Anatomy study note · Upper limb
Shoulder joint
A synovial ball-and-socket joint between the large head of the humerus and the shallow glenoid cavity. It trades stability for a very wide range of movement and depends on the rotator cuff muscles for its strength.
Key points
- Ball-and-socket; shallow glenoid + labrum; lax capsule.
- Stability = rotator cuff (SITS); weakest part = inferior.
- Commonest dislocation: anterior–inferior → axillary nerve at risk.
- Abduction: supraspinatus 0–15°, deltoid after; scapula rotates 1° for every 2° at the joint.
- Long biceps tendon runs inside the joint, under the transverse humeral ligament.
- Nerves: axillary + suprascapular.
- Joint: from mesenchyme between bone ends.
- Synovial cavity forms in the middle layer.
- Synovial membrane: type A (phagocytic) + type B (secretory) cells.
- Joint surfaces: hyaline cartilage, no perichondrium.
The full note in the atlas also covers
Relations · Features · Action · Nerve supply · Histology · Development · Clinical notes
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Written from
- Snell’s Clinical Anatomy by Regions, 10th ed., ch. 3, PDF pp. 303–306, 400–408
- Inderbir Singh’s Human Embryology, ch. 10, PDF p. 144
- BRS Cell Biology & Histology, 7th ed., ch. 7, PDF pp. 117–120, 131
More from the upper limb
- Sternoclavicular joint
- Subclavius
- Subscapular nerves
- Subscapularis
- Supinator
- Suprascapular nerve
- Supraspinatus
- Supratrochlear (cubital) lymph node
- Teres major
- Teres minor
- Thenar muscles
- Thoracodorsal nerve
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