Final answer:
The stimulating the outer lateral portion of a newborn's soles will elicit a positive Babinski sign, indicating dorsiflexion of the foot and extension of the toes. This reflex is commonly tested in newborns to assess neuromuscular function.
Step-by-step explanation:
The question is referring to the plantar reflex in newborn infants. When the outer lateral portion of a newborn's soles is stimulated, it will elicit a positive Babinski sign. This sign is characterized by the dorsiflexion of the foot and extension and splaying of the toes.
The plantar reflex is commonly tested in newborns to assess neuromuscular function. As the child grows and learns to walk, the plantar reflex changes and the toes curl and the foot shows plantar flexion instead of dorsiflexion. This reflex is suppressed in adults due to the descending input of the corticospinal tract.
The Babinski reflex in adults could indicate reduced myelination of the spinal tract, and this may be a sign of a neurological problem.