Orofacial Development: Mandible and TMJ

Question 1

mandibular process is what part of 1st PA

Answer 1

lower part

Question 2

what does mandibular process differentiate into

Answer 2

soft tissue, cartilage and bone

Question 3

what is a primary cartilage that develops early from hyaline

Answer 3

Meckel’s cartilage

Question 4

what iis the developmental precursor for middle ear bones (malleus/incus) and provides scaffold for mandible to develop around

Answer 4

Meckel’s cartilage

Question 5

secondary cartilages help wiith growth of what

Answer 5

mandible

Question 6

types of secondary growth cartilage

Answer 6

condylar, angular, coronoid, and symphyseal

Question 7

external permanent structures of mandibular process

Answer 7

1. chin
2. lower lip and commissure (formed by fusion of max and mand process)

Question 8

internal permanent structures of mandibular processs

Answer 8

1. mandible
2. condyle of mandible/TMJ
3. mucosa of anteriior 2/3 tongue
4. middle ear bones (malleus and incus)

Question 9

what develops from derivatives of Meckels’ cartilage (2 middle ear bones)

Answer 9

Primary (temporary) TMJ joint

Question 10

what develops from squamous portion of temporal bone and condylar head of mandible (both PA1)

Answer 10

secondary (permanent) TMJ joint

Question 11

___ and ___ appear as two distinct regions of ectomesenchyme of first arch during development

Answer 11

temporal bone and condyle

Question 12

___ is a primary cartilage that extends as rod of hyaline cartilage from ear to midline of mandibular process (not fused in midline)

Answer 12

meckels

Question 13

steps of primary TMJ development

Answer 13

1. Meckel’s cartilage differentiates from ectomesenchyme of mand 1st PA
2. differentiation of Meckel’s cartilage
3. posterior region of meckel’s ossifies
4. formation of temporary (primary) TMJ
5. malleus and incus become incorporated into middle earcavity

Question 14

what stage do incus and malleus form

Answer 14

stage 3

Question 15

what stage do malleus and incus artiiculate an dmove

Answer 15

stage 4

Question 16

adult derivative and function of the following Meckel’s cartilage region:

posterior region

Answer 16

AD: malleus, incus, anterior ligament of malleuss

function: malleus and incus 1st PA articulate with stapes middle ear bone 2nd PAL
anterior ligament attenuatess movement of malleus

Question 17

adult derivative and function of the following Meckel’s cartilage region:

middle region

Answer 17

AD: sphenomandibular ligament

function: limits inferior displacement of mandible; passive support to TMJ

Question 18

adult derivative and function of the following Meckel’s cartilage region:

anterior regiion

Answer 18

AD: degenerates eventually

function: signaling center - stimulates development of symphyseal cartilage (secondary growth cartilage)

Question 19

what contributes to 2 middle ear bones and 2 ligaments

Answer 19

meckels

Question 20

does meckels contribute to mandible

Answer 20

NOOO

Question 21

secondary/permanent TMJ develops from what

Answer 21

PA1st mandibular and PA1st maxillary

Question 22

what structures of TMJ are 1st PA derivatives and received innervation from CN V

Answer 22

ALL STRUCTURES

Question 23

___ and ___ develop as secondary growth cartilage

Answer 23

condyle and articular eminince

Question 24

the ___ stays as fibrocartilage until 20 yrs and is a significcant source of mandibular growth

Answer 24

condyle

Question 25

bone remodeling of adult mandible occurs in response to what

Answer 25

mechanical load

Question 26

___ is associated with condylar head and artiicular eminence to facilitate remodeling

Answer 26

fiibrocartilage

Question 27

is there hyaline in the TMJ

Answer 27

NOOOO

Question 28

what are TMJ arttiicular joint surfaces covered with? why?

Answer 28

perichondrium (DRCT) - DRCT allows for repair and strimulates remodeling in response to occlusal loads

Question 29

what type of cartilaginous growth occurs in TMJ

Answer 29

apposititonal due to perichondrium

Question 30

articular disc is comprised of what CT

Answer 30

fibrous CT (DRCT)

Question 31

what is divided into thick, peripheral anterior and posterior bands

Answer 31

articular disc

Question 32

what is thin, avascular, and lacks innervation in articular disc

Answer 32

central intermediate zone

Question 33

sensory receptors are found where in regards to disc

Answer 33

joint capsule, ligaments, retrodiscal pad, periphery of disc, and lateral pterygoid muscle

Question 34

what type of innervation to capsule to provide feedback about joint poisition and masticatory force

Answer 34

proprioceptive innervation

Question 35

what type of innervation in capsule to alert to trauma

Answer 35

sensory pain receptors and fibers

Question 36

when does mandible develop LATERAL to meckel's

Answer 36

step 3 - maturation stage

Question 37

how does mandible ossify

Answer 37

1. endochondral (condyle) 2. intramembranous (body and ramus)

Question 38

primary ossification site of mandibular body begins where

Answer 38

bifurcation of inferior alveolar nerve into incisive and metnal branches

Question 39

ossification of body and ramus occurs where compared to the points of initial ossification

Answer 39

POSTERIORLY

Question 40

what nerve do we find when given a histo slide of the mandible

Answer 40

inferior alveolar nerve

Question 41

what cartilages are transient, forming in association w/ only bones that develop by intramembranous ossificccation

Answer 41

secondary growth cartilage

Question 42

what develops after ossification begins and aid in the growth of intramembranosu bones

Answer 42

secondary growth cartilage