The Equine Neck

Equine neck; equine cervical vertebrae, intervertebral joints, equine Nuchal Ligament

Equine neck; equine cervical vertebrae, intervertebral joints, equine Nuchal Ligament

The tale of this unsung hero and a guide to everlasting cervical happiness in your horses. 

By Alexa Linton, Equine Sports Therapist

There is something uniquely beautiful about the neck of a horse. That curve, the arch of the poll, the dip towards the shoulder. In function, those elegant lines came to be out of necessity, with such length required to balance out long limbs, allowing them to reach to the ground to graze for up to 20 hours a day. With the head and neck making up about 10 percent of their total body mass, horses use their neck to maintain balance, stability, and their spatial awareness when they are in motion. Over time, the equine neck has shifted in function and importance, and in the factors that impact and promote its well-being, but the fundamentals have stood the test of domestication.

A horse pulls back in a trailer. A horse is held in constant and/or full flexion of the neck without release. A horse tends to travel with the head up and the neck and back in tension. Or, a horse has a poorly fitting saddle. These examples are just a few of the reasons a horse may need support to bring their neck back into a healthy state. Thankfully, most neck injuries fall in the soft tissue category, as the more fragile parts of the cervical spine are quite well protected by a rather brilliant anatomical make-up. Although rare, spinal cord compression can occur in the cervical spine, signalled by a lack of coordination in movement, and a decrease in muscle strength and lower body awareness. In these cases, contact your veterinarian immediately. 

Equine neck; equine cervical vertebrae, intervertebral joints, equine Nuchal Ligament

During movement, the horse uses its head and neck for balance and stability, and to maintain a horizontal visual plane. Photo: Shutterstock/Olga I

On that note, let’s get our inner geek on and find out what’s happening under the skin.

The Bones of the Matter

Just like us, horses have seven cervical vertebrae, functioning to protect the spinal cord, connect the head and the trunk, and allow for complex motor movements of the head. This S-shaped part of the spine is built to be adaptable and mobile, and plays an essential role in activities like balance, feeding, grooming, locomotion, and visual and auditory orientation. 

In most intervertebral joints of the horse, including most of the cervical spine, the joint is built like a shallow ball-and-socket, providing stability without limiting mobility, and allowing primarily the movement of flexion-extension, with side bending and axial rotation as secondary movements. The first two cervical vertebrae, commonly referred to as the atlas and axis, are atypical, with unique structures characteristic of their function - the intervertebral disks are replaced by a single synovial articulation and the atlantoaxial joint (between the first and second cervical vertebrae) is a pivot joint allowing substantial rotation, critical for visual and vestibular health. To create this pivot joint, the axis has a process called the dens or odontoid which projects upwards into the vertebral foramen of the atlas. The hinge joint between the occiptal bone of the skull and the atlas, called the atlanto-occipital joint, or in most horse circles, the poll, allows for maximum flexion and extension. The remaining five vertebrae (C3 to C7) are more typical, with facet joints creating an articulation between the vertebrae, a vertebral body, and an intervertebral disc sandwiched in between, and varying ranges of mobility depending on their form, with the most mobile and susceptible vertebrae being C6 and C7. 

Equine neck; equine cervical vertebrae, intervertebral joints, equine Nuchal Ligament

The Nuchal Ligament

Meet a key player in the neck! This powerful ligament begins at the nuchal line of the occipital bone and extends to the lumbar vertebrae via a thick cord of tissue called the funicular portion, with a sheet-like lamellar portion extending down to the second cervical vertebrae through the fifth cervical vertebrae (in the past it also extended to C6 and C7). It plays an essential role in suspending the head and upper cervical vertebrae and limiting axial rotation when standing and in movement. 

Under Saddle 

Lowering or flexing the neck places the nuchal ligament under tension, and induces separation of the spinous processes in the thoracic region and an elevation of the spine, therefore creating a structure capable of supporting a rider’s weight, and freeing up the longissimus dorsi muscle for creating momentum rather than protecting the spine. This is just one of the many benefits of allowing your horse to travel in a relaxed, unrestrained, and lowered neck position for portions of your ride, or in a position of self-carriage and relaxed collection. More extreme positions, such as extreme neck flexion or extreme low neck, could be potentially adverse to the horse and the health of their neck and spine.

Equine neck; equine cervical vertebrae, intervertebral joints, equine Nuchal Ligament

Flexion of the neck places the nuchal ligament under tension, and extreme neck flexion can negatively impact the health of the horse’s neck and spine. Photo: Canstock/Virgonira

When you ride, take a moment to watch the movement of your horse’s neck. Their oscillations in gait are directly linked to the movement patterns of their trunk and legs. In fact, during movement, the head and neck play a critical role in facilitating both balance and stability, helping to hold the visual field in a horizontal plane and supporting healthy vestibular function. It is natural for the added weight of a rider to cause head and neck elevation, often referred to as hollow neck, as horses attempt to find their balance. However, this type of carriage over extended periods can increase the possibility of arthritis and soft tissue compensations, such as an overdeveloped brachiocephalicus muscle at the base of the neck, or tenderness in the back, and indicates high stress levels in the horse. 

What Can You Do? 

To help promote a healthy, happy neck, remember to keep your rides interesting and varied, only riding in contact for a maximum of ten minutes, and altering the head and neck posture and routine frequently. For young horses, vary their head and neck posture more often while they build strength and stamina. Listen to your horse by watching the ears, feeling for a tight back both in and out of the saddle, and observing any tension in the jaw or neck. 

Equine neck; equine cervical vertebrae, intervertebral joints, equine Nuchal Ligament

Photos courtesy of Alexa Linton 

To build stability within the deep ventral muscles of the lower cervical region where the nuchal ligament is no longer present, equine anatomist Sharon May-Davis suggests emulating the action of browsing for short periods of time (10 to 20 minutes maximum) by hanging hay nets high up and encouraging your horse to reach. This is something I look forward to trying with my mare in the months to come.

Most horses can benefit greatly from soft tissue release in the muscles, fascia, and ligaments of the neck, as this is an area where tension is often held. A regular equine therapy visit can help to free up the cervical region while releasing the whole spine. Need a recommendation? I’m happy to help guide you to a therapist that works for your needs. 

Main article photo: Shutterstock/Svetlana Ryazantseva

This article was originally published in the Autumn 2018 issue of Canadian Horse Journal.