Medial Longitudinal Arch
Also written as: MLA — Medial Longitudinal Arch
The primary weight-bearing arch of the foot, extending from the calcaneus to the first metatarsal head, whose height and rigidity are central considerations in orthotic design.
Full Definition
The medial longitudinal arch (MLA) is the highest and most clinically significant of the foot's three longitudinal arches, formed by the calcaneus, talus, navicular, three cuneiforms, and first three metatarsals. It functions as a spring-like structure during gait, absorbing shock during loading and storing and returning elastic energy during propulsion. Collapse of the MLA is associated with pes planus, tibialis posterior dysfunction, and a range of lower-limb overuse injuries. Orthotic support of the MLA — through medial arch fillers, navicular pads, and rearfoot posting — is one of the most common orthotic interventions. Editors should distinguish MLA from the lateral longitudinal arch and the transverse arch.
Usage
Usage note: MLA is standard in clinical and orthotic documentation. 'Medial arch' is acceptable in lay summaries. Avoid the colloquial 'inner arch' in formal clinical text.
In Context
- "Orthotic support was directed at maintaining the medial longitudinal arch height throughout the stance phase of gait." — Orthotic prescription
- "Radiographic assessment revealed a collapse of the MLA consistent with stage II tibialis posterior dysfunction." — Radiology referral letter