Face Development and Pharyngeal Arches-Ziermann Flashcards
1
Q
pharyngeal arches
A
means branchial gill
2
Q
6th arch is not visible during development
A
only the 1, 2, 3, and 4th arch are externally visible
3
Q
Neural crest cells important for head and neck structures. True or false?
A
True
4
Q
Head has 7 pairs of somitomeres that are never completely separated. True or false?
A
TRUE
5
Q
Hindbrain neural crest gives rise to what pharyngeal arches ?
A
2,3,4, and 6 arches
The midbrain neural crest gives rise to 1st pharyngeal arch.
6
Q
There are not somitomeres!!!!
A
The mesoderm in head is NOT segmented.
7
Q
Occipital lateral plate mesoderm and cranial paraxial mesoderm make what?
A
make the head and neck muscles
8
Q
What is the content of each pharyngeal arch?
A
A membrane (ectoderm and endoderm) A mesenchymal core (mesoderm and neural crest) An internal pouch (endoderm) An external cleft/groove (ectoderm)
9
Q
5th pharyngeal arch fails to form. What arches do form?
A
ultimately 5 arches (1st, 2nd, 3rd, 4th, and 6th) by the end of 4th week
10
Q
What is the stomodeum?
A
the primitive oral cavity
11
Q
The oral cavity (stomodeum) is surrounded by what 5 swellings?
A
1 Frontonasal + 2 Maxillary + 2 Mandibular
development is from rostral to caudal
heart is developing???
12
Q
The axial orientation in embryo is different in the adult
A
medial is medial
but anterior is rostral and posterior is caudal.
Superior is dorsal and inferior is ventral. ????
13
Q
Nasal placode–> nasal pit
A
the rim also rises due to mesenchymal proliferation
14
Q
When you cry really hard your nose leaks?
A
Duct drains into inferior meatus of nose –>
postnatal drainage of excess tears
15
Q
Frontonasal process becomes
A
forehead, dorsum (bridge) and apex of nose
16
Q
Medial nasal processes migrate to each other and fuse to become what?
A
–> fuse–> intermaxillary process/segment
17
Q
Intermaxillary process gives rise to:
A
Middle part or philtrum of upper lip
Middle part of upper jaw and associated gingiva (gums)
Primary palate
18
Q
Lateral nasal process gives rise to:
A
Alae of the nose
19
Q
Fusion of different process we decrease width of UPPER mouth
A
no lower lip cleft because they were never separate in the first place!!!
20
Q
Invasion of mesoderm form what?
A
giving rise to facial muscles
21
Q
Maxillary prominences form:
A
Lateral part of upper lip
Upper jaw (Maxilla)
Secondary palate
22
Q
Why is the tongue important in the formation of the bony palate?
A
need tongue to occupy space for proper jaw development
descend of the tongue is influenced by growth of Meckel’s cartilage and mandible
23
Q
What is the first time nasal sac is connected to oral cavity?
A
Oronasal membrane RUPTURES (7th week): connection of primitive nasal cavities with oral cavity is primitive choana
Floor of nasal cavity formed by posterior extension of intermaxillary process (fusion of medial nasal prominences) = primary palate (development starts in week 5)
24
Q
mesoderm giving rise to
A
primary palate
25
palatine shelves
(lateral palatine processes)
| ???
26
secondary palate
??
membranous ossification
also in the primary ossification
27
Definitive choanae
???
28
incisive foramen continues into adulthood forming BVs
???
29
What forms the uvula?
????
30
How do we get facial clefts?
???
31
cleft upper lip (side)
intermaxillary cleft has not fused with the maxillary cleft
32
cleft upper lip (middle)
something hasn't fused???
33
cleft palate: primary
???
34
cleft palate: secondary
???
35
Tongue development from the FIRST arch (trigeminal nerve)
arches form swellings
median tongue bud or tuberculum impar
lateral swellings of 1st arch: distal tongue buds or lateral lingual swellings
36
2nd pharyngeal arch
arch develops midline swelling: copula
37
copula is overgrown by midline swelling of 3rd & 4th pharyngeal arches called
hypopharyngeal eminence
38
4th pharyngeal arch
epiglottis
39
Line of fusion between anterior 2/3 and posterior 1/3 marked by terminal sulcus
Line between both distal tongue buds marked median sulcus on anterior 2/3
Intersection of terminal and median sulc
foramen cecum--> site of origin of thyroid gland
40
Why is the tongue important in the formation of the bony palate?
need tongue to occupy space for proper jaw development and to move palate upwards so you don't get proper palate closed
41
Thyroid gland is a derivative of what?
is a derivative of the endodermal tissue from the 1st and 2nd pharyngeal arch
foramen cecum is the site of origin of the thyroid gland
42
Thyroglossal duct is SUPPOSED to disappear. IF not you get?
Thyroglossal duct cysts form (anterior side of neck) from persistent thyroglossal duct
43
Pyramidal lobe on thyroid gland
is not pathology just a polymorphism????
44
Most arch cartilage are derived from?
neural crest cells of the midbrain and hindbrain regions
| but their connective tissues is neural crest derived
45
Cartilages from 4th and 6th arches apparently develop from what to form what cartilages?
lateral plate mesoderm
thyroid and cricoid cartilage are mesoderm derived (they are laryngeal cartilages)
46
Mandibular process: dorsal portion Meckel’s cartilage forms what?
forms malleus and incus
first two bones ossicles in the ear
47
Meckel’s cartilage is used as a template region to later form our mandible but IT does not give rise to the mandible
the mesenchymal cells surrounding the Meckel's cartilage are what form the mandible
48
Hyoid bone is a mixture of 2 pharyngeal arches. Explain
the 2nd arch cartilage: Reichert's cartilage
- LESSER horns of the hyoid bone and the UPPER half of the hyoid body
- stapes, styloid process, stylohyoid ligament
the 3rd arch cartilage
-GREATER horns of the hyoid bone and LOWER half of the hyoid bone
49
skull develops from meso
from mesenchyme around the developing brain
50
Cartilaginous XY: with cartilaginous precursors (ossify or not)
with cartilage
51
Membranous XY: without cartilaginous precursors (ossify)
without cartilage
52
Membranous neurocranium
Formed by intramembranous ossification: development of bone that occurs within mesenchymal tissue WITHOUT prior cartilage formation
53
When we are born we still have openings (fontanelles). Explain.
The flat bones of the skull, (e.g., frontal, parietals, squamous part of temporal, and occipital bones) are all membranous.
membranous bones of the skull do not fuse with each other prenatally --> new born babies have unclosed sutures and fontanelles
important for our brain to still grow to a proper size
54
Forensics
an indication to distinguish age using the skull
55
Chondrocranium= Cartilaginous neurocranium
- formed by combination of paraxial mesoderm and neural crest cells
- development: cartilage forms around the brain beginning at the notochord (parachondral cartilage)
WITH REFERENCE TO THE SELLA TURCICA:
- bones that lie rostral to this are derive from neural crest cells
- bones that lie posterior to this are derived from paraxial mesoderm
The base of the skull is formed when the cartilages from from these two sources fuse and ossify by endochondral ossification.
56
- blue is neural crest derived
| - orange is mesoderm derived
????
57
The ethmoid bone is formed from?
formed from the trabeculae cranii (paired chondrification centers in front of developing pituitary gland)
58
Sphenoid bone is from what 3 different sources?
- sphenoid body is formed from hypophysial cartilage
| - lesser wing and greater wing are both derived from mesenchymal condensation called ala orbitis
59
The temporal bone is derived from?
derived from periotic capsule
60
The occipital bone is derived from?
parachondral cartilage
61
The only part that stays open in adult is what?
is where there is vasculature or cranial nerves passing through
62
Viscerocranium is formed from what pharyngeal arches?
mainly from the first two pharyngeal arches
Divided into membranous viscerocranium and chondral (cartilaginous) viscerocranium
63
Membranous viscerocranium
Maxillary process (dorsal): intramembranous ossification
mesenchyme will ossify
64
Mesenchymal cells surrounding the Meckel's cartilage will ossify to form what?
mandible
65
Nasal bones should be ossified intramembranously via the cartilaginous nasal capsule. When the nasal bones are hypoplastic or not visible at 11-13 weeks' gestation, what may this indicate?
risk for fetus with trisomy 21 and other chromosomal abnormalities
66
Which cartilage of the 1st arch forms the malleus and incus?
Which cartilage of the 2nd arch forms the stapes and the styloid process?
Meckel's cartilage
Reichert's cartilage
67
Frontnasal process cranial neural crest form what?
Frontal, nasal, lacrimal, inferior nasal concha, primary palate/premaxilla
68
1st Arch forms what bones?
Maxilla, Zygomatic bone
| Meckel’s cartilage -->malleus and incus; mesenchymal cells around the meckel's cartilage gives rise to the mandible
69
2nd Arch forms what bones?
Stapes, styloid process, stylohyoid ligaments, parts of hyoid bone (derived from Reichert’s cartilage)
70
3rd Arch: Parts of hyoid bone?
lower portion of the hyoid body
| greater horn of the hyoid bone
71
1st arch: CN V
2nd arch: CN VII (facial nerve)
3rd arch CN IX (glossalpharyngeal nerve)
4th arch: CN X
muscles of mastication
muscles of facial expression
stylopharyngeal muscle
laryngeal musculature, pharyngeal plexus
72
1st/ mandibular arch muscles
-muscles of mastication attach to the mandible: temporalis, masseter, medial and lateral Pterygoids
- mylohyoid
- anterior belly of digastric
- tensor veli palatini
- tensor tympani
73
Some cells of the mesenchyme in the pharyngeal arch give rise to striated muscles of the pharyngeal arches
Somatic mesoderm in the mandibular process gives rise to what muscles?
- Muscles of mastication (temporalis, masseter, medial and lateral pterygoid)
- Mylohyoid
- anterior belly of digastric, tensor veli palatini, tensor tympani
74
In babies muscles of facial expression are fully developed but not functioning. Explain.
can only use 2-4 month after birth because????
75
2nd/hyoid arch muscles
- muscles of facial expression: Anatomy of face lecture
platysma: cervical branch of facial nerve:
- frontalis/occipitalis: temporal branch of facial nerve/ posterior auricular nerve
- procerus: temporal branch of facial nerve
- orbicularis oculi: temporal and zygomatic branch of facial nerve
All buccal branch of facial nerve:
- levator labii superioris
- levator labii superioris alaeque nasi
- zygomaticus minor
- risorius
- orbicularis oris
- levator angulis oris
- zygomaticus major: buccal AND zygomatic branch of facial nerve
- depressor anguli oris: buccal AND marginal mandibular branch of facial nerve
- depressor labii inferioris: marginal mandibular branch of facial nerve
mentalis: mandibular branch of facial nerve
buccinator: buccal branches of facial nerve
- posterior belly digastric
- stylohyoid
- stapedius
76
What is the only muscle derived from 3rd arch and innervated by glossopharyngeal nerve?
Stylopharyngeus muscle
77
What are the 4th arch muscles?
muscles related to the pharynx except for stylopharyngeus muscle:
-superior, middle, and inferior pharyngeal constrictor
muscles of the soft palate (except tensor veli palatini)
cricothyroid muscle
cricopharyngeus muscle
all innervated by CN X (vagus nerve)
78
What are the 6th pharyngeal arch muscles?
- muscles related to larynx
| - skeletal muscles of esophagus
79
Pharyngeal arch arteries are derived from what cells?
Mesodermal and neural crest (from mesenchymal chore) cells contribute to the formation of pharyngeal arch arteries
80
What is the first structure to develop in each arch (I-IV)
the aortic (pharyngeal) arch artery (1-6): This is a communicating blood vessel between dorsal aorta and ventral aorta (aortic sac in humans).
81
While the 4th aortic arch artery is forming, the arteries of the 1st and 2nd arches are breaking up into capillary plexuses, and pretty much disappear except for?
except: maxillary, stapedial and hyoid aa.
82
3rd arch artery becomes what?
part of the common carotid artery
83
Left 4th arch artery becomes what?
part of the arch of the aorta
84
Right 4th arch artery forms what?
proximal part of right subclavian artery
85
6th arch arteries become what?
the pulmonary artery
86
if outflow tract is not ???
cannot make pulmonary arch or aorta
-you get mixed blood which is not healthy
87
Why is right aortic arch pathological?
- Retention of dorsal aorta on right side
- Ductus arteriosus deflected to right
- Up to 1/3 of tetralogy of Fallot
88
Aberrant right subclavian artery
| 1% of normal population but 40% of what?
40% of Down syndrome
89
Pouches are INSIDE of the pharyngeal apparatus. What ectodermal lined recesses that appear on the OUTSIDE of the pharynx between arches?
pharyngeal clefts
There are 4 pharyngeal pouches and 4 pharyngeal clefts!!
90
1st Pharyngeal pouch and cleft
pouch becomes the tympanic cavity and which then grows laterally into the cleft forming the external auditory meatus
auditory tube and middle ear (tympanic) cavity
91
You can hear your swallowing sounds, why?
2st pharyngeal pouch becomes the tube????
92
2nd – 4th Pharyngeal CLEFTS
are overgrown by expansion of the 2nd pharyngeal arch (hyoid operculum) and usually OBLITERATED
93
What may anterior and lateral neck cyst be due to?
anterior cyst: thyroglossal ducts
lateral cyst: cervical cyst due to remnants of pharyngeal clefts 2-4
94
Cyst formation on the lateral side of the neck may be due to what? What about on the preauricular? What about on the midline of neck?
Chidinma has cyst formation on the preauricular which is due to the defect in the development of the 1st pharyngeal cleft.
Cyst formation on the lateral neck is due to remanants of pharyngeal clefts 2-4.
Cyst formation on midline neck is due to thyroglossal duct cysts.
95
2nd Pharyngeal pouch
Forms numerous infoldings that become the crypts of the palatine tonsil
96
3rd and 4th Pharyngeal pouches dorsal portions form what? What do their ventral portions form?
Both divide into a superior/dorsal and inferior/ventral portion
Dorsal portions:
3rd: forms inferior parathyroid glands
4th: forms superior parathyroid glands
Chief (or principal) and oxyphil cells are derived from the endodermal lining of the pouch
Ventral portions:
3rd: thymus
4th: ultimobranchial body which releases signaling factors to induce the migration and differentiation of nearby neural crest cells into parafollicular cells of the thyroid gland
97
3rd ventral portion of the pouch forms what?
forms the thymus – the epithelial reticular cells are derived from the endodermal lining of the pouch
T-cell progenitors from the bone marrow infiltrate the cortex to establish the definitive thymus.
enabling neural crest migration in the thyroid gland
98
The most common disorder in which this occurs is DiGeorge syndrome. Microdeletion in the long (or "q") arm of chromosome 22, leading to a hypoplasia of 3rd and 4th pharyngeal pouch derivatives
NOTE: hypoplasia of 3rd and 4th arches can also disrupt the 1st and 2nd arches, leading to the following additional findings:
Micrognathia (reduced jaw), cleft palate, hearing loss
99
- Reduced size of maxillary process resulting in micrognathia (small jaws)
- underdeveloped zygomatic bone resulting in downward slanting of eyes and drooping part of lateral lower eyelids
- mandibulofacial dysostosis
What syndrome is this characteristics?
Treacher Collins syndrome
100
What are characteristics of Pierre Robin sequence?
- hypoplasia of mandible which results in tongue being displaced upward leading to a cleft palate and defect of eye and ears
- glossoptosis
101
Describe what is being fused for each below?
```
Upper lip:
Lower lip:
Cheek:
Primary palate:
Secondary palate:
```
If these tissues fail to meet, a gap appears where tissues should have joined (fused). Facial cleft
This may happen in any single joining site, or simultaneously in several or all of them.
Upper lip: fusion of medial nasal processes (philtrum, medial part of upper lip) and; maxillary processes (lateral parts of upper lip)
Lower lip: fusion of mandibular processes
Cheek: fusion of lateral portions of maxillary and mandibulary swellings
Primary palate: posterior extension of intermaxillary process (= fused inferior tips of medial nasal processes)
Secondary palate: medial walls of maxillary processes
