Overview
The scapula (scapula) is a flat, roughly triangular bone lying against the lateral surface of the first ribs. Its dorsal border is extended by the scapular cartilage. Cattle have no clavicle: the thoracic limb is attached to the trunk by muscles only (synsarcosis), chiefly the serratus ventralis, trapezius, rhomboideus and pectoral muscles.
Key features
- Spine of the scapula (spina scapulae): ridge dividing the lateral surface into two fossae. In cattle it is displaced towards the cranial border, so the infraspinous fossa is much larger than the supraspinous fossa; the muscles of the same names originate in them.
- Acromion: distal end of the spine, well developed in cattle (absent in the horse); the acromial part of the deltoideus originates on it.
- Glenoid cavity (cavitas glenoidalis): shallow articular surface that receives the head of the humerus.
- Supraglenoid tubercle: cranial to the glenoid cavity; origin of the biceps brachii muscle. The small coracoid process projects from its medial side and gives origin to the coracobrachialis.
- Neck of the scapula: narrowing proximal to the glenoid cavity.
- Borders: the cranial border is thin; the caudal border is thick.
Clinical relevance
- Palpation landmarks: the spine and acromion are palpable in the live animal; the scapula marks the caudal boundary of the neck triangle recommended for injections.
- Fractures: uncommon in cattle; they follow severe trauma such as falls or collisions.