Don't get on my nerves!

 There has been quite a lot of spotlight recently on bridle fit, nose bands, bits etc etc, so I thought I’d do a little post on nerves and locations, to arm you with a little knowledge to be able to take these factors into consideration when fitting a bridle. A correct bridle fit really is just as important as a properly fitted saddle. A horse that displays unwanted behaviour is not trying to “get one over on you” or “being a pain”, it's just a horse that has no other way of communicating with you other than through its behaviour and is most probably uncomfortable or in pain.  

There are so many really important factors to take into consideration when fitting a bridle, some are, the shape of the horse’s head, asymmetry in the head, space between the base ears and the wing of the atlas, space and pressure on the base of the ears, pressure on the TMJ, location and pressure on the facial nerves and arteries and so many more.

Another one is also whether to use a nose band at all, some horses may like the security and stability it could bring to the bit, but whether you decide to use a noseband is entirely personal preference and depends on your horse.  In practice I have seen how overly tightly and badly fitted nosebands can really have negative painful effects on the masseter muscles, TMJ and poll area. Complete removal of the noseband and subsequent sports therapy treatment thankfully remedied the painful situation in these horses. I personally also have found in some of the horse’s I’ve owned myself have gone positively remarkably well without one. 

🦴 Moving onto the anatomy, as you can see from the  diagrams above (credit sourced below) the horse has many nerves that cover and run like a small network over the horse’s head, constantly transmitting information to and from the brain and allowing motor functions. Two of the most important nerves that I decided to highlight for important consideration when fitting a bridle are the Trigeminal nerves and facial nerves. I decided to use this horse’s skull and play dough.. you can see the trigeminal nerve (Green) which has three main branches, ophthalmic, maxillary and mandibular, and the facial nerves (Purple).  The exact locations of the facial nerves do slightly vary from horse to horse, but you can see their approximate location, -however none of these are to scale! because remembering this is playdough and was tough to work with and a limit to how thin it could be rolled!

The Trigeminal nerve is the largest of the cranial nerves, it has three branches and is the one most associated with the awful condition of head shaking. Other problems associated with pain in this nerve can also be displayed as behavioural issues such as struggling to get a bridle on, chewing on the bit, playing with the tongue, soreness or sensitivity in the temporal muscles and poll region, and sensitivity and or tension in the masseter muscles. This nerve, branching into three, travels from the brain into the orbit of the eye, along the length of the maxilla and the length of the mandible. Its job is to transmit information for both sensory information such as temperature, pressure, pain and proprioception and for the motor function of mastication.

Sensory information responsibilities of each branch
Ophthalmic branch- mucous membranes of the nasal cavity, orbit of the eye, skin of the eyelids, eyebrows, forehead and nose
Maxillary Branch -Lower eyelids, nose, upper lip, upper jaw, inc teeth!
Mandibular Branch – Skin of temporal region, lower lip and chin, mastication muscles, some ear parts, mucous membranes of rostral two thirds of tongue, gums and teeth!

🦷Yes, you heard it correct! Teeth!🦷... contrary to old fashion beliefs where we were all told horses teeth don’t have nerves, well, it has long been scientifically proven that nerve fibres enter through the root opening into the root canal of the tooth. However, it is thought that sensitivity from extreme heat or that we experience as toothache, does not exist in horses. Anyway teeth are a whole other topic for another day.. although there is a nice video below for you to peruse 🦷😊

The facial Nerve – This nerve is located lying across the superficial facia of the masseter muscle on each side of the head, coming out from the parotid gland just below the TMJ, and can even sometimes be seen with the naked eye in thinner skinned less hairy horses when they yawn or are chewing. Unfortunately, it is a nerve that can be easily damaged by a blow to the head, sadly then resulting in paralysis of the facial muscles on that side. The muzzle would then be pulled to opposite side of the head by the muscles that would be still functioning there. Its role is to supply motor function to all the facial muscles, from as far up as the ear down to the lips, nostrils and muzzle. It also processes taste sensations from the tongue. 

💡So, with all this in mind as you can now probably understand how important it is to ensure a correctly fitting bridle does not exert any unnecessary pressure onto sensitive areas such as around the infraorbital foramen and the TMJ where you can clearly see where a large number of nerves are situated around and emerge from. My job here was not to advise on bridle fitting as that is a monster of a topic, but to make you aware of some of the sensitive nerves of the head and their functions. So, if unsure on bridle fitting for your horse or pony, please do consult a qualified bridle fitter in your area because my post really is just the tip of the iceberg when it comes to thinking about the horse’s anatomy and bridle fitting. 

🐴If you are interested in finding out more here are some good resources:
https://www.horsesinsideout.com/.../bridle-fit-for-a...

There is an excellent webinar found on the Dr. David Marlin website, by Diane Fisher who is a consultant bridle fitter for the British Equestrian world program, an SMS Master Saddlefitter, and qualified bridle fitter, a UKCC British Dressage accredited coach, and a lecturer and assessor for the Society of Master Saddlers saddle & bridle fitting courses. Diane talks in depth about her research and pressure testing into bridle fitting, all the important considerations when fitting a bridle, frequent problems that she comes across and interesting findings around ear bonnets. It really is worth a watch. https://drdavidmarlin.com/webinar-equine-bridles-diana.../
https://www.bhs.org.uk/horse-care.../features/bridle-fit/

🦷If you are interested in teeth and caring for your horse’s mouth, Dr. Chris Hannes has an excellent book out called “Caring for the horse’s teeth and mouth” and has a very interesting experiment with a bucket for you to try out if you use a curb bit and chain. 

Credit sources to
Illustrated head anatomy for health, performance, bridle fit and design By Gillian Higgins.
Caring for the horse’s teeth and mouth By Dr. Chris Hannes.
Horse Anatomy by Robert A. Kainer and Thomas O. McCracken.
Equine Bridles Webinar By Diane Fisher.
Drawn Images courtesy of https://pressbooks.umn.edu/largeanimal.../chapter/neck-head/