Anatomy Flashcards by Diewitt Duong

How would you anatomically classify the TMJ?

Bilateral synovial diarthodial ginglymoid joint.

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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

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Articular disk composed of?

Fibrocartilage? Some say it’s dense fibrous connective tissue. Seems like a debate on terminology

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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

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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

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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

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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)

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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

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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

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___ 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

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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

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Stylomandibular ligament

Origin
Insertion
Function?

Styloid process
Mandibular angle
Limits protrusion

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Sphenomandibular ligament

Origin
Insertion
Function

Sphenoid spine
Mandibular lingula
Suspends the mandible

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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

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Which muscles open the mandible? (4)

Lateral pterygoid
Suprahyoid group (digastric, geniohyoid, mylohyoid)

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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

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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

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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

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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)

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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)?

1. Facial expression (incl. buccinator) 2. Posterior belly of digastric and stapedius 3. Taste from anterior 2/3 of tongue 4. 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)?

1. Taste from posterior 1/3 of tongue 2. Provides secretomotor innervation to parotid gland 3. 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?

1. Sternocleidomastoid 2. 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?

1. After 20 mm 2. McCollum and Stuart 3. 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?

1. Osteoarthritis 2. Pain and closed lock (limited condylar translation) 3. 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?

1. Capsulitis 2. Synovitis 3. 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 1. Clenching occurs when Superior belly or inferior belly of lateral pterygoid is contracted maximally? 2. Protrusive movement with incisal guidance? SLP or ILP

1. SLP 2. ILP

Which muscle is active (EMG-wise) in suspending the mandible? Which muscles active (EMG-wise) in opening the mandible? (2)

Lateral pterygoid - Upper head (minimally though - it’s not as active as other muscles during their action) Suprahyoid (rotation) and Lateral pterygoid (Lower head) (translation)

Which muscles are active during clenching? (3) Which muscles are active during grinding? (2)

Clenching: Masseter, temporalis, and lateral pterygoid (upper head) Grinding: Temporalis and lateral pterygoid (lower head - protrudes mandible forward)

TMJ Exam - Walk through "I follow a systematic approach involving history and a clinical exam including range of motion, joint sounds, and palpation."

I follow a systematic approach involving history and a clinical exam including range of motion, joint sounds, and palpation. 1. History (chief complaints, pain soreness, any joint sounds, jaw locks, trouble opening wide, clench/grind, history of trauma, med history like arthritis) 2. Range of Motion - Observe deviation - Max opening (40-55 incisors). If limited, passive or active - Lateral movement (8-12 mm) -Protrusive movement (8-10 mm) 3. joint sounds (fingers over poles). Note sounds (when like early/late, reciprocal click on open/close) 4. Muscle palpation and tenderness. Temporalis, masseter, med/lat pterygoids (impossible), accessory muscles (SCM and trapezius if neck pain) 5. Joint palpation for tenderness during open/close

Crepitus during protrusion indicates what? Crepitus during opening movement indicates what? Difference between osteoarthosis and osteoarthritis

Changes in the temporal joint surface Changes in the condylar surface Osteoarthosis (painless) or osteoarthritis (pain)