Scapula
The scapula (shoulder blade) is a large, flat, roughly triangular bone that lies against the thoracic wall. It does not form a true bony joint with the trunk but is attached solely by muscles (synsarcosis or the thoracic sling). The spine of the scapula runs along its lateral surface and divides it into the supraspinous and infraspinous fossae. The glenoid cavity at the distal end articulates with the humerus to form the shoulder joint. In the horse the scapula is oriented cranioventrally and is critical for forelimb extension and weight bearing. The angle of the scapula affects stride length. The scapular cartilage is a crescent-shaped cartilaginous extension at the dorsal border of the scapula. It enlarges the area for muscle attachment and acts as a shock absorber during locomotion. The cartilage gradually ossifies with age, becoming more brittle and less effective as a shock absorber in older horses.
Origin: N/A (bone)
Insertion: N/A (bone)
Action: Connects the forelimb to the trunk via the muscular sling; the angle of the scapula determines the range of shoulder joint motion and stride length
Scapular fractures are uncommon but serious. The thoracic sling is critical for suspending the thorax between the forelimbs. Scapular cartilage ossification is a normal age-related change. Relevant in evaluations of shoulder function and after trauma.
## Overview Scapular fracture is a break of the shoulder blade from direct trauma such as kicks, falls, or collisions. The spine of the scapula and supraglenoid tubercle are common sites. Signs inclu
Injury to the suprascapular nerve as it crosses the cranial border of the scapula, typically from direct trauma (collision with doorframes, trees). Causes denervation atrophy of the supraspinatus and
Sudden severe lameness or swelling over the shoulder after trauma should be evaluated immediately. Correct saddle fit helps protect the region.
## Overview Scapular fracture is a break of the shoulder blade from direct trauma such as kicks, falls, or collisions. The spine of the scapula and supraglenoid tubercle are common sites. Signs include sudden severe forelimb lameness, swelling over the shoulder, and pain on manipulation. Muscle atrophy resembling sweeney can develop over weeks. ## Causes Direct trauma. ## Diagnosis Radiographs or ultrasound of the scapula. ## Treatment Conservative management for many fractures. Surgical repair for selected supraglenoid or displaced fractures. Prognosis varies by location. ## Recovery and Prognosis Fair to good for many body or spine fractures. Supraglenoid fractures have a more guarded athletic outlook. ## Prevention Trauma avoidance. Signs include: sudden severe forelimb lameness; swelling over the shoulder; limb may swing outward; pain on manipulation; later muscle atrophy
Injury to the suprascapular nerve as it crosses the cranial border of the scapula, typically from direct trauma (collision with doorframes, trees). Causes denervation atrophy of the supraspinatus and infraspinatus muscles. Signs include: Characteristic lateral shoulder instability ('shoulder slip') during weight bearing; rapid atrophy of supraspinatus and infraspinatus creating a visible hollow above the scapular spine; lateral subluxation of the shoulder during weight bearing; Rapid dramatic wasting of the muscles on either side of the scapular spine; the scapular spine becomes extremely prominent; shoulder instability; the shoulder may pop laterally during weight bearing; often from running into a solid object.; Obvious muscle wasting below the scapular spine; shoulder visibly slips laterally during walking; angular shoulder appearance; often recovers spontaneously over months if nerve not severed.
Scapular fractures are uncommon but serious. The thoracic sling is critical for suspending the thorax between the forelimbs. Scapular cartilage ossification is a normal age-related change. Relevant in evaluations of shoulder function and after trauma.
Sudden severe lameness or swelling over the shoulder after trauma should be evaluated immediately. Correct saddle fit helps protect the region.
See the Scapula (Shoulder Blade) on our interactive 3D horse model. Open 3D Model