The tongue is mostly made up of muscle, but it also contains fat, glands and a mucus membrane. The extrinsic and intrinsic muscles in the tongue are skeletal muscles, which means that they are voluntarily controlled by the central nervous system.
Extrinsic tongue muscles are attached to parts of the body outside the tongue, such as surrounding bone structures. These muscles enable the tongue to move in and out, vertically and horizontally, and back and forth. The muscle that lowers the tongue and moves it forward is called the genioglossus.
The muscle that lifts and pulls the tongue back is the styloglossus. The muscle that lifts the back end of the tongue is the palatoglossus, and the muscle that causes the sides to curl is the hyoglossus. The intrinsic muscles are fully within the tongue, enabling it to shift in shape and size. Interspersed with the skeletal muscles of the tongue are glands and fat. The tongue is divided into two symmetrical halves by a partition called the median septum.
Covering the muscles of the tongue is a mucus membrane that protects the body from pathogens and microbes and keeps the mouth moist. Blood flows into the tongue through the lingual artery. The surface of the tongue is covered with papillae that contain taste buds. Salivary glands in the tongue and mouth secrete saliva, which aids with digestion.