The arms and hands that we use to manipulate tools originated as the forelegs of quadrupeds. In these four-legged vertebrates, the forelegs pull the body forward, while the hindlegs push. The intrinsically tensional work undertaken by the forelegs facilitated their evolution into the non-specialized tool manipulators we today utilize. We continue to manifest locomotive dynamics in our hands and arms in the developmental stage of crawling. In crawling the part of the hand that continues to competently support bodyweight is the aspect of the palm nearest the wrist. In this composition, the hand and wrist competently manage compressional weight-bearing. The automaticities that functionalize grasp using this sensory input are called the Hands Supporting and Symmetrical Tonic Neck Reflexes. These stiffen the frame of support from the palms to the head based on weight sensing at this part of the palm. Discussion of the classic exemplar of crawling can be read in the post on crawling:
CRAWLING
Discussion of our reflexive automaticities can be read in this post:
DEVELOPMENTAL REFLEXES
In Primates, the progression of our evolution involved the transformation of the arms and hands from weight-bearing to grasp. Grasp enabled Primates to move vertically as well as horizontally through the arboreal canopy. Another evolutionary development related to this was the development of the round Iris. The thumb positioned in opposition to the fingers facilitates grip. The fingers work as a unit to hook onto a branch etc. and are locked in place by the opposing thumb. The sensory component of grasp monitors for slipping on the palm at the first knuckle. If slipping is sensed on the palm at the level of these knuckles grasp is increased. This automatic motor function is called Hand Grasp. This is easy to demonstrate and experience.
SORT VIDEO DEMO OF GRASP
Fine motor skills emerged in our hands as they morphed into the handles for non-specialized tool application. These fine motor skills are based on individual manipulation of the fingers against the opposing thumb. This originally evolved to access previously inaccessible nutrient sources such as Termites using a stick, or the marrow of bones using a rock. Fine-Motor skills, therefore, are linked strongly to the mouth, a correlation discussed in writings on the Babkin Palmomental Developmental Reflex.
One of many diagnostic tools used for evaluating the level of maturation of the hand’s automaticities and developmental reflexes globally is how an individual approaches grasp. If the individual uses the pads of the Thumb and Fingers to grasp when supporting their weight rather than fully encapsulating the grasped object with their hand, this suggests that individuals underlying mammalian motor automaticities had incompletely matured before becoming dominated by the neurologically complex Fine-Motor skills. Training grasp as demonstrated in the video above will facilitate further maturation of this automatically. Doing so will add vigor to the locomotive system.
DIAGNOSTIC TOOLS AND THERAPY
One of many diagnostic tools used for evaluating the level of maturation of the hand’s automaticities and developmental reflexes globally is how an individual approaches grasp. If the individual uses the pads of the Thumb and Fingers to grasp when supporting their weight rather than fully encapsulating the grasped object with their hand, this suggests that individuals underlying mammalian motor automaticities had incompletely matured before becoming dominated by the neurologically complex Fine-Motor skills. Training grasp as demonstrated in the video above will facilitate further maturation of this automatically. Doing so will add vigor to the locomotive system.