Mandible is the 1st bone to be calcified in the skull? / mandible formed before frontal bone?
A- True.
B- False.
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The horseshoe-shaped lower jaw (mandible) is the largest facial bone and the only motile bone of the skull. The teeth are embedded in the middle, horizontal part of the lower jaw. The mandible with the temporomandibular joint on the temporal bone attaches to the lateral, upwardly bent branches. Read everything important about the lower jaw: anatomy, function and important diseases!
What is the lower jaw?
The lower jaw bone consists of a body (Corpus mandibulae), whose rear ends on both sides in the jaw angle (Angulus mandibulae) in an ascending branch (Ramus mandibulae) go over. The angle between the body and the branch (angulus mandibulae) fluctuates between 90 and 140 degrees, depending on the strength of the masticatory apparatus - it reaches 150 degrees in newborns. It decreases with strong development of the masticatory muscles.
The basis of the mandible is the basal arch, which includes the base, the middle part of the branch and the articular process. The basal arch is slimmer towards the top, here sits the alveolar arch, which carries the Zahnfächer the lower set of teeth. He is a little smaller and narrower than the basal arch and jumps back against the chin.
When teeth are missing, the alveolar arch changes its shape. In complete tooth loss, it can even disappear completely, because a functionally unstressed bone is destroyed (inactivity atrophy). As a result, the lower jaw body appears narrower and lower, the mouth is "sunken" - if not restored by dentures the shape.
The outer surface of the lower jaw body:
In the midline of the lower jaw, on the chin protrusion, lies a small bone border - the point at which the two halves of the lower jaw are grown together after the embryonic period and ossified in the first year of life. Underneath, a bony triangle (Protuberantia mentalis) forms the lower boundary and two small bumps on either side of it form the lower corners of the triangle - the protruding chin.
At the level of the first to second molars, between the base and the alveolar margin lies the mental foramen, an exit point for nerves and vessels that lead from the canalis mandibulae to the skin.
A small elevation on the outer surface of the lower jaw body, the Linea obliqua, runs obliquely upwards to the Ramus (ascending branch of the lower jaw). Two muscles are inserted into it: one pulls the corners of the mouth down, the other pulls the lower lip down and to the side.
Somewhat underneath, a muscle has its approach, which extends from the neck to the second rib and is counted among mimic muscles. Above, at the alveolar process and just below the molars, the muscle begins, with the corners of the mouth pulled to the side and lips and cheek pressed against the teeth. He helps suckle by stiffening the cheeks and urges the food between the teeth while chewing.
The inner surface of the lower jaw body:
Near the bone band, where the two mandibular bones have grown together, are two small, strong bony prominences, which serve as a reinforcement and as a point of attachment for two muscles - the muscle, which sticks out the tongue, as well as an oral floor muscle. Due to this bony reinforcement, the lower jaw breaks in an impact always sideways from the chin area.
Beneath these bony prominences lies a pit for the insertion of the muscle, which is important for opening the mouth. Parallel to the course of the linea obliqua outside runs inside the lower jaw body, a line (linea mylohyoidea), attaches to the floor muscles. Above and below this line there are depressions in which the lower and the lower jaw glands lie.
The lower jaw carries in the alveolar arch the compartments for the tooth roots. The individual compartments are - as in the upper jaw - separated by bone septa, in teeth with multiple roots, the individual root fan bones are further divided. The bone of the alveolar process has a structure of fine trabeculae, which transfers the pressure created during chewing from the teeth to the jaws.
A- True.
B- False.
---------------------------------
The horseshoe-shaped lower jaw (mandible) is the largest facial bone and the only motile bone of the skull. The teeth are embedded in the middle, horizontal part of the lower jaw. The mandible with the temporomandibular joint on the temporal bone attaches to the lateral, upwardly bent branches. Read everything important about the lower jaw: anatomy, function and important diseases!
What is the lower jaw?
The lower jaw bone consists of a body (Corpus mandibulae), whose rear ends on both sides in the jaw angle (Angulus mandibulae) in an ascending branch (Ramus mandibulae) go over. The angle between the body and the branch (angulus mandibulae) fluctuates between 90 and 140 degrees, depending on the strength of the masticatory apparatus - it reaches 150 degrees in newborns. It decreases with strong development of the masticatory muscles.
The basis of the mandible is the basal arch, which includes the base, the middle part of the branch and the articular process. The basal arch is slimmer towards the top, here sits the alveolar arch, which carries the Zahnfächer the lower set of teeth. He is a little smaller and narrower than the basal arch and jumps back against the chin.
When teeth are missing, the alveolar arch changes its shape. In complete tooth loss, it can even disappear completely, because a functionally unstressed bone is destroyed (inactivity atrophy). As a result, the lower jaw body appears narrower and lower, the mouth is "sunken" - if not restored by dentures the shape.
The outer surface of the lower jaw body:
In the midline of the lower jaw, on the chin protrusion, lies a small bone border - the point at which the two halves of the lower jaw are grown together after the embryonic period and ossified in the first year of life. Underneath, a bony triangle (Protuberantia mentalis) forms the lower boundary and two small bumps on either side of it form the lower corners of the triangle - the protruding chin.
At the level of the first to second molars, between the base and the alveolar margin lies the mental foramen, an exit point for nerves and vessels that lead from the canalis mandibulae to the skin.
A small elevation on the outer surface of the lower jaw body, the Linea obliqua, runs obliquely upwards to the Ramus (ascending branch of the lower jaw). Two muscles are inserted into it: one pulls the corners of the mouth down, the other pulls the lower lip down and to the side.
Somewhat underneath, a muscle has its approach, which extends from the neck to the second rib and is counted among mimic muscles. Above, at the alveolar process and just below the molars, the muscle begins, with the corners of the mouth pulled to the side and lips and cheek pressed against the teeth. He helps suckle by stiffening the cheeks and urges the food between the teeth while chewing.
The inner surface of the lower jaw body:
Near the bone band, where the two mandibular bones have grown together, are two small, strong bony prominences, which serve as a reinforcement and as a point of attachment for two muscles - the muscle, which sticks out the tongue, as well as an oral floor muscle. Due to this bony reinforcement, the lower jaw breaks in an impact always sideways from the chin area.
Beneath these bony prominences lies a pit for the insertion of the muscle, which is important for opening the mouth. Parallel to the course of the linea obliqua outside runs inside the lower jaw body, a line (linea mylohyoidea), attaches to the floor muscles. Above and below this line there are depressions in which the lower and the lower jaw glands lie.
The lower jaw carries in the alveolar arch the compartments for the tooth roots. The individual compartments are - as in the upper jaw - separated by bone septa, in teeth with multiple roots, the individual root fan bones are further divided. The bone of the alveolar process has a structure of fine trabeculae, which transfers the pressure created during chewing from the teeth to the jaws.
The lower jaw branches:
The lower jaw branches are distinguished by two projections: the articular process and the ossified approach of the temporal muscle.
The articular process (condylar process) has a condyle and a neck. At the neck of a pit sets in the muscle, which pulls the lower jaw forward and to the side. The condyle forms the temporomandibular joint in a pit of the temporal bone, together with an intervertebral disc (meniscus articularis).
The ossified approach of the temporal muscle (coronoid processus) is the second projection on each mandibular branch. The temporal muscle pulls up the auricle and tenses the skull plate. The muscle, which makes it possible to close the mouth and advance the lower jaw, also starts at the coronoid process. This extension is pointed in the adult pointed, curved backward in old age.
The lower jaw branches have numerous indentations, incisions and roughness, which serve as average sites for nerves and vessels or muscle attachment sites.
What problems can the lower jaw cause?
A mandibular fracture may be accompanied by fractures of the tooth roots.
As a Progenie doctors call a jaw malposition in which the lower incisors bite over the upper. Those affected have a protruding chin.
In the case of the jaw clamp, the mouth can no longer be opened; it can no longer be closed when the jaw is locked. Possible causes include inflammatory processes (as in mumps), dislocation (dislocation) or fracture of the temporomandibular joint, scars or tumors.
The salivary glands in the lower jaw may be inflamed or malformed. In addition, tumors and metastases (secondary tumors of malignant tumors) can form here.
What is the function of the lower jaw?
The lower jaw is the only moving bone of the skull. Through his movements against the upper jaw food bites are chewed and crushed. He also helps with the sound.
Movements of the lower jaw:
The mandible can perform various movements: the mandible can be advanced (protrusion) and retracted (retrusion) in addition to opening and closing the mouth, sideways away from the midline and back to the midline.
Where is the lower jaw located?
The lower jaw forms the lower part of the facial skull. Its two lateral branches are connected in the jaw joint movable with the temporal bone.
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