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Causes of displacement of bone fragments in mandibular fractures
05-09-2009
Causes of displacement of bone fragments in mandibular fractures
The displacement of fragments of the mandible is due to the action of the applied force, under the influence of its own weight and strength reduction of bone fragments attached to the fragments of the muscles. The last factor is decisive. As already noted, the lower jaw is moved under the influence of two muscle groups: to raise (rear group) and down (front group) the lower jaw. All the muscles are attached in pairs and symmetrical points. They operate on the entire lower jaw and reinforce the effect of each other. The muscles that drive the lower jaw, weak muscles, pick it up. This is due not only to their smaller cross-section, but the influence of these muscles on the chin at a sufficiently acute angle. Lower jaw combines the muscle in a single, well-working system. When the integrity of the lower jaw broken, and the fracture gap does not pass the midline, form two or more unequal-sized fragments. Synchronicity in the work of this system is broken. Jaw muscles on each side affect unequal in size and scattered fragments of left and right, while the muscles that drive the jaw, not separated and attached mainly in the inner surface of the chin to the larger fragments. They overcome the resistance of the chewing muscles attached to it, and pull the end of the large fragments down. This is due to the fact that the strength of the chewing muscles, raising the lower jaw with one hand, the less strength of all muscles, lowering the lower jaw. Greater the displacement of fragments, the larger the area of attachment of muscles at each of the fragments. In view of the muscles can be grouped according to their functions, which gives additional information on the nature of displacement of fragments of the mandible:
• displacement of the lower jaw upward (jaw closing):
temporal, chewing, medial webbed muscle;
• lowering of the mandible: digastric, mandibulohyoid, mentohyoid muscle;
• displacement of the lower jaw forward: lateral webbed, webbed medial (at the bilateral reduction), chewing (superficial layer);
• displacement of the lower jaw back, previously put forward anteriorly: temporal (rear beams), digastric and mentohyoid muscle;
• displacement of the lower jaw to the left: right lateral and medial pterygoid, left temporal, digastric, hyoid and jaw-mentohyoid muscle;
• displacement of the mandible to the right: left lateral and medial pterygoid, right temporal, digastric, hyoid and jaw-mentohyoid muscle.
Thus, the front group of muscles displaces the end of large fragments down. Mandibulohyoid muscle rotates along its longitudinal axis, tilting teeth in oral side. Lateral and to a lesser extent, the medial pterygoid muscles are shifting more otlomok (and under certain conditions and less) in the direction of the fracture, chewing and temporal muscles - less otlomok up. In addition, the masseter moves the base of small fragments outward, bending oral alveolar part with teeth. Webbed lateral muscle on the side of small fragments of his few shifts medially. Based on clinical experience, we can see that the displacement of fragments of the mandible is upwards, downwards, inwards, outwards. Perhaps their displacement in the horizontal plane (length), when the ends of the fragments, placing one on the other, touching their lateral surfaces. It is more common in oblique fractures, or in situations where lateral movement over the cross section of a broken section of bone.
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Articles for theme "fracture of the jaw":
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05-09-2009
There are four variants of the mechanism of fracture of the mandible: bend, shear, compression, separation. The lower jaw, having an arched shape, when a mechanical force is experiencing stress of bone tissue in the most crooked, or the most delicate of areas. Established in the limits of the lower jaw are the foundation and condylar neck of the appendix, angle, area openings and canine chin, chin department. It is in these most «weak» ground breaking lower jaw as a result of its inflection.
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05-09-2009
There are numerous classification neognestrelnyh fractures of the mandible. Conveniently enough for practical purposes is, in our opinion, the classification proposed by BD Kabakov, and VA Malyshev.
Classification of fractures of the mandible on BD Kabakov and VA Malyshev
A. For localization.
I. Fractures body of the mandible:
• the presence of the tooth in the fracture gap;
• in the absence of teeth in the fracture gap.
II. Fractures of the branches of the jaw:
• own branch;
• coronoid process;
• condylar sprouts: base, neck, head.
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03-09-2009
When combined craniocerebral trauma (CoN ™) as a result of mechanical impact damage occur simultaneously, the facial skeleton, bones of the cranial trauma and brain. Possible closed craniocerebral trauma (CCT), without damage to the bones of the skull, combined with fractures of the face. Fractures of facial bones, combined with head injury is diagnosed in 6.3% [Fraerman AP, YE Gelman, 1977], or 7,5% of victims [Lebedev VV, 1980]. Enough high frequency of craniofacial injuries caused not only by their anatomical proximity, but also the fact that some of the facial bones of the skeleton are involved in the formation of the skull base.
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03-09-2009
In practice, the surgeon-dentist found unilateral or sagittal fractures of the upper jaw. They tend to occur when the injuring object has sharp edges and the force is applied downward in an oblique direction, mainly at the side of a single department or zone of the upper jaw of the upper lip with one hand. It breaks down the body of the upper jaw with a wing-offshoot sphenoid bone of the party or without it. In the area of the anterior and infratemporal walls (tuber) of the upper jaw fracture line passes above the bottom of the maxillary sinus, and in the hard palate - lateral of the median suture.
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03-09-2009
Assume that the left is fractured along the middle and the right - the bottom type. Fracture line runs from the junction point of the frontal sprouts upper jaw with the nasal part of frontal bone on the left, extends on the inner wall of the orbit and beyond - in accordance with a fracture in Le Fort II, but with only one left. Nasal septum is broken at different levels depending on the transmission line fracture of nasal bones. The right line of the fracture begins at the pear-shaped holes, and further extends the type characteristic of a fracture in Le Fort III (ris.
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