Human mouth

The human mouth is a vital part of the body. It serves as the first section of the alimentary canal. This is the long pathway food travels through the body. The mouth receives food and produces saliva to aid digestion. It also plays a major role in human communication. While the throat produces the primary aspects of the voice, the mouth helps shape sound. The tongue, lips, and jaw are all necessary for speech.

The mouth is divided into two distinct regions. The first region is known as the vestibule. This is the space located between the teeth, lips, and cheeks. The second region is called the oral cavity proper. The sides and front of this cavity are bounded by the alveolar process. This is the part of the bone that contains the teeth. The back of the cavity is bounded by the isthmus of the fauces. The roof of the oral cavity is the hard palate. The floor is formed by the mylohyoid muscles.

A specialized tissue called the oral mucosa lines the mouth. This is a mucous membrane epithelium. It keeps the inside of the mouth moist. The mucosa lines the gums and the underside of the tongue. It also lines the inner aspect of the mandible, which is the lower jaw. This lining receives secretions from the sublingual and submandibular salivary glands. The posterior border of the oral cavity is a complex junction. It includes the junction of the hard and soft palates. It also includes the circumvallate papillae on the tongue and the retromolar trigone.

Nerves provide sensation to the teeth and the periodontium. The periodontium is the tissue that supports the teeth. These sensations are carried by the maxillary and mandibular nerves. These are divisions of the trigeminal nerve. The maxillary nerves supply the upper teeth. They include the superior alveolar nerves. These branches include the posterior superior, anterior superior, and middle superior alveolar nerves. These nerves form the superior dental plexus. The mandibular nerves supply the lower teeth. The inferior alveolar nerve runs inside the mandibular canal. It gives off branches to all lower teeth to form the inferior dental plexus.

Many other nerves supply the gingiva, or the gums. The infraorbital nerve supplies the gums near the upper incisors and canines. The greater palatine nerve supplies the gums on the palatal side of the upper teeth. The sublingual nerve supplies the gums on the tongue side of the lower teeth. The mental nerve supplies the gums on the facial side of the lower incisors. The buccal nerve supplies the gums on the cheek side of the lower molars. These nerves allow the mouth to feel a wide range of sensations.

The mouth is essential for several biological functions. It is used for eating, drinking, and biting food. It also helps with breathing. Humans usually breathe through the nose. Mouth breathing acts as a backup system if the nose is obstructed. Infants are born with a sucking reflex. They instinctively use their lips and jaw for nourishment. Some people use their mouths for tasks usually done by hands. Disabled artists may use their mouths to hold brushes or tools. They use tongue and cheek muscles to paint or write. This can be strenuous for the neck and jaw muscles.

The lips are also important for facial expression. They mark the transition from mucous membrane to skin. A closed mouth forms a line between the upper and lower lip. A smile is shaped like an up-open parabola. A frown is shaped like a down-open parabola. During embryo development, the philtrum is formed. This is the vertical depression between the upper lip and the nasal septum. It forms where the nasomedial and maxillary processes meet. If these processes do not fuse, a cleft lip or cleft palate can occur. You may also notice nasolabial folds. These are creases that run from the nose to the sides of the mouth. They often become more prominent as a person ages.