The humerus is connected to the scapula by the shoulder joint (articulatio humeri).
This joint is formed between the articular surfaces on the glenoid cavity of the scapula (cavitas glenoidalis);
and the head of the humerus (caput humeri).
The joint capsule is quite thin, elastic, poorly strengthened with ligaments, so the joint is often dislocated in various directions.
The articular capsule is attached along the edge of the glenoid labrum (labrum glenoidale)
on the scapula and along the anatomical neck (collum anatomicum) on the humerus.
According to the classification, the joint is spheroidal, multiaxial, simple and not combined.
The following range of motions is possible in the joint:
around the frontal axis: flexion and extension
around the sagittal axis: abduction and adduction
around the vertical axis: rotation
When shifting from the frontal axis to the sagittal, circumduction (circumductio) is carried out
The fixing apparatus of the joint is represented by several ligaments:
The coracohumeral ligament (ligamentum coracohumerale) begins at the external edge and base of the coracoid process of the scapula and, running in external and inferior directions, inserts into the superior part of the anatomical neck of the humerus.
Glenohumeral ligaments (ligamenta glenohumeralia) – are located under the fibrous layer of the capsule and additionally strengthen the joint.
There are several additional structures to this joint.
The glenoid labrum (labrum glenoidale), which deepens the glenoid cavity
The axillary synovial bursa (bursa synovialis axillaris). It does not communicate with the joint cavity.
The subtendinous bursa of the subscapularis muscle (bursa subtendinea m. subscapularis) is located at the base of the coracoid process of the scapula, under the tendon of the subscapularis muscle. It communicates with the joint cavity.
The intertubercular tendon sheath (vagina tendinis intertubercularis) envelops the tendon of the long head of the biceps brachii muscle, running through the joint above the head of the humerus.
The subdeltoid bursa (bursa subdeltoidea) does not communicate with the joint cavity.
The following vessels and nerves take part in the blood supply and innervation of the joint.
Arteries: supracapular artery (a. suprascapularis), anterior circumflex humeral artery (a. circumflexa humeri anterior), posterior circumflex humeral artery (a. circumflexa humeri posterior), circumflex scapular artery (a. circumflexa scapulae), thoraco-acromial artery (a. thoracoacromialis)
Veins: suprascapular vein (v. suprascapularis)
Nerves: axillary nerve (n. axillaris)
- shoulder joint
- articulatio humeri
- glenoid cavity of the scapula
- cavitas glenoidalis
- head of the humerus
- caput humeri
- labrum glenoidale
- anatomical neck
- collum anatomicum
- coracohumeral ligament
- ligamentum coracohumerale
- glenohumeral ligaments
- ligamenta glenohumeralia
- axillary synovial bursa
- bursa synovialis axillaris
- subtendinous bursa of the subscapularis muscle
- bursa subtendinea musculi subscapularis
- intertubercular tendon sheath
- vagina tendinis intertubercularis
- subdeltoid bursa
- bursa subdeltoidea