Equine Anatomy & Physiology Equine Science & Technology

Equine Anatomy

Equine Anatomy Equine Bodily Systems The skeleton of the horse consists of 206 bones. The muscular system provides movement both internally and externally The digestive system converts feed into a form that can be used by the body for maintenance, growth, and reproduction. Sexual reproduction is the process of creating new organisms of the same species through the union of male and female sex cells-sperm and eggs.

What is the function of bone? Bone helps with: Movement Support Protection

What is bone made of? Bone is comprised of: 26% minerals (mostly calcium phosphate and calcium carbonate) 50% is water 4% is fat 20% is protein Bone requires adequate amounts of vitamins and minerals in the ration.

Important Terms Related to the Skeleton Skeletons can be divided into two sections, which include Axial Skeleton—These bones are on or close to the midline axis of the body and include the skull, vertebrae and ribs.

Important Terms Related to the Skeleton Appendicular skeleton—These bones project from the body in the pectoral (front) and pelvic (hind) limbs, and are connected to the body through the bones of the girdles.

Other Important Terms, Con't. Joints points where two or more bones meet. Ligament Tough band of connective tissue connecting one bone to another.

Other Important Terms, Con't. Tendon Thick band of connective tissue that attaches muscle to bone. Compact Bone layer of protective hard bone tissue surrounding every bone Spongy Bone soft bone filled with many holes and spaces surrounded by hard bone.

Types of bones in the animal body Long Bones They serve as support columns. They assist the animal in body support, locomotion and eating. Femur

Types of bones in the animal body Short Bones They are shaped like a cube and are located in complex joints, such as the knee and hock. They diffuse concussion and diminish friction. Example: Hock

Types of bones in the animal body Flat Bones They protect vital organs such as the brain, the heart, and the lungs. They are longer and wider than they are thick. Example: Scapula

Types of bones in the animal body Pneumatic bones--they contain air spaces called sinuses that are in contact with the atmosphere. Example: Frontal face bones. Irregular Bones--important to the protection and support of the central nervous system and are points of some muscle attachment. Example: Vertebrae Sesamoid Bones--they are flat and round. They are located along the course of tendons. Example: Kneecap or patella

Muscular System

Function of the animal muscular system Provides movement in conjunction with the skeletal system Important in life support Used by some humans for food Ask students why we need the muscular system before going over this slide.

Classifications of Muscles Voluntary Movement of the muscle is under the control of the animal Involuntary Movement of the muscle is not controlled by the animal Ask students if the following are voluntary or involuntary: Heart (cardiac), lungs (involuntary), bicep (voluntary), big toe muscles (voluntary)

Types of Muscles Smooth Muscles Involuntary muscles, found in the walls of internal organs and the blood vessels. Fibers are under involuntary control and appear spindle-shaped. Additional definitions: Flexor: decreases the angle between two bones when it contracts (biceps) Extensors: Increases the angle between two bones when it contracts (triceps)

Types of Muscles Cardiac Muscles Muscles that form a network to make up the heart. Additional definitions: Flexor: decreases the angle between two bones when it contracts (biceps) Extensors: Increases the angle between two bones when it contracts (triceps)

Types of Muscles Skeletal Muscles: Have a striped appearance, include voluntary and involuntary, attached to and moves your bones. This is a majority of the muscle tissue in your body. Additional definitions: Flexor: decreases the angle between two bones when it contracts (biceps) Extensors: Increases the angle between two bones when it contracts (triceps)

The Muscle System Brachiocephalicus Deltoidus located in the neck, running from the head to the humerus, allows the foreleg to move forward and effects movement in the shoulder, such as when the horse is in collection, the shoulder is raised. Deltoidus  located over the shoulder, begins at the scapula and runs down to the humerus, enables flexion of the foreleg.

Brachiocephalicus Deltoidus

The Muscle System Triceps Brachii Pectoralis involves 3 muscle strands, it is the most important muscle that extends the elbow.   The 3 strands run from the scapula and humerus into the ulna at the top of the forearm. Pectoralis  Goes from the sternum to the humerus.  This is one of the 4 muscles that make up the Pectorals.

Triceps Brachii Pectoralis

The Muscle System External Obliquus Abdominis Trapezius The largest of the abdominal muscles, running backwards This muscle aids flexion of the back, and assists in exhaling.   Trapezius  Located in the neck and is a wide muscle of 2 bands that start on the top side of the neck and run down to the shoulder area.   These muscles help to raise the shoulder.

Trapezius External Obliquus Abdominis

The Muscle System Latissimus Dorsi Quadreceps Femoris Supports the back, helps to pull the body forward during movement.  Runs from the top of the back forward to the shoulder and humerus. Quadreceps Femoris  Located in the hind quarters and has 4 strands of muscle, working together they help with extension of the stifle joint and flexion of the hip.

Quadraceps Femoris Latissimus Dorsi

The Muscle System Superficial Gluteal runs across the hip and down to the femur.   This muscle that enables flexion of the hip and the forward movement of the joint.   It is a thick and fleshy muscle, which gives the shape of the croup.   Used in kicking and rearing movements.

Superficial Gluteal

The Muscle System Biceps Femoris Deep Digital Flexor Is located in the hind quarters, allows the hind leg to extend,  allows abduction of the leg, and such movements as rearing and kicking.  Deep Digital Flexor Is part of 3 strands of muscle in the hind leg, joining the humerus and the bones of the lower leg, it extends the elbow, and flexes the carpus and lower leg.

Biceps Femoris Deep Digital Flexor

Equine Anatomy Muscular System The muscular system provides movement both internally and externally. Muscles are the active organs of motion and are characterized by their property of contracting or changing shape when stimulated. Each muscle is supplied by one or more nerves that bring commands from the brain to make it contract.

Equine Anatomy Muscular System Muscles compose about 50 percent of the total body weight. The muscle system is made up of three types of muscles smooth or involuntary, cardiac or involuntary striated, and striated or skeletal muscle.

Equine Anatomy Digestive System The digestive system converts feed into a form that can be used by the body for maintenance, growth, and reproduction. It consists of all the parts of an organism involved in taking food into the body and preparing it for assimilation, incorporation into the body. In its simplest form, the digestive system is a tube extending from the mouth to the anus with associated organs.

Equine Anatomy Digestive System This includes the mouth, esophagus, stomach, intestines, anus, and other associated organs like the liver, teeth, pancreas, and salivary glands. The entire digestive tract of a mature light horse is approximately 100 feet long, and has a total capacity of about forty to fifty gallons. Approximately 65 percent of the capacity of the digestive system is in the cecum and colon, which digests the forages consumed by the horse.

Equine Anatomy Reproductive organs of the stallion The primary sex organ of the stallion is the testicle, of which there are two. The testicles produce sperm and a hormone called testosterone, which regulates and maintains the male reproductive tract, and is responsible for the masculine appearance and behavior of the stallion. Sperm production takes place within the testicles in the seminiferous tubules- a mass of minute, coiled tubules, the inner wall or surface of which produces the sperm.

Equine Anatomy Reproductive organs of the stallion Theses tubules merge into a series of larger ducts, which carry the sperm to a coiled tube called the epididymis. The epididymis is the place where the sperm are stored and where they mature. The testicles and epididymis are enclosed in the scrotum The scrotum’s chief function of which is thermo-regulatory – to maintain the testicles temperatures several degrees cooler than the body proper.

Equine Anatomy Reproductive organs of the stallion From the epididymis the sperm move through a tube, the vas deferens, into the urethra. The urethra has a dual role; Urine is carried from the bladder through the penis, and Sperm is carried from the junction with the vas deferens to the end of the penis. Along the urethra are the accessory sex glands- the prostate, the vesicular glands (seminal vesicles), and the bulbourethral (Cowper’s) glands. Their fluids nourish and preserve the sperm and provide a medium for its transport. The combined sperm and fluid is called semen.

Equine Anatomy Reproductive organs of the mare The primary sex organ of the mare is the ovary, of which there are two. The ovaries are bean-shaped organs, 2 to 3 inches long that produce eggs. Each egg is contained in a bubble-like sack called a follicle. There are hundreds of follicles on every ovary. When the follicle is about 1 in. in diameter a hormone causes it to rupture and discharge the egg. This process is known as ovulation.