When examining a patient, right & left refers to the patient's right and left, not to the examiner's right and left.
Posterior: toward the top of the head.
Inferior: toward the bottom of the feet
Lateral: toward the right or left.
Medial: toward the median plane.
Proximal: closer to the origin.
Distal: farther than the origin.
For the skeleton, the origin is the acial skeleton (vertebral column).
For the circulatory system, the origin is the heart.
For the nervous system, the origin is the brain.
Relative to Axial Skeleton
Relative to the Heart