Control L3 the head and neck Flashcards
What are the four main muscles of mastication?
- Masseter
- Temporalis
- Lateral pterygoid
- Medial pterygoid
What is the main accessory muscle of mastication?
Double bellied digastric muscle
What is in the joint capsule at the temporomandibular joint?
Articular disc and two spaces filled with synovial fluid
What is the origin of the masseter muscle?
the zygomatic arch
Where does the masseter muscle insert?
onto the ramus of the mandible by the mandibular angle
What happens when the masseter muscle contracts?
the mandible is elevated towards the maxilla.
What movements of the jaw is the masseter involved in?
Elevation and protrusion
What travels through the space created by the mandibular notch?
a neurovascular bundle
What artery supplies the masseter?
The masseteric artery
What nerve innervates the masseter?
masseteric nerve (from the trigeminal nerve)
Where does Temporalis muscle originate?
Temporal fossa
Where does the Temporalis muscle insert?
coronoid process of the mandible
How does the Temporalis muscle move the mandible/jaw?
Elevates and retracts
What innervates the Temporalis muscle?
deep temporal nerve (branch of the trigeminal nerve)
What artery supplies Temporalis?
deep temporal artery
Where does the lateral pterygoid muscle originate?
the lateral surface of the lateral pterygoid plate and the greater wing of the sphenoid bone.
Where does the lateral pterygoid muscle insert?
neck of the condylar process of the mandible and the articular disc of the temporomandibular joint capsule
How does the lateral pterygoid move the jaw/mandible?
Depresses and moves it medially causing side to side movements
What innervates the lateral pterygoid muscle?
The nerve to the lateral pterygoid from the mandibular division of the trigeminal nerve
What artery supplies the lateral pterygoid muscle?
the pterygoid branches of the maxillary artery and the ascending palatine branches of the facial artery
How many heads do both the lateral and medial pterygoid muscles have?
Two each (upper and lower for lateral and anterior and posterior for medial)
Where does the medial pterygoid muscle originate from?
the posterior surface of the maxilla and medial surface of the lateral pterygoid plate of the sphenoid bone
Where does the medial pterygoid muscle insert?
Medial/deep surface if the ramus of the mandible (near the mandibular angle)
How does the medial pterygoid muscle move the jaw/mandible?
Elevate, protrude and move the jaw side to side (like a cow chewing)
What nerve innervates the medial pterygoid muscle?
Nerve to the medial pterygoid from the mandibular branch of the trigeminal nerve
What artery supplies the medial pterygoid muscle?
The pterygoid branches of the maxillary artery and the muscular branches of the facial artery
Where does the medial pterygoid muscle lie in comparison to the lateral pterygoid muscle?
Deep to the lateral pterygoid
How does the digastric muscle act as an accessory muscle of mastication?
It helps depress the jaw/mandible.
How many bellies does the digastric muscle have?
Two - anterior and posterior bellies
Which muscle travels through a small loop of collective tissue attached to the hyoid bone?
The digastric muscle
What separates the posterior and anterior bellies of the digastric muscle?
One muscle belly forms a tendon which passes through the connective tissue loop on the hyoid bone and then becomes muscular again and forms the other muscle belly.
Where does the digastric muscle originate?
the mastoid process
Where does the digastric muscle insert?
onto the digastric fossa of the mandible
What movement is caused by the digastric muscle?
Depression of the mandible or elevation of hyoid bone
What nerve innervates the anterior belly of the digastric muscle?
The mylohyoid nerve which originates from the trigeminal nerve
What nerve innervates the posterior belly of the digastric muscle?
The facial nerve
What artery supplies the anterior belly of the digastric muscle?
The submental branch of the facial artery
What artery supplies the posterior belly of the digastric muscle?
the posterior auricular and occipital arties
What happens in the temporomandibular joint capsule when the jaw is depressed?
The condylar process moves out of the mandibular fossa.
What are the two synovial cavities in the temporomandibular joint capsule?
superior and inferior - separated by articular disc
What is the tubercle anterior to the mandibular fossa called?
Articular tubercle
What must happen to allow the rotation of the condylar process?
Forward displacement of the condylar process from the mandibular fossa
What allows for the sliding of the condylar head during depression of the mandible?
The action of the lateral pterygoid muscle stretching the articular disc in the joint capsule forward towards the articular tubercle. Once the articular disc reaches the articular tubercle, the condylar head becomes displaced from the mandibular fossa.
What happens at the temporomandibular joint capsule during elevation of the mandible?
The condylar head retracts back into the mandibular fossa bringing the articular disc with it
What can cause a clicking/popping sound and pain when elevating the jaw?
The articular disc not moving back into the joint capsule alongside the condylar head.
What disease is caused by chronic failure of the articular disc to move back into place with the condylar head upon mandibular elevation?
TMJ dysfunction
What prevents excessive sideways and backwards movement of the mandible when elevated?
The stability of the joint capsule due to the shape of the temporal bone and the ligaments preventing hyper retraction.
In what position/state is the mandible most likely to be dislocated from the temporomandibular joint?
When the mandible is depressed or when you open your mouth too wide overstretching the muscles and causing the condylar process to get pulled, and stuck, in front of the articular tubercle.
What cranial nerve is the trigeminal nerve?
Nerve V
What are the three branches of the trigeminal nerve? What is the shorthand for each?
V1 = opthalmic nerve
V2 = maxillary nerve
V3 = mandibular nerve
What ligaments cause wrinkles as we age and the skin around them sags?
Retaining ligaments
What are the main soft tissue layers of the face? (From most superficial to deepest)
- Skin
- Subcutaneous fat
- Superficial muscular aponeurosis layer/ system (SMAS) containing muscles and retaining ligaments
What is the main role of the SMAS?
To produce facial expressions
What muscle is located on the cheek?
The buccinator muscle
What is the anatomical name for the corner of the mouth?
Oral commissure
Where do lots of the facial muscles articulate/blend together?
Next to the oral commissures
What is the area by the oral commissures where lots of facial muscles meet known as?
Modioli
Where does the orbicularis orus muscle originate?
Medial aspect of mandible and maxilla, the perioral skin (i.e. skin around the mouth) and modiolus
Where does the orbicularis orus muscle insert?
The skin and mucous membrane of the lips
What movement is produced by the orbicularis orus?
Closing the mouth, compresses and protrudes the lips.
Where does the depressor anguli oris muscle originate?
The mental tubercle and the oblique line of the mandible
What other muscle is the depressor anguli oris continuous with at its origin?
The platysma muscle
Where does the depressor anguli oris muscle insert?
The modiolus
What movement is caused by the depressor anguli oris?
Decompression of the angles of the mouth i.e. frowning
Where does the Levator anguli oris muscle originate?
The canine fossa of the maxilla
Where does the levator anguli oris muscle insert?
Modiolus
What movement is caused by the Levator anguli oris?
Elevation of the angle of the mouth i.e. smiling
Where does the zygomaticus major muscle originate?
The posterior part of the lateral aspect of the zygomatic bone
Where does the zygomaticus major muscle insert?
Modiolus - blending with muscles of the upper lip
What movement is caused by the zygomaticus major muscle?
Elevating and everting (widen the smile bringing check muscles backwards) the angle of the mouth
Where does the depressor labii inferioris muscle originate?
The oblique line of the mandible
What muscle is the depressor labii inferioris continuous with?
Platysma muscle
Where does the depressor labii inferioris muscle insert?
Skin and submucosa of the LOWER lip
What movement is caused by the depressor labii inferioris?
Depression of lower lip inferolaterally
Where does the levator labii superioris muscle originate?
The zygomatic process of the maxilla and the maxillary process of the zygomatic bone
Where does the levator labii superioris muscle insert?
Blends with muscles of upper lip
What movement is caused by the levator labii superioris muscle?
Elevation of upper lip exposing the maxillary teeth
Where does the zygomaticus minor muscle originate?
Anterior part of the lateral aspect of the zygomatic bone
Where does the zygomaticus minor muscle insert?
It blends with the muscles in the upper lip blending medially to the zygomaticus major muscle.
What movement is caused by zygomaticus minor?
Elevates the upper lip exposing the maxillary teeth.
Where does the mentalis muscle originate?
The incisive fossa of the mandible
Where does the mentalis muscle insert?
The skin of the chin
What movement is caused by the mentalis muscle?
Elevating, everting and protruding the lower lip, wrinkling the skin of the chin
What is the nickname for the menatlis muscle?
The sulking muscle
What muscles are known as the dilators of the mouth?
Depressor anguli oris
Levator anguli oris
Zygomaticus major
Zygomaticus minor
Depressor labii inferioris
Levator labii superioris
Mentalis muscle
Where does the buccinator muscle originate?
- Superiorly at the alveolar process of the maxilla
- inferiorly at the alveolar part of the mandible
- posteriorly at the pterygomadibular raphe and buccinator crest of the mandible
Where does the buccinator muscle insert?
Modiolus blending with other muscles of upper lip
What movement is caused by the buccinator muscle?
Compression of the cheeks against the molar teeth i.e. sucking/suckling
What major role in maceration does the buccinator have?
Controls the bolus of food in the mouth