Locomotor economy and the origin of bipedality: reply to Steudel-Numbers

Children develop a wide range of gross motor skills during the first three years, as increasing muscle strength, balance, coordination, and nervous system maturation allow greater control over body movements. Development generally progresses from basic postural control to independent movement and later to activities such as jumping, climbing, and pedaling.Motor Development During the First YearMost infants begin rolling during the first several months, although the timing and direction can vary.

Piaget’s preoperational stage, from about ages 2 to 7, is characterized by rapid growth in symbolic thinking. Children increasingly use words, images, and objects to represent ideas, although their reasoning remains largely intuitive. During this period, number sense develops from memorized counting toward an understanding of quantity and basic arithmetic.Counting and CardinalityChildren younger than age 3 may recite number words without fully understanding their numerical meaning. During the...

Physical development during the prenatal period and early childhood follows two major directional principles: cephalocaudal and proximodistal development. These general patterns happen simultaneously and help explain changes in body proportions and the gradual development of motor skills.Cephalocaudal DevelopmentThe cephalocaudal principle describes development from the head downward toward the lower body. During prenatal development, the head and brain structures develop rapidly before many...

The human leg comprises an intricate system of muscles that facilitate the movement of feet and toes. Within this system, the muscles are categorized into the anterior, lateral, and posterior compartments, each with a unique set of muscles carrying out specific functions.
Anterior Compartment
The anterior compartment includes muscles that contribute to the dorsiflexion of the foot. This compartment houses the tibialis anterior, extensor hallucis longus, and extensor digitorum longus muscles.

The indirect motor or extrapyramidal pathways originate in the brainstem, the lower portion of the brain that connects it to the spinal cord. They consist of several distinct tracts, each with specialized functions. The four main tracts of the indirect motor pathways are the vestibulospinal tract, the reticulospinal tract, the tectospinal tract, and the rubrospinal tract.
The vestibulospinal tract originates in the vestibular nuclei of the brainstem. The vestibular system detects changes in...