The document summarizes the sternoclavicular joint and acromioclavicular joint of the shoulder girdle. It describes the articular surfaces, ligaments, joint capsule, movements, and functions of each joint. The sternoclavicular joint connects the clavicle to the sternum and allows elevation, depression, protraction, and retraction. Stability is provided by ligaments including the interclavicular and costoclavicular ligaments. The acromioclavicular joint connects the clavicle to the acromion and scapula. It is stabilized by the acromioclavicular and coracoclavicular ligaments and allows protraction, ret

1. Prepared by: Minel Aşcıoğlu 220i-2a MPF-2
Azerbaijan Medical University
Joints Of The Shoulder Girdle

2. Articulating Surfaces:
• The sternoclavicular joint consists of the sternal end of the clavicle, the
manubrium of the sternum, and part of the 1st costal cartilage. The
articular surfaces are covered with fibrocartilage.
STERNOCLAVICULAR JOINT:

3. • The articular surfaces are concavo-
convex, thus forming a sellar or
saddle joint. The radius of these
curvatures differs, making the
articular surfaces incongruent. The
sternal end of the clavicle is larger in
size than the clavicular notch of the
sternum.
• Joint congruency is provided by the
presence of a
fibrocartilaginous intra-articular
disc.

4. • The joint is surrounded by a fibrous
joint capsule which is thickened
anteriorly and posteriorly.
• Due to the lack of bony congruence,
joint stability is provided by two sets
of ligaments and the intra-articular
disc. The ligaments are divided into;
• Intrinsic ligaments; anterior and
posterior sternoclavicular ligaments
• Extrinsic ligaments; interclavicular
and costoclavicular ligaments
Ligaments and Joint Capsule

5. • Sternoclavicular ligaments (anterior and posterior) – these strengthen the
joint capsule anteriorly and posteriorly.
• Interclavicular ligament – this spans the gap between the sternal ends of
each clavicle and reinforces the joint capsule superiorly.
• Costoclavicular ligament – the two parts of this ligament (often separated
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.

6. • Due to the shape of its articular surfaces, the sternoclavicular joint is
classified as a saddle joint. However, functionally, it has the features of
a ball-and-socket joint, making it a multiaxial joint with the
movements:
• Elevation – depression (40°)
• Protraction – retraction (35°)
• Axial rotation (20-40°)
• Sternoclavicular (SC) joint movements use the lateral end of the
clavicle as a reference point. So during SC elevation the lateral end of
the clavicle elevates, while during depression the lateral end of the
clavicle lowers. In protraction the lateral end of the clavicle moves
anteriorly while in retraction it moves posteriorly.
Movements

7. •Serratus anterior
Forward
movement
•Trapezius and rhomboids
Backward
movement
• Trapezius,sternocleidomastoid,
levatorscapulae and rhomboids
Elevation
• Pectoralis minor and subclavius
Depression

8. Levator Scapulae
muscle
Serratus
Anterior Muscle
Rhomboid
Minor Muscle
Rhomboid Major
Muscle

9. • The AC joint is the articulation
between the acromial end of
clavicle and the clavicular facet of
the acromion of scapula.
• It is a plane synovial joint, with flat
articular surfaces which are
approximately the same in size.
ACROMIOCLAVICULAR JOINT:

10. • The acromioclavicular joint is
completely enclosed by a fibrous
capsule. Its inner surface is lined with a
synovial membrane, bounding the
synovial cavity of the joint. The capsule
is externally supported by the
acromioclavicular ligament
and trapezius muscle on its superior
aspect. The posterior capsular surface
is strengthened by the trapezius
muscle solely, while the anterior
surface is supported by the deltoid
muscle.
Ligaments and Joint Capsule
Trapezius Muscle

11. • The AC joint is stabilized by the two sets of ligaments;
• Intrinsic:
• Acromioclavicular ligament – runs horizontally from the acromion to the
lateral clavicle. It covers the joint capsule, reinforcing its superior aspect.
• Extrinsic:
• Conoid ligament – runs vertically from the coracoid process of the
scapula to the conoid tubercle of the clavicle.
• Trapezoid ligament – runs from the coracoid process of the scapula to
the trapezoid line of the clavicle.
• Collectively, the conoid and trapezoid ligaments are known as
the coracoclavicular ligament. It is a very strong structure, effectively
suspending the weight of the upper limb from the clavicle.

13. • Having the clavicle as a bone in common, the movements within
acromioclavicular and sternoclavicular joints are closely related to
each other. More specifically, the most important function of the
AC joint is to enable a wider range of movements (RoM) within the
pectoral girdle.
• The AC joint is a multiaxial joint which has three degrees of
freedom;
• Protraction - retraction
• Elevation - depression (total range of motion 15°)
• Lateral rotation - medial rotation (total range of motion 30°)
Movements

14. • The conoid part
prevents backward
movement of the lateral
part of the clavicle
without any similar
movement of the
scapula; the trapezoid
part prevents any such
forward movement.

15. REFERENCES:
• https://teachmeanatomy.info/upper-limb/joints/sternoclavicular/
• https://www.kenhub.com/en/library/anatomy/sternoclavicular-joint
• https://teachmeanatomy.info/upper-limb/joints/acromioclavicular/
• https://www.kenhub.com/en/library/anatomy/acromioclavicular-ac-joint

16. THANK YOU!