Orofacial Anatomy Exam II Review PDF

Orofacial Chapters 3, 10, 16, 28, 29, 30, Anatomy and 31 Exam II Review Proximal Contact Areas Proximal contact areas are where the proximal surfaces of teeth touch one another. Located on the mesial and distal surfaces of each tooth at the wide...

Orofacial Chapters 3, 10, 16, 28, 29, 30, Anatomy and 31 Exam II Review Proximal Contact Areas Proximal contact areas are where the proximal surfaces of teeth touch one another. Located on the mesial and distal surfaces of each tooth at the widest portion and the greatest curvature A proximal contact Prevents food from packing between teeth Offers support and anchorage to teeth Offers resistance to displacement COPYRIGHT © 2019 BY ELSEVIER, INC. ALL RIGHTS RESERVED. Proximal Contact Areas (Cont.) A contact point is where the occlusal cusp of one tooth touches the occlusal portion of another tooth in the opposing arch. COPYRIGHT © 2019 BY ELSEVIER, INC. ALL RIGHTS RESERVED. Cervical Embrasure A cervical embrasure occurs when there is gingival recession between teeth, and the interdental papilla and bone no longer fill the entire interproximal space. The more papilla that is missing, the larger the cervical embrasure. Cervical embrasures, also called gingival embrasures, occur often as pathologic consequences from periodontal or orthodontic causes, and these embrasures offer a place in which bacteria, calculus, and food debris can accumulate. COPYRIGHT © 2019 BY ELSEVIER, INC. ALL RIGHTS RESERVED. Embrasures (Cont.) Purpose of embrasures 1. Allow food to be moved away from contact areas. 2. Dissipate and reduce the forces of occlusal trauma. 3.Provide self-cleaning by the action of the tongue, cheeks, and lips. 4. Protect the gingiva from undue trauma. COPYRIGHT © 2019 BY ELSEVIER, INC. ALL RIGHTS RESERVED. Facial and Lingual Contours This contour varies in degree from tooth to tooth, but generally the location of the buccal height of contour of anterior and posterior teeth is always the same—at the cervical third of the tooth. The lingual height of contour of anterior teeth is at the cervical third of the tooth, but the lingual crest of curvature of posterior teeth is at or near the middle third. The crest of curvature refers to the widest part of the crown of the tooth; it is the same as the height of contour COPYRIGHT © 2019 BY ELSEVIER, INC. ALL RIGHTS RESERVED. Curvature of the Cementoenamel Junction Curvature of the cervical lines, or cementoenamel junction (CEJ) depends on the height of the contact area above crown cervix and on the diameter of the crown labiolingually or buccolingually. The mesial curvature of a tooth is greater than the distal curvature of the same tooth. The mandibular anterior teeth show less curvature than their maxillary counterparts. COPYRIGHT © 2019 BY ELSEVIER, INC. ALL RIGHTS RESERVED. Papillae—Circumvallate or Vallate V-shaped row Circular, raised About 13 elevations About two thirds of the way back Point of the V faces posteriorly. Marks area that develops from different pharyngeal arches Rest in troughs Surrounded by taste buds around lateral surfaces Salivary glands at bottom of trough - salivary glands are known as the glands of von Ebner. Copyright © 2019 by Elsevier, Inc. All rights reserved. 8  Tongue Muscles— Extrinsic Muscles (Cont.) Palatoglossus Runs from anterior soft palate down and forward into lateral borders of the tongue Elevates the posterior part of tongue; pulls it slightly backward Genioglossus Originates from superior genial tubercles, inserts into midline of the tongue from tip to base Aids in protrusion, retrusion, or depression of the tongue Copyright © 2019 by Elsevier, Inc. All rights reserved. 9 Open contact and Diastema An open contact exists if two adjacent teeth do not touch tightly at their contact areas. This open space between the contact areas traps food debris If the open contact is very wide it is called a diastema. A large diastema could be big enough so that food does not get trapped and can be washed away. General Rules of Tooth Identification 1. Curvature of the cementoenamel junction (CEJ) is about 1 mm less on the distal surface of the tooth than on the mesial. 2. If the tooth roots curve, they usually curve distally, especially at the apex of the root. 3. The distal incisal edges of anterior teeth are more rounded than the mesial incisal edges. Copyright © 2019 by Elsevier, Inc. All rights reserved. 11 Maxillary Lateral Incisors — Right vs. Left Mesioincisal angles more square than distoincisal angles Crest of cervical line more often displaced toward distal from labial or lingual view Mesiocervical line curves more incisally than distocervical line Copyright © 2019 by Elsevier, Inc. All rights reserved. 12 Maxillary First Molars Occlusal view: strong oblique ridge less likely to be crossed by a groove Three roots Often has five cusps Cusp of Carabelli on mesiolingual cusp Right vs. left: mesiolingual cusp larger than distolingual Copyright © 2019 by Elsevier, Inc. All rights reserved. 13  Importance of Deciduous Teeth Deciduous teeth maintain a place for permanent teeth. Allow for bone growth of dental arches As bone grows, space develops between the teeth. Primate space: Space between maxillary lateral incisor and canine or between mandibular canine and first molar Leeway spaces: Space between first and second molars Copyright © 2019 by Elsevier, Inc. All rights reserved. 14  Essential Differences Between Deciduous and Permanent Teeth Buccocervical ridges on deciduous molars much more pronounced Narrower occlusal table of the occlusal surface buccolingually Roots of deciduous molars are also proportionately longer and narrower because the crowns of deciduous teeth are very short Roots also flare apically to allow room for permanent teeth to develop between them Usually lighter in color Pulp chambers relatively large Pulp horns much closer to enamel Dentin between pulp chambers and enamel is thinner. Enamel relatively thin and consistently deep Copyright © 2019 by Elsevier, Inc. All rights reserved. 15 Scalp Muscles— Occipitofrontalis (Epicranius) Paired muscle Groups of fibers in front and back connected by a broad flat band of fascia Fibers originate from connective tissue of the scalp. Allows for forward or backward movement of the scalp Forward movement = frown or squint Backward movement = raising forehead skin as in surprise Copyright © 2019 by Elsevier, Inc. All rights reserved. 16  Eye Muscles Muscles close the eyes and move the eyebrows. Orbicularis oculi Orbital part—encircles the eye Palpebral part—muscle fibers in the eyelid Attaches to the skull at medial and lateral edges of the orbit Levator palpebrae superioris Raises the upper eyelid Supplied by cranial nerve III (oculomotor nerve) Copyright © 2019 by Elsevier, Inc. All rights reserved. 17 Nose Muscles Primarily encircle the opening of the nostrils. Nasalis opens and closes the nostrils. Dilator naris—pulls down on nostrils causing them to flare or dilate Compressor naris—causes nostrils to close or compress Copyright © 2019 by Elsevier, Inc. All rights reserved. 18 Mouth Muscles —Orbicularis Oris Circles the oral cavity in the tissue of the lip Bony attachment at the anterior nasal spine and the midline above the chin Fibers circle the lip like a purse string. Closes and compresses the lips – “kissing” Copyright © 2019 by Elsevier, Inc. All rights reserved. 19 Muscles Generally Origin: the end attached to the least movable structure Insertion: the other end, attached to the more movable structure Action: the work that is accomplished when muscle fibers contract Copyright © 2019 by Elsevier, Inc. All rights reserved. 20  Muscles of Mastication— Lateral Pterygoid Muscle Actions Protrude and depress mandible (both heads function) Lateral excursion to opposite side of contracted muscle Two origins 1. Superior origin from infratemporal crest of the greater wing of sphenoid bone 2. Inferior origin from lateral side of the lateral pterygoid plate Some fibers insert into anterior border of the TMJ disk. Remainder of fibers insert into neck of the condyle on anterior and medial side. Copyright © 2019 by Elsevier, Inc. All rights reserved. 21 Muscles of Mastication Four pairs of muscles of mastication Attached to the mandible Develop from the first (mandibular) pharyngeal arch Responsible for: Elevating Protruding Retruding Moving the mandible laterally Innervated by the fifth cranial nerve (trigeminal nerve) More specifically, innervated by the third part of the fifth nerve Blood supply comes from the maxillary artery. Copyright © 2019 by Elsevier, Inc. All rights reserved. 22 Muscles of Mastication Copyright © 2019 by Elsevier, Inc. All rights reserved. 23 Mouth Muscles—Buccinator During chewing, food that is forced into the vestibule is pushed back up onto the occlusal surfaces in part by the contraction of the buccinator muscle. The buccinator muscle is frequently referred to as an accessory muscle of mastication because of the help it provides in chewing food. People with paralysis of this muscle have difficulty chewing because food builds up. Copyright © 2019 by Elsevier, Inc. All rights reserved. 24  Mouth Muscles— Depressor Labii Inferioris Origin is the area beneath the angles of the mouth and just above the inferior border of the mandible. Fibers run up and medially to insert into the fibers of the orbicularis oris toward the middle of the lower lip. Pulls the lower lip down, as in a pout Copyright © 2019 by Elsevier, Inc. All rights reserved. 25 Introduction Muscles of the ears, scalp, neck, eyes, nose, and mouth are all innervated by the seventh (VII) cranial nerve (facial nerve). All are areas that can display emotion or attentiveness. Copyright © 2019 by Elsevier, Inc. All rights reserved. 26 Movements of the Jaw and Larynx Mandibular protrusion Lateral pterygoid muscles Mandibular retrusion Posterior or horizontal fibers of temporal muscle Digastric muscle Lateral excursion of the mandible One lateral pterygoid muscle acting by itself Left lateral pterygoid muscle contraction moves mandible to the right. Copyright © 2019 by Elsevier, Inc. All rights reserved. 27 Structure of the Temporomandibular Joint—Articulation The articulation between the temporal bone and the mandible The surface of one bone moves over the surface of the other. Two joints that move and function as one Bilateral joint because the mandible is fused at the midline Articular disk is the small fibrous pad between bones of the TMJ. Upper surface is concave and convex to match the contours of the mandibular fossa (also called glenoid fossa). Thickest at posterior end (posterior band), thinnest in the middle (intermediate zone) Copyright © 2019 by Elsevier, Inc. All rights reserved. 28 Structure of the Temporomandibular Joint— Synovial Cavities Synovial cavities located above and below articular disk Epithelium lines these cavities and secretes synovial fluid. Allows the surfaces to rub without irritation Copyright © 2019 by Elsevier, Inc. All rights reserved. 29 Structure of the Temporomandibular Joint—Fibrous Capsule The TMJ is surrounded by a fibrous capsule. Temporomandibular ligament thickens the lateral side. Prevents the condyle from being displaced Stylomandibular ligament and sphenomandibular ligament control movement on the medial side. Copyright © 2019 by Elsevier, Inc. All rights reserved. 30 Rotational Movement As teeth begin to separate, first, there is a rotational movement in the lower synovial cavity between the disk and the condyle below. Posterior elastic lamina pulls posteriorly on the disk so the disk and Condyle rotate on one another. As the jaw opens farther the rotational movement continues. Additional anterior gliding movement along the posterior slope of the articular eminence also occurs. Copyright © 2019 by Elsevier, Inc. All rights reserved. 31 Gliding Movement Between the disk and the temporal bone Condyle and disk move forward until slightly anterior to the crest of the articular eminence. Superior head of lateral pterygoid controls the posterior movement of the disk. Controls the release of contraction Balances the posterior pull exerted by the elastic lamina Lower posterior collagenous lamina prevents injury. Keeps the elastic lamina and disk from being pulled too far forward https://www.youtube.com/watch?v=_TJd7lKC064 https://www.youtube.com/watch?v=ZcNn3C3QyeI Copyright © 2019 by Elsevier, Inc. All rights reserved. 32 Problems Associated with the TMJ—Pain In reference to pain originating in the disc, that the central portion of the disc has no nerve supply, which is why a hole can be worn through the disc and not be recognized. May be referred pain Check radiograph Palpate area Pain often comes from muscle spasms, the ear, or malocclusion. Four nerves, the V, VII, IX, and X, supply the sensory areas around the ear. Copyright © 2019 by Elsevier, Inc. All rights reserved. 33 Internal Problems of the TMJ— Sounds (Grinding) Grinding (crepitus) sound may come from adhesions in synovial membranes of the joint. arthritic changes. perforations of the disk. Treatment includes ultrasonography; may continue to recur. Copyright © 2019 by Elsevier, Inc. All rights reserved. 34  Soft Palate— Palatoglossus Muscle Palatoglossal, palatopharyngeal folds: (also known as anterior and posterior faucial pillars) tissue in front of the tonsils on the sides of the throat wall Palatoglossus muscle—under the palatoglossal fold Origin: posterior end of the hard palate and anterior end of soft palate Runs downward, laterally and forward to insert in the posterolateral part of the tongue Pulls the soft palate down on lateral edges, narrows the space between the left and right anterior faucial pillars Nerve supply: part of eleventh (XI) cranial nerve and branches of tenth (X) cranial nerve Copyright © 2019 by Elsevier, Inc. All rights reserved. 35 Actions (bodily function)—Speech To speak: we pull the soft palate up and back to contact the posterior pharyngeal wall Accomplished primarily by the levator veli palatini and muscles of the uvula If soft palate is unable to adapt well to the posterior pharyngeal wall, speech will have a nasal sound. Can be caused by enlarged adenoids Copyright © 2019 by Elsevier, Inc. All rights reserved. 36 Actions (bodily function)—Swallowing 1. Tongue moves up and back. 2. Food bolus shifted to posterior part of tongue and into oral pharyngeal area 3. Muscles of soft palate raise posterior end of soft palate to contact posterior pharyngeal wall, narrows the fauces. 4. Elevators and dilators lift and widen the pharynx to receive food bolus. Copyright © 2019 by Elsevier, Inc. All rights reserved. 37 Actions—Swallowing (Cont.) 5. Constrictors compress the upper part of the oral pharynx and push the bolus down into laryngeal pharynx. 6. Some pharyngeal muscles elevate thyroid cartilage of larynx. 7. Epiglottis shields the laryngeal opening, food moves into esophagus. 8. Food waits there for peristaltic contractions to take over. Copyright © 2019 by Elsevier, Inc. All rights reserved. 38 Soft Palate— Levator Veli Palatini Elevates posterior end of the soft palate Origin: the petrous part of temporal bone and medial wall of auditory canal Contraction: pulls posterior end of soft palate up and back to contact the posterior pharyngeal wall, opens auditory tube if closed Nerve supply: the X and XI cranial nerves. Copyright © 2019 by Elsevier, Inc. All rights reserved. 39  Hyoid Muscles— Suprahyoid Group (Mylohyoid Muscle) Forms floor of the mouth Action related to depression of the mandible or elevation of the hyoid bone Originates from mylohyoid line on medial surface of each side of mandible Inserts into hyoid bone Left and right muscles fuse together in midline of neck. This type of fusion is a raphe. Nerve supply from trigeminal nerve Blood supply is branch of inferior alveolar artery. Copyright © 2019 by Elsevier, Inc. All rights reserved. 40  Muscles of Mastication— Temporal Muscle Also known as temporalis muscle If entire muscle contracts, it elevates the mandible. If posterior fibers contract, it pulls mandible backward (retruding the mandible). Origin from temporal fossa Inserts into coronoid process of mandible Fibers sometimes run down anterior border of ramus as far as the third molar. If entire muscle contracts, it elevates the mandible. Copyright © 2019 by Elsevier, Inc. All rights reserved. 41  Sternocleidomastoid Muscle Involved in tilting and rotating the head Origin in upper border sternum and medial third of clavicle Inserts into mastoid process of temporal bone Innervated by the eleventh (XI) cranial nerve (accessory nerve) Blood supply is a branch of external carotid artery. Often involved in referred pain Copyright © 2019 by Elsevier, Inc. All rights reserved. 42  Muscles of Mastication— Masseter Muscle Most powerful muscle of mastication Contraction elevates the mandible, closes the mouth. Originates from two areas on the zygomatic arch Superficial head from the inferior border of the anterior two thirds of the zygomatic arch Deep head arises from the inferior border of the posterior third of the zygomatic arch and the entire medial side. Fibers of superficial head run down and back to insert into the angle of mandible. Copyright © 2019 by Elsevier, Inc. All rights reserved. 43 Trapezius Muscle Action: shrugging shoulders Origin is external occipital protuberance on occipital bone and superior nuchal lines, and spinous processes of cervical and thoracic vertebrae. Insertion is acromion process and spine of scapula and lateral third of clavicle. Adducts, elevates, and slightly rotates scapula Some of nerve supply comes from second, third, and fourth cervical nerves. Can involuntarily contract under tension, in conjunction with migraine, in connection with certain malocclusions When in spasm can cause TMJ pain Copyright © 2019 by Elsevier, Inc. All rights reserved. 44 Muscles of Facial Expression— Buccinator During chewing, food that is forced into the vestibule is pushed back up onto the occlusal surfaces in part by the contraction of the buccinator muscle. The buccinator muscle is frequently referred to as an accessory muscle of mastication because of the help it provides in chewing food. People with paralysis of this muscle have difficulty chewing because food builds up. Copyright © 2019 by Elsevier, Inc. All rights reserved. 45 Internal Problems of the TMJ—Subluxation When a person opens his or her mouth too wide and cannot close it or when closing causes popping When the condyle glides too far forward and moves anterior to the articular eminence Condyle cannot reposition in its proper place. If a patient cannot close the mouth, place your thumbs on the occlusal surface of mandibular posterior teeth with the index fingers beneath the inferior border of the mandible, and push down while guiding the jaw slowly back into its posterior position. It is advisable to wrap your thumbs in gauze so that they are protected in case the patient closes down on them. Copyright © 2019 by Elsevier, Inc. All rights reserved. 46  Naming Teeth Dentition Permanent Dental arch Quadrant Tooth name Deciduous Maxillary Right Incisor Mandibular Left Canine Premolar Molar Copyright © 2019 by Elsevier, Inc. All rights reserved. 47 Maxillary Central Incisors (#8) Greater crown-to- root ratio than lateral incisors Mesioincisal angle sharp (90 degrees) Contact area in incisal third Broad, smooth lingual fossa with cingulum Copyright © 2019 by Elsevier, Inc. All rights reserved. 48