Dorothy FarrarLower jaw
The mandible is the lower portion of the jaw . It forms the largest facial skull bone.
Definition
The lower jaw (mandible) is part of the facial skull. Together with the upper jaw (maxilla), it is part of the chewing apparatus. It is also known as the jawbone. In contrast to the upper jaw, the lower jaw has freedom of movement.
At the same time, it represents the strongest and most extensive bone in the human facial skull. It is composed of the corpus mandibulae, which resembles the shape of a U, and the rami mandibulae. These are two branches that rise at the angles of the mandible (Anguli mandibulae).
Anatomy
The corpus mandibulae has a bend like a horseshoe. The upper limit is marked by the alveolar process (Paris alveolaris mandibulae). This has a total of 16 bony tooth sockets. If teeth are lost in old age , the alveolar process also disappears. The transition to the Angulus mandibulae occurs on both sides at the lower edge of the Corpus mandibulae.
The corpus mandibulae has two surfaces. These are the outer surface (facies externa) and the inner surface (facies interna). The facies externa is the outward side of the lower jaw. The merging of the left and right parts is marked by a small ridge of bone.
The ridge of bone divides and merges into the chin prominence (Protuberantia mentalis). It has an elevation on the right and left sides called the mental tubercle. The course of the incisive fossa can be found under the incisors. This partly forms the origin of the musculus mentalis and musculus orbicularis oris.
The facies interna marks the inside of the lower jaw. At the lower part of the symphysis are the spinae mentales. These small protrusions are the origin of the geniohyoid muscle as well as the genioglossus muscle. Below the spinae is the mandibular digastric fossa. It marks the starting point of the digastric muscle.
Also part of the lower jaw is the lingula mandibulae (bony tongue), which covers a small hole that runs through the lower jawbone. It serves as a passage for the inferior alveolar nerve (lower jaw nerve). This is responsible for the sensitive supply of the lower jaw.
This nerve is a split-off of the mandibular nerve. This in turn originates from the trigeminal nerve, the fifth cranial nerve. Other important nerves of the mandible are the masseteric nerve, the medial pterygoid nerve, the lateral pterygoid nerve and the deep temporal nerve.
Function
The lower jaw serves to carry out the movements that arise when chewing and to close the oral cavity . He can only pursue this task through his freedom of movement in all directions. It is also important for human language because it produces certain sounds.
The human lower jaw is equipped with four pairs of muscles that perform special functions that complement each other. The masticatory and temporal muscles ensure the closure of the jaw. In addition, the temporal muscle is important for mandibular retraction. The inner wing muscle also plays its part in closing the jaw. The outer wing muscle is responsible for opening and shifting in the front direction. Furthermore, it converts the grinding sliding movements to the right and left side.
The different nerves of the lower jaw also fulfill special functions. The teeth and dental sockets of the mandible are supplied by the inferior alveolar nerve, while the deep temporal nerves supply the temporal muscles.
The chin nerve in turn supplies the lower lip and chin, while the masseter nerve transmits data towards the masseter muscle. Medial and lateral pterygoid nerves innervate the external and internal alar muscles.
The inferior alveolar artery and inferior alveolar vein are responsible for the blood supply to the lower jaw.
Diseases
- Craniomandibular Dysfunction (CMD)
- Teeth grinding (bruxism)
- TMJ osteoarthritis
Disturbances in the chewing apparatus usually also affect the lower jaw. In most cases, this is a craniomandibular dysfunction (CMD). This includes disorders of the structural, functional and biochemical area. But the psyche can also have an influence on these impairments of the lower jaw.
CMD becomes noticeable, for example, through problems opening or closing the jaw. It may even have difficulty biting off food, speaking, or laughing. It is not uncommon for those affected to also suffer from pain in the mouth or teeth. It can even radiate to the neck , cervical spine or shoulders.
If the teeth do not adjust properly to each other, complaints such as tinnitus , dizziness , earache , difficulty swallowing and blurred vision are conceivable. There are many possible causes of lower jaw pain. These primarily include grinding teeth (bruxism), arthrosis of the jaw joint or displacement of the cartilage disc in the jaw joint.
Hello and welcome to my Health Guide & Encyclopedia! My name is Dorothy Farrar, and I'm the founder and main author of this platform.
My passion for health and wellness started at a young age when I became interested in the connection between the food we eat and the way we feel. This fascination led me to study nutrition and dietetics in college, where I learned about the importance of a balanced diet and the impact of various nutrients on the body.