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Mandible and Hyoid Bones gross features.pptx
- 1. MANDIBLE DR. ABDUL RAUFMEMON ANATOMY DEPARTMENT LUMHS JAMSHORO
- 2. MANDIBLE •Horseshoe shaped boneof viscerocranium. •Largest bone of viscerocranium. •Besides the bones of the middle ear, mandible is only mobile bone in the skull.
- 7. •Unlike other bonesof the skull, the mandible doesn’t articulate with the surrounding bones via sutures, •It articulates rather by synovial joint called the temporomandibular joint. •Joint allows it to be attached to skull while at same time produce various translatory and rotatory movements. •These movements allow complex actions like chewing and speaking.
- 11. BODY •Body is horizontalportion. •It consists of two parts: •Alveolar part •Base of mandible
- 13. ALVEOLAR PART OFBODY OF MANDIBLE •It is the upper portion of the body. •It consists of two bony lamellae: •Thick buccal lamella, •Thin lingual lamella. •They are parallel to each other, •They form shallow trench on the upper surface of the alveolar part. •Lamellae are connected by interalveolar septa, •These septae cut the trench into sockets which house the mandibular teeth.
- 19. BASE OF BODYOF MANDIBLE •It is inferior part of body •It has several anatomical landmarks. •Mandibular symphysis: •Fibrous tissue in the midline, •It ossifies by the first year of life. •It unites the left and right halves of the mandible in order to form a single, symmetrical bone.
- 21.
- 22. MENTAL TUBERCLE • Paired bony prominence oneach side of the mental protuberance.
- 23. OBLIQUE LINE • Crest extend fromramus to body of mandible. • provides insertion point for depressor anguli oris
- 24. MENTAL FORAMEN • Opening inferior to second mandibular premolar tooth •It provides passage for mental nerve and vessels.
- 29. INTERNAL SURFACE OFTHE BASE OF MANDIBLE DIGASTRIC FOSSA •Paired depression on lower margin •Located on each side of the midline.
- 31. MENTAL SPINES • Pairedbony eminences on the midline. • Provide attachment for the genioglossus and Geniohyoid muscles.
- 32. SUBMANDIBULAR FOSSA • Paired depressionon each side of the mental spines • It houses submandibular gland.
- 33. SUBLINGUAL FOSSA •Depression located superior to themental spines •It lodges sublingual gland.
- 34. MYLOHYOID LINE •Paired oblique crest onthe sides •Provides attachment to mylohyoid muscle
- 36.
- 37. MANDIBLE • Consists oftwo parts • Body, • Rami.
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- 42. RAMUS •It is verticalpart of the mandible. •It unites with the body at angle of mandible (i.e. gonial angle). •Angle can range from 110° to 130° •Angle can vary depending on the age, sex and ethnicity. •Angulation is larger in men usually.
- 46. SUPERIOR PART OFTHE RAMUS •It consists of two processes: •Coronoid process (anterior process) •Condylar process (posterior process). •Incisure between them is called the mandibular notch •Notch crossed by the masseteric nerve and vessels.
- 48. MEDIAL SURFACE OFTHE RAMI •Pterygoid tuberosity: •Rough area for the insertion of the medial pterygoid muscle. •Inferior alveolar (Mandibular) foramen: •Starting point of the mandibular canal which is traversed by the inferior alveolar nerve and its branches. •Mylohyoid sulcus: •Contains the mylohyoid artery and nerve.
- 49. POSTEROLATERAL ASPECT OF RAMUS •MASSETERIC TUBEROSITY •Rough surface for insertion of masseter muscle.
- 51. Muscles that originatefrom the mandible Buccinator muscle Buccinator ridge of mandible Mentalis muscle Incisive fossa of mandible Depressor labii inferioris muscle Oblique line of mandible Depressor anguli oris muscle Mental tubercle and oblique line of mandible Anterior belly of digastric muscle Digastric fossa Genioglossus muscle Superior mental spine Geniohyoid muscle Inferior mental spine Mylohyoid muscle Mylohyoid line
- 52. Muscles that insertto the mandible Lateral pterygoid muscle Pterygoid fossa Temporalis muscle Apex and medial surface of coronoid process of mandible Medial pterygoid muscle Medial surface of ramus (pterygoid tuberosity) and angle of mandible Masseter muscle Lateral surface of ramus and angle of mandible Platysma Lateral surface of ramus and angle of mandible
- 53. CLINICALS •Alveolar bone resorptionoccurs when the teeth are lost •There is a lack of structures to support the bone •There is increased pressure upon the bone due to chronic denture wearing.
- 54. MANDIBULAR FRACTURES • Intra-and extracapsular condylar fractures are the most frequent mandibular fractures • They usually result due to car accidents or indirect force due to violence. • Other mandibular fracture areas include • Body, • Angle, • Symphysis, • Ramus, • Alveolus • Coronoid process • In decreasing order of frequency.
- 55. MANDIBULAR FRACTURES •A mandibularfracture rarely occurs in isolation. •Fracture on one side is frequently associated with a fracture on the contralateral side. •Therefore, if one fracture is observed, another should be searched for. •E.g.: Fractured neck of the mandible is often observed in conjunction with a fracture of the contralateral mandibular body.
- 56. FRACTURES OF THECORONOID PROCESS
- 57. FRACTURES OF THENECK OF THE MANDIBLE
- 58. FRACTURES OF THEANGLE OF THE MANDIBLE
- 59. FRACTURES OF THEBODY OF THE MANDIBLE
- 60. TOOTH APLASIA •It iscommon in, •Third molars, •Premolars •Lateral incisors. •This can lead to gaps in the teeth and an uneven alveolar ridge.
- 62. OSTEORADIONECROSIS • It isa disorder that occurs due to cancer treatment • Bone disintegrates because of radiation.
- 63. OSTEOMYELITIS • is aninfection that can cause chronic sequestrations and bone disintegration within the mandible. • It is irreversible and the mandible often needs resecting.
- 64. CYST FORMATION •Most oftenhappens in the mandible where the molars sit. •There are many types of cyst •Common symptom is large bone resorption and bone weakening if the cyst is left untreated.
- 68. HYOID BONE •It isa ‘U’ shaped bone •Located in the anterior neck. •It lies at the base of the mandible (approximately at the level of C3), •Here it acts as a site of attachment for the anterior neck muscles.
- 70. STRUCTURE OF THEHYOID BONE •BODY: • Central part of the bone. • It has, • Anterior convex surface, • Posterior concave surface.
- 72. •GREATER HORN: • Projects from eachend of the body in a posterior, superior and lateral direction. • It acts as a site of attachment for numerous neck muscles.
- 73. •LESSER HORN: • Arisesfrom superior aspect of hyoid bone, near the origin of the greater horn. • It projects superoposteriorly (toward the styloid process of the temporal bone). • Stylohyoid ligament attaches to the apex of the lesser horn.
- 75. MUSCULAR ATTACHMENTS •It isunique in the fact that, •It does not articulate with any other bones, •It is suspended in place by the muscles and ligaments that attach to it.
- 77. Oral Cavity and Pharynx SuprahyoidInfrahyoid •Middle pharyngeal constrictor •Hyoglossus •Genioglossus •Digastric •Stylohyoid •Geniohyoid •Mylohyoid •Thyrohyoid •Omohyoid •Sternohyoid
- 79. LIGAMENTS •Three main ligamentsattached to the hyoid bone •Stylohyoid, •Thyrohyoid, •Hyoepiglottic. •They support the position of the hyoid in the neck.
- 80. • Stylohyoid ligament It extends •From styloid process of temporal bone • To the lesser horn of the hyoid bone.
- 82. Thyrohyoid membrane • originates from thesuperior border of thyroid cartilage • Attaches to the posterior surface of the hyoid bone and the greater horns.
- 84.
- 85. FRACTURE OF THEHYOID BONE •It is well protected by mandible and cervical spine, •Due to it fractures are relatively rare. •Hyoid bones fractures are characteristically associated with strangulation •It is found in 1/3 of all homicides by strangulation. •It is therefore a significant post-mortem finding. •It is also result of trauma, with clinical features of •Pain on speaking, •Odynophagia •Dyspnoea.