Jenna Week 5 & 6: Impact of the Sphenoid Bone on Metabolism
As Jenna’s feet continue to become increasingly stable and strong, we started doing some basic footwork tasks. Her favourite is walking off the trail that we normally run on, and stepping over various sized logs. This helps her to navigate her own foot placement as well as activates core and stabilizing muscles since the terrain is less predictable than a flat gravel path. Included with these short bursts of log stepping there are also small up and down hills that we weave through. She responds positively every time we have done this activity. Always eager and inquisitive. She is also provided daily access to the larger paddock spaces with varied terrains which helps improve movement tolerance and hoof growth.
Jenna’s exercise program continued to progress up to 5km walk-runs approximately 3-4 times per week with lighter walking only on alternate days. She was doing well with this increased exercise, but did suffer one minor setback. She presented with soreness in the hip/SI joint region which lead to one week of just walking combined with manual treatments to that specific area. Following this she was able to resume the previous exercise program with no issues. Just as with humans, it is possible she had delayed onset muscles soreness, pulled a muscle, or even just stepped awkwardly in her paddock, but with quick and proper management, these types of small setbacks can be rehabbed very quickly.
I conducted an observation and palpation assessment of the major cranial bones. The findings were shocking to say the least.
Before going into details about the assessment findings, I would like to explain the relevance of assessing cranial bones. There are 34 bones in the equine cranium. These bones are held together by suture joints which look like tiny little zigzags to the naked eye, but their structure is much more complex than was originally noted in early studies.
For a very long time these bones were thought to be fused, however research has now concluded that there is in fact a very small amount of movement ~ 1mm available between these joints.
Why is this important?
Trauma to the head, muscle imbalance, dental issues, medications, ill-fitting tack, and even hind end restriction can affect the cranium. In fact, there are direct fascial lines that link the sacroiliac joint (SI Joint – hind end) to the temporomandibular joint (TMJ – jaw). I find these connections fascinating because it is something I see commonly in horses but have difficulty convincing owners and trainers of the anatomical relevance. Any shift in cranial bone(s) can have far reaching effects through the skeletal chain and vice versa from the hind end up.
As we know, the cranium protects the brain but it also houses all the cranial nerves, some of which extend past the cranium such as the vagus nerve discussed last week. As well, the motor control centre is housed in the brain and is in charge of controlling the entire body! The brainstem exits at the foramen magnum (a large hole at the base of the skull) and continues down the back - what we know as the spinal cord. For these reasons it is important to meticulously check the position and movement of each cranial bone when assessing the whole horse.
Jenna’s cranial assessment revealed a dramatic cranial shear to the right. A cranial shear is when one or more bones has moved off axis taking with it the associated internal structures of the brain.
Specifically, her sphenoid bone was palpated presenting as torsioned and sheared to the right. This shear is even visible just by looking at the external structure of her face. Her left eye is sunken inward and dropped in comparison to the right. There are fewer wrinkles above her left eye indicating tissue tension in the area. The left nostril is pulled up towards the eye and her frontal bone (forehead) on the left is sunken when compared to the right.
The outer bones of the face are a direct reflection of what the internal bones are doing. As discussed above, the bones of the cranium are held together by suture joints that do in fact move, therefore it is impossible to move one bone without it affecting other bones. Think of a jigsaw puzzle that is fully intact then take two corners and rotate them in opposite directions – you will see the entire puzzle move with gaps and twists occurring between individual pieces, unless pressure gets so high that pieces then collapse inward or break apart in an upward direction.
The Sphenoid Bone
The sphenoid bone sits in the center of the cranium. It is often referred to as “bat shaped” because of its distinctive form which closely resembles that of a bat in flight. It consists of a body at the center and two large wing like projections from the body.
As is pictured below, there are many holes (foramen) which are exit points for certain blood vessels and nerves – one of which being the optic nerve (eyes!). I am trying to give a clear picture visually to help people understand how a torsion could easily affect the functionality of many other structures within the cranium and body.
Since this bone articulates with 12 other cranial bones, it can have a vast effect on the overall cranium if it is out of place. The surface of the sphenoid bone is named the sella turcica which is latin for Turkish seat due to its saddle like shape (how suitable in the case of horses). This small saddle shaped depression is home to the pituitary gland – a very important little gland. The pituitary gland takes messages from the brain and uses these messages to produce hormones that affect the rest of the body. Specifically, the anterior portion of the pituitary gland produces adrenocorticotropic hormones (ACTH) which stimulates the adrenal glands to secrete cortisol which regulates growth, metabolism, and body composition.
This bone and the subsequent pituitary gland positioning are of particular importance to me for this case study as Jenna arrived with a diagnosis of Equine Cushings. If the sphenoid bone is torsioned, a compression to the pituitary gland can occur causing dysfunction in the hormones being produced which could present very similarly to Cushings. There is evidence of cranial sheers being misdiagnosed for metabolic syndromes in humans which lead me to ask the obvious question – could this be the same for horses???
I treated her cranium three times and the results were astonishing. The before and after photos below demonstrate just how moveable these bones actually are. Her left eye moved closer to midline and appears less sunken. She regained more symmetrical wrinkling above both eyes. Her left nostril is more in line with the right one and her forehead muscles and bones are closer to even. This photo was taken after the third treatment but all treatments occurred within the same week. Not only did Jenna demonstrate some pretty massive releases during treatment, she also appeared to be substantially more vibrant and energetic immediately after. Unfortunately, without the ability to restrict Jenna’s Cushings medicine and re-test her hormone levels it will be difficult to know whether or not the cranial sheer was the main contributing factor or not, but this case has sparked a very strong desire to conduct research in this field as I see so many horses affected by proposed metabolic syndromes.
In the videos below I go through 19 of the 34 bones that make up the face and head one by one. In the first video demonstration, palpation, and treatment of the following cranial bones: the occiput, parietals, temporals, temporomandibular joint (TMJ), zygomas, lacrimals, mandibles, trigeminal nerve, hyoid, maxillas, nasals, and the incisors. In the second video I show you treatment of her sphenoid bone.