Muscles can be classified as either shunt or spurt muscles. A shunt
muscle has its proximal attachment near the joint it acts over and its
distal attachment at a greater distance away from the joint. As a shunt
muscle contracts it applies force along the bones and pulls the joint
surfaces together in order to stabilise the joint. The brachialis and
brachioradialis are examples of shunt muscles.
The opposite can be said of spurt muscles, as their proximal attachment is away from the joint and its distal attachment is close. This enables the spurt muscle to apply force across the bone instead of along to create movement about the joint. Spurt muscles tend to be prime movers and the bicep brachii is classified as a spurt muscle.
Muscles can also be described as being spurt or shunt muscles. These roles are largely unknown in the strength training world but are described in the orthopedic and physical therapy fields. Again, we will consider the elbow joint.
When a muscle acts on a bone it actually produces a force that, if one were to do a vector analysis, could be resolved into two component forces. These components are an angular component and a transarticular component. The angular component is actually the perpendicular or vertical component of the muscle's force. We normally call this the rotary component. If allowed to act alone this force would cause the bone to rotate around the joint. The rotary component is also known as a swing component.
The transarticular component is a parallel or horizontal component. It acts along the shaft of the bone and may produce a force that pulls the bone away from the joint or toward it, depending on the angle of the joint. This component, therefore, is also known as either a stabilizing component or a destabilizing component. When the component is stabilizing it is also known as a shunt component and shunt muscles are muscles that tend pull the bones of a joint together.
The opposite can be said of spurt muscles, as their proximal attachment is away from the joint and its distal attachment is close. This enables the spurt muscle to apply force across the bone instead of along to create movement about the joint. Spurt muscles tend to be prime movers and the bicep brachii is classified as a spurt muscle.
Muscles can also be described as being spurt or shunt muscles. These roles are largely unknown in the strength training world but are described in the orthopedic and physical therapy fields. Again, we will consider the elbow joint.
When a muscle acts on a bone it actually produces a force that, if one were to do a vector analysis, could be resolved into two component forces. These components are an angular component and a transarticular component. The angular component is actually the perpendicular or vertical component of the muscle's force. We normally call this the rotary component. If allowed to act alone this force would cause the bone to rotate around the joint. The rotary component is also known as a swing component.
The transarticular component is a parallel or horizontal component. It acts along the shaft of the bone and may produce a force that pulls the bone away from the joint or toward it, depending on the angle of the joint. This component, therefore, is also known as either a stabilizing component or a destabilizing component. When the component is stabilizing it is also known as a shunt component and shunt muscles are muscles that tend pull the bones of a joint together.