Human mouth

Head and neck

Mouth

Human Mouth

The mouth, a central component in human anatomy, is the primary entryway to the alimentary canal and receives both food and saliva. Beyond its crucial role in the digestive system, the mouth is integral to human communication. While the foundational elements of voice production occur in the throat, the tongue, lips, and jaw also significantly contribute to the diverse range of sounds present in human speech.

The mouth's interior is usually moist, coated by a mucous membrane, and houses the teeth. The transition from the mucous membrane to the external skin is marked by the lips.

Anatomy

Mouth Cavity

The mouth cavity, or the oral cavity, is the initial section of the mouth. Its boundaries include:

• Laterally and anteriorly: Alveolar process (home to the teeth)
• Posteriorly: Isthmus of the fauces
• Superiorly (roof): Combination of the hard and soft palates
• Inferiorly (floor): Constructed by the mylohyoid muscles and is predominantly occupied by the tongue.

Orifice

When closed, the mouth's orifice forms a boundary line separating the upper and lower lips. This line's appearance can change based on facial expressions—forming an upward-opening curve during a smile and a downward-opening one while frowning. A permanently downturned mouth can be a standard facial feature. In certain cases, such as in Prader-Willi syndrome, a downturned mouth is a notable characteristic.

Innervation

The mouth's innervation is intricate, with the teeth and the periodontium (tissues supporting the teeth) receiving signals from the trigeminal nerve's maxillary and mandibular divisions.

• Maxillary Teeth: These, along with their periodontal ligament, are served by the superior alveolar nerves—divisions of the maxillary segment.
• Mandibular Teeth: These and their periodontal ligament receive innervation from the inferior alveolar nerve, part of the mandibular division.

A detailed breakdown of the oral mucosa's innervation is vast, with the various regions receiving signals from a combination of the infraorbital nerve, greater palatine nerve, nasopalatine nerve, sublingual nerve, mental nerve, and the buccal nerve.

Development

Developmental features of the mouth include the philtrum, a vertical indentation in the upper lip. It forms when the nasomedial and maxillary processes meet during embryonic development. Failure in their complete fusion can lead to conditions like hare lip and/or cleft palate. Moreover, the nasolabial folds, deep tissue creases running from the nose to the mouth's sides, often become more prominent with age.

Function

Central to various vital processes, the mouth facilitates essential functions:

• Eating and Drinking: It plays a pivotal role in mastication (chewing) and the intake of liquids.
• Breathing: Serving as an auxiliary respiratory passage.
• Communication: Key for speech production and articulation.

In addition, newborns inherently possess a sucking reflex, prompting them to suckle for nutrition.

See Also

• Digestive system
• Human anatomy
• Speech production
• Facial expressions
• Head and neck anatomy
• Mouth breathing
• Index of oral health and dental articles
• List of basic dentistry topics

This article uses anatomical terminology. For an overview, see Anatomical terminology.