2-Neuromuscular determinants Flashcards
TMJ type of joint
Ginglymoarthrodial
joint
2 types of TM joint movements
i) ROTATE (hinging movement lower compartment)
ii) TRANSLATE (gliding movement upper compartment)
NORMAL DISC POSITION -rest (o’clock)
12 o`clock
Opening
20-25 mm (limited mouth opening)
Rotation only:
so, ANTERIOR DISC DISPLACEMENT
WITHOUT REDUCTION
Opening
>40 mm (full mouth opening)
TRANSLATION
Type of cartilage on Synovial joint articular surfaces of TMJ (i.e Temporal bone articulating surface)
Hyaline cartilage
Type of cartilage on condyle of TMJ (i.e TMJ articular surfaces)
Fibrocartilage tissue
Function of Hyaline cartilage in TMJ
Absorbs shock and reduces friction
during movement.
Function of TMJ articular surfaces: Fibrocartilage in TMJ
Fibrous cartilage can withstand force of movements
** _____ TMJ cartilage has limited capacity to heal and repair
Hyaline cartilage (Synovial joint articular surfaces)
** _____ TMJ cartilage has greater capacity to heal and repair;
It is less susceptible to the effects of aging, less
likely to breakdown overtime
Fibrocartilage tissue (TMJ articular surfaces)
_______ prevents direct articulation of the condyle and temporal bone
Articular disc
Shape of articular disc
Biconcave (fibrocartilaginous structure)
Posterior attachment of the disc is called _______
retrodiscal tissue
Articular disc is innervated. T/F?
F.
Articular disc is “Non-innervated”
Retrodiscal tissue is Innervated. T/F?
T. Retrodiscal tissue is Innervated
When the jaws is closed, the anterior prominance of the condyle is at the _______ part of the disc.
central thin part of the disc
Disc follows the condyle during opening.T/F
T
Synovial membrane provides ____ and ____ lubrication.
- Boundary lubrication
* Weeping Lubrication
Capsular ligament: Superior attachment
Superior: Attach temporal bone along the border of glenoid fossa and articular eminence
Capsular ligament: Inferior attachment
Condyle
Capsular ligament: Posterior attachment
Posteriorly: Postglenoid process
Capsular ligament: Function
- Retain synovial fluid inside
* Resist any medial, lateral or inferior forces that tends to dislocate the articular surfaces
**TMJ lateral pole palpation: Painful
Which ligament is inflamed?
Capsular ligament
Capsular pain is provoked when the inflamed capsule
is stretched. T/F
T
Which movement provokes the capsular pain? A. Protrusion B. Lateral movement C. Medial movement D. Wide opening of jaw E. All of the above
E. All of the above
Temporomandibular (TM) ligament is also called
Lateral ligament
TM ligament attachments: Outer oblique
Outer oblique; is attached to the articular tubercule , runs posteroinferiorly to the outer surface of the condylar neck
TM ligament parts
1) Outer oblique
2) Inner horizontal
TM ligament attachments: Inner horizontal
Inner horizontal
; is attached articular tubercule , runs anteroposteriorly to attach to the lateral pole of the condyle and posterior part of the disc
Outer oblique ligament function
Limits rotational opening (20
25mm) and protects retromandibular structures
Inner horizontal ligament function
- Limits posterior movement of condyle and disc to protect retrodiscal tissues.
- Prevent the condyle from entering the middle cranial fossa during condylar neck fractures
Collateral Ligament is also called
discal ligament
Collateral Ligament attachment
Attach medial edge of the disc to the medial pole of the condyle and lateral edge of the disc to the lateral pole
Collateral Ligament function
Allows disc to move passively with the condyle as it glides
________ ligament divides the TMJ into Divides joint into superior and inferior joint cavities
Collateral (discal) Ligament
Sphenomandibular ligament
Spine of the sphenoid bone, runs downward and
outward to lingula of the mandible
________ TMJ ligament does NOT influence on mandibular movement
Sphenomandibular ligament
Stylomandibular ligament :attachment
Styloid process to the angle and posterior border of mandibular ramus
Stylomandibular ligament: function
Limits excessive mandibular protrusive movement
Masticatory muscles
- Temporalis Muscle
- Masseter Muscle
- Medial Pterygoid Muscle
- Lateral Pterygoid Muscle
Accessory masticatory muscles
- Suprahyoid Muscles
- Infrahyoid Muscles
- Sternocleidomastoid Muscle
- Trapezius Muscle
- Splenius Capitis Muscle
- Platysma
- Buccinator Muscle
Temporalis: Origin
Temporal fossa and the lateral surface of
the skull
Temporalis: Insertion
as a tendon into the coronoid process
of the mandible
Temporalis: Action
Elevates and retrudes mandible
Masseter Muscle: Origin
Origin from the inferior border and medial surface
of the zygomatic arch
Masseter Muscle: Insertion
Insertion into angle and the ramus of mandible
Masseter Muscle:Action
Action powerful elevator of the mandible
Superficial part involved in protrusion
Medial Pterygoid: Origin
Origin: from the pterygoid fossa of the sphenoid bone
and the tuberosity of the maxilla
Medial Pterygoid: Insertion
Insertion into the medial surface of the mandible
Inferior Lateral Pterygoid: Origin
Origin: lateral surface of the lateral pterygoid plate
Inferior Lateral Pterygoid: Insertion
Insertion: pterygoid fovea of the condyle neck
Inferior Lateral Pterygoid: Action
Action: (O-PC)
i) Active during opening in conjunction with mand.
depressors,
ii) protrusion
iii) In unilateral contraction mediotrusive movement
Superior Lateral Pterygoid: Origin
Origin: infratemporal surface of the sphenoid bone
Superior Lateral Pterygoid: Insertion
Insertion: onto the pterygoid fovea under the condyloid process of the mandible , capsule, disc (
Superior Lateral Pterygoid: Action
Action: active only in conjunction with elevator muscles and during power stroke (clenching)
Suprahyoid muscles
- Digastric Muscle
- Stylohyoid Muscle
- Mylohyoid Muscle
- Geniohyoid Muscle
Infrahyoid muscles
- Sternohyoid Muscle
- Sternothyroid Muscle
- Thyrohyoid Muscle
- Omohyoid Muscle
Digastric Muscle: Origin
from the digastric groove medial to the mastoid
process to the hyoid bone
Digastric Muscle: Insertion
into the lower border of the mandible
Digastric Muscle: Action
elevates the hyoid bone when the mandible is fixed
and
depresses and pull backward the mandible when the hyoid bone is fixed by the suprahyoid and infrahyoid musles
Stylohyoid Muscle: Origin & Insertion
- Origin: Styloid process
* Insertion: hyoid bone
Stylohyoid Muscle: Action
elevation and retraction of the hyoid bone during swallowing
Masseter: Innervation
- Masseteric nerve.
- mOTOR: Mandibular Branch of CN V
TMJ: Innervation
Innervation (CN V3):
- Auriculotemporal Nerve
- Deep temporal Nerve
- Masseteric Nerve
Temporalis: Innervation
- Anterior and Posterior Deep Temporal Nerve
- Motor Innervations (Mandibular Branch of
CN V)
Medial Pterygoid: Innervation
- Medial Pterygoid Nerve
- Motor Innervations (Mandibular Branch of
CN V)
Lateral Pterygoid: Innervation
- Lateral Pterygoid nerve
- Motor Innervations (Mandibular Branch of
CN V)
Masseter: Blood supply
Maxillary artery
Temporalis: Blood supply
Middle and deep temporal
artery (Branch of external
carotid and maxillary arteries)
Medial Pterygoid: Blood supply
Maxillary artery
Lateral Pterygoid: Blood supply
Maxillary artery
TMJ: Blood supply
-Deep auricular and anterior
tympanic artery ( Branches of
m axillary artery)
-Superficial temporal (Branch of
external carotid)
Sensory neuron
carry information from organ (muscle) to CNS
Motor neuron
carry information from CNS to organ (muscle)
** Muscle spindles are found in ____________ muscles (elevators/depressors)
elevator muscles
** Muscle spindles send signals to contract to oppose the ________ force
gravity force
Golgi tendon monitor _____ of the muscle
tension
Eg : Chewing gum muscle tension
** Nociceptors: Tissues of masticatory system for ___ stimulus
pain
**Myotatic (stretch) reflex on masseter
-A sudden downward force is applied to the chin
(small rubber hammer)
-Activate muscle spindles response masseter contraction
**The Myotatic (stretch) reflex is important in determining the ______ position of the jaw
resting
**Nociceptive (flexor) reflex
Reflex to painful stimulus–
protective.
-In masticatory system it is activated by unexpectedly biting on a hard object
**Elevators ______(START/STOP) CONTRACTING and DEPRESSOR _____ (START/STOP)
CONTRACTING to open the jaw
Elevators STOP CONTRACTING and DEPRESSOR START CONTRACTING to open the jaw
**When the Condyle rotates up to 20
25mm opening
____ ligament
tightens and limits rotation
TM ligament
**Condyle translates up to max opening of 40-60 mm
_____ ligament prevents further movement
Capsular ligament
**The opening movement (depression of mandible): Muscles
(LG MD)
- lateral pt ,
- geniohyoid ,
- mylohyoid,
- digastric
**The closing movement (elevation of mandible): Muscles
(MTMp)
- Masseter,
- temporal,
- medial pt
Note: Disc and condyle moves back
**Primary muscle for protrusion
Primarily inferior lateral pterygoid muscle
Describe protrusion
Condyles and discs are pulled forward by Inferior lateral pterygoid m.
**Muscles involved in protrusion on the mandible
- Primarily inferior lateral pterygoid muscle
- Slight activity of the masseter & medial pt muscle to stabilize the position of the mandible
**Protrusion of mandible is limited by __?
Forward movement is limited by the posterior portion of the joint capsule
**Retrusion is limited by _______?
The capsular and TM ligament of the TMJ limit retrusion further
**Muscles involved in retrusion
From the max protruded position, the posterior temporalis assist the middle
temporalis during mandible retrusion
**Left lateral movement of the mandible: Muscles involved
- The Rt (BS) lateral pt & Rt Medial Pt muscle active
- The middle portion of the Lt ( ws ) temporalis & masseter muscles assist to stabilize the condyle
**Left lateral movement of the mandible: Left condyle?
-The left Lateral pole of the condyle can move backward only about 1 to 2 mm
until restricted by the deep horizontal band of TM Ligament
•Under guidance of this ligament , the center of the Lt condyle is forced to `move slightly anteriorly and laterally
**Left lateral movement of the mandible: Right condyle?
•RT condyle is pulled forward , downward, and medially along the articular eminence
Clicking (TMJ)
A click (pop) is a single sound of short duration
Crepitation (TMJ)
Crepitation is a grating sound of two bones
Range of motion should be assessed with a ruler during wide opening between the ________
incisor edges
Opening pattern should be _____ (curved/straight)
straight
**A restricted mouth opening
______ indicates TMJ and/or muscle problem
< 40
In individuals with increased overbite, amount of overbite should be ______(added/subtracted) to/from the measured range of movement
added
Any lateral movement less than ____ is recorded as a restricted movement
8mm
Protrusive movement less than _____ is recorded as a restricted movement
8mm
