Maxilla, Mandible & Hyoid Bone by Dr. RIG.pptx

Gross & Neuro-Anatomy

1. Maxilla, Mandible & Hyoid Bone Dr. Rabia Inam Gandapore Assistant Professor Head of Department Anatomy (Dentistry-BKCD) B.D.S (SBDC), M.Phil. Anatomy (KMU), Dip. Implant (Sharjah, Bangkok, ACHERS) , CHPE (KMU),CHR (KMU), Dip. Arts (Florence, Italy )

2. Teaching Methodology LGF (Long Group Format) SGF (Short Group Format) LGD (Long Group Discussion, Interactive discussion with the use of models or diagrams) SGD (Short Group) SDL (Self-Directed Learning) DSL (Directed-Self Learning) PBL (Problem- Based Learning) Online Teaching Method Role Play Demonstrations Laboratory Museum Library (Computed Assisted Learning or E-Learning) Assignments Video tutorial method

3. Goal/Aim (main objective) Norma Frontalis : Identify the skeletal features of norma frontalis (including Zygoma , Maxilla & Mandible). Describe muscle attachments. Enlist structures passing through foramina. Enumerate relevant clinical problems of Norma frontalis .

4. Specific Learning Objectives (cognitive) At the end of the lecture the student will able to: Identify the skeletal features of norma frontalis , Lateralis , Basalis , Verticalis , Occipitalis . Describe muscle attachments. Enlist structures passing through foramina. Enumerate relevant clinical problems

5. Psychomotor Objective: (Guided response) Ask student to submit assignment of tabulated form of the structures passing through all foramen and fossa

6. Affective domain To be able to display a good code of conduct and moral values in the class. To cooperate with the teacher and in groups with the colleagues. To demonstrate a responsible behavior in the class and be punctual, regular, attentive and on time in the class. To be able to perform well in the class under the guidance and supervision of the teacher. Study the topic before entering the class. Discuss among colleagues the topic under discussion in SGDs. Participate in group activities and museum classes and follow the rules. Volunteer to participate in psychomotor activities. Listen to the teacher's instructions carefully and follow the guidelines. Ask questions in the class by raising hand and avoid creating a disturbance. To be able to submit all assignments on time and get your sketch logbooks checked.

7. Lesson contents Clinical chair side question: Students will be asked if they know what is clinical relevance of Pterion & Asterion Outline: Activity 1 The facilitator will explain the student's about skeletal features of norma frontalis , Lateralis , Basalis , Verticalis , Occipitalis . Describe muscle attachments. Enlist structures passing through foramina. Enumerate relevant clinical problems Activity 2 The facilitator will ask the students to submit assignment of tabulated form of the structures passing through all foramen and fossa Activity 3 The facilitator will ask the students a few Multiple Choice Questions related to it with flashcards.

8. Recommendations Students assessment: MCQs, Flashcards, Diagrams labeling. Learning resources: Langman’s T.W. Sadler, Laiq Hussain Siddiqui, Snell Clinical Anatomy , Netter’s Atlas , BD Chaurasia’s Human anatomy, Internet sources links.

9. Maxilla

10. Maxilla Maxilla is the 2 nd Largest bone of face 2 maxillae form the whole of the upper jaw Maxilla assists in forming 3 cavities: 1. Roof of the mouth 2. Floor & lateral wall of nose 3. Floor of the orbit

11. 2 Fossae Infratemporal Pterygopalatine 2 Fissures Inferior Orbital Pterygomaxillary

12. Body of Maxilla Body of maxilla is pyramidal in shape, with its 1. Base: directed medially at N asal surface (lateral wall of nose) 2. Apex: directed laterally at Z ygomatic process of maxilla 3.Roof: formed by floor of orbit & traversed by infraorbital canal 4. Floor: formed by alveolar process of maxilla, Lies about 1.2cm below level of floor of nose

13. It has four surfaces & encloses a large cavity: Maxillary sinus. 1. Anterior or facial 2. Posterior or infratemporal 3. Superior or orbital 4. Medial or nasal

14. Four Processes of Maxilla Zygomatic Process Frontal Process Alveolar Process Palatine Process

15. Functions Speech and voice resonance Reduce the weight of skull Filtration of inspired air Immunological barrier Regulation of intranasal pressure

16. Superiorly: it articulates with 3-bones 1. Nasal 2. Frontal 3. Lacrimal Medially: 5 bones 1. Ethmoid 2. Inferior nasal concha 3. Vomer 4. Palatine 5. Opposite maxilla Laterally: 1 Bone Zygomatic Bone

17. At birth: -Transverse and anteroposterior diameters greater than vertical diameter - Frontal process is well marked - Body consists of a little more than the alveolar process - Tooth sockets close to floor of orbit - Maxillary sinus is a mere furrow on lateral wall of nose In Adults - Vertical diameter is greater due to developed alveolar process -Increase in the size of the sinus In Old -Infantile condition -Its height is reduced as a result of absorption of the alveolar process

18. Mandible

19. Mandible Latin word Mandibula “Jawbone or inferior Maxillary bone) Movable bone of skull “ Ball & Socket Joint Formed by fusion of left & right processes & joins to form mandibular symphysis , ( faint ridge in midline) composed of fibrocartilage It fuses together in early childhood .

20. Components: M andible consists of: Horseshoe-shaped body P air of rami B ody of mandible & meets with ramus at angle of mandible or gonial angle.

21. 1. Body of Mandible

22. 1. Body of Mandible 1). Body : curved somewhat horse-shoe shaped. It has: A). 2-surfaces Internal surface External surface B). 2- borders Upper border Lower border

23. A).SURFACES

24. a) External Surface I n midline,a faint ridge indicating line of fusion of 2 halves during development at symphysis menti . This ridge divides below and encloses a triangular eminence, the mental protuberance , B ase of which is depressed in center but raised on either side to form mental tubercle . Running backward and upward from each mental tubercle is a faint ridge, oblique line (attachment to depressor labii Inferioris ,   depressor anguli oris , platysma   is attached below it) which is continuous with anterior border of ramus .

25. On either side of symphysis,below incisor teeth , is a depression, incisive fossa , gives origin to   mentalis muscle ( small portion of orbicularis oris muscle attachement ) for passage of mental vessels & nerve . Mental foramen below second pre-molar tooth , it transmits terminal branch of inferior alveolar nerve and vessels .

26. b ) Internal Surface On Medial surface of body of mandible in median plane are Mental spines or genial tubercles . G ive origin to: Above: Genioglosses muscle ( origin: S uperior genial tubercle ) Below : Genio -hyoid muscle ( origin: Inferior genial tubercle )*( P osterior surface of symphysis menti ) Below mental spines, on either side of middle line, is an oval depression for attachment of anterior belly of digastric Mylo -hyoid line an oblique ridge that runs backward and laterally from area of mental spines to an area below and behind 3 rd molar tooth which gives origin to   mylohyoid muscle . P osterior part of this line, near alveolar margin, gives attachment to a small part of S uperior Constrictor of pharynx &   pterygomandibular raphe (immediately behind 3rd molar).

27. S ub-mandibular fossa , for superficial part of submandibular salivary gland , lies below posterior part of mylohyoid line S ublingual fossa ,for sublingual gland lies above anterior part of mylohyoid line.

28. B).Borders

29. a. Upper Border (The Alveolar Crest) I n adults contains 16 sockets for roots of teeth. Inter-alveolar septa is one of thin plates of bone separating alveoli of teeth in the  mandible . To outer lip of superior border, on either side ,   buccinators muscle   is attached as far forward as 1 st molar tooth.

30. B. Lower Border (The Base) D igastric fossa is a small,roughened depression on base, on either side of symphysis menti . A nterior bellies of the digastric muscles are attached in fossae. At point where it joins lower border of ramus a shallow groove; for   facial artery.

31. 2 ).The Ramus

32. R amus has 2-processes 2-surfaces 4- borders 2 processes are seperated by mandibular notch(* masseteric nerve & vessels pass through it ) Pterygoid fovea a concave surface on uppermost medial side of   ramus located behind mandibular notch & below of   condyloid process P terygoid fovea is located on anterior surface of neck of mandible & serves for attachment of   lateral pterygoid muscle . C ondyle & posterior mandibular ramus make up mandibular buttress establishing posterior facial height.

33. 1. Processes 1 ). Anteriorly: Coronoid process , it recieves on its medial surface attachement of temporalis muscle . 2). Posteriorly: Condyloid process, consists of two portions: C ondyle or Head (TMJ joint-Mandibular fossa, Palpable infront of tragus) N eck (attachment of lateral pterygoid muscle + auriculotemporal nerve & superficial temporal artery related to medial side of neck)

34. 2. Surfaces A). L ateral surface of ramus is flat & has oblique ridges ( buccinator muscle , depressor anguli oris ) at its lower part; it gives attachment to masseter muscle . Incisive fossa: Mentalis muscle , orbicularis oris . Posterio -superior part: Parotid gland Lower border: Platysma ,Investing layer of deep fascia

35. B). M edial surface of ramus Mandibular foramen , for inferior alveolar nerve & vessels (*maxillary artery) . In front of foramen is a projection of bone: lingula , for attachement of sphenomandibular ligament . The foramen leads into mandibular canal , which opens on lateral surface of body of mandible at mental foramen . The incisive canal is a continuation forward of mandibular canal beyond mental foramen & below incisor teeth . Mylohyoid groove  runs obliquely downward & forward, and lodges mylohyoid vessels  & nerve (* lingual nerve is related to medial surface of ramus infront of mylohyoid groove ) . Behind this groove is a rough surface, for insertion of   Medial pterygoid muscle

36. 3. BORDERS 1 ).Upper border of ramus thin & curved downwards forming mandibular notch 2).lower border of ramus backward continuation of base of mandible 3).Posterior border of ramus lower border ends posteriorly & becomes continuous with posterior border at angle of mandible 4).Anterior border of ramus thin, while posterior border is thick

37. Blood, Nerves & Lymph Supply

38. Nerves Inferior alveolar nerve branch of mandibular division of   trigeminal nerve , E nters mandibular foramen & runs forward in mandibular canal , supplying sensation to teeth . At mental foramen the nerve divides into 2 terminal branches: a. I ncisive nerve: runs forward in mandible & supply anterior teeth. b. M ental nerve: exits mental foramen & supply sensation to lower lip.

39. Arterial Supply I nferior alveolar artery which is a branch of the maxillary artery (branch of external carotid ). This travels through mandibular canal (which can be found on the internal aspect of the mandible). From here, this artery branches off into dental and incisive branches to supply the lower teeth. I nferior alveolar artery then exits the canal via the mental foramen to give rise to the mental branch , which goes on to supply the chin

40. Venous Supply: Internal Jugular vein & external jugular vein through maxillary vein, facial vein & pterygoid plexus I nferior alveolar vein is the sole collector of blood from the mandibular teeth pumped around mandible & it drains into pterygoid venous plexus.

41. Lymph Nodes P arotid, S ubmandibular S ubmental

42. Variation Gender: Males : have squarer, stronger & larger mandibles than females. M ental protuberance: more pronounced in males but can be visualized & palpated in females. AGE : Infants & Children: mandible is obtuse 140 degree angle Adults : angle reduces to about 110-120 degree because ramus become almost verticle Old Age: angle again becomes obtuse about 140 degree because ramus is oblique.

43. Muscle Origin Insertion Nerve Supply Action 1 Platysma Deep fascia over pectoralis major and deltoid Body of mandible and angle of mouth Facial nerve cervical branch Depresses mandible & angle of mouth 2 Sternocleidomastoid Manubrium sterni and medial third of clavicle Mastoid process of temporal bone & occipital bone Spinal part of accessory nerve & C2, C3 Two muscles acting together extend head & flex neck; one muscle rotates head to opposite side 3 Digastric - Posterior belly Mastoid process of temporal bone Intermediate tendon is held to hyoid by fascial sling Facial nerve Depresses mandible or elevates hyoid bone Digastric- Anterior belly Body of mandible Nerve to mylohyoid

44. Clinical Relevance

45. Mandibular Fractures Parasymphysis region lateral to the mental prominence is a naturally weak area susceptible for parasymphyseal fracture. This is because of the presence of incisive fossa and mental foramen B ody of mandible is considerably thicker than ramus & junction between these two portions constitutes a line of structural weakness Strength of lower jaw varies with presence or absence of teeth. The presence of impacted lower third molars or excessive long roots of canines make the area more vulnerable for fracture

46. HYOID BONE

47. Hyoid bone  ( lingual bone  or  tongue-bone U shaped & consist of 1).A Body 2).Two pairs of horns a).Two-Greater Cornua b).Two-Lesser Cornua It is attached to: a. Skull by stylo -hyoid ligament b. Thyroid cartilage by thyro -hyoid membrane .

48. It is mobile & lies in neck just ABOVE : L arynx BELOW: M andible . Hyoid bone forms a base for tongue & is suspended in position by muscles that connect it to: Mandible S tyloid process of the temporal bone T hyroid cartilage Sternum Scapula . Unlike other bones, hyoid is only distantly articulated to other bones by muscles or ligaments .

49. Functions It aids in tongue movement & swallowing . H yoid bone provides attachment to: Above: Muscles of the floor of mouth   & tongue Below: Larynx B ehind: Epiglottis  and P harynx

50. BODY It has 1). Anterior and posterior surfaces ( 2 surfaces ) 2). Upper and lower borders ( 2 borders ) 1. Anterior surface: - Convex & is directed forward and upward. - Its divided by a median ridge into 2 lateral halves . 2. Posterior Surface: - Concave & is directed backward and downward -each lateral end of body is continuous posteriorly with greater horn or cornua . (Till middle life connection between body & greater cornua is fibrous )

51. HORNS or CORNUA: 1 ). Greater cornua : F lattened from above downwards. - Each cornua tapers posteriorly,but ends in a tubercle. It has: a).2-surfaces (upper and lower) b).2-borders (medial and lateral c).A tubercle 2). Lesser cornua : S mall conical pieces of bone which project upwards from junction of body & greater cornua . - They are connected to body by fibrous tissue . - Occasionally, connected to greater cornua by synovial joints which usually persist throughout life, but may get ankylosed .

52. Muscles of Hyoid Bone A ). SUPERIOR 1). Hyo-glossus 2 ). Middle pharyngeal constrictor 3). Genio-glossus 4). Genio -hyoid 5). Stylo -hyoid ligament 6). Intrinsic muscles of the tongue 7 ). Mylo -hyoid 8). Supra hyoid muscle 8). Digastric & Stylo -hyoid muscles B ). INFERIOR 1 ). Omo -hyoid 2 ). Sterno -hyoid 3 ). Thyro -hyoid

53. Muscle Origin Insertion Nerve Supply Action 4 Stylohyoid Styloid process Body of hyoid bone Facial nerve Elevates hyoid bone 5 Mylohyoid Mylohyoid line of body of mandible Body of hyoid bone & fibrous raphe Inferior alveolar nerve Elevates floor of mouth & hyoid bone or depresses mandible 6 Geniohyoid Inferior mental spine of mandible Body of hyoid bone 1st cervical nerve Elevates hyoid bone or depresses mandible 7 Sternohyoid Manubrium sterni & clavicle Body of hyoid bone Ansa cervicalis ; C1, 2 & 3 Depresses hyoid bone 8 Sternothyroid Manubrium sterni Oblique line on lamina of thyroid cartilage Ansa cervicalis ; C1, 2, and 3 Depresses larynx 9 Thyrohyoid Oblique line on lamina of thyroid cartilage Lower border of body of hyoid bone 1st cervical nerve Depresses hyoid bone or elevates larynx 10 Inferior belly Omohyoid Upper margin of scapula and suprascapular ligament Intermediate tendon is held to clavicle and first rib by fascial sling Ansa cervicalis ; C1, 2, and 3 Depresses hyoid bone Superior belly Omohyoid Lower border of body of hyoid bone

54. Blood S upply lingual artery which runs down from   tongue to greater horns of bone . A branch of this artery, the suprahyoid branch runs along the upper border of hyoid bone & supplies blood to the attached muscles.

55. Clinical Significance

56. Obstructive Sleep Apnea Hyoid bone physiological functions, includes: Breathing, swallowing & speech . P lay a key role in keeping upper airway open during sleep, & development and treatment of  obstructive sleep apnea (characterized by repetitive collapse of upper airway during sleep). I nferiorly positioned hyoid bone is strongly associated with presence & severity of disorder.   Movement of hyoid bone is also modify upper airway properties  S urgical procedure   potentially increase & improves airway is called  hyoid suspension .

57. Fracture Due to its position, hyoid bone is not easily susceptible to fracture. In a suspected case of murder, a  fractured hyoid  strongly indicates throttling or  strangulation  in an adult. Not necessarily the case in children & adolescents, where hyoid bone is flexible as ossification is yet to be completed.

58. Thank You