It is relatively common for the Flexor digitorum superficialis to be missing from the little finger, bilaterally and unilaterally, which can cause problems when diagnosing a little finger injury.
The grasp reflex (newborn reflexes) It occurs when placing an object, such as a finger, onto the infant's palm (palmar grasp) or sole (plantar grasp). The infant responds by flexing fingers or curling the toes. The palmar grasp usually disappears by 3 to 4 months and the plantar grasp by 6 to 8 months.
This is a reflex that happens in infants with you firmly stroke the sole of their foot. It is an uncontrollable response. It is also called plantar reflex. By the age of two this reflex should have disappeared but if it presence in children older than two years of age and adults it could be a sign of a neurological disorder that could be affecting their spinal cord or brain.