Fusiform muscle

Musculus fusiformis

Definition

Muhammad A. Javaid

A fusiform muscle is a type of skeletal muscle characterized by its spindle-shaped structure — thick in the middle (the belly) and tapering sharply towards tendons at both ends. The name derives from the Latin word fusus, meaning "spindle.

Speed and Agility vs. Force of Contraction

The muscle fibres run parallel to the long axis of the muscle and converge towards tendons at both ends.

  • Movement efficiency: This parallel arrangement is optimally designed for speed, efficient movement, and a large range of motion, allowing of rapid shortening.

  • Force limitation: Conversely, fusiform muscles typically generate less maximum force when compared to muscles with a pennate (feather-like) fibre arrangement.

They are adapted for agility and wide excursions rather than maximal power or endurance.

Examples

Common examples of fusiform muscles include the biceps brachii (arm), sartorius (thigh), and brachioradialis (forearm).

References

  • C.-n. (Joyce) Chen, L.D.V. Thompson, L.A. Snow, Chapter 1 - Muscle Structure and Function, Editor(s): Jeffrey D. Placzek, David A. Boyce, Orthopaedic Physical Therapy Secrets (Third Edition), Elsevier, 2017, Pages 1-9,