The oral cavity is a complex structure located in the head and neck region, consisting of several organs and tissues that play crucial roles in different functions such as speech, mastication, swallowing, and respiration. In this article, we will explore the anatomy of the oral cavity, including its structures and functions. So, the oral cavity comprises the lips, cheeks, teeth, gums, tongue, floor of the mouth, hard and soft palate, and the tonsils.
A number of bones contribute to the framework of the oral cavity; these are the paired maxillae, palatine and temporal bones, as well as the unpaired mandible, sphenoid and hyoid bones.
The cavity is separated into anterior and posterior parts by the dental arches (or teeth): the anterior oral vestibule sits anteriorly to the teeth and behind the lips, whilst the oral cavity proper describes the area behind the teeth.
The inside of the oral cavity is constantly lubricated by salivary glands which also participate in food digestion by secreting enzymes that start the digestion of carbohydrates. These glands are the parotid, submandibular and sublingual glands.
The oral cavity is lined by the oral mucosa, covered with stratified squamous non-keratinized epithelium. It contains a large number of glands. The area of the mucous membrane, attached around the neck of the teeth on the periosteum of the alveolar processes of the jaws, is called the gum. The oral cavity communicates with the pharynx through the isthmus of the pharynx.
The lips are two fleshy structures that form the opening of the oral cavity. They are composed of skin, subcutaneous fat, muscles, and connective tissues. The skin that makes up your lips is different from the skin on the rest of your face and body. Lip skin does not have sebaceous glands or a top stratum corneum layer. This difference in anatomy makes lips thinner, softer and more susceptible dehydration and/or skin cancer as compared to face and body skin. Hydrating your lips and protecting your lips with a daily sunscreen is important to keep them unlined and healthy. The lips play an essential role in various functions, including speech, expression, and food intake.
The muscles of the lips are responsible for the movement and control of the lips. The orbicularis oris muscle encircles the mouth and is responsible for the puckering and shaping of the lips during speech and expression. The levator labii superioris muscle raises the upper lip, while the depressor labii inferioris muscle lowers the lower lip.
The lips also contain a network of blood vessels that supply oxygen and nutrients to the lips and remove waste products. The blood vessels are located close to the surface of the lips, giving them their characteristic red color.
The lips play an essential role in speech production by controlling the flow of air through the mouth. The lips help to form various sounds, such as "p," "b," and "m," by creating a brief closure of the mouth, followed by a burst of air. The lips also play a crucial role in facial expressions, such as smiling, frowning, and kissing.
In addition to their role in speech and expression, the lips also play a critical role in food intake. The lips help to prevent food and liquid from escaping the mouth during eating and drinking, and they also help to guide food and liquid towards the teeth and tongue for further processing.
The cheeks, the sides of the mouth, are continuous with the lips and have a similar structure. A distinct fat pad is found in the subcutaneous tissue (the tissue beneath the skin) of the cheek; this pad is especially large in infants and is known as the sucking pad. On the inner surface of each cheek, opposite the second upper molar tooth, is a slight elevation that marks the opening of the parotid duct, leading from the parotid salivary gland, which is located in front of the ear. Just behind this gland are four to five mucus-secreting glands, the ducts of which open opposite the last molar tooth.
Teeth are hard, calcified structure that is part of the body's digestive system. They are located in the mouth and is responsible for cutting, tearing, and grinding food during the process of mastication. Teeth are made up of several layers, including the enamel, dentin, pulp, and cementum. There are four different types of teeth in the human mouth: incisors, canines, premolars, and molars. Each type of tooth is specialized for a specific function in the process of biting, tearing, and grinding food. You can read more in our separate article about teeth.
Gums, also known as gingiva, plural gingivae, in anatomy, connective tissue covered with mucous membrane, attached to and surrounding the necks of the teeth and adjacent alveolar bone. Before the erupting teeth enter the mouth cavity, gum pads develop; these are slight elevations of the overlying oral mucous membrane. When tooth eruption is complete, the gum embraces the neck region of each tooth. As well as being attached to adjacent alveolar bone, gum is connected to the cement of each tooth and to the tooth enamel. Healthy gums are pink, stippled, and tough and have a limited sensibility to pain, temperature, and pressure. The gums are separated from the alveolar mucosa, which is red, by a scalloped line that approximately follows the contours of the teeth. The edges of the gums around the teeth are free and extend as small wedges into the spaces between the teeth (interdental papillae). Internally, fibres of the periodontal membrane enter the gum and hold it tightly against the teeth.
Functions of Gums:
Protecting the teeth: The gums cover the tooth roots and help to protect them from damage, such as abrasion or decay. They also provide a barrier against bacteria and other harmful substances that can cause infection or disease.
Supporting the teeth: The gums provide support to the teeth by attaching them to the underlying bone through the periodontal ligament. This helps to stabilize the teeth and prevent them from moving or becoming loose.
Sensing temperature and pressure: The gums are rich in nerve endings and are sensitive to temperature and pressure changes. This allows us to feel the texture and consistency of food while we eat and helps us to avoid biting down too hard on something that could potentially damage our teeth.
Maintaining oral hygiene: The gums play a critical role in maintaining good oral hygiene. They help to keep the teeth clean by providing a seal around them and preventing food particles and bacteria from getting trapped between the teeth and gums. They also produce a fluid called gingival crevicular fluid that helps to remove bacteria and other debris from the mouth.
The tongue is the central part of the oral cavity. It’s a muscular organ whose base is attached to the floor of the oral cavity, whilst its apex is free and mobile.
The tongue is predominantly muscle. There are 8 muscles: 4 intrinsic and 4 extrinsic. His mobility and strength are important for the processes of speech and mastication. These abilities are determined by the tongue muscles. Muscles that make up the inside of the tongue are called the intrinsic muscles of the tongue. They are responsible for many of the tongue’s functions; such as talking, mastication and any other action that requires the tongue to move. These muscles control movements such as twirling, curling, flattening and broadening of the tongue.
Muscles that are located outside the tongue and only attach to it in specific regions are called the extrinsic muscles of the tongue. These assist the tongue and support it in more complex actions such as protrusion and retraction.
The 4 intrinsic muscles of the tongue are: the superior longitudinal, inferior longitudinal, transverse and vertical muscles.
The 4 extrinsic muscles of the tongue are: the genioglossus, hyoglossus, styloglossus and palatoglossus muscles.
Besides the muscles, the other important feature of the tongue is its mucosa. The dorsal tongue mucosa is covered with lingual papillae which function as the sensory receptors for taste. There are four types: filiform, fungiform, vallatae and foliate papillae.
All the papillae act as taste receptors except for the filiform, which have a purely mechanical role. You may wonder what that mechanical role is. Well, filiform papillae are present on the tongue of every vertebrate species and are quite prominent in cats. So basically, they are very sharp and serve for the cleaning of fur. Luckily for us, soap was invented in 2800 BC so we don’t have to lick our skin in order to get clean. This is why our filiform papillae have shrunk and became less prominent.
The floor of the mouth is the area located under the tongue and between the lower jawbone (mandible) and the muscles of the neck. It contains a number of important structures, including the tongue, the sublingual gland, and the submandibular gland.
Functions of the Floor of the Mouth:
Speech and swallowing: The tongue, which is located in the floor of the mouth, plays a crucial role in speech and swallowing. It helps to move food around in the mouth during chewing and helps to push the food back into the throat during swallowing.
Saliva production: The sublingual and submandibular glands, which are located in the floor of the mouth, produce saliva that helps to moisten the mouth and aid in digestion.
Blood vessels and nerves: The floor of the mouth contains a number of blood vessels and nerves that supply the tongue, the gums, and other structures in the mouth.
The palate is a bony-muscular partition that forms the roof of the oral cavity and the floor of the nasal cavities. It consists of two main parts: the hard palate and soft palate. The hard palate is the anterior bony portion, while the soft palate is the posterior muscular part.
The palate completely separates the oral cavity and nasal cavities. This division is essential for preventing pressure changes within these cavities, thus enabling important processes such as suckling and breathing. Additionally, due to its position and structure, the palate plays an important role in articulation (formation of speech), digestion and swallowing.
The hard palate is the immobile hard bony portion of the palate. It comprises the anterior two-thirds of the palate. The hard palate is formed by the fusion of two pairs of facial bones in the midline, the maxillae (upper jaw bones) and palatine bones. The palatine processes of the maxillae form the anterior three-quarters of the hard palate, while the horizontal plates of the palatine bones form the remaining posterior one-quarter. The hard palate is arched superiorly forming a concavity which accommodates the tongue. It is bounded on its anterolateral aspects by the alveolar processes and teeth of the maxillae. Posteriorly, the hard palate is connected to the muscular soft palate. The oral aspect of the hard palate is covered by oral mucosa that is firmly bound to the underlying bone and overlies the mucus-secreting palatine glands and neurovascular structures. The nasal aspect on the other hand is covered by respiratory mucosa.
The hard palate bears several openings that transmit important neurovascular structures that supply the palate and oral cavity. In the midline, on its anterior end, the hard palate bears the incisive fossa, which transmits the nasopalatine nerve and the sphenopalatine vessels. At its posterior end, close to the second maxillary molars, the hard palate has two paired openings, the greater and lesser palatine foramina which transmit the greater and lesser palatine nerves and vessels respectively.
The soft palate (velum) is the posterior muscular portion of the palate that continues from the posterior border of the hard palate. It is a mobile soft tissue flap that curves posteriorly and inferiorly into the pharynx, demarcating the nasopharynx from the oropharynx. It blends laterally with the palatoglossal and palatopharyngeal arches of the oropharynx. These arches form the boundaries of the tonsillar fossa which houses the palatine tonsils. On its posterior free margin, the soft palate bears a conical projection in the midline known as the uvula. The epithelial lining of the oral surface of the soft palate contains a small number of taste buds.
The soft palate has no bony component but contains the palatine aponeurosis. This structure is the fibrous aponeurotic expansion of the tensor veli palatini muscles that attaches to the posterior border of the hard palate. The palatine aponeurosis serves as the principal structural component of the soft palate to which the other muscles of the palate attach. The soft palate is composed of five pairs of muscles that enable it to move:
The tensor veli palatini and levator veli palatini are two muscles that arise from the base of the skull and descend into the palate. During swallowing and yawning, these muscles tense and elevate the soft palate.
The palatoglossus muscles ascend from the sides of the tongue into the palate and lower the soft palate onto the tongue, narrowing the oropharyngeal opening.
The palatopharyngeus muscles ascend into the palate from the posterior border of the thyroid cartilage. This muscle tenses the soft palate while elevating the pharynx during swallowing.
The final muscle of the soft palate is the musculus uvulae, which arises from the posterior margin of the hard palate and passes into the mucosa of the uvula. It elevates and retracts the uvula.
Function
The palate is involved in feeding, breathing, swallowing, and speech. Along with the tongue, the bony hard palate portion allows for the creation of a partial vacuum force that draws fluid into the oral cavity. This is an essential function in infants as it enables them to suckle. During nasal breathing the soft palate assumes a lowered position, allowing air to move freely in and out of the pharynx through the nasal cavities. During swallowing, however, the soft palate elevates, closing off the nasopharynx to prevent food and liquids from the oral cavity and oropharynx from entering the nasal cavities. The soft palate also plays a key role in the gag reflex; touching the surface of the soft palate or the uvula evokes the gag reflex and can cause vomiting.
Together with the tongue, the palate plays a key role in articulation (speech production) and language by altering airflow through the oral cavity in order to create a variety of speech sounds. Sounds made with the tongue against the hard palate such as the ‘n’ sound in ‘man’ are referred to as palatal sounds. On the other hand, velar sounds are made with the back of the tongue against the soft palate (velum), for example, the ‘k’ sound in ‘cat’.
Tonsils are a pair of small, soft tissues located at the back of the throat, one on each side. They are part of the lymphatic system, which helps the body fight off infections. The tonsils play an important role in the body's immune system, but they can also be a source of health problems. In this article, we'll explore the functions of the tonsils, their potential health problems, and treatment options.
Functions of the Tonsils:
Immune System: The tonsils are an important part of the immune system, helping to fight off infections in the throat and upper respiratory tract. They contain lymphocytes, which are specialized white blood cells that help to identify and destroy harmful pathogens, such as bacteria and viruses.
Filtering: The tonsils act as a filter, trapping bacteria and other foreign particles that enter the body through the mouth and nose. This helps to prevent these harmful substances from entering the rest of the body.
Antibody Production: The tonsils produce antibodies in response to infections, helping the body to recognize and fight off similar infections in the future.
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