The phrase "lateral head" typically refers to a specific part of the human body, specifically a muscle. It refers to the outer side or surface of a muscle or body part, usually located away from the center or midline. Full definition
This intense compound movement powerfully hits the anterior and lateral heads of the deltoid. (fitnessandpower.com)
These include a printable and flexible gyroscope that measures rotational motion of the head and body balance and a printable and flexible 3 - D accelerometer that measures lateral head motion and body balance. (sciencedaily.com)
«Tri» means, well, three and «ceps» means head — they have the long, medial and lateral heads which are located on the upper inside, lower inside and lateral side respectively. (fitnessandpower.com)