Where is mandible bone

During development, the first pharyngeal arch forms two processes that eventually fuse at the mandibular symphysis to form the mandible. At birth, the mandibular symphysis is composed of fibrocartilage. Within one year of life, the symphysis fuses and a subtle ridge remains at midline on the anterior surface of the body.

The body is the anterior portion of the mandible and is bound by two surfaces and two borders. The body ends and the rami begin on either side at the angle of the mandible, also known as the gonial angle. The ramus contributes to the lateral portion of the mandible on either side. The coronoid process and condyloid process are located at the superior aspect of the ramus.

The coronoid process is anterior and the condyloid process is posterior; the two are separated by the mandibular notch. The ramus is bound by two surfaces and four borders and contains two processes.

The coronoid process is located at the superior aspect of the ramus. Its anterior border is continuous with that of the ramus, and its posterior border creates the anterior boundary of the mandibular notch. The temporalis muscle and masseter insert on its lateral surface. The condyloid process is also located at the superior aspect of the ramus and is divided into two parts, the neck and the condyle. The neck is the thinner portion of the condyloid process that projects from the ramus.

The condyle is the most superior portion and contributes to the temporomandibular junction by articulating with the articular disk.

Occurring during the sixth week of intrauterine development, the mandible is the second bone to ossify, following the clavicle. This cartilage serves as a template for the development of the mandible. A fibrous membrane covers the left and right Meckel cartilage at their ventral ends, each of which gives rise to a single ossification center.

These two halves eventually fuse via fibrocartilage at the mandibular symphysis. Thus, at birth, the mandible is still composed of two separate bones. Ossification and fusion of the mandibular symphysis occur during the first year of life, resulting in a single bone.

The remnant of the mandibular symphysis is a subtle ridge at the midline of the mandible. The mandible constantly changes throughout an individual's life. At birth, the gonial angle is approximately degrees.

By age four, teeth have formed, causing the jaw to elongate and widen; these changes in the mandible's dimensions cause the gonial angle to decrease to approximately degrees. By adulthood, the gonial angle is decreased to approximately degrees. Blood supply to the mandible is via small periosteal and endosteal vessels. The periosteal vessels arise mainly from the inferior alveolar artery and supply the ramus of the mandible.

The endosteal vessels arise from the peri-mandibular branches of the maxillary artery, facial artery, external carotid artery, and superficial temporal artery; these supply the body of the mandible. Lymphatic drainage of the mandible and mandibular teeth are primarily via the submandibular lymph nodes; however, the mandibular symphysis region drains into the submental lymph node, which subsequently drains into the submandibular nodes.

The main nerve associated with the mandible is the inferior alveolar nerve, which is a branch of the mandibular division of the trigeminal nerve. The inferior alveolar nerve enters the mandibular foramen and courses anteriorly in the mandibular canal where it sends branches to the lower teeth and provides sensation. At the mental foramen, the inferior alveolar nerve branches into the incisive and mental nerve. The mental nerve exits the mental foramen and courses superiorly to provide sensation to the lower lip.

The incisive nerve runs in the incisive canal and provides innervation to the mandibular premolar, canine, and lateral and central incisors. Males generally have squarer, more prominent mandibles than females. This is due to the larger size of the mental protuberance in males and the decreased gonial angle.

The gonial angle is 90 degrees in males, compared to in females. In rare instances, a bifid or trifid inferior alveolar canal may be present. This can be detected on X-ray as a second or third mandibular canal. Branches of the inferior alveolar nerve commonly run through these extra foramina and can confer a risk for inadequate anesthesia during surgical procedures involving the mandible. A cleft chin can result from inadequate or absent fusion of the mandibular symphysis during embryonic development.

This often results in a depression of the overlying soft tissue at the midline of the mandible. This is a genetic condition that is inherited in an autosomal dominant fashion and found more frequently in the male population.

Orthognathic surgery, which includes mandible osteotomies and sagittal split osteotomies, is corrective jaw surgery performed to improve bite malalignment, sleep apnea, temporomandibular joint disorders, and structural issues such as cleft palate and micrognathia. Mandible osteotomy is performed on patients with micrognathia, a condition in which the mandible is undersized. Micrognathia may result in pain and difficulty chewing: correction is often needed.

This procedure is performed by transecting the mandible between the first and second molars, bilaterally; the mandible is extended into its new position and stabilized with hardware. The knee - The patella. The hand - Four sesamoid bones can be found in the hand. The foot - There are two of these unique bones where the first metatarsal bone connects to the big toe. Bones are classified according to the shape: long, short, flat, irregular , sesamoid and sutural.

They are one of five types of bones : short , long, flat, irregular and sesamoid. Short bone TA A A short bone is one that is cube-like in shape, being approximately equal in length, width, and thickness. The only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles.

Short bones provide stability and support as well as some limited motion. There are three different skeleton designs that fulfill these functions: hydrostatic skeleton, exoskeleton, and endoskeleton. Hydrostatic Skeleton. A hydrostatic skeleton is a skeleton formed by a fluid-filled compartment within the body, called the coelom. Human Appendicular Skeleton. Planar, hinge, pivot, condyloid, saddle, and ball-and-socket are all types of synovial joints.

Planar Joints. Planar joints have bones with articulating surfaces that are flat or slightly curved faces. Hinge Joints. Condyloid Joints. Saddle Joints. Ball-and-Socket Joints. The end of the long bone is the epiphysis and the shaft is the diaphysis.

When a human finishes growing these parts fuse together. The outside of the flat bone consists of a layer of connective tissue called the periosteum. The skeleton Skull — including the jaw bone. Spine — cervical, thoracic and lumbar vertebrae, sacrum and tailbone coccyx Chest — ribs and breastbone sternum Arms — shoulder blade scapula , collar bone clavicle , humerus, radius and ulna.

Hands — wrist bones carpals , metacarpals and phalanges. Pelvis — hip bones. The short bones are small and cuboid shaped, many of which can be found around the extremities hands and feet. Examples include the sesamoid bones , the tarsals of the ankle, and the carpals of the wrist. Orthognathic surgery treats problems stemming from a misaligned jaw, as well as sleep apnea, cleft palate , and temporomandibular joint disorders. Those with micrognathia may require this type of surgery to correct alignment.

After surgery, a significant amount of rehabilitation will be needed, with emphasis placed on ensuring proper positioning of the mandible with regards to the rest of the skull. Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life.

Breeland G, Patel BC. Anatomy, head and neck, mandible. In: StatPearls. Multi-institutional analysis of surgical management and outcomes of mandibular fracture repair in adults.

Craniomaxillofac Trauma Reconstr. Chronic suppurative osteomyelitis of mandible: a case report. Published Your Privacy Rights. To change or withdraw your consent choices for VerywellHealth. At any time, you can update your settings through the "EU Privacy" link at the bottom of any page. These choices will be signaled globally to our partners and will not affect browsing data. We and our partners process data to: Actively scan device characteristics for identification.

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