The lumbrical muscles do not attach to the proximal phalanx directly, but rather connect the tendons of flexor digitorum profundus (below, ie volar) to the extensor tendons (above, ie dorsal) and produce flexion by pulling on the extensor tendons as they pass over the proximal phalanx.
By the time they are 12 months old, most babies can weigh three times what they weighed at birth and gain about an inch per month in length. The average infant at one year may be between 2630 inches long. Social and Emotional Development-Infants respond when you say their name. They begin to fear strangers.
Gaining the strength to hold her head up is the foundation on which the development of all your baby's other movement is based. It will help her to roll over, sit up, crawl and walk. By six months, your baby will have developed neck muscles strong enough to hold her head up and look from side to side. Your baby will take it slowly. She'll gradually develop head control over her first six months.