Tongue biomechanics and motor control

Abstract

The tongue is one of the most intriguing of the skeletal muscles, considering that it consists of several muscles and as a group, takes many shapes. It plays a vital role in respiration, suckling, acquiring and manipulating food, swallowing, and speech. Obviously, not all species use the tongue in the same way, so the tongue has adapted to deform into different shapes and mechanisms of movement to meet the needs of the animal. Even when considering only mammalian tongues, two categories of tongue have been proposed (Doran 1975). The type II tongues in animals such as marsupials, monotremes, and pholidota protrude at least 100 % of their resting length to gather food such as ants or flies. Many of these tongues reach their prodigious lengths by a hydrostatic mechanism typically created by contraction of the vertical and transverse lingual muscles, compressing the longitudinal muscles, resulting in more elongation of the tongue (McClung and Goldberg 2000; Smith and Kier 1989). While intriguing, the type II tongues are not discussed further.