Equine Massage

 

Lesson Two

 

In this lesson we will be learning about the muscles, how they hold the skeleton together and how they work.

It will be of value now to have an equine anatomy book, or several, available.  A good knowledge of equine anatomy, both skeletal and muscular, is imperative if you wish to give a good equine massage with specific intent, rather than just giving a pleasant rubdown. 

Here are books I’ve found clear and helpful.  The first one is required, but it is helpful to have more than that, especially if you are planning on doing equine massage professionally, since each shows the skeleton and muscles in slightly different ways.  The first four on the suggested list are easiest to find. They do comparative anatomy between horses and other animals.  The Cyclopedia Anatomicae compares anatomy between horses, other animals and humans.

              There is one required textbook for this course:

                               • Horse Anatomy Coloring Atlas, Robert A. Kainer    **Visit Amazon to order the book: https://a.co/d/fPJmJli

 

                  Suggested:

 

                             The Horse Anatomy Workbook, Maggie Raynor

 

                               Color Atlas of Veterinary Anatomy - The Horse Volume 2: Raymond R Ashdown and Stanley H. Done

 

                             • The Anatomy of the Horse: Robert F. Way and Donald G. Lee, Breakthrough Publicat

 

                            • The Visible Horse, DVD

 

                            • An Atlas of Animal Anatomy for Artists: W. Ellenberger, H Dittrich & H Baum, Dover Publications Inc., New York, N.Y

 

                            • Cyclopedia Anatomicae: Gyorgy Feher, Black Dog & Leventhal Publishers, New York, N.Y.

 

 

ANATOMICAL BALANCE

When horsemen refer to balance in a horse, they can be speaking of many different kinds of balance.  They might be talking about the balance the horse exhibits when moving free, or perhaps the way the horse organizes and uses its body when under saddle in the various styles of riding and work. These are forms of dynamic balance – balance while moving.

There is also static balance.  Static balance is about how the horse holds its body when standing still.

But there is another way of looking at balance.  Both dynamic balance and static balance are dependent upon how the bones of the skeleton are arranged—how the muscles hold the bones in place and how the joints function.

Each joint in the body has its own design and specific movement pattern. There is a specific way in which each bone is formed in order to fit against the other bones.  As with any well designed piece of machinery, it works best when the design of the joint is not abused or compromised.

Anatomical balance has to do with the specific design of the joints in a body and how the muscles hold the bones of the skeleton together in such a way that the joints work within the parameters of their design.  This balance is based upon the way the structure (skeleton and muscles) is designed to work. When opposing muscles of a pair have equal tension on either side of a bone - no muscle tension pulling the joint in any direction - we refer to this as anatomical balance or anatomical position; the bone is stabilized between the two opposing muscles of a pair with equal tension.

Movement away from that position is done by the contraction of one of the muscles of that pair--this muscle is called the agonist.  The agonist is directly responsible for causing or affecting movement.

The other muscle of the pair, on the other side of the bone, the antagonist, produces the opposite movement.

Even when there are multiple pairs of muscles working to make a specific movement in a body, one group, the agonist, will move the bone, and the other group, the antagonist, will move it back.  There will be more about this in the section on how muscles work.  The important thing to know here is that when a body is standing still, the best balance is the one where the agonist and antagonist have equal tone.  This is the balance that will give optimum results with the least amount of wear and tear on the muscles and joints of a body.  Anytime there is some kind of unequal tension in muscle pairs or groups of muscles, movement, comfort and health can be compromised.

Abnormalities in the bones themselves or injuries that damaged bones, joints and muscles are two common reasons for improper and balanced movement (these are beyond the scope of this course).  On the other hand, incorrect tension in the muscles and tendons that support and move the joints is a much bigger factor than most horse owners realize, and this is where massage can be of great value.

Good anatomical balance and movement is greatly dependent upon correct tension in the muscles that operate the joints and move the skeleton.  A well balanced horse is going to have better movement overall.

The entire field of the physiology of muscles and how they work is, again, far beyond the scope of this course.  These processes are quite complicated.  We will learn a shortened version of some aspects of muscle function that will be sufficient information for what we need to know and understand in order to do equine massage in a competent and professional manner.

You will learn how muscles work to move bones (we touched on this briefly when describing anatomical balance), how muscles contract and how muscles protect themselves from injury caused by over-stretching.  You will learn these processes as they relate to a single pair of muscles, but in reality, most movement involves many pairs of muscles working in together.

 

DEFINITIONS AND TERMS

These are some definitions that you should know as anatomy books and other professionals will use these terms.

There are two terms that define distance in the body.  They are proximal and distal. 

Proximal is defined as “nearest to the center part of the body” and it usually refers to the end of a bone or muscle that is closest to the center of the body or the spine. 

Distal is the opposite of proximal when speaking of bones and muscles—located farthest from the center of the body and closer to the feet or tail.

You also will hear the terms cranial and caudal.

Cranial describes the end of a muscle or bone that is closest to the head (cranium)

Caudal describes the end of a muscle or bone that is closest to the end of the spinal cord and beginning of the tail otherwise known as “caudus equina”

The following define the three parts of a muscle: the origin, the belly and the insertion.

Origin: one of the ends of a muscle that is usually closest to the center of the body (proximal) and is characterized by stability and the closeness of the muscle fibers to the bone from which it originates. 

Belly: the center portion of the muscle that contains the muscle fibers and does the work. 

Insertion: the end of the muscle that attaches to a second bone that is farther from the center of the body (distal).  In many cases, the insertion may be a tendon.

 

HOW MUSCLES WORK

There are two terms that you will need to know for understanding how muscles work to move the bones of the body. 

These terms are agonist and antagonist.  These are the broad, general terms for muscles that work in a pair to move bones.

All muscles work in pairs to move bones and these muscles will be on opposite sides of a bone.  In a correctly working pair, one of these muscles (the agonist) will contract to initiate some kind of movement.  As it does so, the other muscle of the pair (the antagonist) will stretch in order to allow the desired movement to happen.  When we want to return the bone to its previous position, the process will reverse; the antagonist will contract and the agonist will lengthen.

There are two types of agonist/antagonist muscle pairs – flexors/extensors and abductors/adductors. 

Flexors and extensors are on the front side and back side of bones and move the bones forward and backward.  The flexors initiate movement of a bone and the extensors return the bone to its normal position.  The muscles on the back of the legs are generally flexors.  The muscles on the front of the legs are the generally extensors. 

The other types of agonist/antagonist muscles that you need to know about are the abductors/adductors. 

These move the legs out to the side, away from the body and then back to the body.  The abductors are the ones that initiate this sideways movement (take away  = abduct)  away from the body; the adductors move them back to the body.  The muscles on the inside of the horse’s upper hind legs are adductors.  Most lateral work that horses do involves using the abductors and adductors. 

As an agonist contracts in order to initiate a movement, it will move one bone closer to another at the joint between the two bones.  This makes the angle between these two bones smaller.  This works in horse’s bodies as well as in humans.

Here are two examples – one human, one horse. 

Let your arm hang by your side and notice that the angle of the elbow joint between your upper arm and your forearm is 180 degrees.  Now, bring your lower arm up toward your shoulder and see how that joint angle gets smaller.

Next, notice that when your horse is standing, the angle between its cannon bone and the upper foreleg, at the knee joint, is 180 degrees.  When you pick up the horse’s foot the knee bends, making the angle at the joint smaller than 180 degrees.

Correct function of a muscle pair means that both muscles contract and extend and do so in conjunction with one another.  When one is contracting, the other has to extend.  If this does not happen, there will be a restriction in the movement of the bone.

If a muscle has, for some reason, lost some of its capacity to stretch and stays in a semi-contracted state, it will inhibit the movement of the bone.  This is referred to as a co-contraction pattern (one muscle stays in contraction even when it should be stretching, so both muscles of a pair are in contraction simultaneously).

When one muscle attempts to contract while the opposing muscle stays in a contracted state it makes the desired movement difficult.

In time these muscles have to work harder and harder to make movement happen—they are working at cross-purposes instead of together.  A common term for this phenomenon is muscle bound.  When this happens, the range of motion of the joint controlled by these muscles becomes restricted because the muscles do not allow the joint to work to the full range.  Many movement problems are the result of co-contraction patterns.  In the horse, one of the most noticeable examples of this type of restricted range of motion can be seen in the hip joints often due to hamstring tightness.

When muscles contract, most people probably visualize it as a process whereby the muscle fibers tighten and bunch up as they shorten.  This is not the way it really happens.  When muscles contract, the normal process involves the sliding of one type of muscle fiber over another type of muscle fiber.  This sliding action allows for a fluid motion in the contraction and an equally fluid motion in the lengthening.

This means that both contraction and lengthening can happen with ease and suppleness rather than with a tight, cramped movement that is so often seen when conscious effort is made to force a movement by deliberate contractions.  Deliberate contractions, such as seen in human body builders, will increase the size of the muscle fibers by creating scar tissue in the fibers.  This scar tissue will eventually interfere with the correct working of the muscles and great care needs to be taken to keep muscles that are used in this way supple by a specifically planned stretching program.

The same is true with horses. When conditioning and building muscles in their training, it is important to have a stretching routine. This will help you avoid sore and tight muscles that will interfere with the training program. *Stretching should be done by a knowledgeable professional with great sensitivity so as not to cause injury to the horse.

Just as the contraction process can be forced, so can the stretch process.

When this happens there is always a chance that a muscle could be damaged or torn by over-stretching, but the body has a process called the stretch reflex to protect muscles in that event.

When a muscle is in danger of being pulled beyond its capacity to stretch safely, the stretch reflex is activated and over-rides the stretch, causing the muscle to contract instead.  So, any kind of over-stretching, whether accidental or even in a planned stretching program, could result in muscles tightening instead of lengthening.

When the stretch reflex is activated and results in muscles tightening, the muscles will stay in a contracted state until something resets the muscles tension and allows the muscles to return to their normal state.  Massage is very effective in dealing with this type of muscle problem.

Muscles can be tight in a contracted state and not stretch well (this is what we usually think of when we talk about tight muscles), but they can also be tight in the extended state, with capacity to contract.  Both conditions present problems—one muscle needs to learn to contract with greater ease, one needs to learn to stretch with greater ease.  And it is usually the case that if one muscle of a pair is tight in contraction, its opposite will be tight in extension.  This is particularly true if the muscle problem has been present for an extended period of time.

 

MUSCLES, TENDONS AND LIGAMENTS

We need to learn the difference between muscles, tendons and ligaments.

A muscle is composed of individual muscle fibers that are wrapped with connective tissue; then groups of these muscle fibers, wrapped in their individual connective tissue, are bundled together and wrapped with more connective tissue.  This grouping and wrapping goes on until a specific muscle is formed.  Then, muscles doing the same type of work may be wrapped together by connective tissue, so you can begin to see that there is a lot of connective tissue involved.  One good example is a ham.  It shows quite clearly the white connective tissue that surrounds the various muscles that make up the ham.

Some muscles go from one broad surface to another, so they are broad at both their origin and their insertion (the Rhomboid is a good example).  Click here to see a picture of the superficial equine muscles.

But sometimes a large muscle’s insertion may attach to a much smaller bone or to a very small point on a bone.  For that to be possible, somehow that end of the muscle has to come to a small point so that it can attach to a small point.  It does this by losing the muscle fibers that produced the bulk in the muscle as it comes closer to its insertion point, and what remains is all of the connective tissue that had surrounded the muscle fibers.  (Think about all of that white fibrous tissue at the end of the ham bone—those are tendons.)  From this you can see that a tendon is an integral part of a muscle, not something separate.  Because it is composed of only connective tissue, this tendon portion of the muscles is quite strong, but, without the muscle fibers, it lacks the great elastic quality of the muscle belly.

Look at your anatomy charts and you can find numerous examples of muscles with tendon extensions.  The Latissimus dorsi is a good one in horses. 

The horse’s lower legs, front and hind, are basically operated by tendons that extend down from muscles that originate either in the upper portions of the legs or in the lower areas of the shoulder or haunch.  This is also true in humans; our lower legs and our forearms have numerous tendon attachments.  One of the easiest examples to find is in the four big muscles on the front of our thighs—the quadriceps.  These are four muscles large enough to cover the entire front of our thigh bone (femur) and they all converge into one tendon that attaches to our knee cap.

Because of its lack of muscle fibers, a tendon does not have the good blood supply and circulation that the muscle belly has.  For that reason, a tendon injury can take longer to heal than if the injury is to the body of the muscle.  (Anyone who has ever had a horse bow a tendon knows all about this.)

bowed tendon

Bowed Tendon

 

Ligaments are really a completely different category from muscles and tendons.  They are very strong bands of rather inelastic tissue whose primary job is support, not movement.  They hold things in place.  The horse’s lower legs are full of ligaments that support the tendons and prevent injuries caused by excessive or abnormal movement.  These make up a large part of the “stay apparatus” that allow the horse to sleep while standing.

ligaments2

The horse’s neck is supported by a large ligament system, part of which runs from the poll to the withers and then there are the supporting ligaments on the sides of the neck that go from the withers to the neck vertebrae.  Ligaments have a poor blood supply and circulation.  If injured they take much longer to heal than muscles or tendons.

 

SKELETAL ANATOMY

Even though this course is about massaging muscles, you also need to know the horse’s basic skeletal anatomy.  The job of the muscles is to move the bones.  The skeleton and muscles together are an integral system, essentially a lever and pulley system with the bones as the levers and the muscles as the pulleys.

There are also bony landmarks that will aid you in finding specific muscles in your learning process.          Click here to see the equine skeleton.

In the descriptions of the skeleton and the muscles we will use as many common names and horse related terms as possible rather than medical terminology, though for the muscles we will use their Latin names. This will help you cross reference names in your anatomy books, with your own knowledge and out in the field while working. 

You will need an equine anatomy book for reference while you are studying this. After we have gone through the horse’s skeleton, we will start learning the major muscles that will be important for the horse’s movement; the primary ones that you will be massaging.

There will be occasional and interesting comparisons to the human body, however we will keep our primary scope of learning equine.

h & h skeleton

Axial Skeleton

The axial skeleton consists of the skull, spine and tail of the horse.

  1. SKULL  The skull of the horse is composed of two sections.  The larger section houses the brain and the upper portion of the face and jaw.  The other section is the lower jaw that hinges to the upper portion of the skull just below the ear.  This is called the TMJ or temporal mandibular joint Familiarize yourself with where this joint is on the horse.  There will be many times you will do massage work in this area.  Watch as a horse chews, this will help pinpoint the jaw joint.
  2. CERVICAL (neck) The neck of both horse and human is composed of seven vertebrae. They are designated C-1 through C-7, with C-1 being commonly called the Atlas. The shape of these vertebrae is the same in both humans and horses; only the size is different.  A common thought is that the cervical area is located at the upper portion of the neck below the mane. It is located in the lower portion of the neck and the bones can be felt with soft flat hand pressure in that area and on most horses we can see a wider area at C-4-5.
  3. THORAX AND RIBS  The thoracic vertebrae and attached rib cage compose the next section of the spine.  The horse has 18 vertebrae and ribs and all of the ribs are attached to the sternum which is located on the front of the chest, between the frong legs and through and behind the girth area.  The withers are actually thoracic vertebrae – see skeleton diagram.
  4. LUMBAR  Next in line, behind the thoracic vertebrae are the lumbar vertebrae.  In humans we call this area the low back, in horses we call it the loins.  Horses have six lumbar vertebrae.  This section of the spine has no bony stabilizing structures, such as ribs or pelvic bone, to support it.  All of its support comes from muscles.  This lack of support is one of the reasons why horses and humans have numerous problems in this area; the trade-off for both is flexibility.
  5. SACRUM AND PELVIS  Coming after the lumbar vertebrae is a small, elongated, triangular bone called the sacrum.  This bone is actually composed of five bones that have fused. In the horse’s hindquarters, the back edges of the pelvic bone do not come in contact with the sacrum, but are above it.  What we call the croup of a horse are the two sides of the pelvic bone called the tuber sacrale or sacral tuberosities (bony landmark) where they come close to each other above the sacrum. The joint between the sacrum and the 6th lumbar vertebrae (the lumbosacral joint) is under the croup (tuber sacrale).  There are strong ligaments as well as muscles holding all of these bones in place.  The important advantage of this arrangement is that it allows for a much greater downward movement of the sacrum at the lumbar/sacral joint that allows for the dropping of the horse’s pelvis in the trot and canter.
  6. COCCYX (tail bones).  Finally, at the end of this column of bones, are the tail vertebrae or coccyx.  The average horse has 18 tail vertebrae, but this can vary by one or two.

Appendicular Skeleton

The name appendicular skeleton comes from the word appendages that in the case of the horse are legs and hooves.

FORELEGS

1.SCAPULA (shoulderblade) We think of the scapula as the first bone of the arm. This bone is a flat and triangular shaped. It lies on the rib cage and is attached by muscles only.  The horse’s scapulae lie up against the sides of the rib cage. This limits the forelegs of the horse to primarily forward/backward motion.  This position against the rib cage helps stabilize the front legs for their job of supporting the front portion of the horse. 

2. HUMERUS Attached to the scapula at the shoulder joint is a sturdy bone called the humerus.  In the horse this bone goes from the point of the shoulder (shoulder joint and bony landmark) to the elbow.  The humerus lies against the ribs and is supported by them and is held in place by muscles.  This arrangement provides a front to back motion of the humerus, but only a very small amount of side-to-side movement; and this is possible only as the humerus swings forward.  In the horse, this shoulder joint has traded mobility for stability (in keeping with its support function) and injuries to the humerus and this joint are infrequent.

3. RADIUS AND ULNA   There are two bones below the humerus, the radius and the ulna, and they are known in humans as the forearm.  In the horse, these two bones also form the forearm, but in the horse they have fused into a single bone.  This fusion of the two bones restricts the elbow joint to only a forward/back motion.  It has become a simple hinge joint rather than a “multi-tasked” joint.  Again, this adaptation enhances stability and sacrifices mobility.

4. CARPAL BONES At the end of the radius and ulna in the human skeleton is a group of small bones (carpals) that form our wrist or carpal joint.  The horse has a similar group of bones in the foreleg, often called the horse’s knee. There may be confusion in different texts about this joint however please understand that regardless of the fact that we often call this joint a “knee”, it is the same joint as our carpal or wrist joint.  (The horse does actually have a true knee joint on the hind legs and we call it the stifle). 

5. METACARPALS (canon bone and splint bone)  The canon bone is the large bone below the knee (carpal joint)and alongside is the splint bone. The splint bones are the vestigial remains of the other two metacarpals that the horse had when it was originally a three-toed animal.  These splint bones have lost all function and the canon bone is the primary means of bony support for this lower leg region.

6. PHALANGES (long pastern, short pastern and coffin bone) In the horse, below the metacarpal (cannon bone) are also three bones that are the equivalent of our finger bones.  We call them the long pastern bone, the short pastern bone, and the coffin bone.  You will hear them referenced to as P1, P2 and P3. In the horse, these bones have a greater range of motion than do our fingers.  This range of motion accommodates the forward/back swing of the front legs. What is a fascinating thought in studying the horse’s forelegs, is that the horse is essentially standing on the tip of a finger!

HINDLEGS

The horse has a thighbone (femur) and hip joint exactly like a human. There is also a knee joint (called the stifle in the horse), a tibia and fibula (these are the bones of our lower leg), a heel/ankle joint (the hock of the horse) and a corresponding arrangement of its lower leg (cannon bone, fetlock, pastern, hoof) similar to its lower front leg. The bones of the horse’s hind legs are basically the same as those of the human leg. They are also long in comparison to the front legs just as our legs are longer than our arms. The horses angulation of the hind legs has to be more acute in order to bring it into some kind of balance with the forehand.  This greater angulation of the bones under the horses body gives the horse greater pushing power for propulsion.

1. FEMUR   The femur (thighbone) attaches to the pelvis at the hip joint and angulates slightly forward to the stifle joint.

2. STIFLE JOINT The horses stifle joint is exactly the same as the human knee joint—same shape, same function (remember that what we call the knee in the horse is actually the equivalent of the human wrist).  This joint has the same structure, the same ligaments, the same muscles attached to it and it has the same bony protection in front of the joint (the knee cap or patella) as does the human knee.

3. TIBIA AND FIBULA Below the stifle in the lower leg are two bones, the tibia and fibula. In the horse, the fibula is a long slender splint bone that that extends part way down the tibia and does not provide any added support to the hindleg. The tibia which is the supporting bone, angles down and back, and ends at a large joint we call the hock. 

4. HOCK JOINT The hock (bony landmark) is the same joint as the ankle in a human.  This can be a troublesome joint for many horses.

5. HIND LOWER LEG   Below the hock, you’ll find the same arrangement as described in the front leg below the carpal joint. The hind cannon bone, the fetlock and the 3 pastern bones

 

Muscle Anatomy

This section describes some of the major muscles involved with movement in the horse’s body that are accessible to massage, as well as what these muscles do and some of the problems that can occur when these muscles are not working properly.  (This is not intended as an in-depth anatomical lesson)

You will need to refer to your anatomy books as we go through this section.

I will not be describing any lower leg muscles and function.  The legs below the knee and hock are primarily composed of tendons and ligaments and because of the tough, inelastic nature of these, techniques for working on them are limited, and if not done correctly, can do damage. 

There are two major layers of muscles on the skeleton that are going to be our focus.  They are the superficial (those just under the skin) and the next layer, the deep, just under the superficial layer.  These second layer muscles are sometimes easily accessible in many areas of the horse’s body and sometimes not.

 

A note about the torso—in the human body the torso is considered the area from the shoulders to the bottom of the pelvis, but for my description of the horse’s muscular anatomy I will consider the torso to be the thoracic portion of the spine (the thoracic vertebrae and rib cage) and the lumbar vertebrae (loins).  I will discuss the pelvis in conjunction with the hind legs.  Because of the way the horse’s hind legs fold under the pelvis, this seems a better way to view it.

★★All the muscles described occur on both sides of the body.  They are mirror images of each other.

 

 THE TORSO

The muscles of the torso connect the two ends of the horse, the rider sits on them and many of a horse’s problems start in its back.  Even when problems originate in other areas, soreness and tightness can be referred into the back.

The five important muscles in the torso are:

  1. Long back muscles (Spinalis, Longissimus dorsi, Iliocostalis)
  2. Latissimus dorsi
  3. External oblique
  4. Internal oblique
  5. Rectus abdominis

 

1.Long back muscles. Click here for picture. These muscles are some of the most important ones that you will deal with in massaging a horse.  They are the major support and protection for the spinal vertebrae and are subject to major problems involving tightness, soreness and muscles spasms from multiple sources.  They are also the extensors that have to lengthen when the abdominal muscles contract. There are three of these muscles on either side of the spine. 

Starting closest to the spine and moving outward, they are the Spinalis, Longissimus dorsi and the Iliocostalis.  The forward (cranial) attachments of these muscles are to the withers, the ribs and under the scapula.  They run the entire length of the back and attach to the forward (cranial) edge of the pelvis.

The Iliocostalis  This is easy to feel where it attaches to the pelvis because its attachment is on the point of the hip (bony landmark see equine skeleton Tuber coxae) and its outer edge, between the point of the hip and the last rib; it feels like a hard, ropey ridge.  Some equine anatomy books show these as one single muscle, but there are really three.  The human body has these same muscles, positioned in the same way and their purpose is the same—support and protection of the spine and to extend as the abdominal muscles contract.

 

2. Latissimus dorsi This is a large flat muscle, somewhat triangular in shape, that connects the horse’s back to the humerus in the lower portion of the shoulder. The origin portion of this muscle, which attaches along the spine, is connective tissue.  This is why we can palpate the long back muscles under it.

The middle portion contains the muscle fibers.  The insertion portion (attaching to the humerus) is tendon (no muscle fibers).  This is a good example of a large muscle narrowing down to a tendon in order to attach to a small point.

This muscle offers support and control to the movement of the shoulder in its forward/back swing.  As the shoulder swings forward, this muscle extends; its contraction helps bring the humerus backward.  Because this muscle connects the back to the front legs, over-stretching of the front legs can put excess stress on a horse’s back, and, conversely, problems in the back can affect shoulder swing.

 

3. External oblique Click here for picture. This is a large, relatively thin muscle that covers much of the rib cage.  It starts out narrow at the point of the hip and spreads out over the ribs.  The top edge attaches to the individual ribs.  The bottom edge merges into a band of fascia (connective tissue) that then merges into the abdominal muscles.  This fascia provides a direct link between the external oblique and the abdominal muscles and gives a rider a way of initiating a contraction of the abdominals.  The External oblique is the muscle that lengthens and shortens the sides of the horse as it moves. These muscles, on both sides of the horse, are important for correct bending.  The movement in the lower edge of this muscle is easy to see when a horse is trotting.  These muscles also expand and contract in time with a horse’s breathing.  In a horse that has heaves, the lower edge of this muscle is very noticeable in its contraction; we call it the “heave line”.

 

4. Internal oblique  Click here for picture.  This muscle could be thought of as both a muscle on the side of the horse and one in its lower torso area (belly line).  The loin/flank area of the horse has no bony support other than the lumbar vertebrae; there are only muscles supporting and holding up this portion of the abdomen (akin to out lower abdomen).  The major muscle in this area, and one accessible for massage, is the Internal oblique.  It starts out narrow at its attachment to the point of the hip and then broadens out as it swings down to the mid-line of the belly.  It acts as a sling, holding up the contents of the abdominal cavity.  It encompasses the area we call the flank and groin.  Tightness and muscle spasms are common in this area and it is an important area to work on, but it is also one of the most difficult.  Many horses, in response to pressure here, will kick first and ask questions later.  Work in this area should be approached with care.

 

5.Rectus abdominis The Rectus abdominis (abs) are a line of muscles on either side of the center line of the belly.  They are connected to the lower edge of the External oblique by fascia.  In both horses and humans the Rectus abdominis are long, relatively narrow muscles that attach to the pubic bone of the pelvis, run along both sides of the center line of the belly and then attach to a number of the ribs.  In the horse their contraction exerts a pull on the pubic bone that draws the pelvis down as the hind legs swing forward.  Their contraction also lifts and supports the long back muscles, supporting and holding the torso up from underneath.  Good abdominal muscle tone is as important for the horse as it is for humans in keeping the back healthy and working correctly.  Our term for a horse with poor abdominal strength is “hay belly”; for people the term is “pot belly”.  Click here for picture – chest and abdominal muscles.

 

 

 THE HIND QUARTERS WITH THE HIND LEG

The muscles of the hindquarters are listed below. The muscles of the haunches are bulky, dense, powerful muscles whose primary function is propulsion.  These are power muscles; their job is to send the horse forward.  They are easy to massage because of their size and accessibility.

      1. Gluteal muscles—Gluteus medius and Gluteus maximus

      2. Tensor fascia latae

      3.Quadriceps—Rectus femoris, Vastus medialis, Vastus Intermedius, and Vastus lateralis

      4.Hamstrings—Bicepts femoris, Semitendinosus, Semimembranosus

      5.Adductors

      6.Gaskin

      7.Gastrocnemius and lower hamstring attachments

Click here for picture of superficial haunch muscles.

Click here for picture of deep haunch muscles.

1.Gluteal muscles There are three gluteal muscles, but one, Gluteus minimus, is deep and not accessible to us for massage.  The other two, Gluteus medius and Gluteus maximus, form the bulk of the muscle mass on the top of the haunches.  (Other names you might see for these muscles are middle glute for Gluteus medius and superficial glute for Gluteus maximus.)  Together these two muscles attach to the edge of the pelvic bone where it joins the loins (iliac crest) and along the edge of the sacrum.  They both converge and attach to the upper portion of the femur at the hip joint.  Their contraction and extension works to stabilize the forward/backward swing of the horse’s hind legs..

 

2. Tensor fascia late   This muscle is important in the working of the stifle.  It originates from the point of the hip as a muscle and then becomes fascia (connective tissue) as it approaches and covers the outside of the stifle.  It helps to support the stifle.  Its contraction, along with the contraction of the quadriceps, pulls the stifle forward and its extension allows the stifle to move backward.  The best results from massage on this muscle would be in its upper portion where there are muscle fibers.

 

3. Quadriceps  In the horse these are four large muscles on the front of the femur that are important for correct functioning of the stifle  They are covered by the fascia of the Tensor fascia latae, but they are still accessible for massage.  They are the three vastus muscles (Vastus medialis, Vastus intermedius, Vastus lateralis) and the Rectus femoris.  They work in conjunction with the Tensor fascia latae to bring the stifle forward.  The best access to these muscles is an area just in front of the hip joint and on the inside of the stifle joint.  Humans have these same muscles and they do the same job of bringing the human knee forward, but there is one significant difference.  In the human, all four muscles converge into one large ligament that crosses the knee and is known as the patellar ligament.  In the horse the attachments of these muscles at the stifle are separate and distinct.

 

4. Hamstrings   If the quadriceps and the Tensor fascia latae pull the stifle forward, something has to pull it back; the hamstrings do this.  They are a group of three muscles that run down the back of the horse’s haunch.  Starting on the outside of the haunch and moving around to the inside, they are the Biceps femoris, Semitendinosus, and Semimembranosus.  The Biceps femoris is a large, fairly broad muscle with its origin on the sacrum.  It crosses over the hip joint and swings to the outside of the haunch for its lower attachment.  The Semitendinosus and Semimembranosus are long, but bulky muscles, also with their origins on the sacrum, that go down the back of the haunch.  Their lower attachments are in the area where the haunch tapers into the hind leg.  When these muscles contract they pull the leg backward.  The agonist/antagonist action of these two muscle groups (quadriceps and hamstrings) produce the swing of the hind legs in both horses and humans.  But there is a major difference in horse and human anatomy in the arrangement and position of the hamstrings.  In humans the hamstrings have their upper attachment (origin) at what we refer to as our “seat bones” (Ischial tuberosity).  With the attachment here, our legs swing from the hip joint without changing the vertical position of our pelvis.  In the horse these muscles continue on past the Ischial tuberosity (the point of the buttock, or the horse’s seat bones) and attach to the sacrum.  With the hamstrings positioned in this way, when they lengthen in response to the contraction of the quadriceps, this extension goes all the way up to the sacrum, not just to the point of the buttock.  Lengthening in this way allows the horse’s pelvis to be pulled downward from its normal horizontal position and sets the horse’s hind legs up for a powerful reach under the body and then a powerful push that sends the horse forward.  This dropping of the pelvis as the hind legs come forward is what creates “engagement”.  These three muscles are fully accessible and respond well to massage over their entire surface.

 

The last three muscles, or muscle groups, of the hindquarters are easy to find and massage.

5. Adductors   The adductors are the big muscles of the haunch that are between the hind legs.  The biggest muscle, and the one you’ll make the most contact with, is Gracilis.  Tightness in these adductors can restrict the swing of the hind legs.  These muscles are positioned the same in humans.

 

6. Gaskin Horsemen use the term “gaskin” for two small muscles on the front of the hind leg just above the hock.  The gaskin is actually two small muscles whose tendons run all the way down the front of the hind leg to the hoof.  These muscles are important because any tightness or soreness in them can exert tension on their tendons in the lower leg.  Release of tension in these muscles can help relieve tension on the tendons.

 

7. Gastrocnemius The gastrocnemius is on the back of the hind leg.  It is also a small muscle with an important tendon.  You’ll find the muscle belly just below the hamstring’s lower attachments.  Its tendon attaches to the top of the hock.  In humans this is known as the Achilles tendon.  Tension in this muscle can stiffen hock movement.

 

THE FOREHAND, SHOULDERS AND FRONT LEGS

This section of the lesson on muscle anatomy is not intended to deal with all the muscles of the horse.  This is especially true of the forehand because many of the muscles are not accessible to us for massage.  It is only the important muscles that we can get to that will be described.

What we call the forehand of the horse is actually the front portion of the rib cage (from the withers and shoulders to the front of the chest), the shoulders and the front legs.

Some of the muscles of the forehand support the bottom of the rib cage, some are responsible for moving the shoulder blades and front legs, and some hold the shoulder blades in place against the ribs.  You will see these three divisions in the descriptions.

 

Support Muscles

There are four pectoral muscles in the chest area and three of these are the major support for the bottom of the rib cage.  The Rectus abdominis muscle supports the torso from the pubic bone to the beginning of the rib cage. The largest of the pectoral muscles takes over support where the Rectus abdominis ends.  It is a long, fairly large muscle that attaches along the entire length of the breast bone (sternum) and then, close to the elbow joint, it attaches to the humerus.  When this muscle contracts, it elevates the rib cage at the withers.  This muscle acts in much the same way as the human Pectoralis major.

Two other pectoral muscles also attach the front legs to the body of the horse; they also go from the rib cage to the humerus.  One can be found directly between the front legs.  The other is in the front of the chest; what we would normally call the chest muscle.

These muscles are easy to find and massage.

 

Muscles That Move the Shoulder Blade and Front Legs

The concept in moving the front legs is simple—the muscles located in front of the shoulder pull the humerus forward; muscles behind the shoulder pull the humerus back.  The major muscles involved in pulling the leg forward (ones that we can access and massage) are the Biceps brachii and the lower portion of the Brachiocephalicus. 

The Biceps brachii is in the front of the chest, next to the chest pectorals and distal to the shoulder joint.

The Brachiocephalicus is a long muscle that originates just behind the horse’s ear—on the first cervical vertebrae (the Atlas).  It goes down the entire length of the lower neck, following the contour of the neck vertebrae, then over the point of the shoulder and inserts on the humerus.  It is a prime mover in the process of bringing the leg forward.

Massage on the lower portion of the neck and lower portion of the shoulder will relieve tension in the lower portion of this muscle as well as other important muscles of this area.

 

The important muscles that pull the leg back are the Latissimus dorsi and the Triceps.  I described the Latissimus dorsi when describing the muscles along the back of the horse’s torso because of its attachment, as fascia, along the thoracic vertebrae.  Its muscle belly (the portion with muscles fibers) is behind the shoulder and its strong tendon attaches to the humerus.  Its contraction exerts a strong backward pull on the humerus.  Because the muscle fibers of this muscle are behind the shoulder and just under the skin, massage to this area can be beneficial in increasing shoulder mobility.

 

The Triceps pull the front leg back in a different way.  This muscle forms the back portion of the shoulder (the big, fleshy portion behind and below the scapula) and is triangular in shape.  Its origin attaches all along the back edge of the scapula and also at two points on the humerus, and then all the muscle fibers converge to attach at the point of the elbow.  When this muscle contracts it closes the angle between the scapula and the humerus, and thereby pulls the humerus backward.

 

Muscles That Hold the Scapula Against the Rib Cage

There are two groups of muscles that keep the scapula in place against the rib cage.

One group is between the rib cage and the scapula.  The other group is on the outside of the scapula.  In both instances (inside or outside) the process of stabilizing the scapula against the rib cage occurs at the top of the scapula—leaving the bottom free to swing forward and back.

The important muscles between the scapula and the rib cage are the Rhomboid and Serratus.

The Rhomboid attachment to the scapula is on the inside upper edge.  The other end of this muscle attaches to the withers.  So, the scapula is hanging from the withers, and the Rhomboid is the attachment between the two. Tightness of this muscle in the horse can adversely affect the balance of the entire forehand.  There is also a neck portion of the Rhomboid, which I will discuss with the neck muscles.

Below the Rhomboid attachment on the inside of the scapula is the attachment of the Serratus.  At its origin at the top of the scapula it is a small, dense muscle mass that then divides into 13 long, slender muscles.  These 13 muscles attach the top of the scapula to the middle of the rib cage on the first nine ribs and to the last four neck vertebrae.  This arrangement of the Serratus is important because when the Serratus is working correctly it causes the neck to stretch down and helps to bring the back up.  Much of this muscle arrangement is cover by the scapula or heavy, dense muscles, but we have access to some portions of these individual muscles that attach to ribs six through nine, and can also make contact with those attaching to the lower neck vertebrae.

Because these thirteen “fingers” of the Serratus all originate from a common muscle mass, we can have a positive effect even on the sections we can’t reach if we can get some of these “fingers” to release tension.  This is why relaxing the neck helps soften the rib cage and vice versa..

Click here to see the serratus with the shoulder blade in place.

Click here to see the serratus with the shoulder blade removed.

Click here to see the serratus in the extended state.

Click here to see the serratus in the contracted state.

 

There is only one major muscle on the outside of the scapula that holds it in place—this is the Trapezius.  It stabilizes its top portion, while still allowing the bottom to swing with the movement of the front legs.  The form and function of the Trapezius is the same in humans and horses.  It is a big triangular muscle that originates along the spine of the scapula and fans out in two directions to attach to the horse’s topline.  One section attaches to the withers and the area of the back just behind the withers.  The other section goes up the crest line of the neck covering most of the Rhomboid muscle.  This muscle is a powerful anchor and stabilizer for the scapula, as well as support for the neck.

The Trapezius is an extensor and when working correctly the extension of the Trapezius allows the neck to arch out in front of the horse’s torso.  But if the Trapezius contracts it will cause the neck to arc upward, resulting in what horsemen call ewe-necked’ or “star-gazer”.  This contraction of the Trapezius will also pull the horse’s back down in the portion under the saddle.  (Notice that the result of this contraction is the opposite of what happens when the Serratus contracts and lifts the back.)

There are two other muscles of the shoulder that I want to mention because their purpose is different than the others I’ve described and they are big enough that massage can be beneficial even though they are covered by other muscles of the shoulder.  They are Supraspinatus and Infraspinatus.

These are long muscles that run lengthwise down the scapula, one on either side of the spine of the scapula.  They are attached to the scapula along almost their entire length so that there is very little extension possible except at their tendons.  These strong tendons cross the shoulder joint (point of the shoulder) and attach on the humerus side of this joint.  The purpose of these muscles and their tendons is to support the shoulder joint in its proper position against the rib cage.

As you have probably gathered, there is a complexity of muscles contained in a fairly small area in the shoulders, and often it can be difficult to isolate exactly which muscles you may be massaging.  Fortunately, massaging the bulk of the shoulder and the areas behind it and in front of it will benefit all of them.

The reason for describing them in detail as I did was to give you a better understanding of how the shoulders and front legs are organized in relationship to the rib cage and how they work to produce movement.

 

THE NECK AND HEAD

Neck

Comparing human and horse anatomy in the neck will show basic similarities in muscles and structure, but the extension of the neck hanging out in space in front of the horse requires some special adaptations, especially in deep muscles and ligaments.

At the deep level these systems of supporting ligaments and muscles are not accessible for massage and, in the case of ligaments, do not readily respond to massage.

Only the superficial and second levels that we can massage are being described, but releasing tension in these superficial muscles can gradually have an effect on the deeper muscles as well.

Muscles along the crest are going to be support muscles, muscles that hold the neck up.  There is a very strong ligament that forms the crest line of the neck (the Nuchal ligament); it runs from the withers to the poll, and it is to this ligament that the supporting neck muscles attach.

The important muscles attaching to this ligament are the cervical (neck) portions of the Rhomboid, Trapezius and the Splenius. 

The Rhomboid and Trapezius attach to the Nuchal ligament and connect the crest line of the neck to both the rib cage and the scapula.  The Splenius supports the side of the neck; it starts at the withers and spreads out to attach to the upper neck vertebrae.  All of these muscles are easy to massage.  Click here for picture.

Supporting the vertebrae of the lower portion of the neck is the cervical portion of the Serratus.  (Remember that the Serratus attaches to the ribs as well as to the neck vertebrae.)  This cervical portion of the Serratus goes from its origin on the under side of the scapula to the last four neck vertebrae.  This is a very important muscle for obtaining correct carriage of the neck.  Its attachments to the neck vertebrae occur where the neck has its downward arch.  If these muscles have correct tension, their contraction will lift these lower neck vertebrae, causing the crest line muscles to extend and allow the topline to lengthen.

If muscle tone is poor in these cervical Serratus, it allows this portion of the neck to “sag”, causing a dip in the crest line of the neck.  Horsemen refer to this configuration as “ewe-necked” or “star-gazer”.  Correct function of the Serratus has a significant effect on how the horse is able to use the rest of its body.

The Serratus attachments to the lower neck vertebrae are under the Brachiocephalicus, but can be massaged through it.

The Brachiocephalicus is a long muscle on the lower side of the neck.  It starts behind the horse’s ear, follows the contour of the neck vertebrae, goes over the point of the shoulder and finally attaches to the humerus.  Its contraction is involved with the forward/back swing of the front legs as well as giving support to the neck from the bottom, much as the abdominals and pectorals support the torso.

There is one other muscle that can cause tension in the neck.  This is the fourth pectoral, the Cranial Deep Pectoral.   You will remember that the other three pectorals attached the humerus to the rib cage.  This fourth pectoral lies lengthwise along the front edge of the scapula and forms another attachment of the scapula to the humerus.  It can be felt as a long, tight ridge in front of the scapula, and tension in this muscle can easily prevent any softening and lengthening of the neck.

Massage to all of these neck muscles produces positive responses not only physically, but mentally as well.

 

Head

Because of its endorphin points, massage to the head, especially the ears and poll, can be a powerful and relaxing experience for the horse.  I have been told that cavalry officers would “pull” their horse’s ears in between cavalry charges to relax them.  This relaxing head massage can be especially beneficial for nervous horses and is also a nice finishing touch to any kind of equine massage, except pre-event stimulation massage.

The work we will do on the head is primarily to release tension in the jaw line and balance the jaw joint (Tempro mandibular joint or TMJ) and poll.

There is a long, thin muscle Zygomatic that runs from the corner of the horse’s mouth up into the ridge of the cheekbone.  Pressure to this muscle where it meets the big cheek muscle Masseter will produce a relaxation of the horse’s mouth and jaw line.  This relaxation in the mouth helps when you are doing work on the TMJ joint.  The TMJ of the horse is found in the same place as you would find it on the human skull, it is a bony prominence just in front and slightly down from the ear.

Working to release the TMJ doesn’t involve so much of massaging muscles, but more of releasing the joint itself.

In addition to the massage work that involves the jaw, there are numerous small muscles around the poll—behind it, on the forehead and around the ears, and it is important to loosen these if you are going to obtain good poll flexion.  Poor poll flexion can stiffen a horse throughout its entire body.

The other muscles I address when there is tension in the poll are the ones of the throatlatch.  Even when the poll muscles are capable of extending to give good poll flexion, tight muscles in the throatlatch area can prevent this flexion.  I think of it as trying to flex the head when there’s a tennis ball in the throat area.

Horses that crib often have difficulties with poll flexion because of over-developed, tight muscles in the throat area.

This brings us to the end of this survey of skeletal anatomy and the major muscles important for support and movement that are accessible for us to massage. 

Lesson three will cover the horse’s gaits and movement patterns.

Click here to take quiz

 

Assignment:

The aim of this assignment is to enable a student to become so familiar with the horse’s muscular and skeletal anatomy that they can put a hand any place on a horse’s body and know what muscle is under their hand, what the shape of that muscle is, where the origin and insertion attachments of the muscle are, what bones are under that muscles and what the job of the muscle is – what movement of the bones does the muscle activate. 

Use your anatomy books as you do this assignment.

You are not looking for a comparison of the conformation and muscle density.  You will need to look at a minimum of three horses in order to practice on for this assignment.

On three horses, find the bones of the skeleton that we covered in the lesson.  If a bone is covered by substantial muscle mass, be able to visualize where it is and its shape.  Touch the bones where ever possible.  Follow the progression of the bones, starting with the head and going back to the tail.  Also, with finger tips, trace leg and foot bones – fronts and hinds.

On three horses, find muscles of the horse’s body that we covered in the lesson.  Touch these muscles, tracing the outlines with your finger tips whenever possible.  Start at the head and work back to the tail.

After your exploration of the horse’s bones and muscles, write a report describing your thoughts, ideas and any new awareness about what you are feeling – perhaps new things you did not know about horses and their bodies. 

Did you have any “ah ha” moments about things that suddenly made sense to you that you may not have understood before? 

I would like any thoughts that occur to you as you are turning the descriptions of the muscles and bones in the lesson into a tactile journey of the horse’s body.

Send your report to: pegasus.simat@gmail.com