Mastication Flashcards
What is the zygomatic arch?
a bar of bone formed by the zygomatic process of the temporal bone, and the temporal process of the zygomatic bone [temporal + zygomatic]
What is the superior temporal line?
a line formed by the connection of the temporal fascia [parietal]
What is the inferior temporal line?
the most superior attachment site of the temporalis muscle. [parietal]
What is the spine of the sphenoid?
an inferior projection located posteriorly of the foramen spinosum. It is the superior attachment of the sphenomandibular ligament [sphenoid]
What is the mandibular fossa?
the cranial portion of the temporomandibular joint (TMJ); it articulates with the condyle of the mandible [temporal]
What is the petrotympanic fissure?
a slit of bone just distal to the mandibular fossa (medial); chorda tympani exits skull through this fissure [temporal]
What is the articular tubercle?
Inferior projection of the zygomatic arch which forms the anterior limit of mandibular fossa [temporal]
What is the infratemporal crest?
an inferior attachment site for the temporalis muscle [sphenoid]
What is the styloid process?
a thin, inferior projection of the temporal bone located posterior to the mandibular fossa, and anterior to the mastoid process. Superior attachment for stylomandibular ligament, and stylohyoid ligament. Also, an attachment site for the styloglossus, stylohyoid, and stylopharyngeus mm. [temporal]
What is the maxillary tuberosity?
the posteroinferior projection of the maxilla. Attachment site for a portion of the medial pterygoid m.
What is the greater wing of the sphenoid?
Superolateral projection from the body of the sphenoid; can be seen internally and externally and is largest component of sphenoid bone [sphenoid]
What is the foramen ovale?
A large, oval foramen, which transmits V3 (mandibular n.), lesser petrosal n., and accessory meningeal a. [sphenoid]
What is the lateral plate of the pterygoid process?
Lateral surface is attachment site of lateral pterygoid m.; medial surface is attachment site for medial pterygoid m. (relationships of the pterygoid mm. to lateral plate is the basis for medial vs. lateral in their names) [sphenoid]
What is the Ramus?
Ascending portion of mandible; continuous with body of mandible; provides attachment for all muscles of mastication [mandibule]
What is the lingula?
Sharp projection overlapping the mandibular foramen; attachment site for sphenomandibular ligament; palpable landmark for inferior alveolar n. anesthetic blocks [mandible]
What is the coronoid process?
Anterior projection of the ramus of the mandible; attachment site for temporalis m. [mandible]
What is the condylar process?
Consists of articular surface of mandible which is a component of the temporomandibular joint (TMJ) [mandible]
What is the pterygoid fovea?
Depression located on anterior surface of neck of the condylar process; attachment site for lateral pterygoid m. [mandible]
What is the temporal crest?
Ridge on medial surface of coronoid process that extends to approximately the 3rd molar; temporalis m. has an attachment here [mandible]
Temporals Superior/inferior attachment, innervation, and action
Temporal fossa - Coronoid process & ramus of mandible - Deep temporal brs. (V3) - Elevation of mandible (e.g. closing mouth); slight retraction of mandible
Masseter Superior/inferior attachment, innervation, and action
Maxilla & zygomatic arch - Angle & ramus of mandible - Masseteric n. (V3) - Elevation of mandible; retraction & protraction (dependent on fibers contracting)
Lateral pterygoid Superior/inferior attachment, innervation, and action
Superior head: Greater wing of sphenoid Inferior head: Lateral aspect of lateral pterygoid plate of sphenoid - Superior head: Articular disc & capsule of TMJ Inferior head: Pterygoid fovea of mandible - Nerve to the lateral pterygoid (V3) - Superior head: (considerable current debate/research) activated during clenching of jaw, balancing, protraction Inferior head: depresses the mandible (e.g. opens the mouth)
Medial pterygoid Superior/inferior attachment, innervation, and action
Sphenoid, palatine, and maxillary bones - Mandible (mirrors the masseter m.) - Nerve to the medial pterygoid (V3) - Elevation and protrusion of mandible
What kind of joint is the TMJ? How is it formed?
The TMJ is a compound synovial hinge joint formed by the mandibular fossa of the temporal bone receiving the condyle of the mandible.
What separates the mandibular fossa and the condyle of the mandible? What does it separate them into?
These structures are separated by a fibrocartilaginous articular disc. It separates them into superior and inferior joints
What does the superior joint of the TMJ joint allow for?
protrusion and retraction of the mandible
What does the inferior joint of the TMJ allow for?
elevation and depression of the mandible with minor pivoting actions
What do the muscles of mastication do in regards to the TMJ?
They produce the movements at the TMJ
What is the innervation of the TMJ and the arterial supply?
Afferently innervated by the auriculotemporal n., and supplied by branches of the maxillary and superficial temporal aa.
What major ligaments and other connective tissues limit the range of motion of the temporomandibular joint?
The stylomandibular ligament, lateral (temporomandibular) ligament, sphenomandibular ligament, and retro-articular tissue.
How does the stylomandibular ligament affect the TMJ?
“reinforcing ligament.” does not afford any mechanical constraints to the joint.
What are the attachments of the stylomandibular ligament?
from the styloid process of the temporal bone to the posterior border of the ramus and angle of the mandible.
How does the lateral (temporomandibular) ligament affect the TMJ?
it restricts posterior and lateral movement of the condylar process of the mandible
What are the attachments of the lateral temporomandibular ligament?
it attaches the articular tubercle of the temporal bone to the neck of the condylar process of the mandible. It completely covers the condylar process of the mandible and is intimately related to the articular capsule.
How does the sphenomandibular ligament affect the TMJ?
the sphenomandibular ligament is tense when the TMJ is in an intermediate position (slightly opened)
What are the attachments of the sphenomandibular ligament?
It extends from the lingula of the mandibular foramen to the spine of the sphenoid
What tissue is often the site of edema/pain in temporomandibular disorder (TMD)?
the retro-articular tissue
Where is the retro-articular tissue located?
(retrodiscal pad/zone) is located between the posterior portion of the articular disc and the articular capsule, containing neurovasculature.
What is a temporomandibular disorder?
Temporomandibular disorder (TMD) is a general term for a pathology related to the temporomandibular joint, including muscles of mastication, ligaments, bone, articular disc, and neurovasculature
What are some possible causes of TMD?
Possible causes of TMD are disease, arthritis, occlusal changes, and muscle spasms, among others.
What is a common complaint associated with TMD?
Crepitus (clicking)
What happens to the TMJ when it is subluxated?
the mandibular condyle moves anterior to or onto the articular tubercle of the temporal bone.
How can dislocation of the TMJ occur?
traumatic blows, or from weakening of the supportive structures of the joint i.e. ligaments, articular capsule, etc. In these cases, even yawning could cause dislocation
Describe the path of V3
The mandibular nerve exits the skull through the foramen ovale into the infra temporal fossa
What are the divisions of the mandibular nerve.
V3 has a main trunk, and anterior division, and a large posterior division
What are the chief innervations of the mandibular nerve?
Efferent to the muscles of mastication, afferent to the mandible, mandibular teeth and gingiva, and skin superficial to a portion of the temporal region.
Is V3 superficial, or deep in the infra temporal fossa?
its is one of the deepest structures of the infra temporal fossa
How do the branches of the mandibular n. relate to branches of the maxillary a.?
They will often accompany arteries of a similar name, and may be located concurrently.
What nerves are included in the trunk of the mandibular nerve?
medial pterygoid br., tensor tympani br., tensor veli palatini br., meningeal br.
What is the nerve to the medial pterygoid m. responsible for?
efferent innervation to the medial pterygoid m.
What are the nerves of the anterior division of the mandibular n. (V3)?
masseteric n., deep temporal n., nerve to lateral pterygoid m., and long buccal n.
What are the innervations of each nerve of the anterior division of the Mandibular n.?
Masseteric n. - efferent innervation to masseter m., Deep temporal n. - efferent innervation to temporalis m,; variable number of branches, Nerve to lateral pterygoid - efferent innervation to lateral pterygoid m.; typically a branch of the buccal n., Buccal n. (long buccal n.) - afferent innervation to skin overlying buccinator and buccal mucous membrane;
Where can the long buccal nerve be found?
can be located passing between the two heads of the lateral pterygoid m.
What nerves are included in the posterior division of the mandibular n.?
Auriculotemporal n., Lingual n., Inferior Alveolar n.
What are the innervations of the auriculotemporal n.?
afferent innervation to TMJ, to a portion of the skin of external acoustic meatus, to the skin of the anterior auricle of the ear, and to the skin of the superior V3 dermatome (anterior and anterosuperior to the ear) Postganglionic parasympathetic fibers from the otic ganglion travel with the auriculotemporal n. to the parotid gland
What are the innervations of the lingual n.?
afferent innervation to presulcal part (anterior 2/3rds, excepting vallate papillae) of the tongue and the mucosa of the floor of the oral cavity. Joined by the chorda tympani n. in the infratemporal fossa
What are the innervations of the inferior alveolar n.?
afferent innervation via branches to all mandibular teeth and gingiva. Gives off nerve to mylohyoid; enters the mandibular foramen. Forms inferior dental plexus and 2 terminal branches: incisive br. and mental n.
Where do you inject anesthetic for an IAN block?
around the vicinity of the mandibular foramen
What is anesthetized when and IAN block is carried out?
All mandibular teeth on the ipsilateral side, skin of the lower lip and chin, and the gingiva and mucosa associated with the lower lip and mandibular teeth
Where is the otic ganglia found?
closely associated with the trunk of the mandibular nerve just deep to the foramen ovale.
What is the otic ganglia?
parasympathetic ganglion associated in location with the deep portion of the mandibular n. (V3) trunk, just inferior to the foramen ovale
Describe the path pre and post ganglionic fibers take to get from the glossopharyngeal n. to the parotid gland.
Glossopharyngeal (exits through jugular foramen) > (enters through tympanic canaliculus into middle ear) becomes tympanic nerve > becomes tympanic plexus > gives of lesser petrosal n. > exits foramen ovale > synapses in otic ganglia > post ganglionic parasympathics are transported to parotid via auriculotemporal n.
Describe the path pre and post ganglionic fibers take to get from the facial n. to the submandibular/sublingual glands.
Facial n. (gives off before exiting skull) > exits petrotympanic fissure > join w/ lingual n. > synapse in submandibular ganglia > neurovasculature to submandibular and sublingual glands
What innervations aside from parasympathetics is the chorda tympani involved in?
special sensory from presulcal part of tongue
Where is the pterygoid venous plexus? Describe it.
around the muscles of mastication and surrounding the 2nd part of the maxillary a. (pterygoid part). These veins are typically large in caliber and obvious during dissection.
What are the tributaries of the pterygoid venous plexus?
alveolar brs., buccal, deep temporal, greater palatine, masseteric, middle meningeal, and sphenopalatine.
What communications make the pterygoid venous plexus able to spread infection?
Cavernous sinus (via small veins that pass through the foramen lacerum and ovale, as well as emissary foramina), to the face via the deep facial v., and to the orbit via the inferior ophthalmic v.
How is the maxillary vein formed? what does it join with to create?
formed by the coalescence of veins from the pterygoid plexus of veins, accompanies the maxillary a., first part (mandibular part), and joins with the superficial temporal v. to form the retromandibular v.
What arteries supply the muscles of mastication?
anterior and posterior deep temporal aa., masseteric a., pterygoid a.
What do the anterior and posterior deep temporal aa. supply?
the temporalis muscles
What does the masseteric a. supply?
masseter m., may also be a supply to the TMJ
What does the pterygoid a. supply?
the lateral and medial pterygoid mm.
What arteries of the maxillary a. supply the meninges?
the middle meningeal a. and the accessory meningeal a.
What does the middle meningeal a. supply?
bones of cranial vault, and meninges
What branch of the maxillary artery is the middle meningeal a.?
the first
What does the middle meningeal a. pass through?
fibers of the auriculotemporal n.
Where does the middle meningeal a. enter the skull?
foramen spinosum
When present, what does the accessory meningeal a. supply?
pterygoid m. and tensor veil palatini m. - also, small supply to the meninges
Where does the accessory meningeal a. enter the skull?
foramen ovale
What arteries supply the TMJ?
Maxillary a., and superficial temporal a.
What aspect of the TMJ does the maxillary a. supply? Superficial temporal a.?
the maxillary a brs. will supply the medial TMJ, while the superficial temporal a. brs. will supply it laterally.
What is so unique about the TMJ?
only place in the body where we see two joints connected bilaterally by a bone (mandible)
Where does most of the force between the condylar process and the skull base occur?
at the articular tubercle
Where does the facial n. exit the pons?
What are the names for the anterior and posterior processes of the mandibular fossa?
Anterior: articular tubercle/eminence
- Posterior: Postglenoid process
Where will you inject anesthetic for an IAN block
Medial/lateral to the inferior attachment of the sphenomandibular ligament (lingula). This is where the IAN enters the mandible (mandibular foramen)
What makes the posterior aspect of the TMJ joint capsule weak?
the retrodistal pad (retroauricular tissue) is there. it contains the neurovasculature supply of the disk which makes it weaker here.
