Muscle of the Month: Triceps Brachii
The first of my new feature 'Muscle of the Month' starting with the Triceps Brachii, a key muscle in the fore limb which has multiple functions. Read on to find out more about the anatomy, function, injury risk, and treatment options if needed.
The Triceps Brachii is located in the forelimb of the dog on the upper arm. It is a large muscle which is made up of 4 heads; long, lateral, medial and accessory. All 4 of these heads work together to extend or straighten the elbow joint. The long head also works in isolation to flex the shoulder joint, bringing the limb upwards and towards the body.
All muscles have an origin, the place where the muscle starts, and an insertion, the place where the muscle ends. The origin of the Triceps Brachii is the caudal border of the scapula, which means the edge of the shoulder blade that is closest to the back end, and it also begins on the surface of the humerus bone. All 4 of the heads insert or end in the same place, the olecranon, which is the bony part you can feel on the back of the dog's elbow.
What does it do?
So you now know that the Triceps Brachii extends the elbow, and flexes the shoulder, but what does that really mean?
When dogs are standing, the elbow is in an extended or straightened position, and this is achieved by small contractions in the Triceps Brachii muscle, working against the force of gravity and the resistance of the dog's weight to remain upright.
The muscle is also at work when the dog is running or jumping, because again it resists gravity and weight, meaning the dog does not collapse down on the fore limb when they land. The weight of the dog will naturally cause the elbow to flex, the Triceps Brachii works against this to keep the dog upright.
Can the Triceps Brachii become injured?
The most common injury seen in the muscle is a strain, meaning the muscle or associated tendon is damaged. Muscle strains are graded from 1-3 depending on severity;
Grade 1 - muscle fibres stretched, no tear
Grade 2 - some muscle fibres torn
Grade 3 - Complete tear, all fibres torn
Agility dogs are more likely to suffer with strains of the Triceps Brachii muscle, because of the nature of the activity. Landing from jumps and other obstacles, such as the A Frame, cause forces to travel up the limb to the muscle, and in agility this action is repetitive. Dogs can also lose their footing when they land, and possibly slip when weaving if the ground is wet, or slip in the tunnels. No warm up, or a poor warm up can also increase the risk of injury to the muscle.
If your dog has suffered a strain of the the Triceps Brachii, symptoms you are likely to see include; a shortened stride, when landing the dog will drop down into greater elbow flexion appearing to collapse on the front leg, the dog may be reluctant to jump or weave, and they may appear stiff on the limb after they have been resting.
Besides injury, the Triceps Brachii can also become weak if not used correctly and it can also become tight if it is over used or used incorrectly. In cases such as these, you will see similar symptoms. I often see dogs that have changed the way they move and as a result caused issues in the triceps muscle. A change in movement can be due to pain in the forelimb or pain in the hind limbs, resulting in extra weight being placed on the forelimbs to compensate.
As a physiotherapist, I use massage therapy and stretching to loosen tight areas in the muscle tissue and to make the muscle more flexible. I also create targeted exercise programmes to ensure the Triceps Brachii is strengthened so it can function optimally.
For more information about what I do and how I could help your animal please do get in touch. Be sure to check back next month for 'Muscle of the Month'.