Final answer:
When the medial arch is collapsed, creating 'flat feet', this is a form of pes planus or 'fallen arches'. Pes planus is a condition where the longitudinal arches of the foot depress or collapse, particularly on the medial side.
Step-by-step explanation:
When the medial arch is collapsed, creating 'flat feet', this is a form of pes planus or 'fallen arches'. Pes planus is a condition where the longitudinal arches of the foot depress or collapse, particularly on the medial side. This can occur due to prolonged, excessive, or repeated stretching of the ligaments that support the arches, resulting in a gradual lengthening of the ligaments.