Scapula

thumb|250px|Lopatka z přední strany, s popisky thumb|250px|Lopatka zezadu, s popisky Scapula (shoulder bone, shoulder blade, wing bone) is a flat bone, triangular in shape. It is placed on a posterolateral aspect of the thoracic cage, ranging from the level of the second rib to the level of the seventh rib.

Scapula connects with the humerus (upper arm bone) in the glenohumeral (shoulder) joint and the clavicula (collar bone) in the acromioclavicular joint. There is no direct connection between the thoracic cage and scapula. It is held in place thanks to surrounding muscles.

Main functions of the scapula are:

Being the origin and instertion of various muscles

Helping the movement of the upper limb (thanks to forces redirected by fornix humeri)

Protecting of the thoracic cavity from the dorsal side

The three borders of the scapula are:

Margo medialis

medial border, parallel to the longitudinal axis of the spine

Margo lateralis

lateral, or axillary border

Margo superior

superior border

Those three borders connect in three angles:

Angulus superior

margo superior and medialis

Angulus inferior

margo medialis and lateralis

Angulus lateralis

margo lateralis and superior

Dorsal surface

The back of the scapula is divided into two unequal parts by the spine of the scapula (spina scapulae). The spine ends in a process called the acromion. The acromion forms the cavity of the glenohumeral joint. The portion of the dorsal surface above the spine is called the supraspinous fossa. M. supraspinatus originates there. The portion of the dorsal surface below the spine is called the infraspinous fossa, much larger than the supraspionous fossa. M. infraspinatus originates there. Both muscles are parts of the rotator cuff, rotating the humerus and providing stability for the glenohumeral joint. The coracoid process originates from the superior border.

Ventral surface

The front of the scapula has a concavity called the subscapular fossa. M. subscapularis originates in the fossa.

Lateral surface

The glenoid cavity can be found at the lateral angle. The acromion the the coracoid process make its top border. Above and below the cavity, two tubercles serve as origins of muscles: Supraglenoid tubercle - origin of the long head of m. biceps brachii Infraglenoid tubercle - origin of the long head of m. triceps brachii