What type of joint is the sternoclavicular joint according to its form and biomechanics?

Biomechanically, the sternoclavicular joint is a multi-axial joint allowing movement around three axes: elevation and depression, protraction and retraction, and clavicular rotation. An articular disc divides its cavity into two chambers, making it a complex joint.

What is the shape-based classification of the acromioclavicular joint?

The provided study materials do not specify a direct shape classification of the acromioclavicular joint based on articular surface geometry. It is only noted that its articulating surfaces are the acromion of the scapula and the clavicle, the capsule is thin, and an articular disc is occasionally present.

Which ligaments belong to the proper ligaments of the scapula?

Among the proper ligaments of the scapula, the materials mention the superior transverse scapular ligament. It forms part of the scapular ligamentous apparatus; the suprascapular nerve runs inferior to it, whereas the suprascapular artery passes superior to this ligament.

What are the sources of blood supply to the acromioclavicular joint?

The provided materials indicate the participation of the clavicular branch of the thoracoacromial artery in the vascularization of the acromioclavicular joint. Other vascular sources for this joint are not listed.

Why is the sternoclavicular joint called a complex joint?

The joint is termed complex because an intra-articular cartilage disc is located inside its capsule, dividing the single joint cavity into two separate chambers.

Which joint serves as the only bony connection between the arm and the trunk?

This function is performed exclusively by the sternoclavicular joint (articulatio sternoclavicularis).

What fascicles make up the coracoclavicular ligament?

This critical stabilizer of the acromioclavicular joint consists of two parts: the trapezoid ligament (trapezoideum) and the conoid ligament (conicum).

Home › Human Anatomy › Joints of the Pectoral Girdle

Joints of the Pectoral Girdle

Articulationes cinguli membri superioris

For medical students2 min readUpdated 2026-10-10

The bones of the pectoral girdle form a reliable support for the free upper extremity. Their joints provide not only high mobility of the arm, but also act as the sole connective link between the limb and the trunk.

Unique ConnectionThe sternoclavicular joint is the only attachment site of the arm to the axial skeleton.

Articular DiscDivides the sternoclavicular joint cavity into two isolated compartments.

Main StabilizerThe coracoclavicular ligament is the most critical stabilizer of the scapula.

Sternoclavicular Joint

The sternoclavicular joint (articulatio sternoclavicularis) performs a crucial biomechanical function: it is the only point of connection between the free upper extremity and the trunk.

Three main structures participate in forming this joint:

Sternal end of the clavicle;
Clavicular notch located on the manubrium of the sternum;
Cartilage of the 1st rib (specifically the cartilaginous part, not the body of the rib).

The joint capsule is loose and attaches strictly along the margins of the articulating surfaces. A distinctive feature of this articulation is the presence of an articular disc within the cavity. It completely divides the joint cavity into two independent chambers, classifying the joint as complex.

Biomechanics

According to the shape of its articular surfaces and range of motion, it is a multi-axial joint (moving around three axes). The following movements are possible:

Elevation and depression of the clavicle;
Protraction (forward movement) and retraction (backward movement) of the clavicle;
Rotation of the clavicle along its longitudinal axis.

Ligamentous Apparatus of the Sternoclavicular Joint

The loose joint capsule is securely reinforced by a robust complex of ligaments that limit excessive mobility and protect the joint from dislocation:

Anterior and posterior sternoclavicular ligaments (lig. sternoclaviculare anterius et posterius) — blend into the capsule from their respective sides;
Interclavicular ligament (lig. interclaviculare) — spans between the medial ends of the right and left clavicles, passing over the manubrium of the sternum;
Costoclavicular ligament (lig. costoclaviculare) — a powerful band anchoring the clavicle to the cartilage of the 1st rib.

Acromioclavicular Joint

The acromioclavicular joint (articulatio acromioclavicularis) is the articulation between the scapula and the clavicle.

The articular surfaces are formed by the acromion of the scapula and the lateral end of the clavicle. Unlike the sternoclavicular joint, the capsule here is thin, although it attaches similarly along the margins of the articular surfaces. An articular disc may occasionally be found within the cavity of this joint, but its presence is inconstant.

Functions and Ligaments

The range of motion in this joint is small, but it is critically important for ensuring coordinated rotation of the scapula together with the clavicle during arm elevation.

The joint is supported by the following ligamentous apparatus:

Acromioclavicular ligament (lig. acromioclaviculare) — reinforces the capsule superiorly.
Coracoclavicular ligament (lig. coracoclaviculare) — acts as the most vital stabilizer of the joint. It consists of two anatomical parts: the trapezoid ligament (lig. trapezoideum) and the conoid ligament (lig. conicum).

Mnemonic

To remember the clavicular ligaments near the sternum, use the directional rule: anterior/posterior (sternoclavicular), inferior to the rib (costoclavicular), and lateral to the opposite clavicle (interclavicular).

Frequently asked questions

What type of joint is the sternoclavicular joint according to its form and biomechanics?: Biomechanically, the sternoclavicular joint is a multi-axial joint allowing movement around three axes: elevation and depression, protraction and retraction, and clavicular rotation. An articular disc divides its cavity into two chambers, making it a complex joint.
What is the shape-based classification of the acromioclavicular joint?: The provided study materials do not specify a direct shape classification of the acromioclavicular joint based on articular surface geometry. It is only noted that its articulating surfaces are the acromion of the scapula and the clavicle, the capsule is thin, and an articular disc is occasionally present.
Which ligaments belong to the proper ligaments of the scapula?: Among the proper ligaments of the scapula, the materials mention the superior transverse scapular ligament. It forms part of the scapular ligamentous apparatus; the suprascapular nerve runs inferior to it, whereas the suprascapular artery passes superior to this ligament.
What are the sources of blood supply to the acromioclavicular joint?: The provided materials indicate the participation of the clavicular branch of the thoracoacromial artery in the vascularization of the acromioclavicular joint. Other vascular sources for this joint are not listed.
Why is the sternoclavicular joint called a complex joint?: The joint is termed complex because an intra-articular cartilage disc is located inside its capsule, dividing the single joint cavity into two separate chambers.
Which joint serves as the only bony connection between the arm and the trunk?: This function is performed exclusively by the sternoclavicular joint (articulatio sternoclavicularis).
What fascicles make up the coracoclavicular ligament?: This critical stabilizer of the acromioclavicular joint consists of two parts: the trapezoid ligament (trapezoideum) and the conoid ligament (conicum).

Go deeper

Axes of rotation and range of motion in the sternoclavicular joint
Role of the articular disc in dividing the joint cavity
Anatomical differences between the trapezoid and conoid ligaments
Synchronization of clavicular and scapular movements