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.
Q: When will my baby start to hold her head up? A: When your baby is first born, her neck is far too weak to support her head, but it will quickly get stronger. By 2 months, you may notice your baby briefly popping her head up during tummy time, even if only for a few wobbly seconds.