1. Muscular system

2. The horse has a large muscular system which allows movement of the horse, gives it definitions as well as allowing posture like standing by contracting both muscle groups at the same time.

3. 3 Types of Muscles Smooth Cardiac Skeletal

4. Smooth muscle

5. Smooth Muscle Found in digestive, circulatory, and urogenital systems Sustained, rythmic contractions Made up of spindle-shaped cells with a single nucleus Least specialized Involuntary movement

6. Cardiac muscle

7. Cardiac Muscle Found only in the heart Highly specialized Rapid, rhythmical contraction and relaxation Never tires, allowing heart to continually pump blood Involuntary movement

8. Skeletal muscle

9. 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

10. When considering the anatomy of a riding horse it is the voluntary muscles which are significant. These are divided in to two groups - Flexor muscles which bend the joint and extensor muscles which straighten the joint. When a horse is standing both muscles act simultaneously to stabilize the joint, thus preventing either flexion or extension.

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

13. Splenius A triangular muscle located on the side of the neck Action- Acting alone, the splenius draws the head and neck towards the side

14. 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.

15. Latissimus dorsi Located on along the back down to the chest Acting alone helps move the front legs and chest

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

17. 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

18. External Intercostal A series of thin, flat muscles between the ribs Action - Move the ribs upward and forward and assist in inspiration.

19. Posterior Deep Pectoral Broad flat muscle Extends from under the abdomen Action – to pull the scalpula in a backward direction

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

21. 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

22. 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-Treatment- 2/Muscles-Of-The-Neck-Rhomboideus.html http://chestofbooks.com/animals/horses/Health-Disease-Treatment- 2/Muscles-Of-The-Neck-Rhomboideus.html