Flexor digitorum superficialis ( flexor digitorum sublimis ) is an extrinsic flexor muscle of the fingers at the proximal interphalangeal joints.

These are situated at the proximal end of the bone, that is the end that connects with the scapula.

Vygotsky introduced the notion of zone of proximal development, an innovative metaphor capable of describing the potential of human cognitive development.

Vygotsky (1978) referred to this as the Zone of Proximal Development and believed that fostering development within this zone leads to the most rapid development.

However, unlike Piaget, he claimed that timely and sensitive intervention by adults when a child is on the edge of learning a new task (called the zone of proximal development) could help children learn new tasks.