08/12/2025
Equine TMJ
The temporomandibular joint (TMJ) is a synovial joint that connects the mandible to the temporal bone. Its function is to open and close the mouth and move the jaw in an elliptical fashion, facilitating chewing.
The main muscles involved are the masseter, temporalis and medial pterygoideus. There is a cartilaginous meniscus disc within the joint as shown in picture 3, this is to provide cushioning when chewing.
The TMJ can be influenced by a number of things including bridle fit, padded headpieces and short enough cheek pieces, ensuring buckles are adjacent to the eye are paramount in maximising comfort and performance.
TMJ dysfunction has different severities ranging from trouble chewing and opening of mouth, to mild swelling around the joint, resistance to take a consistent contact and head shaking. These are all valid reasons to consult with your vet. Common conditions include osteoarthritis, trauma and fracture (Jasinski et al).
A gentle stretch is a lovely way of relieving tension in this area by carefully encouraging your horse to open and close their mouth, please see attached video, you can see how much she enjoys the release afterwords 😍
Stay tuned for the canine version! 📷 from Horses inside out head anatomy