Bipeds require that all of the functions spread out between four legs in Quadrupeds function within the structure of just two legs. That our species accomplished this feat is quite remarkable, particularly given that they did this using the same body plan that evolved over hundreds of millions of years of refinement of four-legged gait. This observation also applies to Birds with their ability to fly, an equally impressive adaptation. Getting up on our hind legs changed many of the functional roles of our physiology, which are delineated here. Although this section is specific to Stance, these mechanisms for managing our mass within Gravity equally apply to our Locomotive Core’s role in Movement. The section on Movement can be found here:
LOAD LINES OF THE LOCOMOTIVE CORE
Our Locomotive Core originates at the soles of sour feet. Our feet are so critical to the function of this, and our other Cores, that there is a special section dedicated to their structural and functional roles (FEET). Viewing the diagram one can see that the load vectors of this Core cross the pelvis at the Sit Bones and Sacroiliac Joints and then converge at the Manubrium (At the level of the T1, T2 vertebrae)(It is worth noting that this structure functions similarly in both standing and sitting). The load vectors then cross the contralateral Atlanto-Occipital Joints, ending at the Sphenoid attribute of the orbit of the eyes. The contralateral eye to the foot load-carrying foot becomes dominant (this can be validated by standing on one foot and noticing which eye is higher and brought forward). Like the feet, Cranial Organization supports the function of multiple Cores and therefore requires a separate section (HEAD). The load vector crossing the mid-line of our body at the Manubrium also facilitates the engagement of the contralateral arm. This is discussed in the section on the Manipulation Core.
/Animals are creatures that move. It is therefore not possible to fully describe stabilization of the Core in Gravity using a static model. It is still a useful place to begin a description of the Core. In static standing on two legs, the loading line of the Core originates on the bottom of the feet in our bilateral stance mode. It passes through the middle of the knee, though the sit bones, through the Sacrum, along the spine to the base of the skull at the Atlas. The line continues along the base of the skull to the eye socket, with the Front-Plane on the anterior surface of the Sphenoid Bone, and the Back-Plane on the Sphenoid posterior surface. There is further discussion on the Head’s relation to the Core here:
When standing on one leg (Tripod Stance), or in gait, the Gravity Line passes through the Head of the Femur and Sacro-Illiac Joint above the loading leg, up the side of the spine to the eye on that side, which becomes dominant. You may be able to feel the difference in your vision (and hearing) between standing on one leg or two.
STANDING ON ONE LEG
When standing on one leg one of the diagonal lines becomes vertical. For example, the line from the right foot to the left eye becomes perpendicular to the ground. This loading line can be validated by standing on one foot and observing if the other eye gains dominance, even for the non-dominant eye.
Specific attributes of stance are discussed in these papers or sections:
Postural Extension and Flexion describe this mechanism of core function, which is highly adapted to our species and is discussed separately here:
LATERAL STABILIZATION OF THE CORE
LATERAL STABILIZATION OF THE CORE
Assessing the Locomotive Core is greatly assisted by the ability to identify the optimal organization for posture using landmarks. This section discusses these landmarks and other tools to aid in assessing how efficiently the Locomotive Core handles the body’s mass in Gravity.
CORE STABILIZATION OF COMPLEX ACTIONS
For fine motor control of the arms, the Locomotive Core’s job is to provide a stable foundation. This vital function of the Locomotive Core, the inhibition of movement, is an entirely different functional circuit than our freeze protective reaction. Stabilization of the Locomotive Core is a complex attunement of activation of muscles in coordination with fine motor control, requiring the involvement of our Neo-Cortical motor systems.
There is a section discussing the complex evolution of the arms beyond their fundamental role in locomotion:
Overview of discussions on our Locomotive Core:
Overview of discussions on our core neurophysiology:
THE FOUR CORES
Overview of the models presented on the Website: