Muscles Of Mastication Flashcards
What are the muscles of mastication
Join to the mandible to allow for movement during chewing and grinding
5 main movements of mandible allowed by muscles of mastication
Forwards (protrusion)
Backwards (retraction)
Up/close (elevation)
Down/open (depression)
Side to side (rotation)
Muscles of mastication clinical relevance
Impact of inferior dental blocks (hematomia, trauma)
Pain during mastication
Trismus (difficultly opening)
Clenching and grinding (masseter pain)
Principle muscles of mastication
Masseter
Temporalis
Lateral pterygoid
Medial pterygoid
2 parts of masseter
Superficial
Deep
Masseter
Thick quadrilateral muscle
Most powerful of muscles of mastication.
Origin and insertion of superficial part of masseter
Origin - anterior 2/3rds lower border of zygomatic arch.
Insertion - superficial surface of the ramus of mandible.
Origin and insertion of deep part of masseter
Origin - posterior 1/3rd of lower border of whole medial surface of zygomatic arch.
Insertion - ramus above angle of mandible (superior to superficial)
Action of masseter muscle
Fibres contract to close/elevate the mandible
Innervation and blood supply for masseter
Nerve - masseteric nerve (anterior division of mandibular nerve).
Blood - temporal and maxillary artery
What gland duct passes through masseter muscle
Parotid gland duct
Origin and insertion of temporalis
Fan shaped muscle of either side of head.
Origin - whole of temporal fossa, bound at top by inferior temporal line, converge and descend into tendon that passes through zygomatic arch.
Insertion - top and medial surface of coronoid process and ramus of mandible.
Action of temporalis muscle
Anterior fibres run vertically and elevate the mandible.
Posterior fibres run obliquely and horizontally to elevate the mandible and retract head of condyle back into glenoid fossa.
Nerve and blood supply of temporalis
Nerve - anterior division of mandibular nerve
Blood - superficial temporal and maxillary arteries
A short, thick muscle, triangular in shape and arises from 2 heads
Lateral pterygoid
Origin and insertion of upper head of lateral pterygoid muscle
Origin - infratemporal surface of greater wing of sphenoid bone.
Insertion - pterygoid fovea on anterior of neck of mandible.
Some fibres may insert with TMJ structures.
Origin and insertion of lower head of lateral pterygoid
Origin - lateral surface of lateral pterygoid plate of sphenoid bone.
Insertion - pterygoid fovea on anterior of neck of mandible.
Some fibres may insert with TMJ structures.
Action of the lateral pterygoid muscles
Bilateral contraction - opens and protrudes the mouth.
When contract alternately - grinding side to side motion/rotation.
Innervation and boood supply of lateral pterygoid
Innervation - mandibular branch
Blood supply - maxillary artery
Origin and insertion of large deep head of medial pterygoid
Origin - medial surface of lateral pterygoid plate of sphenoid.
Insertion - fibres pass inferiorally, posteriorly and laterally to medial surface of ramus and angle of mandible.
Origin and insertion of small superficial head of medial pterygoid muscle
Origin - tuberosity of maxilla and pyramidal process of palatine.
Insertion - fibres pass inferiorally, posteriorly and laterally to medial surface of ramus and angle of mandible.
Action of medial pterygoid muscle
Elevates the mandible
Along with lateral pterygoid, protrudes the mandible.
Nerve and blood supply of medial pterygoid muscle
Nerve - medial pterygoid branch of mandibular nerve.
Blood - pterygoid branches of maxillary artery.
Accessory muscles of mastication
Digastric
Buccinator
Geniohyoid
Genioglossus
Origin and insertion of anterior belly of digastric muscle
Origin - arises from digastric fossa on lower border of mandible.
Insertion - meet above hyoid bone at intermediate tendon, held with fibrous sling anchoring to body of hyoid bone.
Origin and insertion of posterior belly of digastric muscle
Origin - digastric notch on mastoid process of temporal bone.
Insertion - meet above hyoid bone at intermediate tendon, held with fibrous sling anchoring to body of hyoid bone
Action of digastric muscle
Depression of mandible
Elevate hyoid bone during chewing and swallowing
Nerve and blood support of anterior belly of digastric muscle
Nerve - mylohyoid nerve
Blood - sub mental branch of facial artery
Nerve and blood supply of posterior belly of digastric muscle
Nerve - digastric branch of facial nerve
Blood - posterior auricular/occipital artery
Buccinator origin and insertion
Origin - Pterygomandibular raphae and buccal alveolar bone
Insertion - fibres run horizontally to orbicularis oris at corners of mouth
What muscle forms the cheek
Buccinator
Action of Buccinator
Pulls corners of mouth back
Compress cheek against buccal surface of molars
Regulates vestibular region with tongue; keeps food in line with occlusal surfaces of teeth during mastication
Innervation and blood supply of Buccinator
Nerve - facial nerve, buccal branch
Blood - facial and maxillary arteries
Geniohyoid
Narrow muscle situation above medial part of mylohyoid line
Origin and insertion of geniohyoid
Origin - inferior genial tubercle
Insertion - fibres run inferiorly and posteriorly into body of hyoid bone.
Action of geniohyoid
Aids in deglutition and opening of mouth, depresses mandible.
Innervation and blood supply of geniohyoid muscle
Nerve - hypoglossal nerve
Blood supply- sublingual branch of lingual artery
Genioglossus muscle origin and insertion
Origin - superior genial tubercle on inner surface of mandible.
Insertion - dorsum of tongue, large fan shape muscle.
Superior fibres pass superiority to tip of tongue.
Inferior fibres insert onto body of hyoid bone
Action of Genioglossus
Depresses the tongue
Inferior fibres retract the tongue
Superior fibres protrude the tongue
Innervation and blood supply of Genioglossus
Innervation - hypoglossal nerve
Blood supply - sublingual branch of lingual artery and sub mental branch of facial artery.
