Thoracic sling – a lesson in anatomy
Understanding the anatomy of the thoracic sling is essential in our ability to make good decisions when it comes to training our horses.
The thoracic sling has become an important topic in the past couple of years – and rightly so! While the idea of a swinging back and active hind legs is something we have been told since we first started riding lessons, the concept of the thoracic sling and its role in healthy biomechanics is something a lot of riders haven't heard of before.
The general idea is that the muscles that attach the front legs to the trunk (the thoracic sling), need to be strong, but supple in order to act as shock absorbers and allow the spine to have a healthier range of movement. Issues in the thoracic sling can lead to anything from back issues, to hoof imbalances, and even nerve impingements. Because it is sometimes hard to imagine how this area can have such a big impact, it helps to be able to visualise the anatomy involved. So, here's a short visual lesson in anatomy.
Photo 1
In the first photo we can see the spine and the ribs, and the yellow lines represent the nerves exiting from the vertebral column. This is the brachial plexus. Dysfunction of the thoracic sling can lead to nerve impingements in this area.
Photo 2
In the second photo we've added the scalene and longus colli muscles. These deep muscles work to lift the base of the neck. They can only do their job, if the thoracic sling is functional.
Photo 3
The third photo shows how the scapula covers this area. We can see that the brachial plexus partly lies underneath the scapula. You can imagine how tight muscles that limit the range of motion of the scapula, can have a negative impact on the brachial plexus and the scalene and longus colli muscles.
Photo 4
The fourth photo shows the thoracic sling – mainly the serratus and the pectoral muscles. These muscles are responsible for how the thorax is positioned between the scapulae. If these muscles are restricted and tight, it reduces the range of movement of the entire area.
If we want to understand function, we need to have a good grasp of anatomy. While these drawings are very much simplified, I do hope they provide a visual aid for remembering how the thoracic sling works.