Anatomy My SY work... One of my seminar for class of motor points...!!

1. By:
Sharmin Susiwala
SY BPT
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2.  Muscles of mastication develop from the
mesoderm of the first pharyngeal arch.
 They are innervated by the Mandibular
division of the trigeminal nerve.
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3.  They are functionally classified as:
 Jaw elevators:
 Masseter
 Temporalis
 Medial pterygoid
 Upper head of lateral pterygoid
 Jaw depressors
 Lower head of lateral pterygoid
 Anterior digastric
 Geniohyoid
 Mylohyoid
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4.  It has 3 layers:
 Superficial layer:
 Origin: lower border of the zyg.arch(ant 2/3)
 Insertion: lateral surface of the ramus
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5.  Middle layer:
 Origin: Medial surface of the anterior 2/3
Lower border of the posterior 1/3 of zyg arch.
 Insertion: lateral surface of the ramus
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6.  Deep layer:
 Origin: Medial surface of zygomatic arch
 Insretion: upper part of the ramus
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7.  Action:
 Elevation (deep fibers)
 Protraction (superficial fibers)
 Nerve supply:
 Anterior division of mandibular nerve (masseteric
nerve)
 Blood supply:
 Transverse facial artery
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9.  Has 2 heads:
 Deep head (anterior, middle and
posterioe fibers)
 Superficial head (much smaller)
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10.  Origin: Temporal fossa, Temporal fascia
 In an area bound by the inferior temporal line above and the
infra temporal crest below
 Insertion:
 Cronoid process in its medial aspect (apex, anterior and
posterior border)
 Anterior border of the ramus.
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11.  Action:
 Elevation (anterior fibers)
 Protraction (posterioe fibers)
 Nerve supply:
 Anterior division of the mandibular nerve
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13.  Has 2 heads:
 Upper head:
 Origin: infratemporal surface & crest of the greater wing of sphenoid
 Insertion: enters the TMJ & inserted into:
a) ptrygoid fovea of the neck of the mandible
b) articular disc
c) capsule of TMJ (anterior aspect)
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14.  Lower head:
 Origin: Lateral surface of the lateral
pterygoid plate
 Insertion: as upper head
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15.  Action:
1. Both muscles produce
depression of the mandible.
2. Lat. & Med pterygoid on 1 side protrude
the mandible to the
opposite side.
3. Lat & Med pterygoid on the 2 sides cause
side to side movement
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16.  Nerve supply: Anterior division of mandibular
nerve (nerve to lateral pterygoid)
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18.  Has 2 heads
 Superficial head:
 Origin: a) maxillary tuberosity
b) neighboring part of palatine
bone.
_ Insertion: Medial surface of the angle &
ramus below the mandibular
foramen.
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20.  Deep head:
 Origin: Medial surface of the lateral
pterygoid plate.
 Insertion: as upper head.
 Action: 1) both muscles elevate the
mandible.
2 & 3 as in lateral pterygoid.
 Nerve supply: Trunk of the mandibular
nerve (nerve to
medial pterygoid
muscle)
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23. Thank You
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