Muscles of Head & Neck

brief about muscles of head and neck, triangles of neck and its applied anatomy in Oral and Maxillofacial Surgery.

1. GOOD MORNING

2. MUSCLES OF HEAD & NECK PRESENTED BY: CHIRAG M A 1 ST YEAR PG Dept of ORAL & MAXILLOFACIAL SURGERY

3. CONTENTS: INTRODUCTION CLASSIFICATION OF MUSCLES FACIAL MUSCLES MASTICATORY MUSCLE MUSCLES OF NECK APPLIED ANATOMY

4. INTRODUCTION Muscles are formed from Myoblasts of the Mesenchyme which forms the bulk of the mesoderm. There are more than 600 muscles in our body. In man, muscle tissue constitutes 40–50% of the body mass. Muscle cells can be excited chemically, electrically and mechanically to produce an action potential that is transmitted along their cell membranes.

5. CLASSIFICATION MUSCLES CAN BE CLASSIFIED UNDER DIFFERENT CATEGORIES:

6. THE MUSCLES IN HEAD AND NECK CAN BE GROUPED AS: FACIAL MUSCLES WHICH INCLUDES THE MUSCLES OF SCALP, EYE, LIP, NOSE AND EARS . MASTICATORY MUSCLES WHICH INCLUDES THE MUCLES THAT HELP IN THE MOVEMENT OF TMJ. ANTEROLATERAL MUSCLES OF NECK WHICH INCLUDES SUPRAHYOID AND INFRAHYOID MUSCLES.

7. FACIAL MUSCLE FACIAL MUSCLE CONSISTS OF GROUP OF MUSCLES, NAMELY: MUSCLES OF SCALP MUSCLES OF AURICLES MUSCLES OF EYELID MUSCLES OF NOSE MUSCLES AROUND MOUTH

8. OCCIPITOFRONTALIS : IT COVERS THE DOME OF SKULL. Origin & Insertion: IT IS A BROAD, MUSCULOFIBROUS LAYER CONSISTING OF 4 bellies - 2 occipital and 2 frontal which are connected by an EPICRANIAL aponeurosis (galea aponeurotica ). MUSCLES OF SCALP

9. ORBITAL PART ARISES FROM LATERAL 2/3 RD OF HIGHEST NUCHAL LINE & A PART FROM MASTOID PART OF TEMPORAL BONE. FRONTALIS PART IS ADHERENT TO SUPERFICIAL FACSIA OF EYEBROWS. IT IS DEVIDED INTO 3 PARTS: MEDIAL FIBRES – WHICH IS CONNECTED TO PROCERUS INTERMEDIATE fibers – CONNECTED TO CORRUGATOR SUPERCILLI . LATERAL FIBERS – CONNECTED TO ORBICULARIS OCULI .

10. NERVE SUPPLY : POST AURICULAR BRANCH OF FACIAL NERVE TO OCCIPITALIS TEMPORAL BRANCHES OF FACIAL NERVE TO FRONTALIS BLOOD SUPPLY: BRANCHES OF THE SUPERFICIAL TEMPORAL, OPHTHALMIC, POSTERIOR AURICULAR AND OCCIPITAL ARTERIES. ACTION: FRONTALIS: RAISE THE EYEBROWS AND THE SKIN OVER THE ROOT OF THE NOSE, AND AT THE SAME TIME DRAW THE SCALP FORWARD FORMING TRANSVERSE WRINKLES OF THE FOREHEAD. OCCIPITALIS: IN SOME INDIVIDUALS OCCIPITALIS CAN PULL THE SCALP BACKWARDS , BUT OTHERWISE IT MERELY ANCHORS THE APONEUROSIS WHEN FRONTALIS ELEVATES THE EYEBROWS.

11. APPLIED ANATOMY: FRONTALIS MUSCLE IS ONE AMONG THE MANY MUSCLES EXAMINED TO CHECK THE FUNCTIONING OF FACIAL NERVE. TRANSVERSE WRINKLES ON THE FOREHEAD ARE ABSENT WHEN THE PATIENT IS ASKED TO LOOK UPWARDS WITHOUT MOVING HIS HEAD IN CASES OF INFRANUCLEAR LESIONS OF THE FACIAL NERVES .

12. MUSCLES OF AURICLES THERE ARE 3 MUSCLES DEPENDING ON THE SITE OF ATTACHMENT: AURICULARIS ANTERIOR AURICULARIS SUPERIOR AURICULARIS POSTERIOR

13. MUSCLE ORIGIN INSERTION ACTION NERVE SUPPLY AURICULARIS ANTERIOR TEMPORAL FASCIA MAJOR HELIX OF EAR PULLS EAR FORWARDS TEMPORAL BRANCH AURICULARIS SUPERIOR TEMPORAL FASCIA ABOVE EAR PULLS EAR UPWARDS POSTERIOR AURICULAR BRANCH AURICULARIS POSTERIOR MASTOID PROCESS BEHIND THE EAR PULLS EAR BACKWARDS POSTERIOR AURICULAR BRANCH BLOOD SUPPLY IS FROM POSTERIOR AURICULAR ARTERY .

14. MUSCLES OF EYELID MUSCLES OF EYELIDS ARE: ORBICULARIS OCULLI CORRUGAROR SUPERCILLI LEVATOR PALPEBRAL SUPERIORIS Extraocular muscles

15. ORBICULARIS OCULLI: IT SURROUNDS THE CIRCUMFERENCE OF ORBIT. IT HAS 3 PARTS: ORBITAL PALPEBRAL LACRIMAL PART OF MUSCLE ORIGIN INSERTION ORBITAL MAJORLY FROM NASAL PART OF MAXILLA AND FRONTAL PROCESS OF MAXILLA LATERAL PALPERBRAL LIGAMENT PALPEBRAL MEDIAL PALPEBRAL LIGAMENT BLENDS WITH CORRUGATOR MUSCLE LACRIMAL CREST OF LACRIMAL BONE, BEHIND THE SAC. TARSI OF EYELID

16. NERVE SUPPLY: TEMPORAL AND ZYGOMATIC BRANCH OF FACIAL NERVE. ACTION: THE MAJOR ACTION OF MUSCLES HELP IN OPENING AND CLOSING OF EYELIDS . APPLIED ANATOMY: PARALYSIS OF ORBICULARIS OCULLI LEADS TO DROOPING OF EYELID AND INABILITY TO CLOSE THE EYE; HENCE EXCESSIVE TEARING WILL BE NOTED.

17. CORRUGATOR SUPERCILLI: SMALL PYRAMIDAL MUSCLE LOCATED AT MEDIAL END OF EACH EYEBROW. ARISES FROM MEDIAL END OF THE SUPERCILLIARY ARCH AND INSERTED INTO DEEP SURFACE OF SKIN, ABOVE THE MIDDLE OF THE ORBITAL ARCH . NERVE SUPPLY: temporal BRANCH OF FACIAL NERVE.

18. LEVATOR PALPEBRAL SUPERIORIS: IT IS MUSCLE THAT HELPS IN ELEVATING EYELID. ORIGIN: ARISES FROM THE UNDER SURFACE OF THE LESSER WING OF THE SPHENOID, ANTEROSUPERIOR TO THE OPTIC FORAMEN. INSERTION: BLENDS WITH THE ORBITAL SEPTUM AND INSERTS INTO THE ANTERIOR SURFACE OF THE SUPERIOR TARSUS .

19. Extraocular muscles EXTRA OCULAR MUSCLES ARE AS FOLLOWS: 4 RECTI MUSCLES: SUPERIOR RECTUS INFERIOR RECTUS MEDIAL RECTUS LATERAL RECTUS 2 OBLIQUE MUSCLES: SUPERIOR OBLIQUE INFERIOR OBLIQUE

20. RECTIC Muscle : ALL THE RECTI MUSCLES ARISES FROM A COMMON FIBROUS RING WHICH SURROUNDS THE UPPER, MEDIAL, AND LOWER MARGINS OF THE OPTIC FORAMEN AND ENCIRCLES THE OPTIC NERVE. TWO SPECIALIZED PARTS OF THE FIBROUS RING A LOWER, LIGAMENT/TENDON OF ZINN: GIVES ORIGIN TO INFERIOR RECTUS AND LOWER HEAD OF LATERAL RECTUS . AN UPPER, SUPERIOR TENDON OF LOCKWOOD: GIVES ORIGIN TO SUPERIOR RECTUS, MEDIAL RECTUS AND UPPER HEAD OF LATERAL RECTUS.

21. EACH MUSCLE PASSES FORWARD AND IS INSERTED INTO THE SCLERA BY A TENDINOUS EXPANSION 6MM ABOVE THE MARGIN OF THE CORNEA.

22. Oblique muscles: Arises: above and medial to the origin of superior rectus. The fibers become a rounded tendon and pass through fibrocartilaginous ring or pulley attached to the trochlear fovea of frontal bone. Insertion: sclera of the lateral part of the bulb of the eye Between insertions of superior rectus and lateral rectus. Arises: from the orbital surface of the maxilla, lateral to the lacrimal groove . The fibres pass laterally backward and upwards between inferior rectus and the floor of the orbit Insertion: sclera of the lateral part of the eye between superior rectus and lateral rectus behind the insertion of superior oblique. SUPERIOR OBLIQUE INFERIOR OBLIQUE

23. NERVE SUPPLY: ALL THE MUSCLES EXCEPT SUPERIOR OBLIQUE AND LATERAL RECTUS, ARE SUPPLIED BY OCULOMOTOR NERVE . WHERE AS SUPERIOR OBLIQUE AND LATERAL RECTUS IS SUPPLIED BY TROCHLEAR AND ABDUCENT NERVES RESPECTIVELY. BLOOD SUPPLY: All extraocular muscles are supplied by Ophthalmic artery .

24. ACTION: Levator palpebrae superioris: antagonist of orbicular oculi as it raises the eyelid Other extraocular muscles HELPS IN MOVEMENT OF EYE.

25. ASSESSMENT OF MUSCLE ENTRAPMENT FOLLOWING TRAUMA OF MID-FACE REGIONS.

26. MUSCLES OF NOSE MUSCLES OF NOSE CONSISTS OF: PROCERUS NASALIS DEPRESSOR SEPTI

27. PROCERUS: IT IS BLENDED WITH FRONTALIS MUSCLE AND INSERTED INTO THE SKIN OVER THE LOWER PART OF FOREHEAD BETWEEN EYEBROWS . ACTION: DRAWS DOWN MEDIAL ANGLE OF EYEBROWS PRODUCING TRANSVERSE WRINKLES OVER BRIDGE OF NOSE.

28. NASALIS : IT HAS 2 PARTS COMPRESSOR NARIS(TRANSVERSE PART): ARISES FROM THE MAXILLA JUST LATERAL TO NASAL NOTCH AND INSERTED INTO APONEUROSIS ACROSS DORSUM OF NOSE WITH MUSCLE FIBERS FROM THE OTHER SIDE. DILATOR NARIS(ALAR PART): ARISES FROM MAXILLA AND INSERTED TO ALAR CARTILAGE OF NOSE.

29. Action: TRANSVERSE PART HELPS IN COMPRESSION OF NASAL APPERTURE. ALAR PART Draws cartilage downward and laterally opening OF nostril, hence helps in dilation of nostrils .

30. DEPRESSOR SEPTI : IT ARISES FROM THE MAXILLA; ABOVE THE CENTRAL INCISOR AND ASCENDS TO ATTACH TO THE NASAL SEPTUM . ACTION: PULLS NOSE INFERIORLY

31. NREVE SUPPLY: ALL THE MUSCLES OF NOSE ARE SUPPLIED BY BUCCAL BRANCH OF FACIAL NERVE. BLOOD SUPPLY PROCERUS IS SUPPLIED MAINLY BY BRANCHES FROM THE FACIAL ARTERY NASALIS IS SUPPLIED BY THE INFRAORBITAL BRANCH OF THE MAXILLARY ARTERY DEPRESSOR SEPTI IS SUPPLIED BY THE SUPERIOR LABIAL BRANCH OF THE FACIAL ARTERY

32. MUSCLES AROUND THE MOUTH

33. ORBICULARIS ORIS : THE ORBICULARIS ORIS MUSCLE IS A COMPLEX OF MUSCLES IN THE LIPS THAT ENCIRCLES THE MOUTH. IT ARISES FROM ANTERIOR SURFACE OF MAXILLA ANTERIOR SURFACE OF MANDIBLE MODIOLUS INSERTION: PERIPHERAL PART DECUSSATE WITH OPPOSITE FIBRES CROSSING THE MIDLINE TO INSERT INTO THE SKIN NEAR NASOLABIAL SULCUS .

34. IN CASES OF CLEFT LIP THE PERIPHERAL PART RUNS ALL THE WAY TO THE COLUMELLA WHILE THE MARGINAL PART END AT THE MARGIN OF THE DEFECT IN CORRECTION OF CLEFT LIP ORBICULARIS MUSCLE IS EVERTED WITH VERTICAL MATTRESS SUTURES. THE MUSCLE CAN BE DIVIDED INTO HORIZONTAL STRIPS THAT ARE INTERDIGITATED AND SUTURED TO THE UNDERSURFACE OF THE DERMIS. APPLIED ANATOMY:

35. HAS THREE HEADS: ANGULAR HEAD INTERMEDIATE HEAD / INFRAOR B ITAL HEAD ZYGOMATIC HEAD LEVATOR LABI SUPERIORIS

36. LEVATOR LABI SUPERIORIS ALAEQUE NASI IT ARISES FROM THE UPPER PART OF FRONTAL PROCESS OF MAXILLA . WHILE PASSING OBLIQUELY DOWNWARDS, IT SPLITS INTO MEDIAL AND LATERAL SLIPS. THE MEDIAL SLIP INSERTS INTO GREATER ALAR CARTILAGE AND LATERAL SLIP BLENDS WITH LEVATOR LABII SUPERIORIS .

37. ORIGIN AND INSERTION: ARISES FROM THE ZYGOMATIC BONE , IN FRONT OF THE ZYGOMATICOTEMPORAL SUTURE. INSERTED INTO THE ANGLE OF THE MOUTH , WHERE IT BLENDS WITH THE FIBRES OF THE ORBICULARIS ORIS . ZYGOMATICUS MAJOR:

38. ORIGIN AND INSERTION: IT ARISES FROM THE ANTERIOR ASPECT OF LATERAL SURFACE OF ZYGOMATIC BONE. INSERTS INTO THE UPPER LIP MEDIAL TO THE ANGLE OF THE MOUTH. ZYGOMATICUS MINOR

39. LEVATOR ANGULI ORIS / CANINUS ORIGIN AND INSERTION: ARISES FROM THE CANINE FOSSA IMMEDIATELY BELOW THE INFRAORBITAL FORAMEN. INSERTED INTO THE ANGLE OF THE MOUTH INTERMINGLING WITH THOSE OF THE ZYGOMATICUS, TRIANGULARIS AND ORBICULARIS ORIS.

40. NERVER SUPPLY: BUCCAL BRANCH OF FACIAL NERVE. BLOOD SUPPLY: LEVATOR LABII SUPERIORIS IS SUPPLIED BY THE FACIAL ARTERY AND THE INFRAORBITAL BRANCH OF THE MAXILLARY ARTERY. LEVATOR LABII SUPERIORIS ALAEQUAE NASI IS SUPPLIED BY THE FACIAL ARTERY AND THE INFRAORBITAL BRANCH OF THE MAXILLARY ARTERY ZYGOMATICUS IS SUPPLIED BY THE SUPERIOR LABIAL BRANCH OF THE FACIAL ARTERY. CANINUS IS SUPPLIED BY THE SUPERIOR LABIAL BRANCH OF THE FACIAL ARTERY AND THE INFRAORBITAL BRANCH OF THE MAXILLARY ARTERY.

41. ACTIONS: LEVATOR LABII SUPERIORIS: ELEVATOR OF UPPER LIP . WHEN THE WHOLE MUSCLE CONTRACTS IT GIVES THE EXPRESSION OF CONTEMPT. CANINUS: HELPS IN PRODUCING THE NASOLABIAL FURROW. ZYGOMATICUS: HELPS IN SMILING. ZYGOMATICUS MAJOR: PULLS THE ANGLE OF THE MOUTH UPWARDS AND LATERAL ZYGOMATICUS MINOR: ELEVATES THE UPPER LIP

42. ORIGIN AND INSERTION: ARISES FROM THE OBLIQUE LINE OF MANDIBLE , BETWEEN SYMPHYSIS AND MENTAL FORAMEN. INSERTS INTO THE INTEGUMENT OF THE LOWER LIP, ITS FIBRES BLEND WITH THAT OF ORBICULARIS ORIS. BLOOD SUPPLY: INFERIOR LABIAL BRANCH OF THE FACIAL ARTERY AND THE MENTAL BRANCH OF THE MAXILLARY ARTERY. ACTIONS: DRAWS THE LOWER LIP DOWNWARDS AND LATERALLY, AS IN EXPRESSION OF IRONY. DEPRESSOR LABII INFERIORIS

43. ORIGIN AND INSERTION: ARISES FROM THE OBLIQUE LINE OF THE MANDIBLE. INSERTS INTO THE ANGLE OF THE MOUTH . BLOOD SUPPLY: INFERIOR LABIAL BRANCH OF THE FACIAL ARTERY AND THE MENTAL BRANCH OF THE MAXILLARY ARTERY. ACTIONS: DEPRESSES ANGLE OF MOUTH MEDIALLY ALONG WITH PLATYSMA. DEPRESSOR ANGULI ORIS / TRIANGULARIS

44. ORIGIN AND INSERTION: ARISES FROM THE INCISIVE FOSSA OF THE MANDIBLE. INSERTS INTO THE INTEGUMENT OF THE CHIN . BLOOD SUPPLY: INFERIOR LABIAL BRANCH OF THE FACIAL ARTERY AND THE MENTAL BRANCH OF THE MAXILLARY ARTERY. ACTIONS: RAISES AND PROTRUDES THE LOWER LIP AND AT THE SAME TIME WRINKLES THE SKIN OF THE CHIN, EXPRESSING DOUBT. MENTALIS

45. ORIGIN AND INSERTION: ARISES FROM THE OUTER SURFACE OF THE ALVEOLAR PROCESS OF THE MAXILLA AND MANDIBLE , CORRESPONDING TO THE MOLARS ANTERIORLY AND FROM THE ANTERIOR BORDER OF PTERYGOMANDIBULAR RAPHE POSTERIORLY . INSERTION: THE FIBRES CONVERGE TOWARDS THE ANGLE OF THE MOUTH. BUCCINATOR

46. BLOOD SUPPLY: BRANCHES FROM THE FACIAL ARTERY AND THE BUCCAL BRANCH OF THE MAXILLARY ARTERY. ACTION: COMPRESSES THE CHEEKS SO THAT DURING MASTICATION THE FOOD IS KEPT UNDER IMMEDIATE PRESSURE OF THE TEETH. HENCE IT IS CALLED AS ACCESSORY MUSCLE OF MASTICATION .

47. ORIGIN AND INSERTION: ARISES IN THE FASCIA OVER MASSETER AND PASSES HORIZONTALLY FORWARD ABOVE THE PLATYSMA. INSERTS INTO THE SKIN OF THE ANGLE OF THE MOUTH. BLOOD SUPPLY: SUPPLIED MAINLY BY THE SUPERIOR LABIAL BRANCH OF THE FACIAL ARTERY. ACTION: RETRACTS THE ANGLE OF THE MOUTH AND HELPS IN PRODUCING UNPLEASANT GRINNING EXPRESSION. RISORIUS

48. It is defined as a lateral point to the corner of the angle of the mouth where the muscles of facial expression converge. (Jablonski 1982; Manhold and Balbo 1985; Harry and Ogston 1987). The muscles which form the modiolus are: ORBICULARIS ORIS BUCCINATOR CANINUS TRIANGULARIS ZYGOMATICUS MAJOR RISORIUS PLATYSMA LEVATOR LABII SUPERIORIS MODIOLUS

49. SHIMADA AND GASSER (1989) HAVE REPORTED VARIATIONS IN THE LOCATION OF MODIOLUS. TYPE A: MODIOLUS LATERAL TO THE ANGLE OF THE MOUTH TYPE B: MODIOLUS ABOVE THE ANGLE TYPE C: MODIOLUS BELOW THE ANGLE *CLINICAL ANATOMY 2:29-134(1989); VARIATIONS IN THE FACIAL MUSCLES AT THE ANGLE OF THE MOUTH – KAZUYUKI SHIMADA AND RAYMOND F. GASSER

50. COMMON FACIAL EXPRESSIONS SMILING & LAUGHING: ZYGOMATICS MAJOR SADNESS: LEVATOR LABII SUPERIORIS AND LEVATOR ANGULI ORIS GRIEF: DEPRESSOR ANGULI ORIS ANGER: DILATOR NARIS & DEPRESSOR SEPTI FROWNING: CORRUGATOR SUPERCILII & PROCERUS HORROR, TERROR & FIGHT: PLATYSMA SURPRISE: FRONTALIS DOUBT: MENTALIS GRINNING: RISORIUS CONTEMPT: ZYGOMATIC MINOR

51. FACIAL MUSCLES: ACTIONS

52. FACIAL MUSCLES : ACTIONS

53. APPLIED ANATOMY FACIAL PARALYSIS, OFTEN UNILATERAL, MAY BE DUE TO: (1) SUPRANUCLEAR LESIONS IN THE CORTICO NUCLEAR FIBERS FROM THE FRONTAL LOBE, VARIABLY COMBINED WITH NUMEROUS OTHER DESCENDING FIBERS CONVERGING IN THE FACIAL NUCLEUS. (2) NUCLEAR OR INFRANUCLEAR LESIONS INVOLVING LOWER MOTOR NEURONS.

54. SUPRANUCLEAR FACIAL PARALYSIS INVOLVING “UPPER MOTOR NEURON”, MOVEMENTS IN THE LOWER PART OF THE FACE ARE USUALLY AFFECTED. INFRANUCLEAR LESIONS VARY IN THEIR EFFECTS ACCORDING TO THE LESION’S SITE. FACIAL MUSCLES ARE REPRESENTED IN CELL GROUPS WITHIN THE NUCLEUS; THEIR DEGREE OF INVOLVEMENT GOVERNS THE EXTENT OF PARALYSIS, WHICH IS IPSILATERAL.

55. BELL’S PALSY IS AN ACUTE APPARENTLY ISOLATED WITH LMN FACIAL PALSY FOR WHICH NO CAUSE CAN BE FOUND. AETIOLOGY: ASSOCIATED KNOWN CLINICAL CONDITION – DIABETES MELLITUS, SEVERE HYPERTENSION IN LAST TRIMESTER OF PREGNANCY, DENTAL ANESTHESIA. CAUSES – (I) EXPOSURE TO COLD, OEDEMA AND SUBSEQUENT COMPRESSION OF THE NERVE TRUNK CAUSES CIRCULATORY DISTURBANCE, (II) OTHER IMPORTANT CAUSES INCLUDE SUPPURATIVE OTITIS MEDIA, HERPES ZOSTER, HEAD INJURY, GUILLIAN-BARRE SYNDROME, SARCOIDOSIS AND MULTIPLE SCLEROSIS.

56. SYMPTOMS:   SUDDEN FOLLOWING EXPOSURE TO CHILL OR WITHOUT ANY APPARENT PRECIPITATING CAUSE. POST AURICULAR PAIN IS COMMON AND MANY PRECEDE PARALYSIS BY TWO DAYS. THERE MAY BE SPONTANEOUS LOSS OF SENSE OF TASTE AND WATERING OF EYES. SIGNS:   FOREHEAD CANNOT BE WRINKLED , EYES CANNOT BE CLOSED. ON ATTEMPTING CLOSURE EYE BALL TURNS UPWARDS AND OUTWARDS, KNOWN AS BELL’S PHENOMENON. ON SHOWING TEETH, THE LIPS DO NOT SEPARATE ON AFFECTED SIDE. ANGLE OF AFFECTED SIDE DROOPS WITH DRIBBLING OF SALIVA . CHEEKS PUFFS OUT WITH EXPIRATION BECAUSE OF BUCCINATOR PARALYSIS. BASE OF TONGUE LOWERED. PAIN MAY PRECEDE FACIAL WEAKNESS . DEAFNESS MAY RESULT.

57. MASTICATORY MUSCLES THE MUSCLES OF MASTICATION ARE MANINLY CONCERNED IN THE MOVEMENT OF MANDIBLE DURING MASTICATION AND SPEECH. THEY DEVELOP FROM THE MESODERM OF 1 ST BRANCHIAL ARCH AND IS SUPPLIED BY MANDIBULAR NERVE, WHICH IS A NERVE OF THAT ARCH.

58. MUSCLES OF MASTICATION INCLUDE: 1. MASSETER 2. TEMPORALIS 3. MEDIAL PTERYGOID 4. LATERAL PTERYGOID

59. IT IS A QUADRILATERAL MUSCLE THAT COVERS THE LATERAL SURFACE OF RAMUS OF MANDIBLE. IT IS DIVIDED INTO TWO LAYERS: SUPERIFICIAL PART: ORIGINATES FROM THE ANTERIOR 2/3RD OF LOWER BORDER OF ZYGOMATIC ARCH AND INSERTS INTO LOWER PART OF LATERAL SURFACE OF RAMUS. DEEP LAYER: ORIGINATES FROM THE DEEP SURFACE OF ZYGOMATIC ARCH AND INSERTS INTO THE REST OF RAMUS OF THE MANDIBLE . MASSETER

60. NERVE SUPPLY: MASSETERIC NERVE WHICH IS BRANCH OF ANTERIOR DIVISION OF MANDIBULAR NERVE. BLOOD SUPPLY: SUPPLIED BY THE MASSETERIC BRANCH OF THE MAXILLARY ARTERY, THE FACIAL ARTERY AND THE TRANSVERSE FACIAL BRANCH OF THE SUPERFICIAL TEMPORAL ARTERY. ACTION: ELEVATES THE MANDIBLE TO CLOSE THE MOUTH.

61. ORIGIN AND INSERTION: ORIGINATES FROM TEMPORAL FOSSA EXCLUDING THE ZYGOMATIC BONE, AND THE TEMPORAL FASCIA. THE FIBRES CONVERGE AND PASSES DEEP TO THE ZYGOMATIC ARCH AND INSERTS INTO THE MARGINS AND DEEP PORTIONS OF THE CORONOID PROCESS AND ANTERIOR BORDER OF THE RAMUS. TEMPORALIS

62. NERVE SUPPLY: TWO DEEP TEMPORAL BRANCHES FROM THE ANTERIOR DIVISION OF THE MANDIBULAR NERVE. BLOOD SUPPLY: SUPPLIED BY THE DEEP TEMPORAL BRANCHES FROM THE SECOND PART OF THE MAXILLARY ARTERY. ACTIONS: ELEVATES THE MANDIBLE TO CLOSE THE MOUTH. POSTERIOR FIBRES RETRACT THE PROTRUDED MANDIBLE. SIDE TO SIDE GRINDING MOVEMENT

63. MEDIAL PTERYGOID ORIGIN AND INSERTION: IT HAS TWO HEADS: SUPERFICIAL HEAD: ORIGINATES FROM THE TUBEROSITY OF THE MAXILLA AND ADJOINING BONE. DEEP HEAD: ORIGINATES FORM THE MEDIAL SURFACE OF LATERAL PTERYGOID PLATE AND ADJOINING PROCESS OF PALATINE BONE. INSERTED INTO THE ROUGHENED AREA ON THE MEDIAL SURFACE OF ANGLE AND ADJOINING RAMUS OF MANDIBLE , BELOW AND BEHIND THE MANDIBULAR FORAMEN AND MYLOHYOID GROOVE.

64. NERVE SUPPLY: NERVE TO MEDIAL PTERYGOID , A BRANCH OF THE MAIN TRUNK OF MANDIBULAR NERVE. BLOOD SUPPLY: MEDIAL PTERYGOID DERIVES ITS MAIN ARTERIAL SUPPLY FROM THE PTERYGOID BRANCHES OF THE MAXILLARY ARTERY. ACTIONS: ELEVATES MANDIBLE PROTRUSION OF MANDIBLE SIDE TO SIDE GRINDING MOVEMENTS

65. ORIGIN AND INSERTION: IT HAS TWO HEADS UPPER HEAD: ORIGINATES FROM THE INFRATEMPORAL SURFACE AND CREST OF THE GREATER WING OF SPHENOID . LOWER HEAD: FROM THE LATERAL SURFACE OF THE LATERAL PTERYGOID PLATE. ITS FIBRES INSERT INTO PTERYGOID FOVEA ON THE ANTERIOR SURFACE OF THE NECK OF THE CONDYLE MANDIBLE ANTERIOR MARGIN OF THE ARTICULAR DISC AND CAPSULE OF TMJ . LATERAL PTERYGOID

66. NERVE SUPPLY: A BRANCH OF ANTERIOR DIVISION OF MANDIBULAR NERVE . BLOOD SUPPLY: LATERAL PTERYGOID IS SUPPLIED BY PTERYGOID BRANCHES FROM THE MAXILLARY ARTERY. ACTIONS: DEPRESSES MANDIBLE TO OPEN THE MOUTH ALONG WITH SUPRAHYOID MUSCLE. LATERAL AND MEDIAL PTERYGOIDS PROTRUDE THE MANDIBLE. LEFT LATERAL PTERYGOID AND RIGHT MEDIAL PTERYGOID TURN THE CHIN TO THE LEFT SIDE AND VICE VERSA.

67. APPLIED ANATOMY MASSETERIC HYPERTROPHY: IT IS RECOGNIZED AS AN ENLARGEMENT OF ONE OR BOTH MASSETER MUSCLES . MOST PATIENTS COMPLAIN OF FACIAL ASYMMETRY. SUBMASSETERIC SPACE INFECTION: SOMETIMES INFECTION AROUND MANDIBULAR THIRD MOLAR TOOTH TRACKS BACKWARDS, LATERAL TO THE MANDIBULAR RAMUS AND PUS LOCALIZES DEEP TO THE ATTACHMENT OF MASSETER IN THE SUBMASSETERIC TISSUE SPACE.

68. TEMPORALIS MUSCLE FLAP: TEMPORALIS MUSCLE IS USED TO RECONSTRUCT DEFECTS OF THE ORAL TISSUES LIKE TONGUE, TONGUE BASE, BUCCAL MUCOSA, MAXILLA, SOFT PALATE, RETROMOLAR TRIGONE AND TONSILLAR REGION .

69. ANTERO-MEDIAL DISPLACEMENT OF CONDYLE DURING SUBCONDYLAR FRACTURES DUE TO THE SPASM OF LATERAL PTERYGOID. MEDIAL PTERYGOID SPASM RENDERING TRISMUS DUE TO IMPROPER TECHNIQUE OF IAN BLOCK. TRAVERSING OF FACIAL ARTERY ALONG THE ANTERO-INFERIOR BORDER OF MASSETER OVER THE BODY OF MANDIBLE.

70. MUSCLES OF NECK MUSCLES OF NECK CONSISTS OF FOLLOWING GROUP OF MUSCLES: 1. SUPERFICIAL AND LATERAL CERVICAL MUSCLES. 2. SUPRAHYOID MUSCLES. 3. INFRAHYOID MUSCLES. 4. ANTERIOR VERTEBRAL MUSCLES. 5. LATERAL VERTEBRAL MUSCLES. 6. SUBOCCIPITAL MUSCLES. 9/11/2018 73

71. SUPERFICIAL AND LATERAL CERVICAL MUSCLES CONSISTS OF 3 MUSCLES: PLATYSMA TRAPEZIUS STERNOCLEIDOMASTOID 9/11/2018 74

72. ORIGIN AND INSERTION ORIGIN: UPPER PARTS OF PECTORAL AND DELTOID FASCIAE AND FIBRES RUN UPWARDS AND MEDIALLY. INSERTION: ANTERIOR FIBRES TO THE BASE OF THE MANDIBLE. POSTERIOR FIBRES TO THE SKIN OF THE LOWER FACE AND LIP AND MAYBE CONTINUOUS WITH THE RISORIUS. PLATYSMA 9/11/2018 75

73. NERVE SUPPLY: CERVICAL BRANCH OF FACIAL NERVE. BLOOD SUPPLY: BY THE SUBMENTAL BRANCH OF THE FACIAL ARTERY AND BY THE SUPRASCAPULAR ARTERY. ACTIONS: DEPRESSES MANDIBLE. PULLS THE ANGLE OF THE MOUTH DOWNWARDS AS IN HORROR OR SURPRISE. 9/11/2018 76

74. TRAPEZIUS ORIGIN AND INSERTION ORIGIN: SPINOUS PROCESS OF VERTEBRAE C7-T12. INSERTION: EXTERNAL OCCIPITAL PROTRUBERANCE AND SPINE OF SCAPULA. NERVE SUPPLY: ACCESSORY NERVE AND CERVICAL NERVES C3 AND C4. BLOOD SUPPLY: BRANCHES OF OCCIPITAL ARTERY, SUPERFICIAL CERVICAL ARTERY . ACTIONS: ROTATION, RETRACTION, ELEVATION AND DEPRESSION OF SCAPULA. 9/11/2018 77

75. ORIGIN AND INSERTION: ARISES FROM THE STERNUM AND CLAVICLE BY TWO HEADS. MEDIAL HEAD ARISES FROM THE UPPER PART OF THE ANTERIOR SURFACE OF THE MANUBRIUM STERNI. LATERAL HEAD ARISES FROM THE SUPERIOR BORDER AND ANTERIOR SURFACE OF THE MEDIAL THIRD OF CLAVICLE. STERNOCLEIDOMASTOID 9/11/2018 78

76. TWO HEAD ARE SEPARATED FROM ONE ANOTHER AT THEIR ORIGINS BUT GRADUALLY BLEND TO FORM A THICK ROUNDED MUSCLE BELOW THE MIDDLE OF THE NECK. IT INSERTS INTO THE LATERAL SURFACE OF THE MASTOID PROCESS THROUGH A STRONG TENDON AND THROUGH A THIN APONEUROSIS INTO THE LATERAL HALF OF THE SUPERIOR NUCHAL LINE. 9/11/2018 79

77. NERVE SUPPLY: SPINAL PART OF THE ACCESSORY NERVE. BLOOD SUPPLY: BRANCHES OF THE OCCIPITAL AND POSTERIOR AURICULAR AND THE SUPRASCAPULAR ARTERY . ACTIONS: ACTING ALONE, EACH STERNOCLEIDOMASTOID MUSCLE WILL TILT THE HEAD TOWARDS THE OPPOSITE SIDE AND FLEXES LATERALLY TO THE SAME SIDE. ACCESSORY MUSCLES OF RESPIRATION, ALONG WITH SCALENE MUSCLES 9/11/2018 80

78. SUPRAHYOID MUSCLES SUPRAHYOID MUSCLES INCLUDE: DIGASTRIC STYLOHYOID MYLOHYOID GENIOHYOID 9/11/2018 81

79. IT HAS TWO BELLIES UNITED BY AN INTERMEDIATE TENDON. ORIGIN: ANTERIOR BELLY: ORIGINATES FROM THE DIGASTRIC FOSSA OF MANDIBLE . POSTERIOR BELLY: ORIGINATES FROM MASTOID NOTCH OF TEMPORAL BONE . INSERTION: BOTH THESE BELLIES MEET AT THE INTERMEDIATE TENDON WHICH PERFORATES THE STYLOHYOID AND IS HELD BY A FIBROUS PULLEY TO THE HYOID BONE. DIGASTRIC 9/11/2018 82

80. NERVE SUPPLY: ANTERIOR BELLY: NERVE TO MYLOHYOID POSTERIOR BELLY: FACIAL NERVE BLOOD SUPPLY: THE POSTERIOR BELLY IS SUPPLIED BY THE POSTERIOR AURICULAR AND OCCIPITAL ARTERIES . THE ANTERIOR BELLY RECEIVES ITS BLOOD SUPPLY FROM THE SUBMENTAL BRANCH OF THE FACIAL ARTERY ACTION: DEPRESSES MANDIBLE WHILE OPENING MOUTH OR AGAINST RESISTANCE. ELEVATES HYOID BONE 9/11/2018 83

81. STYLOHYOID ORIGIN AND INSERTION: ORIGINATES FROM POSTERIOR SURFACE OF STYLOID PROCESS. INSERTION INTO THE JUNCTION OF BODY AND GREATER CORNUA OF HYOID BONE . NERVE SUPPLY: BRANCHES OF FACIAL NERVE . BLOOD SUPPLY: BRANCHES OF THE FACIAL, POSTERIOR AURICULAR AND OCCIPITAL ARTERIES . ACTIONS: PULLS HYOID BONE UPWARDS AND BACKWARDS. 9/11/2018 84

82. ORIGIN AND INSERTION: ORIGIN FROM MYLOHYOID LINE OF THE MANDIBLE AND INSERTS ON BODY OF HYOID BONE . NERVE SUPPLY: NERVE TO MYLOHYOID BLOOD SUPPLY: THE SUBLINGUAL BRANCH OF THE LINGUAL ARTERY, MYLOHYOID BRANCH OF THE INFERIOR ALVEOLAR ARTERY AND THE SUBMENTAL BRANCH OF THE FACIAL ARTERY. ACTION: HELPS IN DEPRESSION OF MANDIBLE AND ELEVATION OF HYOID BONE. MYLOHYOID 9/11/2018 85

83. ORIGIN AND INSERTION: ORIGINATES FROM INFERIOR MENTAL SPINE (GENIAL TUBERCLES) AND INSERTS TO ANTERIOR SURFACE OF HYOID BONE . NERVE SUPPLY: HYPOGLOSSAL NERVE. BLOOD SUPPLY: DERIVED FROM THE LINGUAL ARTERY . ACTION: ELEVATES THE HYOID BONE. DEPRESSES THE MANDIBLE WHEN HYOID IS FIXED. GENIOHYOID 9/11/2018 86

84. INFRAHYOID MUSCLES INFRAHYOID MUSCLES INCLUDES: THYROHYOID OMOHYOID STRENOTHYROID STERNOHYOID 9/11/2018 87

85. ORIGIN AND INSERTION: IT ARISES FROM THE OBLIQUE LINE ON THE LAMINA OF THE THYROID CARTILAGE , AND IS INSERTED INTO THE LOWER BORDER OF THE GREATER CORNI OF THE HYOID BONE . BLOOD SUPPLY: BRANCHES OF SUPERIOR THYROID ARTERY . NERVE SUPPLY: HYPOGLOSSAL NERVE . ACTION: SMALL SKELETAL MUSCLE ON THE NECK WHICH DEPRESSES THE HYOID AND ELEVATES THE LARYNX. 9/11/2018 88 THYROHYOID

86. OMOHYOID ORIGIN AND INSERTION: ORIGINATES FROM UPPER BORDER OF SCAPULA NEAR SUPRASCAPULAR NOTCH AND GETS INSERTED INTO LOWER BORDER OF HYOID BONE . NERVE SUPPLY: BY SUPERIOR ROOT OF THE ANSA CERVICALIS . BLOOD SUPPLY: SUPPLIED BY BRANCHES FROM THE SUPERIOR THYROID AND LINGUAL ARTERIES. ACTIONS: DEPRESSION AND ELEVATION DURING SWALLOWING OR IN VOCAL MOVEMENTS. 9/11/2018 89

87. ORIGIN AND INSERTION: ORIGINS FROM POSTERIOR SURFACE OF MANUBRIUM STERNI AND INSERTS INTO MEDIAL PART OF LOWER BORDER OF HYOID BONE. NERVE SUPPLY: ANSA CERVICALIS BLOOD SUPPLY: SUPPLIED BY BRANCHES FROM THE SUPERIOR THYROID ARTERY. ACTIONS: DEPRESSES THE HYOID BONE FOLLOWING ELEVATION DURING SWALLOWING AND VOCAL MOVEMENTS. STERNOHYOID 9/11/2018 90

88. ORIGIN AND INSERTION: ORIGIN FROM POSTERIOR SURFACE OF MANUBRIUM STERNI AND ADJOINING PART OF FIRST COSTAL CARTILAGE AND INSERTS INTO OBLIQUE LAMINA OF THE THYROID CARTILAGE . NERVE SUPPLY: HYPOGLOSSAL NERVE . BLOOD SUPPLY: SUPPLIED BY BRANCHES FROM THE SUPERIOR THYROID AND LINGUAL ARTERIES. ACTIONS: DEPRESSES HYOID BONE. ELEVATES THE LARYNX WHEN THE HYOID IS FIXED BY THE SUPRAHYOID MUSCLE. STERNOTHYROID 9/11/2018 91

89. ANTERIOR VERTEBRAL MUSCLES IT CONSISTS OF 4 MUSCLES: LONGUS COLLI LONGUS CAPITIS RECTUS CAPITIS ANTERIOR RECTUS CAPITIS LATERALIS 9/11/2018 92

90. LONGUS COLLI IT IS SITUATED ON THE ANTERIOR SURFACE OF THE VERTEBRAL COLUMN. ORIGIN AND INSERTION: ORIGIN: TRANSVERSE PROCESSES OF C-5 TO T-3 INSERTION:ANTERIOR ARCH OF THE ATLAS . BLOOD SUPPLY: ASCENDING PHARYNGEAL AND VERTEBRAL ARTERIES. NERVE SUPPLY: FROM C2-C6 ACTIONS: FLEXION OF NECK. 9/11/2018 93

91. LONGUS CAPITIS ORIGIN AND INSERTION: ORIGIN: TRANSVERSE PROCESSES OF THE THIRD, FOURTH, FIFTH, AND SIXTH CERVICAL VERTEBRAE. INSERTION: BASILAR PART OF THE OCCIPITAL BONE. BLOOD SUPPLY: BRANCHES OF THE ASCENDING CERVICAL ARTERY. NERVE: BARNCHES OF C1-C3/C4 ACTIONS: FLEXION OF NECK AT ATLANTO-OCCIPITAL JOINT. 9/11/2018 94

92. RECTUS CAPITIS ANTERIOR IT IS A SHORT, FLAT MUSCLE, SITUATED IMMEDIATELY BEHIND THE UPPER PART OF THE LONGUS CAPITIS. ORIGIN AND INSERTION: ORIGIN: IT ARISES FROM THE ANTERIOR SURFACE OF THE LATERAL MASS OF THE ATLAS . INSERTION: INSERTED INTO THE INFERIOR SURFACE OF THE OCCIPITAL BONE , IN FRONT OF THE FORAMEN MAGNUM. NERVE SUPPLY: BRANCHES OF C1, C2. ACTION: AIDS IN FLEXION OF NECK. 9/11/2018 95

93. RECTUS CAPITIS LATERALIS ORIGIN AND INSERTION: ORIGIN: UPPER SURFACE OF THE TRANSVERSE PROCESS OF THE ATLAS . INSERTION: UNDER SURFACE OF THE JUGULAR PROCESS OF THE OCCIPITAL BONE . NERVE: BRANCHES OF C1, C2 ACTIONS: LATERAL FLEXION, STABILISE ATLANTO-OCCIPITAL JOINT 9/11/2018 96

94. LATERAL VERTEBRAL MUSCLES IT CONSISTS OF SCALENI MUSCLES: SCALENUS ANTERIOR SCALENUS MEDIUS SCALENUS POSTERIOR 9/11/2018 97

95. SCALENUS ANTERIOR IT LIES DEEPLY AT THE SIDE OF THE NECK, BEHIND THE STERNOCLEIDOMASTOID MUSCLE. ORIGIN AND INSERTION: ORIGIN: CERVICAL VERTEBRAE (C2-C7) INSERTION: FIRST AND SECOND RIBS BLOOD SUPPLY: ASCENDING CERVICAL BRANCH OF INFERIOR THYROID ARTERY NERVE: CERVICAL NERVES (C3-C7) ACTIONS: ELEVATION OF FIRST AND SECOND RIBS 9/11/2018 98

96. SCALENUS MEDIUS ORIGIN AND INSERTION: ORIGIN: ARISES FROM THE POSTERIOR TUBERCLES OF THE LOWER SIX CERVICAL VERTEBRAE. INSERTION: UPPER SURFACE OF THE 1ST RIB. BLOOD SUPPLY: SUPPLIED BY THE ASCENDING CERVICAL BRANCH OF THE INFERIOR THYROID ARTERY. NERVE SUPPLY: FROM BRANCHES OF C4-C6 . ACTIONS: ELEVATES THE FIRST RIB AND LATERALLY FLEX THE NECK TO THE SAME SIDE. 9/11/2018 99

97. SCALENUS POSTERIOR ORIGIN AND INSERTION: ORIGIN: ARISES FROM POSTERIOR TUBERCLES OF THE LOWER THREE CERVICAL VERTEBRAE. INSERTION: INSERTED BY TENDON INTO THE OUTER SURFACE OF 2ND RIB. BLOOD SUPPLY: ASCENDING CERVICAL A BRANCH OF INFERIOR THYROID ARTERY NERVE SUPPLY: FROM BRANCHES OF C4-C6. ACTIONS: ELEVATES THE 2ND RIB AND TILT THE NECK TO THE SAME SIDE. 9/11/2018 100

98. SUBOCCIPITAL MUSCLES THE SUBOCCIPITAL MUSCLES ARE A GROUP OF MUSCLES DEFINED BY THEIR LOCATION TO THE OCCIPUT. THE MUSCLES ARE NAMED AS: RECTUS CAPITIS POSTERIOR MAJOR RECTUS CAPITIS POSTERIOR MINOR OBLIQUUS CAPITIS SUPERIOR OBLIQUUS CAPITIS INFERIOR 9/11/2018 101

99. RECTUS CAPITUS POSTERIOR MAJOR ORIGIN AND INSERTION: ORIGIN: SPINOUS PROCESS OF THE AXIS (C2) INSERTION: INFERIOR NUCHAL LINE OF THE OCCIPITAL BONE. BLOOD SUPPLY: BRANCH OF OCCIPITAL ARTERY NERVE SUPPLY: BRANCH OF SUB-OCCIPITAL NERVE ACTIONS: IPSILATERAL ROTATION OF HEAD AND EXTENSION 9/11/2018 102

100. RECTUS CAPITUS POSTERIOR MINOR ORIGIN AND INSERTION: ORIGIN: TUBERCLE ON THE POSTERIOR ARCH OF THE ATLAS INSERTION: MEDIAL PART OF THE INFERIOR NUCHAL LINE OF THE OCCIPITAL BONE. BLOOD SUPPLY: BRANCH OF OCCIPITAL ARTERY NERVE SUPPLY: BRANCH OF THE SUBOCCIPITAL NERVE ACTIONS: EXTENDS THE HEAD AT THE NECK. 9/11/2018 103

101. OBLIQUUS CAPITIS INFERIOR ORIGIN AND INSERTION: ORIGIN: SPINOUS PROCESS OF THE AXIS INSERTION: LATERAL MASS OF ATLAS BLOOD SUPPLY: DEEP DESCENDING BRANCH OF THE OCCIPITAL ARTERY. NERVE: BRANCH OF SUBOCCIPITAL NERVE. ACTIONS: ROTATION OF HEAD AND NECK. 9/11/2018 104

102. OBLIQUUS CAPITIS SUPERIOR ORIGIN AND INSERTION: ORIGIN: LATERAL MASS OF ATLAS . INSERTION: LATERAL HALF OF THE INFERIOR NUCHAL LINE . BLOOD SUPPLY: DEEP DESCENDING BRANCH OF THE OCCIPITAL ARTERY. NERVE SUPPLY: BRANCHES OF SUBOCCIPITAL NERVE. ACTION: EXTENDS HEAD AND FLEX HEAD TO THE IPSILATERAL SIDE. 9/11/2018 105

103. TRIANGLES OF NECK STERNOCLEIDOMASTOIDEUS DIVIDES THIS SPACE INTO TWO TRIANGLES. THE TRIANGULAR SPACE IN FRONT OF THIS MUSCLE IS CALLED THE ANTERIOR TRIANGLE . THE TRIANGLE BEHIND IT, THE POSTERIOR TRIANGLE . 9/11/2018 106

104. ANTERIOR TRIANGLE BOUNDARIES: ANTERIORLY: BY THE MEDIAN LINE OF THE NECK. POSTERIORLY: BY THE ANTERIOR MARGIN OF STERNOCLEIDOMASTOID. BASE: INFERIOR BORDER OF THE MANDIBLE AND ITS PROJECTION TO THE MASTOID PROCESS. APEX: MANUBRIUM STERNI. IT CAN BE SUBDIVIDED INTO SUPRAHYOID AND INFRAHYOID AREAS ABOVE AND BELOW THE HYOID BONE. 9/11/2018 107

105. ANTERIOR TRIANGLE OF NECK CONSISTS OF 4 TRIANGLES NAMELY: DIGASTRIC SUBMENTAL MUSCULAR CAROTID TRIANGLES 9/11/2018 108

106. DIGASTRIC TRIANGLE 9/11/2018 109 BOUNDARIES: ANTERO-INFERIORLY – ANTERIOR BELLY OF DIGASTRIC POSTERO-INFERIORLY – POSTERIOR BELLY OF DIGASTRIC SUPERIORLY (BASE) – BASE OF THE MANDIBLE ROOF: SKIN, SUPERFICIAL FASCIA AND DEEP FASCIA. FLOOR: MYLOHYOID MUSCLE (ANTERIORLY) AND HYOGLOSSUS POSTERIORLY.

107. CONTENTS OF DIGASTRIC TRIANGLE ANTERIORLY: STRUCTURES SUPERFICIAL TO MYLOHYOID – SUBMANDIBULAR GLAND FACIAL VEIN SUBMANDIBULAR LYMPH NODES MYLOHYOID NERVE. STRUCTURES SUPERFICIAL TO THE HYOGLOSSUS – INTERMEDIATE TENDON OF DIGASTRIC. HYPOGLOSSAL NERVE. POSTERIOR PART: LOWER PART OF PAROTID. EXTERNAL CAROTID ARTERY. GLOSSOPHARYNGEAL NERVE STYLOID PROCESS. 9/11/2018 110

108. SUBMENTAL TRIANGLE BOUNDARIES: ON EACH SIDE BY THE ANTERIOR BELLY OF DIGASTRIC MUSCLES. BASE: BODY OF HYOID APEX: LIES AT THE CHIN. FLOOR: RIGHT AND LEFT MYLOHYOID AND MEDIAN RAPHE UNITING THEM. CONTENTS: 2-4 SUBMENTAL NODES ANTERIOR BELLIES OF DIGASTRIC MUSCLES. SUBMENTAL VEIN. 9/11/2018 111

109. MUSCULAR TRIANGLE BOUNDARIES: ANTERIORLY: ANTERIOR MEDIAN LINE OF THE NECK FROM THE HYOID BONE TO THE STERNUM. POSTERO-SUPERIORLY: SUPERIOR BELLY OF OMOHYOID POSTERO-INFERIORLY: ANTERIOR BORDER OF THE STERNOCLEIDOMASTOID. CONTENTS: INFRA-HYOID MUSCLES – STERNOHYOID, STERNOTHYROID, THYROHYOID, OMOHYOID. 9/11/2018 112

110. CAROTID TRIANGLE BOUNDARIES: ANTERO-SUPERIORLY – POSTERIOR BELLY OF DIGASTRIC AND STYLOHYOID ANTERO-INFERIORLY – SUPERIOR BELLY OF OMOHYOID POSTERIORLY – ANTERIOR BORDER OF STERNOCLEIDOMASTOID. ROOF: SKIN, SUPERFICIAL FASCIA, INVESTING LAYER OF DEEP CERVICAL FASCIA. FLOOR: THYROHYOID, HYOGLOSSUS, MIDDLE AND INFERIOR CONSTRICTOR MUSCLES. 9/11/2018 113

111. CONTENTS OF CAROTID TRIANGLE ARTERIES: CCA, ICA, ECA AND BRANCHES (SUPERIOR THYROID, LINGUAL, FACIL, ASCENDING PHARYNGEAL AND OCCIPITAL BRANCHES. VEINS: INTERNAL JUGULAR VEIN. NERVES: VAGUS, SPINAL ACCESSORY NERVES, HYPOGLOSSAL NERVE. 9/11/2018 114

112. POSTERIOR TRIANGLE BOUNDARIES: ANTERIORLY BY THE POSTERIOR EDGE OF STERNOCLEIDOMASTOID POSTERIORLY BY THE ANTERIOR EDGE OF TRAPEZIUS INFERIORLY BY THE MIDDLE THIRD OF THE CLAVICLE APEX IS BETWEEN THE ATTACHMENTS OF STERNOCLEIDOMASTOID AND TRAPEZIUS 9/11/2018 115

113. DEVISIONS OF POSTERIOR TRIANGLE THE POSTERIOR TRIANGLE IS DIVIDED INTO TWO BY THE OMOHYOID MUSCLE (INFERIOR BELLY) OCCIPITAL TRIANGLE. SUBCLAVIAN TRIANGLE. 9/11/2018 116

114. OCCIPITAL TRIANGLE BOUNDARIES: ANTERIORLY – SCM POSTERIORLY – TRAPEZIUS INFERIORLY – LOWER BELLY OF OMOHYOID FLOOR: SPLENIUS CAPITIS, LEVATOR SCAPUALE AND SCALENI MEDIUS AND POSTERIOR. ROOF: FORMED BY CUTANEOUS NERVES OF CERVICAL PLEXUS AND THE EXTERNAL JUGULAR VEIN AND PLATYSMA MUSCLE, DEEP FASCIA , SUPERFICIAL FASCIA AND BY SKIN. 9/11/2018 117

115. SUBCLAVIAN TRIANGLE BOUNDARIES: SUPERIORLY – INFERIOR BELLY OF OMOHYOID INFERIORLY – CLAVICLE ANTERIORLY (BASE) – POSTERIOR BORDER OF SCM FLOOR: FORMED BY THE FIRST RIB WITH THE FIRST DIGITATION OF THE SERRATUS ANTERIOR. ROOF: FORMED BY THE INTEGUMENT, SUPERFICIAL AND DEEP FASCIAE AND THE PLATYSMA AND CROSSED BY SUPRACLAVICULAR NERVES 9/11/2018 118

116. CONTENTS OF POSTERIOR TRIANGLE: LYMPH NODES (LEVEL V) SPINAL ACCESSORY NERVE CUTANEOUS BRANCHES OF THE CERVICAL PLEXUS INFERIOR BELLY OF OMOHYOID BRANCHES OF THE THYROCERVICAL TRUNK (TRANSVERSE CERVICAL AND SUPRASCAPULAR ARTERIES) THE THIRD PART OF THE SUBCLAVIAN ARTERY, AND THE EXTERNAL JUGULAR VEIN. 9/11/2018 119

117. APPILED ANATOMY THE EXTERNAL JUGULAR VEIN LIES DEEP TO THE PLATYSMA. AS IT PIERCES THE FASCIA, THE MARGINS OF THE VEIN GETS ADHERENT TO THE FASCIA. SO IF THE VEIN GETS CUT, IT CANNOT CLOSE AND AIR IS SUCKED IN DUE TO NEGATIVE INTRA-THORACIC PRESSURE CAUSING AIR EMBOLISM. 9/11/2018 120

118. THE MOST COMMON SWELLING IN THE POSTERIOR TRIANGLE IS DUE TO ENLARGEMENT OF SUPRACLAVICULAR LYMPH NODES. IT COULD ALSO BE DUE TO LIPOMA CYSTIC HYGROMA OR LYMPHANGIOMA, PHARYNGEAL POUCH OR A CERVICAL RIB. 9/11/2018 121

119. SUPRACLAVICULAR FLAP: IT IS A FASCIOCUTANEOUS FLAP BASED ON SUPRACLAVICULAR ARTERY, A BRANCH OF THE TRANSVERSE CERVICAL ARTERY. IT IS A THIN AND EASY TO HARVEST, WITH GOOD COSMETIC AND FUNCTIONAL OUTCOME FOR RECONSTRUCTION OF COMPLEX HEAD AND NECK ONCOLOGIC DEFECTS. 9/11/2018 122

120. PLATYSMA FLAP: THE PLATYSMA FLAP MAY BE USED TO CLOSE DEFECTS ON THE FACE. DISADVANTAGE OF THIS FLAP IS REMOVAL OF THE PLATYSMA INTERFERES WITH THE BLOOD SUPPLY TO THE OVERLYING SKIN AND CAN LEAD TO NECROSIS OF SKIN. 9/11/2018 123

121. SUBMENTAL FLAP: ITS USE IN RECONSTRUCTION OF BUCCAL DEFECTS. IT PROVIDES A RELIABLE FLAP WITH GOOD REACH AND MINIMAL DONOR SITE MORBIDITY . DONOR DEFECT CAN BE CLOSED PRIMARILY ON THE DONOR SITE SCAR IS HIDDEN UNDER THE MANDIBLE. 9/11/2018 124

122. MYLOHYOID ADVANCEMENT FLAP: IT IS USED IN THE RECONSTRUCTION OF COMPOSITE ORAL CAVITY DEFECTS. THE MYLOHYOID IS RELEASED FROM THE MENTAL SPINE. THE MUSCULAR FLAP IS THEN TRANSPOSED INTRAORALLY AND DRAPED OVER THE SURFACE OF THE RIM MANDIBULECTOMY, FILLING THE VERTICAL HEIGHT OF THE DEFECT. 9/11/2018 125

123. STERNOMASTOID FLAP: THE SKIN PADDLE OF SUPERIORLY BASED STERNOMASTOID FLAP IS HAIRLESS AND THIN AND IS AN IDEAL RECONSTRUCTIVE OPTION FOR MEDIUM SIZED CHEEK DEFECTS. 9/11/2018 126

124. TRAPEZIUS MYOCUTENEOUS FLAP: IT CAN BE USED FOR RECONSTRUCTING DEFECTS OF HEAD AND NECK REGION AND UPPER BACK. ITS LOCATION MAKES IT THE FLAP OF CHOICE FOR DEFECTS OF THE OCCIPITAL, PAROTID AND CERVICAL SPINE REGIONS. 9/11/2018 127

125. CONCLUSION: 9/11/2018 128 UNDERSTANDING THE FUNCTION AND LOCATION OF THE MUSCLES ALLOWS US TO RECOGNIZE ANY ABNORMALITIES IN A PATIENT’S ANATOMY. THOROUGH UNDERSTANDING OF ANATOMY IS IMPORTANT IN TREATING THE ABNORMALITY. “You cannot successfully treat dysfunction unless you understand function.” - J.P.Okeson

126. B.D CHAURASIA’S HUMAN ANATOMY SICHER AND DUBRUL’S ORAL ANATOMY ANATOMY OF HUMAN BODY- HENRY GRAY’S CUNNINGHAM’S MANUAL OF PRACTICAL ANATOMY GRANT’S ATLAS OF ANATOMY NETTERS HEAD AND NECK ANATOMY TEXTBOOK OF HEAD AND NECK ANATOMY – HIATT GARNER DEVELOPMENT OF MUSCULOSKELETAL SYSTEM - HUMAN DEVELOPMENTAL ANATOMY; KURT E JOHNSON REFERENCES 9/11/2018 129

127. CLARIFICATION OF ERB’S POINT AS AN ANATOMIC LANDMARK IN THE POSTERIOR CERVICAL TRIANGLE, LANDERS ET.AL CLINICAL ANATOMY 2:29-134(1989); VARIATIONS IN THE FACIAL MUSCLES AT THE ANGLE OF THE MOUTH – KAZUYUKI SHIMADA AND RAYMOND F. GASSERROGERS C, MEARA J, MULLIKEN J (2014) THE PHILTRUM IN CLEFT LIP. J CRANIOFAC SURG 25(1):9-13 CORRECTION OF SKELETAL DEFECTS IN SECONDARY CLEFT LIP AND PALATE DEFORMITIES – KENNETH E SALYER ET.AL CONTEMPORARY ORAL ONCOLOGY ORAL AND MAXILLOFACIAL RECONSTRUCTIVE SURGERY BY KURIAKOSE. 9/11/2018 130

128. PRINCIPLES AND PRACTICE OF HEAD AND NECK SURGERY AND ONCOLOGY BY PETER H. RHYS EVANS STELL AND MARAN’S TEXTBOOK OF HEAD AND NECK SURGERY AND ONCOLOGY B. HELL, E. HEISSLER, H. GATH, H. MENNEKING, A. LANGFORD: THE INFRAHYOID FLAP. A TECHNIQUE FOR DEFECT CLOSURE IN THE FLOOR OF THE MOUTH, THE TONGUE, THE BUCCAL MUCOSA, AND THE LATERAL PHARYNGEAL WALL. INT. J. ORAL MAXILLOFAC. SURG. 1997; 26.“ 35-41. THE PLATYSMA MYOCUTANEOUS FLAP BY DANIEL NITZAN ET AL. 9/11/2018 131

129. MYLOHYOID ADVANCEMENT FLAP FOR CLOSURE OF COMPOSITE ORAL CAVITY DEFECTS BY RAJA SAWHNEY. CLINICAL ANATOMY - APPLIED ANATOMY FOR STUDENTS AND JUNIOR DOCTORS, 11 EDITION-HAROLD ELLIS COLOR ATLAS OF ANATOMY - A PHOTOG. STUDY OF THE HUMAN BODY 7TH ED [TAHIR99] VRG PRINCIPLES OF ANATOMY AND PHYSIOLOGY 13TH ED - G. TORTORA, B. DERRICKSON (WILEY, 2012) BBS COLOR ATLAS OF ANATOMY - A PHOTOGRAPHIC STUDY OF THE HUMAN BODY ; JOHANNES W.ROHEN, CHIHIRO YOKOCHI, ELKE LÜTJEN-DRECOLL 9/11/2018 132

130. 9/11/2018 133