Where does the long digital extensor insert?

• A. Distal phalanges I-V
• B. Distal phalanges II-V
• C. Proximal phalanges II-V
• D. Tarsal IV

Answer: (B)

The long digital extensor muscle is primarily responsible for extending the digits (toes) of the hind limb. Its insertion point is particularly important for understanding its function in movement and support of the limb.

The long digital extensor inserts at the distal phalanges of digits II to V in domestic animals such as horses and dogs. This allows the muscle to extend the toes during movements like walking or running. By inserting at the distal phalanges, it effectively facilitates the extension of the digits, which is crucial for propulsion during locomotion.

The other options suggest alternative insertion points that do not align with the anatomical and functional characteristics of the long digital extensor. For instance, distal phalanges I-V includes the first digit (the dewclaw in mammals), which is not influenced by the long digital extensor in the same way. The proximal phalanges II-V would also be incorrect because the muscle does not insert there; its primary function is exerted on the distal phalanges. Tarsal IV is not related to the digital extension function, as this option pertains to a tarsal bone rather than a phalanx. Understanding the insertion of the long digital extensor at distal phalanges II-V is essential for recognizing