اللسان

The tongue contains eight muscles divided into two types. Intrinsic muscles, located entirely within the tongue, change its shape for speech and swallowing. Extrinsic muscles originate from skull bones and the soft palate, extending to the tongue to control its position and gross movements like protrusion, depression, elevation, and retraction.

The tongue shapes chewed food into a swallowable bolus and propels it into the pharynx during swallowing. This coordinated action of intrinsic and extrinsic muscles is essential for moving food from the oral cavity to the esophagus, initiating the swallowing process.

The lingual frenulum is a mucosal fold that anchors the tongue to the floor of the mouth. It limits backward movement of the tongue, helping control its position. When the frenulum is too short, a condition called ankyloglossia or tongue-tie can restrict tongue movement and affect feeding and speech.

The tongue has four papilla types: filiform papillae, the most numerous, provide texture but lack taste buds; fungiform papillae are mushroom-shaped and contain taste buds; circumvallate papillae are large bumps at the back containing taste buds; foliate papillae on the sides also contain taste buds for perceiving sweet, salty, sour, bitter, and umami tastes.

The tongue divides into two symmetrical halves along the median sulcus on its surface. It also separates into the anterior oral part, the mobile front two-thirds visible in the mouth, and the posterior pharyngeal part, the fixed back one-third toward the throat. The base connects to the hyoid bone, mandible, styloid processes, and pharynx.

The tongue is essential for articulation and speech production. It modulates airflow through the mouth to produce different sounds. Intrinsic muscles change the tongue's shape, while extrinsic muscles control its position, allowing precise movements necessary for clear speech and sound formation.

Taste buds housed within fungiform, circumvallate, and foliate papillae on the tongue enable gustation. These sensory structures allow perception of five basic tastes: sweet, salty, sour, bitter, and umami. The tongue's position and movement also help distribute food across taste receptors for optimal flavor detection.