TMJ–the master link A properly functioning temporo-mandibular joint is crucial to a horse’ s well being and performance.
by Heather K. Mack, VMD
orses rely heavily on the proper function of the temporo-mandibular joint (TMJ). The ability to move the jaw correctly – side to side, forward and back, up and down – affects not only their ability to masticate, which is the very first step in proper digestion, but also body balance and biomechanics. Yet proper TMJ function often gets overlooked by veterinarians. I practice and teach a dental paradigm based on the principle that the TMJ is the “master link” in equine biomechanics. In balanced equine dentistry, we work toward maintaining equilibrium or a balanced state of repose between two or more antagonistic forces that exactly counteract each other. In doing so, we adjust the angles and planes of the cheek teeth and incisors. This maximizes the surfaceto-surface contact between these biophysical planes and achieves optimal jaw biomechanics. Ultimately,
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integrative veterinary care
we are looking to achieve three-point harmony between the incisors, molar tables and TMJ.
Anatomy The TMJ is a complex array of bones, muscles, ligaments, fascia, nerves and cartilage. It is a synovial joint between the condyles of the mandible and the temporal bone. It is a very strong, tight encapsulated joint with an articular disc that allows for the gliding movement of the condyle. The horse’s TMJ is considerably more complex than a human’s because of three factors: 1. I t is connected to the ears and horses have movable ears with 20 or more muscles. 2. The hyoid bone articulates with the temporal bone. 3. H orses have teeth erupting continuously throughout their lives.
