Download Shoulder Joint

Joints of the Pectoral and Shoulder
Region
Sternoclavicular Joint
Sternoclavicular Joint
It is an articulation between the medial end of the clavicle, the
manubrium sterni, and the 1st costal cartilage. It is synovial
double-plane joint.
Sternoclavicular Joint
The joint is surrounded by capsule which is attached to the
margins of the articular surfaces, the capsule is lined by
Synovial membrane which is also attached to the margins
of the cartilage covering the articular surfaces.
Sternoclavicular Joint
The capsule is reinforced in front of and behind the joint
by the strong sternoclavicular ligaments (Ant. & Post.).
There is also a strong acessory ligament called
costoclavicular ligament attached between the 1st rib
and the end of the clavicle.
Sternoclavicular Joint
■ Articular disc: is a flat fibrocartilaginous disc lies within
the joint and divides the joint’s interior into two
compartments.
■ Nerve supply: The supraclavicular nerve and the nerve to
the subclavius muscle.
Sternoclavicular Joint
Movements
Forward and backward movement of the clavicle takes
place in the medial compartment. Elevation and depression
of the clavicle take place in the lateral compartment.
Sternoclavicular Joint
Important Relations
■ Anteriorly: The skin and some fibers of the
sternocleidomastoid and pectoralis major muscles.
■ Posteriorly: on the right, the brachiocephalic artery; on the
left, the left brachiocephalic vein and the left common carotid
artery.
Shoulder Joint
Shoulder Joint
■ Type: Synovial ball-and-socket joint.
■ Articulation: between the rounded head of the humerus and the
shallow, pear-shaped glenoid cavity of the scapula.
Shoulder Joint
The articular surfaces are covered by hyaline articular cartilage,
and the glenoid cavity is deepened by the presence of a
fibrocartilaginous rim called the glenoid labrum.
Shoulder Joint
■ Capsule: it surrounds the joint and is attached medially to the
margin of the glenoid cavity outside the labrum; laterally, it is
attached to the anatomic neck of the humerus.
Shoulder Joint
■ Capsule: It is strengthened by the ligaments and by the tendons
of the subscapularis, supraspinatus, infraspinatus, and teres minor
muscles (the rotator cuff muscles).
Shoulder Joint
■ Ligaments:
1. The glenohumeral ligaments
are three weak bands of
fibrous tissue that strengthen
the front of the capsule.
2. The
transverse
humeral
ligament
strengthens
the
capsule and bridges the gap
between the two tuberosities.
3. The coracohumeral ligament
strengthens the capsule above
and stretches from the root of
the coracoid process to the
greater tuberosity of the
humerus.
■ Ligaments:
Shoulder Joint
4. Accessory ligaments: The coracoacromial ligament extends
between the coracoid process and the acromion. Its function is to
protect the superior aspect of the joint.
Shoulder Joint
■ Synovial membrane: This lines
the capsule and is attached to the
margins of the cartilage covering the
articular surface. It forms a tubular
sheath around the tendon of the long
head of the biceps brachii. It extends
through the anterior wall of the
capsule to form the subscapularis
bursa beneath the subscapularis
muscle.
■ Nerve supply: The axillary and
suprascapular nerves
Shoulder Joint
Movements
 The shoulder joint has a wide range of movements, and this on
the expense of the stability of the joint. The inferior part of the
capsule is the weakest area.
 The shoulder joint is the most commonly dislocated large joint
in the body.
 The strength of the joint depends mainly on the tone of the
rotator cuff muscles that cross in front, above, and behind the
joint.
Shoulder Joint
Movements
■ Flexion: Normal flexion is about 90°
and is performed by the anterior fibers
of the deltoid, pectoralis major, biceps,
and coracobrachialis muscles.
■ Extension: Normal extension is
about 45° and is performed by the
posterior fibers of the deltoid,
latissimus dorsi, and teres major
muscles.
Shoulder Joint
Movements
■ Abduction: Normally, is 180°, it
occurs both at the shoulder joint and
between the scapula and the thoracic
wall. It is performed by middle fibers
of the deltoid, assisted by the
supraspinatus.
■ Adduction: Normally, about 45°.
This is performed by the pectoralis
major, latissimus dorsi, teres major,
and teres minor muscles.
Abduction of the arm involves rotation of the scapula as well as movement
at the shoulder joint; for every 3° of abduction of the arm, a 2° abduction
occurs in the shoulder joint, and 1° occurs by rotation of the scapula. At about
120° of abduction, the greater tuberosity of the humerus hits the lateral edge of
the acromion. Elevation of the arm above the head is accomplished by rotating
the scapula. S, supraspinatus; D, deltoid; T, trapezius; SA, serratus anterior.
Shoulder Joint
Movements
■ Lateral rotation: Normally, is 40° to
45°. This is performed by the
infraspinatus, the teres minor, and the
posterior fibers of the deltoid muscle.
■ Medial rotation: Normally, about 55°.
This is performed by the subscapularis,
the latissimus dorsi, the teres major, and
the anterior fibers of the deltoid muscle.
■ Circumduction: it is a combination of
the above movements.
Surface anatomy
Surface anatomy
Anterior Surface
Clavicle
The clavicle is situated at the root of the neck and throughout its
entire length lies just beneath the skin and can be easily
palpated.
Surface anatomy
Anterior Surface
Deltopectoral Triangle
This small, triangular depression is situated below the outer
third of the clavicle and is bounded by the pectoralis major and
deltoid muscles.
Surface anatomy
Anterior Surface
Axillary Folds
The anterior axillary fold: is formed by the lower margin of
the pectoralis major muscle and can be palpated between the
finger and thumb. This can be made to stand out by asking the
patient to press his or her hand against the ipsilateral hip.
Surface anatomy
Anterior Surface
Axilla:
The structures can be felt in the axilla:
1. The inferior part of the head of the humerus.
2. The pulsations of the axillary artery.
3. The cords of the brachial plexus.
4. The medial wall of the axilla (formed by the upper ribs
covered by the serratus anterior muscle).
5. The lateral wall (formed by the coracobrachialis and biceps
brachii muscles and the bicipital groove of the humerus).
Surface anatomy
Posterior Surface
Scapula
The spine of the scapula can be
palpated and traced medially to
the medial border of the scapula,
which it joins at the level of the
3rd thoracic spine. The superior
angle of the scapula can be felt
through the trapezius muscle and
lies opposite the 2nd thoracic
spine. The inferior angle of the
scapula can be palpated opposite
the 7th thoracic spine.
Surface anatomy
Posterior Surface
Axillary Folds
The posterior axillary fold: is formed by the tendon of
latissimus dorsi and the lower border of the teres major muscle.
It can be easily palpated between the finger and thumb.