THE MUSCULAR SYSTEM

By Alexis DiStasio and Kate Brown

- Large muscular system which allows movement

- Gives a horse definition- Allows posture

The Equine Muscular System

3 Types of Muscles

Smooth

Cardiac

Skeletal

Smooth Muscle

Found in digestive, circulatory, and urogenital systems

Sustained, rhythmic contractions Made up of spindle-shaped cells with a

single nucleus Least specialized Involuntary movement

Cardiac Muscle

Found only in the heart Highly specialized Rapid, rhythmical contraction and

relaxation Never tires, allowing heart to continually

pump blood Involuntary movement

Skeletal Muscle

Most highly specialized Used for movement and can contract

quickly Function: to provide powerful, rapid

contractions to allow locomotion Attached to limbs of skeleton Voluntary – controlled by brain and

nervous system

- Voluntary muscles are significant.

- Flexor muscles: - bend joint

- Extensor muscles: - straighten joints

Riding Horse

Rhomboideus

This is a long triangular muscle located at the top of the neck Action - To draw the scapula upwards and

forwards

Splenius

A triangular muscle located on the side of the neck Action- Acting alone, the splenius draws

the head and neck towards the side

Trapezius

Situated on the side of the neck and withers.

It is a triangular muscle Action - acting alone the trapezius pulls

the shoulder upwards and forwards.

Latissimus dorsi

Located on along the back down to the chest

Acting alone helps move the front legs and chest

Superficial Gluteus

The most superficial muscle of the croup. It is V-shaped Action – move the thigh outward

Biceps femoris

long, thick, muscle extending from the superior part of the

croup to the stifle Action- It flexes the tibia and with

assistance helps in the act of rearing

External Intercostal

A series of thin, flat muscles between the ribs

Action - Move the ribs upward and forward and assist in inspiration.

Posterior Deep Pectoral

Broad flat muscle Extends from under the abdomen Action – to pull the scapula in a backward

direction

Branchiocephalicus

Long, thick muscle located in the neck Action - help move the neck

Masseter

Thick square muscle Located on the lower jaw Action – brings the teeth of the lower jaw

and the teeth of the upper jaw together

Slow-Twitch Muscle Fibres

Slow contractions and relaxation times Used for maintaining posture when exercising

at slow speeds Gain energy to function through aerobic

(oxygen) metabolism only Activities such as driving, dressage, and

endurance riding

Fast-Twitch Muscle Fibres

Two Kinds: Fast-twitch, high-oxidative fibers Fast-twitch, low-oxidative fibers

Fast-Twitch, High-Oxidative Fibres

Good oxygen capacity Use oxygen to supply energy while

working at high speeds Gain energy through aerobic and

anaerobic metabolism Used during eventing, jumping, polo, and

racing

Fast-twitch, Low-Oxidative Fibres

Does not have good oxygen capacity Burn oxygen quickly Used for short bursts of fast work Anaerobic metabolism only

Work Cited

http://www.eec-equine-therapy.com/Muscular-System.html

http://www.irishhorsesociety.com/horsedata/muscles.htm http://chestofbooks.com/animals/horses/Health-Disease-Tr

eatment-2/Muscles-Of-The-Neck-Rhomboideus.html Anatomy and Physiology of Farm Animals. Pages 164-65 The Equine Body. By Beth Maloney (Chpt. 6)