Muscles of Mastication and Facial Expression (NS) Flashcards
Which nerve innervates the 4 true muscles of mastication?
CNV- Branches of the trigeminal
Name the 4 true muscles of mastication.
- Medial pterygoid
- Lateral pterygoid
- Temporalis
- Masseter
Where does the medial pterygoid originate and insert?
O: Medial surface of lateral pterygoid plate and pterygoid fossa.
I: Medial surface of ramus and angle of mandible.
What are the 2 functions of the medial pterygoid muscle?
- Elevates mandible
2. Lateral deviation
Where does the superior head of the lateral pterygoid originate and insert?
O: Infratemporal crest (G.W. of sphnoid)
I: Disc of TMJ and neck of condyle (pterygoid fossa on medial side).
Where does the inferior head of the lateral pterygoid originate and insert?
O: Lateral surface of lateral pterygoid plate.
I: Disc of TMJ and neck of condyle (pterygoid fossa on medial side)
What is the function of the lateral pterygoid muscle?
- Depresses Mandible*
- lateral deviation
Where does the temporalis muscle originate and insert?
O: Temporal line of temporal fossa
I: Coronoid process and anterior border of ramus
What are the 2 functions of the temporalis muscle?
- Elevates mandible (vertical fibers)
2. Retrusion (horizontal fibers)
Where does the superficial part of the masseter muscle originate and insert?
O: Zygomatic process of maxilla and anterior 2/3 of inferior zygomatic arch.
I: Angle and lower lateral ramus.
Where does the deep part of the masseter muscle originate and insert?
O: Inner surface of posterior 1/3 of zygomatic arch.
I: Superior part of ramus and lateral surface of coronoid process.
What are the 3 functions of the masseter?
- Elevate mandible
- Retrusion
- Protrustion
What is the accessory muscle of mastication?
Buccinator
What nerve innervates the buccinator?
CN VII- Facial nerve
What is the function of the buccinator?
Compresses cheek and manages food bolus.
What 2 nerves are located in the pterygomandibular space?
- Lingual nerve
2. Inferior alveolar nerve
What is the clinical significance of the pterygomandibular space?
This is where you want to place your syringe when anesthetizing the mandible.
What would a consequence be of going too deep in the pterygomandibular space when anesthetizing?
May hit the facial nerve (CNVII)–> temporary paralysis to facial muscles.
Which nerve innervates the muscles of facial expression?
CN VII (Facial)
Which muscle is responsible for closing the eye?
Orbicular oculi
Which muscle is responsible for movement of the lips and closing the mouth?
Orbicular oris
This muscle is responsible for the wrinkle between your eyes and is associated with the nose. It is also a popular site for botox:
Procerus
This muscle of the nose is responsible for dilation/compression (lustful expression ;-) ) of the nostrils.
Nasalis
This muscle is used for smiling and is more lateral and inferior to the other muscle in its group:
Zygomaticus major
This muscle is used for smiling and is more medial and superior to the other muscle in its group:
Zygomaticus minor
Which two muscles elevate the lip?
- Levator labii superioris
2. Levator labii superioris alaeque nasi (more medial)
This muscle is associated with the angle of the mouth and is used for smiling:
Levator anguli oris
This muscle is associated with the angle of the mouth and is used when frowning:
Depressor anguli oris
This muscle depresses the lower lip:
Depressor labii inferioris
This muscle wrinkles the skin on your chin, and is also used when pouting, frowning, or protruding the lip:
Mentalis
What are the 2 muscles of the cheek?
- Buccinator
2. Risorius (more superficial)
What is the function of the risorius?
Moves angle of mouth laterally.
What is the function of the frontalis?
Raises eyebrows
What is the function of the occipitals?
Draws scalp posteriorly
What is the function of the platysma?
Wrinkles neck when clenching.
Which muscle draws the eyebrow down and is also a popular site for botox?
Corrugator supercilli.
