Mandible.pdf

Mandible  Mental angle mandibular condyle Btw it and temporal bone: temporomandibular joint synovial joint: surrounding by...

Mandible  Mental angle mandibular condyle Btw it and temporal bone: temporomandibular joint synovial joint: surrounding by fibrous capsule, fluid coronoid process ramus body mandibular synchondrosis= intermandibular joint Synchondrosis cartilagenous joint: Bones are connected by hyaline cartilage invade very early by os rum, horse carni cartilagenous and fibrous so never os always distinct from each other  TMJ: mtn of jaw: retropulsion and propulsion key components: mandibular condyle: condylar process mandibular fossa articular disc: btw mandibular condyle and fossa within the TMJ Pink: mandibular fossa (where the condyle of the mandible articulate with the temporal bone to form the TMJ for jaw mvt Articular disc: divide the joint in two compartment, upper, lower synovial cavity (dense fibrous connective tisssue Articular capsule: enclose disc and TMJ Find also the lateral ligament = temporomandibular ligament (fibrous) extends from the base of the zygomatic process and the lateral end of the articular tubercle of the temporal bone to the neck of the mandible. Remember: zygomatic process on tympanic part of temporal bone body Blue: convex part of rostral part (incisive) Green: concave part of rostral part (incisive) Red: interalveolar margin White: caudal part (molar) Orange: vascular notch Ramus Pink: lateral Red: where insert Orange: medial temporal muscle white: mandibular notch Orange: masseteric fossa White: mandibular notch Green: head Blue: neck Pink: angular process Orange: pterygoid fossa Metal foramen: 1 opening ruminant/ horse 3-4 carnivores +5 pig Pig Dog temporohyoid joint Found in the hyoid apparatus of certain animals, particularly in horses. It connects the temporal bone of the skull to the stylohyoid bone, which is part of the hyoid apparatus. in carnivores, joins the mastoid process of the temporal bone  Dentition HETERODONTY the teeth of mammals are very differently developed in different regions of the mouth for better performance of special tasks it allows the recognition of incisor (I), canine (C), premolar (P), and molar (M) groups pof teeth premolar + molar teeth together = cheek teeth DIPHYODONTY a single replacement of the teeth first erupted is provided by a second, stronger set that is better adapted to the larger jaws and to the more vigorous mastication of the adult molar teeth are always lacking in the milk set POLYPHYODONTY multiple succession of teeth THECODONTY the teeth are implanted in alveoli/socket set along the margins of the bones SIMPLE /HAPLODONT TEETH teeth consist of a crown covered in a layer of enamel and a single root include canine teeth of all domestic mammals and the incisors of ruminants COMPOUNDTEETH presence of two or more distinct, enamel-capped coronal eminences. have more than one root (they seem to result from the fusion of several single teeth) mode of formation, growth and eruption similar to the previous ones BUNODONT the less specialized, corresponds to an omnivorous diet the cusps are low, wide and more or less in the same plane, often slightly complicated by small secondary tubercles. ex. cheek teeth of the pig SECODONT (secare=cut) teeth, in which the eminences are arranged in a row, are particularly well develloped in carnivores extreme exemple: sectorial/carnassial teeth Brachydont Tooth Description: Low-crowned tooth with a short crown. Eruption and Wear: The crowns are short, and the teeth are almost fully formed by the time they begin to wear down. Examples: Incisors or canines of carnivores. Structure: Non-rooted, consisting primarily of a crown; the embedded part is longer than the visible part, with no clear demarcation. Examples: Incisors of rodents, canines of boars. Hypsodont Tooth Description: High-crowned tooth, typical of animals that eat abrasive foods like herbivores. Crown and Neck: Little distinction between the crown and the neck; described as having a body. Structure: Entire body surrounded by enamel and an outer layer of cementum. Special Features: Enamel characterized by occlusal invaginations or folding. Root: A root develops but is relatively short; teeth grow for a longer period but growth is eventually limited. Examples: Equine incisors, cheek teeth of horses and ruminants. Importance: Increased Durability and The alternating layers of harder and softer materials wear at different rates, creating an uneven, rasp-like surface that is effective for grinding food. Implantation: Each tooth is implanted in a separate alveolus (socket) in the jawbone margin. Attachment: Teeth are attached to their sockets by the periodontal ligament, composed of tough collagen fibers. These fibers connect both the cementum of the tooth and the alveolar bone, suspending the tooth in a sling-like manner. Mobility: This arrangement allows limited mobility of the tooth, enabling slight rotation and tilting during mastication. Joint Type: gomphosis. The pulp inside the tooth contains many nerves. Some of these nerves control blood flow (vasomotor), but most are sensory nerves that detect sensations. Upper Teeth: Supplied by the infraorbital nerve. You can numb the front upper teeth by blocking this nerve at the infraorbital foramen. Lower Teeth: Supplied by the inferior alveolar nerve. You can numb the lower teeth by blocking this nerve a bit behind the last tooth before it enters the jawbone. The front lower teeth can also be numbed by blocking the nerve at the mental foramen. the detailed description of the crown requires some system for indicating its various surfaces vestibular (labial, buccal) lingual contact surfaces mesial distal occlusal or masticatory surface  Dog Dentition: Deciduous (Baby) Teeth: Formula: 2 (I3/3 C1/1 P3/3) 3 incisors, 1 canine, and 3 premolars on each side, both top and bottom. Permanent Teeth: Formula: 2 (I3/3 C1/1 P4/4 M2/3) 3 incisors, 1 canine, 4 premolars, and 2-3 molars on each side, both top and bottom. Incisors: All have a single root. Used mainly for nibbling and grooming. Canine Teeth: The root of the canine tooth is very large, even bigger than the crown. It curves back to lie above (or below) the first premolar. Infections in the upper canine teeth can sometimes create openings into the nasal cavity. Premolars: Form a series of teeth that get bigger and more complex from front to back. The pointed parts of each crown line up to form a serrated cutting edge, helping to cut food quickly and hold it in place. upper P4 has three roots, Increase in size and complexity Molars: The back molars also help cut food but are mainly for crushing, with broader surfaces for chewing. Decrease in size from front to back, upper molars have three roots.  Cat Dentition: Deciduous Teeth: Formula: 2 (I3/3 C1/1 P3/2) 3 incisors, 1 canine, and 3 premolars on top; 3 incisors, 1 canine, and 2 premolars on the bottom. Permanent Teeth: Formula: 2 (I3/3 C1/1 P3/2 M1/1) 3 incisors, 1 canine, 3 premolars, and 1 molar on each side, both top and bottom. Adaptation: Teeth designed for cutting, with a reduced number of molars. Cheek Teeth: Cats' cheek teeth don't have much contact between upper and lower teeth, except at the back where some food crushing is possible. Special Teeth: Upper P4 (sectorial) has three roots; its lower counterpart is M1. Tooth Development: Deciduous teeth erupt by week 3; permanent teeth by 6 months.  Horse Dentition: Deciduous Teeth: Formula: 2 (I3/3 C0/0 P3/3) 3 incisors and 3 premolars on each side, both top and bottom. Permanent Teeth: Formula: 2 (I3/3 C1/1 P3-4/3 M3/3) 3 incisors, 1 canine, 3-4 premolars, and 3 molars on each side, both top and bottom. Incisors: Hypsodont, roots converge, used for aging. Canines: Present in both sexes but rudimentary, especially in mares. Cheek Teeth: First premolar ("wolf" tooth) often absent; upper teeth are wider with complex enamel folding; lower teeth have folded enamel but no infundibula. Tooth Development: Deciduous teeth appear within weeks; permanent teeth by 6-7 months.  Ruminant Dentition: Upper Jaw: No incisor or canine teeth. Lower Jaw: Canines look like incisors and are called the fourth or corner incisors. Premolars: The first premolar teeth don't develop in either jaw. Deciduous (Baby) Teeth: Formula: 2 (I0/3 C0/1 P3/3) This means ruminant calves have 3 lower incisors, 1 lower canine (that looks like an incisor), and 3 premolars on each side. Permanent Teeth: Formula: 2 (I0/3 C0/1 P3/3 M3/3) This means adult ruminants have 3 lower incisors, 1 lower canine (that looks like an incisor), 3 premolars, and 3 molars on each side.  Swine Dentition: Adaptation: Excellent adaptation to an omnivorous diet, presenting all types of teeth. Deciduous Teeth: Formula: 2 (I3/3 C1/1 P4/4) 3 incisors, 1 canine, and 4 premolars on each side, both top and bottom. Permanent Teeth: Formula: 2 (I3/3 C1/1 P4/4 M3/3) 3 incisors, 1 canine, 4 premolars, and 3 molars on each side, both top and bottom. Canine Teeth (Tusks): Hypsodont teeth, feeble in young, voluminous in adults with strong sexual dimorphism. In boars, roots remain open, and tusks grow throughout life. In sows, growth ceases after 2 years, and smaller tusks do not project from the mouth. Cheek Teeth: Crowns increase in length and breadth from first to last in the series. All cheek teeth are brachyodont (bunodont).