ANATOMY & MAJOR FUNCTIONS Flashcards
1
Q
3 major skeletal components
A
maxilla, mandible, temporal bone
2
Q
Maxilla is developmentally from
A
2 bones fused at mid palatal suture
3
Q
Maxilla makes the floor of the
A
nasal cavity and orbit (eye socket)
4
Q
Inferior portion of maxilla
A
hard palate
5
Q
alveolar process job and location
A
in maxilla and mandible - thick ridge of bone in the jaw that holds the dental alveoli, or tooth sockets
6
Q
Alveolar bone surround root is thicker on _____ than _____ in the maxilla. What does this mean?
A
thicker on 2nd/3rd molar than 1st molar - more likely to break bone on 1st molar when extracting
7
Q
Mandible shape
A
U
8
Q
How is the mandible attached to the skull?
A
no bony attachment to skull - suspended by muscle and ligaments
9
Q
Mandible articulates through the
A
condyle
10
Q
Major bony landmarks of the mandible
A
- Body & Alveolar Process
- Angle of the Mandible & Ramus
- Coronoid Process
- Condyle
- Lingula & Mandibular Foramen
11
Q
What are “poles”?
A
medial and lateral projections of the condyle
12
Q
The ____ pole of the condyle is more prominent than the _____ pole
A
medial - lateral
13
Q
Articulating surface of condyle is ____ and extends ______
A
convex - extends more posteriorly than anteriorly
14
Q
Temporal bone articulates
A
at mandibular fossa/articular fossa/glenoid fossa (concavity)
15
Q
Temporal bone concavity is located in
A
squamous portion of temporal bone
16
Q
Where is the squamotympanic fissure located?
A
posterior to the concavity on temporal bone
17
Q
Where is the articular eminence of the temporal bone located and what is it?
A
anterior to the concavity, thick/dense bone
18
Q
The temporal bone articular eminence dictates
A
pathway of condyles during translation
19
Q
Posterior roof of mandibular fossa is
A
thin bone
20
Q
3 movement of the TMJ
A
hinge, sliding, complex
21
Q
Joint responsible for hinge movement of the TMJ
A
ginglymoid joint
22
Q
Joint responsible for sliding movement of the TMJ
A
arthrodial joint
23
Q
Joint responsible for complex movement of the TMJ
A
rotation and slide - combine of hinge and slide (ginglymoid and arthrodial joint)
24
Q
Working side
A
side where teeth are contacting
25
Articular disc
interposed in space between mandibular condyle and temporal bone
26
What type of joint is the articular disc
compound joint
27
What type of tissue is the articular disc? What is its blood supply and innervation?
dense fibrous CT - mostly devoid of blood supply - innervation is limited to the periphery
28
What are the 3 sagittal zones of the articular disc and what are they made up of/what are their jobs?
anterior border - thick band of CT
intermediate zone - thinnest, where articular surface of condyle rests
posterior border - usually thickest band of CT
29
Articular disc is thickest
medially
30
Articular disc shape is determined by
morphology of condyle and fossa
31
Articular disc morphology is maintained unless
altered by a structural change in the joint or by destructive forces acting on it
32
Irreversible changes to articular disc may alter the function of
TMJ
33
During movement and functional demands the articular disc is somewhat
flexible
34
The articular disc is NOT ______ during function
reversibly altered
35
The articular disc is encased in
a disc capsule
36
The boundaries of the articular disc are marked by
ligaments
37
4 bony attachments of articular disc
Posterior Superior - Tympanic Plate (posterior surface of articular fossa)
Posterior Inferior - posterior inferior margin of the articular surface of the condyle
Anterior Superior - anterior margin of the articular surface of the temporal bone
Anterior Inferior - anterior margin of the articular surface of the condyle
38
3 soft tissue attachments of the articular disc and their
Posterior - Retrodiscal Tissue (vascular and innervated)
Anterior - Superior Lateral Pterygoid
Anterior/Posterior and Medial/Lateral - to Capsular Ligament
39
2 cavities of the articular disc and their boundaries
Superior Cavity – bounded by mandibular fossa and superior surface of the disc
Inferior Cavity – bounded by the head of the condyle and inferior surface of the disc
40
What type of "special" joint is the TMJ?
synovial joint
41
What forms the synovial lining of the TMJ
Internal surfaces of upper and lower cavities in the TMJ are lined with endothelial cells
42
Synovial fluid serves both cavities - and is produced in the anterior border of the
Retrodiscal tissue (Synovial Fringe)
43
2 purposes of synovial fluid
metabolic - fluid is medium for providing nutrients
lubrication - between articular surfaces during function
44
2 mechanisms of lubrication
boundary lubrication - during function/movement the synovial fluid flows throughout the cavity and across the articular surface
weeping lubrication - during function the synovial fluid enters/exits surface of articular surfaces
45
Primary form of lubrication in DYNAMIC movement
boundary lubrication
46
Provides lubrication during both STATIC and DYNAMIC function
Weeping lubrication
47
______ are able to absorb a small amount of synovial fluid
articular surfaces
48
4 articular surface histological layers
1 - articular zone
2 - proliferative zone
3 - fibrocartilaginous zone
4 - calcified cartilage zone
49
Articular Zone
- most superficial, functional surface comprised of dense fibrous CT
- collagen fibers arranged in bundles, oriented parallel to articular surface and tightly packed
50
Proliferative Zone
mainly cellular layer (undifferentiated mesenchymal tissue)
51
Fibrocartilaginous zone
- collagen fibrils arranged in crossing pattern (radial patterns)
- Random 3D arrangement resists both compressive and lateral forces
52
Calcified cartilage zone
- deepest zone made up of chondrocytes and chondroblasts
- Zone where cells die – cytoplasm is evacuated, and the resulting scaffold is excellent for bone remodeling
- Endosteal bone growth proceeds as elsewhere in the body
53
All joints have ___ nerve that provides ______ to muscles that control it
1 nerve that provides both sensory and motor innervation
54
What cranial nerve supplies most of the oral cavity?
trigeminal (CN V)
55
Posterior vascularization of the TMJ
superficial temporal artery
56
Anterior vascularization of the TMJ
middle meningeal artery
57
Inferior vascularization of the TMJ
internal maxillary artery
58
Vascularization of the TMJ
Posterior = Superficial Temporal Artery
Anterior = Middle Meningeal Artery
Inferior = Internal Maxillary Artery
Also important = deep auricular, anterior tympanic, and ascending pharyngeal arteries
59
Ligaments are made of
collagenous CT of set lengths
60
When extensive force is used on ligaments
they can be elongated - affecting ligament function
61
Ligaments are ______elements in a joint - meaning that they
passive restraining elements - limit and restrict border movements
62
3 functional TMJ ligaments
collateral (discal) ligaments, capsular ligament, temporomandibular ligament (lateral ligament)
63
Collateral (discal) ligaments attach
articular disc (medial and lateral) to condylar poles
64
Collateral (discal) ligaments divides
joint space into superior and inferior cavities
65
Collateral (discal) ligaments prevent and allow
Prevents medial/lateral movement of disc
Allow anterior/posterior rotation (hinge movements)
66
T/F :Collateral (discal) ligaments have vascular supply and innervation
T
67
Capsular ligament surrounds
entire TMJ
68
Capsular ligament superior attachment
surround the mandibular fossa and articular eminence
69
Capsular ligament inferior attachment
neck of condyle
70
Capsular ligament resists
all movement medial/lateral or inferiorly
71
Capsular ligament retains
synovial fluid
72
T/F: Capsular ligament has innervation
T
73
Innervation of Collateral (Discal) ligaments sense
proprioception, movement, pain
74
Innervation of capsular ligaments sense
proprioception
75
Temporomandibular ligament 2 parts
Outer oblique and Inner horizontal
76
Temporomandibular ligament - outer oblique extends
from lateral border of articular eminence + zygomatic process posteriorly inferiorly to outer surface on condylar neck
77
Temporomandibular ligament - outer oblique resists and limits
Resists excessive condylar dropping
Limits extent and path of opening (rotation until ligament is tight, then translation)
78
Temporomandibular ligament - Inner horizontal extends
lateral border articular eminence + zygomatic process posteriorly and horizontally to lateral pole condyle + posterior portion articular disc
79
Temporomandibular ligament - Inner horizontal limits and protects
Limits posterior movement condyle + disc
Protects posterior articular fossa, Retrodiscal tissue, and lateral pterygoid from over extension
80
2 accessory TMJ ligaments
sphenomandibular and stylomandibular
81
Sphenomandibular ligament extends
from sphenoid bone inferiorly to the lingual
82
Sphenomandibular ligament effect on jaw opening
no significant effects
83
Stylomandibular ligament extends
from styloid process inferiorly to posterior border of ramus of mandible
84
Stylomandibular ligament effect on jaw opening
Tight on mandibular protrusion only
Relaxed on mandibular opening
85
All skeletal muscles have a mixture of these fibers – which reflect their function:
Type I and Type II muscle fibers
86
Type I Muscle Fibers
slow, sustained contraction
- deep red = aerobic metabolism, numerous mitochondria
87
Type II Muscle Fibers
fast contraction but fatigue quickly
- anaerobic metabolism, less mitochondria
88
Major Muscles of Mastication (M.O.M)
masseter, temporalis, medial pterygoid, lateral pterygoid
89
Masseter origin and extension
originates at zygomatic arch and extends down to lateral-lower border of ramus of mandible
90
Parts of the Masseter muscle and their associated fiber orientation
2 heads:
Superficial Portion - fibers run down and back – also used in protrusion
Deep Portion - fibers are predominantly vertical
91
Masseter function
elevates mandible and brings teeth into contact - powerful chewing strokes
92
Elevates mandible and brings teeth into contact
masseter muscle
93
Temporalis muscle origin
large fan-shaped muscle that originates in temporal fossa and lateral surface of the skull
94
Temporalis muscle fiber convergence
Fibers converge as it passes under zygomatic arch
95
Temporalis muscle inserts on the
coronoid process and anterior border of ascending ramus
96
Parts of temporalis muscle and their associated fiber orientation
fiber direction and function
- Anterior = vertical fibers
- Middle = oblique fibers run anteriorly
- Posterior = almost horizontal above the ear
97
Temporalis function
complete contraction - elevates mandible and brings teeth into occlusion
Partial contraction - moves mandible in direction of muscle fibers
- Anterior = vertical
- Middle = elevation and retrusion
- Posterior = mostly retrusion
98
Medial pterygoid muscle origin and extension
originates in pterygoid fossa and extends down/back/outward and inserts into medial surface of angle of mandible
99
Medial pterygoid muscle forms
a muscular sling with the masseter to support the angle of the mandible
100
Contraction of medial pterygoid muscle produces
- Elevation of mandible and occlusion of teeth
- Protrusion of mandible
- Unilateral contraction = mediotrusive movement
101
Lateral pterygoid muscle is described as 1 muscle with 2 "______" that function ______
bellies - oppositely
102
"Bellies" of lateral pterygoid
inferior and superior lateral pterygoids
103
Inferior and superior lateral pterygoids are ___% type ____ fibers
80% - 1
104
Inferior Lateral Pterygoid originates and extends
originates - on lateral surface of lateral pterygoid plate
Extends - back/up/out to insert on neck of condyle
105
Inferior Lateral Pterygoid contraction and associated movement
Bilateral contraction - condyles pulled down articular eminence = depression/protrusion
Unilateral contraction - mediotrusive movement = mandible moves laterally to opposite side
106
is Inferior or Superior Lateral Pterygoid larger?
Inferior
107
Superior Lateral Pterygoid origin and extension
originates - on infratemporal crest of greater sphenoid wing
Extends - horizontally/back/out to insert on: articular capsule and disc (esp. med. 30-40%) & neck of condyle (60-70%)
108
Superior Lateral Pterygoid contraction
in conjugation with elevator muscles, esp. during power stroke of chewing – elevation in function
109
Accessory muscle
digastric
110
Digastric muscle helps
stabilize posterior and anterior portions of mandible
111
Posterior belly of digastric muscle origin and extension
originates form mastoid notch (of temporal bone) to run forward, down and into the intermediate tendon attached to hyoid bone
112
Anterior belly of digastric muscle origin and extension
originates in digastric fossa on lingual side of mandible to run down/back to the intermediate tendon attached to the hyoid bone
113
Digastric contraction
Bilateral contraction against supported hyoid bone (supported by suprahyoid/infrahyoid muscles) = depression + retrusion of mand (teeth brought out of contact)
114
Digastric muscle works with _____ and ____ muscles to elevate the _______ during swallowing
supra hyoid and infra hyoid muscle - hyoid
