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Scapula

Os scapulae

Flat and triangular, the scapula forms the posterior part of the shoulder girdle, articulating with the clavicle and the humerus and giving attachment to numerous muscles. It rests on the posterolateral thorax between the second and seventh ribs. Its surface features include the spine, the acromion, the coracoid process, the glenoid cavity that receives the head of the humerus, the supraspinous and infraspinous fossae, and the subscapular fossa. Fractures usually follow high-energy trauma and often accompany injuries within the thorax. Palsy of the long thoracic nerve causes scapular winging, in which the medial border lifts away from the chest wall, and the acromion may impinge on the rotator cuff.

The scapula sits on the posterolateral aspect of the thorax between ribs 2 and 7. Key features include the spine, acromion, coracoid process, glenoid cavity (for the shoulder joint), supraspinous and infraspinous fossae, and subscapular fossa.

On this page
種類 Bone
器官系 Skeletal
身体部位 Shoulder
親構造 endochondral bone
ラテン語名 Os scapulae
FMA ID 13394

機能

A flat, triangular bone that forms the posterior part of the shoulder girdle. Provides attachment for numerous muscles and articulates with the clavicle and humerus.

臨床的意義

Scapular fractures typically result from high-energy trauma and are often associated with thoracic injuries. Scapular winging occurs with long thoracic nerve palsy. The acromion process can impinge on the rotator cuff.

Frequently Asked Questions

What is the function of the scapula?

The scapula (shoulder blade) is a flat triangular bone that serves as the attachment site for 17 muscles involved in arm and shoulder movement. It forms two important joints: the glenohumeral joint (shoulder joint) via the glenoid cavity, and the acromioclavicular joint via the acromion. The scapula enables a wide range of arm movements through coordinated scapular rotation, elevation, depression, protraction, and retraction.

Where is the scapula located?

The scapula lies on the posterior thoracic wall, overlying approximately ribs 2 through 7. It is a floating bone with no direct bony connection to the axial skeleton — it is held in place entirely by muscles. The spine of the scapula, a prominent ridge on its posterior surface, is easily palpable and leads to the acromion, which projects over the shoulder joint.

What is a scapular winging?

Scapular winging occurs when the medial border of the scapula protrudes abnormally from the posterior chest wall, resembling a wing. The most common cause is paralysis of the serratus anterior muscle due to injury of the long thoracic nerve (C5–C7), which is vulnerable to traction injuries. Less commonly, trapezius weakness from spinal accessory nerve damage causes lateral winging.

References

  1. Foundational Model of Anatomy — FMA:13394 Reference anatomy ontology (University of Washington)
  2. UBERON — UBERON:0006849 Cross-species anatomy ontology (EMBL-EBI Ontology Lookup Service)
  3. Wikipedia — Scapula Encyclopedia article (verified cross-reference)

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Educational Disclaimer

This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for medical decisions.

Data sources: Terminologia Anatomica, Foundational Model of Anatomy, Wikidata.