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.
Week 3 Milestones. By the end of the month your baby will most definitely be able to lift and hold his head off the floor slightly, for a small period of time during tummy time. By this point some babies can lift their heads to about a 45 degree angle, and there are a few that can even lift their heads to a 90 degree angle.