Horse Talk: The Muscular System

Horse Talk: The Muscular System

We look at a horse, and know how strong they are. But do we understand the driving force? The muscular system of the horse is considered the ‘engine’ of the horse where all motion is produced, and makes up 40-50% of the horse’s body weight.
Why is it relevant that we know more about the muscular system? Well, we all want our horses to perform to their full potential right?! To help them reach this, we need to be mindful of how they’re built, and take into account the health and wellbeing of their ‘engine’, the muscular system.
There are 3 types of muscle – cardiac, smooth and skeletal.
Cardiac muscle is highly specialized tissue only found in the walls of the heart. It is an involuntary muscle, controlled by the autonomic nervous system (ANS), same as the human heart. It functions to circulate blood around the body
Smooth muscle is found in the digestive and respiratory tracts (as well as other hollow structures), and is sometimes referred to as Visceral muscle. They also are involuntary. These muscles are responsible for involuntary bodily functions, aiding in digestion, bladder control and bowel movements.
 
The third muscle type – skeletal muscle, is often referred to as ‘striated’, due to its appearance under a microscope. They are voluntary muscles and are responsible for posture and movement.
When we look at skeletal muscle, there are 2 types of muscle fibre that makes up these muscles.
Type 1 fibres are known as ‘slow-twitch fibres’, and are used for endurance activities. They’re more predominant in heavy breeds
Type 2 fibres are known as ‘fast-twitch fibres’, and are more focused on short term speed. They are seen more in breeds such as Thoroughbreds.
 This is the most basic classification of fibre types. Type 2 fibres can then be classified into A, B and C, but that’s a post for another day!

Muscles are named according to their action, shape, origin, insertion, number of divisions, location and direction of fibres. This can make for some interesting names, but it does make them easier to understand! A lot of muscles are also named in Latin; e.g. longissimus dorsi translates to the longest dorsal - which is true! This muscle is the longest and largest in your horse’s body. No one muscle works alone though, it is a group effort that includes the horse’s other systems as well. The skeletal system is dependent on the muscular system for support, however muscles don’t attach directly to bone, they are attached indirectly by tendons.
 
 Some more fun facts about the muscular system
  • When performing a given movement, the muscle executing the actual movement is called the prime mover (or agonist). These muscles are assisted by synergists, which act to reduce excess movement
  • The antagonist (muscle opposite the agonist) must relax for any action to occur
  • The origin of a muscle is the stationary attachment, and the insertion of the muscle is the moveable attachment
  • Oxygen is muscle fuel. To breathe in the required amount of oxygen for strenuous exercise, the horse’s respiratory rate may exceed 150 breaths per minute!
Stay tuned for our next post on the muscular system, where we'll dive deeper into the science behind muscles!
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