This is the Triceps Brachii PDF for you to download
Triceps Brachii is the key functional muscle of the canine forelimb (thoracic limb).
As an intrinsic muscle found in the caudal brachial region, it occupies the space between the scapula - humerus - olecranon of the ulna (point of elbow).
Intrinsic = muscle origin + insertion are within the thoracic limb
The canine Triceps Brachii is a very important antigravity muscle in natural balanced stance, postures and motion in dogs of all ages, breeds and size. This canine muscle has 4 heads;
- Lateral Head; is important as a joint stabiliser and is active when the joint is weight bearing and maintaining a rigid limb. It's also important in natural balanced motion
- Medial Head; is largely composed of Type I slow twitch muscle fibres (red fibres - aerobic - fatigue resistant) and is important in maintaining posture and natural balanced stance
- Accessory Head; lies deep between the other 3 heads and has a significant postural role, as it has a high percentage of Type I (red) slow twitch muscle fibres
- Long Head; spans two joints and is an elbow extensor and shoulder flexor. It has 70% fast twitch muscle fibres (Type IIA - X) as it is involved in burst activity of short durations (high force production) and is very important in canine motion
The long head passes over two joints, whereas the other 3 heads only pass over one joint.
Muscles have the greatest force exerted at their origin and insertion (attachments), so these are the more common sites for muscle injury.
Muscles that pass over two joints will have an action at both joints and are much more prone to injury, compared to muscles that pass over one joint.
Triceps Brachii key action is as an antigravity muscle and elbow extensor, with the long head also being a shoulder flexor due to its attachments. Understanding the arrangement of the different heads with its surrounding fascia will empower your assessment accuracy and efficacy of your selected treatment techniques.
Innervation of Triceps
Triceps Brachii is innervated by the radial nerve, which is the largest nerve in the brachial plexus and very important in relation to canine movement.
As a rule if a nerve passes through a muscle, it tends to innervate it.
Nerve route: The radial nerve arises from C7 - T2 spinal nerves and exits the axillary space passing into the Triceps Brachii and then piggybacks the Brachialis muscle as it spirals distally around the humerus. As it passes into contact with the lateral head of Triceps Brachii, the radial nerve drops distally passing into the extensors of the antebrachium (forearm).
Anti-pull harnesses take the dog out of balance and are not therapeutically helpful.
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