, it works as a connection area between the axial skeleton and the upper limb. One of four joints comprises the Shoulder Complex.

Note

Note: Shoulder complex joints are sternoclavicular (SC), acromioclavicular (AC), scapulothoracic joints, and glenohumeral joints.

The sternoclavicular joint is formed from the articulation of the lateral part of the sternum (breastbone) and the sternal end (medial head)of the clavicle (collarbone), also the superior surface of the first costal cartilage share in the articulation o this joint. All the articular surfaces are covered with fibrocartilage. The joint level is at the first thoracic vertebrae (T1) .

Sternoclavicular joint articulation

Joint Type and Its Movement

The joint is Saddle synovial joint but functionally, it has the features of a ball-and-socket joint , as it multiaxial joint with three degrees of freedom.
The SC joint is extremely strong, it supports the shoulder and coordinates movement in the upper limp with the core of the body, the movement in this joint is sorted into three degrees of freedom:
Elevation – depression (Range of Movement 0-40° ): Elevation is when the lateral end of the clavicle elevates (movement in a superior direction) while the medial end depresses(movement in an inferior direction), during depression the opposite occurs.
The elevation is limited by the costoclavicular ligament and by the tone of the subclavius muscle, while Depression is limited by the articular disc and the interclavicular ligament.
Protraction – retraction (ROM 25-35° ): Protraction is when the lateral end of the clavicle moves forwards (anteriorly) while the medial end, together with the articular disc, moves posteriorly, also during retraction the opposite occurs.
Protraction is limited by the costoclavicular and anterior sternoclavicular ligaments, while Retraction is limited by both posterior sternoclavicular and costoclavicular ligaments.
Axial rotation ( ROM 20-40° ): The clavicle rolls anteriorly or posteriorly around its longitudinal axis.
No muscles have immediate action on the sternoclavicular joint. Instead movement at this joint relies primarily on the motion of the scapula and the pectoral (shoulder) girdle.

Movement of SC joint

Blood Supply

The Blood supply of SC joint comes from branches of the internal thoracic artery, and Suprascapular artery.

Suprascapular artery that supply the joint

Nerve Innervation

while the Nerve innervation of the sternoclavicular joint comes from two sources; superficially by the medial supraclavicular nerve (C3-C4; cervical plexus) and deeply by the nerve to subclavius (C5-C6; brachial plexus) .

Nerve Innervation of SC joint

Capsule and Ligaments

The SC joint is enclosed by a fibrous capsule its thickened anteriorly and posteriorly and loose superiorly and inferiorly and the articular surfaces of the joint are lined with fibrocartilage.
The ligaments that cover this joint are:
Sternoclavicular ligaments: Found within the joint capsule, composed of two ligaments anterior and posterior sternoclavicular ligaments, those extending from the medial head of the clavicle to the superior part of the manubrium.
Interclavicular ligament: Extend and connect between the two sternal(medial) ends of both clavicles. It strengthens and supports the superior aspect of the joint capsule.
Costoclavicular ligament: Extends from the superior surface of the first rib and its costal cartilage to the inferomedial aspect of the clavicle (collarbone).

The major ligaments of the sternoclavicular joint

References

1) Moore K. L., Dalley, A. F., & Agur, A. M. R. (2014)- Clinically Oriented Anatomy 7th Edition (794-796 plates)
2) Netter, F. (2019). Atlas of Human Anatomy (7th ed.). Philadelphia, PA: Saunders.
3) Sternoclavicular joint ,Nicola McLaren MSc, Kenhub.
https://www.kenhub.com/en/library/anatomy/sternoclavicular-joint
4) The Sternoclavicular Joint, Ron Sangal, Teachme anatomy
https://teachmeanatomy.info/upper-limb/joints/sternoclavicular/
5) Sternoclavicular Joint, Physiopedia
https://www.physio-pedia.com/Sternoclavicular_Joint

References of images

Cover Images: Henry Gray (1918) Anatomy of the Human Body: Gray's Anatomy, Plate 325
fig 1: The articular surfaces of the sternum and medial clavicle are incongruent, Musculoskeletal Key.
https://musculoskeletalkey.com/wp-content/uploads/2016/10/A312451_1_En_8_Fig2_HTML.gif
fig 3: Suprascapular artery, Kenhub
https://www.kenhub.com/thumbor/NJArHMLueeUyAO184ZtGeU8BKQw=/fit-in/680x680/filters:fill(FFFFFF,true):watermark(/images/watermark_only.png,0,0,0):watermark(/images/logo_url.png,-10,-10,0):format(jpeg)/images/anatomy_term/arteria-suprascapularis/hZ5QGv13XhclyzhIdQ5w_Suprascapular_artery.png
fig 4: Internal thoracic artery, Kenhub
https://www.kenhub.com/thumbor/qe_wNDd5sw_OF2bL-S6DCjZQHp0=/fit-in/680x680/filters:fill(FFFFFF,true):watermark(/images/watermark_only.png,0,0,0):watermark(/images/logo_url.png,-10,-10,0):format(jpeg)/images/anatomy_term/arteria-thoracica-interna/AFy2Xkf0x9wvEjPxOOiLiQ_Internal_thoracic_artery.png
fig 5: Innervation of the clavicle: a cadaveric investigation, Regional Anesthesia & Pain Medicine
https://rapm.bmj.com/content/rapm/46/12/1076/F2.large.jpg
fig 6: The major ligaments of the sternoclavicular joint, Teachme anatomy
https://teachmeanatomy.info/wp-content/uploads/Ligaments-of-the-Sternoclavicular-Joint.jpg