Page 122 - Edited - Webster HEAD AND NECK - part 1

HN 100
THE PRIMARY MUSCLES OF MASTICATION - 2

A. POSTERIOR ASPECT - BONES
NASAL
KEW CAVITY NOTES (i) COMPARE WITH SI
LEFT CONDYLE OF
MAXILLA MANDIBLE
LATERAL & (ii) THE SPHENOID BONE HAS TWO
MEDIAL VERTICAL PLATES ON EACH SIDE,
ANTERIOR PTERYGOLD CORRECTLY KNOWN AS THE
MARGIN PLATES MEDIAL & LATERAL PTERYGOID
OF (SPHENOID) (pron. “TERRY GOYED” - it means
PHARYNX “WING”) PLATES.
(c.f.SI 36)
ANGLE OF THE MEDIAL PLATES FORM THE
MANDIBLE SKELETON OF THE CONTINUITY
BODY OF MANDIBLE
NASAL CAVITY->NASO-
PHARYNX (c.f. SI36,37) & IT IS TO THESE THAT THE PHARYNX MUST BE ATTACHED: THE MEDIAL
PTERYGOLD PLATES ∴ HAVE NOTHING TO DO WITH THE PTERYGOID mm.
B. POSTERIOR ASPECT-MASTICATORY
MUSCLES K.E.W.
(i) THE MEDIAL PTERYGOLD MM.
ATTACHED TO THE MEDIAL ASPECT OF
LATERAL PTERYGOLD PLATES & TO THE THESE
MEDIAL ASPECTS OF ANGLES OF MUSCLES
MANDIBLE. ACTING TOGETHER, THEY ARE
CLOSE THE JAUS, BUT INDIVIDUALLY IMPALPABLE
THEY DISPLACE THE MANDIBLE TO THE
ANGLE OF
OPPOSITE SIDE. NERVE SUPPLY: V3.
MANDIBLE

K.E.W.
(ii) THE LATERAL PTERYGOID MM.
ATTACHED TO THE LATERAL
NERVE ASPECT OF THE LATERAL
SUPPLY V 3 PTERYGOID PLATE AND TO THE
HEAD OF THE MANDIBLE, EACH IS
CAPABLE OF MOVING THE
MANDIBLE TO THE OPPOSITE SIDE.
ACTING TOGETHER, THE
LATERAL PTERYGOID MUSCLES
OPEN THE JAWS (SEE C., below):
THIS IS A POWERFUL MOVEMENT, CAPABLE OF SUPPORTING BODY WEIGHT FOR A BRIEF
TIME. IF ONE TRIGEMINAL NERVE (V3) IS PARALYZED, ATTEMPTS TO OPEN THE MOUTH PULL
THE MANDIBLE TO THE SIDE OF THE PARALYZED NERVE BECAUSE ACTIVE MEDIAL &
LATERAL PTERYGOID MUSCLES PULL THE MANDIBLE TO THE OPPOSITE SIDE.

C. LATERAL ASPECT LATERAL PTERYGOID
MUSCLE
THIS VIEW SHOWS WHY
THE MEDIAL PTERYGOID
MM. CLOSE THE
MANDIBLE ON THE
MAXILLA, WHEREAS THE
LATERAL PTERYGOID MM. MEDIAL
(i) OPEN THE JAWS & PTERYGOID MUSCLE
(ii) ALSO PROTRACT THE
MANDIBLE, SO THE CHIN K.E.W. OUTLINE OF MANDIBLE
PROTRUDES c.f. TEMPORALIS
M. (SII 66).