Unlike humans, horses don’t have collar bones to connect the limb to the trunk, instead they have a group of strong muscles collectively called the thoracic sling which helps suspend the chest between the forelimbs. The Trapezius is one of the important muscles that make up the thoracic sling.
The Trapezius muscle is the most superficial muscle covering the shoulder region, it is a large flat muscle that is split into two parts: the cervical (neck) and thoracic (chest) part.
Originates:
Cervical Part of Trapezius – Funicular part of Nuchal ligament
Thoracic Part of Trapezius – Supraspinous ligament from T3-10
Inserts:
Cervical Parts of Trapezius – Spine of Scapula
Thoracic Part of Trapezius – Spine of Scapula
Action:
The Cervical part of the Trapezius elevates the shoulder and swings the scapula cranially (towards the head or for ease, forwards). The Thoracic part of the Trapezius again elevates the shoulder but is responsible for swinging the scapula caudally (towards the tail or for ease, backwards).
Could you spot tension in this area?
• Reduced range of motion or a choppy stride
• Reduced coordination and proprioception
• Loss of scapula movement
• Nonspecific loss of power
• Negative reaction when tightening the girth
• This muscle can become hypertrophied (increased muscle size) or atrophied (wasting or thinning of muscle mass) due to poor saddle fit. The Thoracic Trapezius can also become asymmetrical through poor saddle fit and inappropriate saddle pad use.
Do you know some causes of tension in this muscle?
• Poor saddle fit
• Unbalanced riders
• Landing after jumping
• Abrupt movements quick changes in direction and sudden stopping and starting – think showjumpers, polo ponies, eventers, hunters, mounted games horses for example..
If you think I can help with any of the issues mentioned above, don’t hesitate to get in touch!