Anatomy Flashcards
How would you anatomically classify the TMJ?
Bilateral synovial diarthodial ginglymoid joint.
Describe the three zones of articular surface of the condyle head
Is it comprised of vascular/avascular, innervated/non-innervated, lymphatic/alymphatic connective tissue?
Divided into three zones:
- Fibrous connective tissue (durable, absorbs forces)
- Zone of chrondogenesis (mesenchymal cells to repair)
- Zone of secondary cartilage (converts cartilage to bone during growth)
Compromised of avascular, non-innervated, and lymphatic connective tissue
Articular disk composed of?
- Fibrocartilage? Some say it’s dense fibrous connective tissue. Seems like a debate on terminology
How is the articular disk attached to the condyle head?
What effect do these attachments have on condylar movements?
Attached via medial and lateral poles
- They prevent excess mediolateral mobility of the disk
In sagittal view, how is the articular disk divided? (3)
Which is thinnest?
How are the fibrous connective tissue fibrils oriented?
- Posterior band
- Intermediate zone
- Anterior band
Intermediate zone is thinnest
Intermediate zone: Oriented A-P.
Anterior and posterior band: Lateromedial direction
Posterior band of articular disk continues with retrodiscal tissue composed of what kind of loose tissue that attaches inferiorly to what and superiorly to what?
- Loose connective tissue
- Posterior aspect of condylar head
- Superiorly to glenoid fossa
Retrodiscal tissue contains what? (5)
What three parts is it divided into?
- Collagen fibers
- Elastic fibers
- Blood vessels
- Lymphatics
- Nerve endings
A. Temporal (attaches to temporal bone, elastic)
B. Intermediate (loose CT/elastic fibers, contains venous plexus)
C. Condylar (attaches to condyle, dense fibrous CT, helps stabilize)
Histologically, the posterior band of the articular disk is identified as ___
Histologically, the retrodiscal tissue is identified as ___
Are either vascular?
- Dense fibrous connective tissue with limited elasticity
- Fibroelastic (due to its elastic tissues, loose connective tissues)
Retrodiscal tissue is vascular
The anterior band of the articular disk’s dense fibrous connective tissue fibers blend with the fibers of which muscles anteromedially (1) and laterally (2)?
- Anteromedially: Lateral pterygoid muscle (superior head)
- Laterally: Masseter and temporalis muscles
___ is a fibrous sheet that surrounds and limits the temporomandibular joint space.
___ ligament superficially reinforces the articular capsule with two layers. The deeper horizontal layer of the ligament layer does what, and the superficial oblique layer does what?
- Articular capsule
- Temporomandibular ligament
2a. Horizontal - restrict posterior displacement and protects retrodiscal tissues
2b. Limits transition of mandibular rotation resulting in translation of the condyle
Articular capsule
- Innervation?
- Vasculation for posterior and anterior?
- Branches of trigeminal nerve
- Auriculotemporal nerve - Posteriorly: Superficial temporal and maxillary arteries Anteriorly: Masseteric and deep temporal
Stylomandibular ligament
Origin
Insertion
Function?
Styloid process
Mandibular angle
Limits protrusion
Sphenomandibular ligament
Origin
Insertion
Function
Sphenoid spine
Mandibular lingula
Suspends the mandible
Temporomandibular ligament
Outer oblique portion’s
- Origin and Insertion
- Function?
Inner horizontal portion’s
- Origin and Insertion
- Function?
Zygomatic process and posterior condylar neck
F: Restricts condyle rotation movement resulting in translation
Articular tubercle and condylar lateral pole
F: Restricts posterior displacement protecting retrodiscal tissues
Which muscles open the mandible? (4)
Lateral pterygoid
Suprahyoid group (digastric, geniohyoid, mylohyoid)
Temporalis muscle
O
I
Action of vertical fibers and of posterior fibers?
Temporal fossa/side of skull
Coronoid process
Vertical fibers elevate and posterior fibers retried mandible
Which muscles form the mandibular sling?
O’s? I’s?
Masseter
Zygomatic process to mandible angle
Medial pterygoid
Deep head: lateral Pterygoid plate
Superficial head: pyramidal process
Inserts to mandible angle
Lateral pterygoid muscles (superior “upper” and inferior “lower”)
O’s, I’s, A’s?
Superior (“upper”) head of lateral pterygoid
O/I: Sphenoid wing into articular capsule, disc, and neck of condyle
A: Active during power stroke of mandible closure; stabilize disc/condyle
Inferior (“lower”) head of lateral pterygoid
O/I: Lateral pterygoid plate into neck of condyle
A: Protrusive and mediotrusive movements
Suprahyoid muscles
Originate where
Insert where
Action (what muscle are they synergistic with)
Digastric, geniohyoid, and mylohyoid
Digastric anterior belly goes from mandible at midline to hyoid, and then posterior belly from mastoid notch to hyoid
Geniohyoid: Genial tubercle to hyoid
Mylohyoid: Mylohyoid ridge to hyoid
Action: Open the mandible (synergic with inferior belly of lateral pterygoid)
Steps for swallowing?
- Voluntary (1)
- Involuntary phase (2)
- Oral phase (voluntary) - “Preparing the bolus”
- Tongue collects food into bolus, lips seal tightly, soft palate elevates to prevent food from entering nasal cavity - Pharyngeal phase (involuntary) - “Protecting the Airway” - soft palate elevates, epiglottis covers down airway, tongue pushes bolus back, pharyngeal constrictor muscles contract (propelling food down), upper esophageal sphincter relaxes (food enters esophagus)
- Esophageal phase - bolus moves downward via peristalsis
Muscles of facial expression - What does buccinator and zygomatic major do?
Compress cheek, create buccal furrow
Elevates corner of mouth, smile
Muscles of facial expression - What do depressor labii inferiors and levator labii superiors do?
Depress lip
Elevate upper lip
Muscles of facial expression - What do orbicular oris and risorius do?
What about zygomaticus minor?
Pucker lips
Smile, elevate corner of mouth
Raise upper lip
Soft palate - Sounds?
Nasal sounds [m/n/ng] as in [swimming]
Plosives - Sounds?
[b/p] as in [ball/paw]
Fricatives - Sounds?
Anatomic movement?
[f/v] as in [frank/victor]
Incisors must touch “wet-dry line” of lower lip
lower lip to upper tooth
Sibilants (considered a subset of fricative sounds)
[s] or [ch/ee] as in cheese
Distance between incisal is 1 mm, typically called “closest speaking space”
Lingual-dental sounds?
Anatomic movement?
[th]
Tip of tongue touch lingual of maxillary incisors and alveolar ridge
Facial nerve (CN VII) innervates what muscles (2) and provides what parafunctions (2)?
- Facial expression (incl. buccinator)
- Posterior belly of digastric and stapedius
- Taste from anterior 2/3 of tongue
- Secretomotor innervation to salivary and lacrimal glands except parotid (which gets parasympathetic from glossopharyngeal nerve)
Glosspharyngeal nerve (CN IX) innervates what parafunctions (2) and what motor (1)?
- Taste from posterior 1/3 of tongue
- Provides secretomotor innervation to parotid gland
- Motor to stylopharygeous
What nerve provides motor to muscles of the tongue except one?
Hypoglossal (12), except palatoglossus which is Vagus (X)
Four intrinsic muscles and four extrinsic muscles of the tongue?
Superior longitudinal, inferior longitudinal, transverse, vertical
Genioglossus, hyoglossus, styloglossus, palatoglossus
Trigeminal nerve innervates what muscles (8)
Masseter, temporalis, medial pterygoid, lateral pterygoid
Digastric (ant belly), mylohyoid
Tensor veli palatini, tensor typmpani
Accessory nerve (XI) controls what two head and neck muscles?
- Sternocleidomastoid
- Trapezius
After how many mm of rotation, does translation occur?
Who first published on this?
Does translation of the condyle-disk assembly occur in the upper or lower joint compartment?
- After 20 mm
- McCollum and Stuart
- Upper joint compartment
Who published that 10% of the population have MI at CO?
Ramjord and Ash
Which muscle of mastication is attributed to the beginning of the power stroke?
Medial pterygoid
What class lever system is the masticatory system? What are each of the three components?
Can you give examples of the other two types?
Class 3 (“FEL”) - Effort is between the fulcrum and load
Fulcrum: TMJ
Effort: Muscles of mastication
Load: Food placed on teeth
Class I: LFE - Seesaw
Class 2: ELF - Wheelbarrow
What muscle is acknowledged as the most important muscle responsible for retrusion?
Posterior part of temporalis
What’s the most common disorder involving the TMJ disk?
Internal joint derangement or anteriorly displaced disk (posterior band displaced anteriorly w/ or w/o reduction)
Patients w/ anterior displaced disk w/o reduction may progress into what?
If acute, the displacement results in what two things?
Which side does the mandible deviate to?
- Osteoarthritis
- Pain and closed lock (limited condylar translation)
- Towards affected side
What non-inflammatory disorder can affect the TMJ?
Is there an agreement as to the causality between this disorder and TMJ disk displacement?
Most common symptom?
Osteoarthritis - Signs of degeneration of the fibrocartilage, as a failure of the remodeling process
No agreement between osteoarthritic changes and TMJ disk displacement
Pain upon palpation of the affected joint and during function
Most common inflammatory disorders of TMJ (3)
Most common symptom?
- Capsulitis
- Synovitis
- Polyarthritides (from rheumatoid arthritis, gout, lupus, etc)
Symptom: Pain, exacerbated by TMJ loading
Biologic width - Modern interpretations
- What did Vacek 1994 find?
- Ingber 1977 - “biologic width violation”?
- Lipski 2018 - Does every patient need crown lengthening?
- Becker & Ochsenbein 1992 - Thick gingival biotypes?
Vacek - Biologic width 2-4 mm
Ingber - Restorative margins too close caused inflammation, bone resorption, gingival recession
Lipski 2018 - Some patients naturally adapt to sub gingival margins w/o significant inflammation
Becker & Oshsenbein - Thick biotypes develop deep pockets whereas thin develop recession when Biologic width violated
Based on McNamara’s rhesus monkey and Gibbs and Mahan research
- Clenching occurs when Superior belly or inferior belly of lateral pterygoid is contracted maximally?
- Protrusive movement with incisal guidance? SLP or ILP
- SLP
- ILP
