Lect. 6: Head and Neck 1 Flashcards
1
Q
Pharyngeal pouches are made from what primary germ layer?
A
endoderm
2
Q
Pharyngeal grooves (clefts) are made from what primary germ layer?
A
ectoderm
3
Q
Pharyngeal arches are made from what primary germ layer?
A
mesoderm AND neural crest cells
4
Q
How many pharyngeal grooves (clefts) are there?
A
four
5
Q
How many pharyngeal arches are there? Name them.
A
5 (1,2,3,4, and 6)
6
Q
Name the 4 structures located within a pharyngeal arch.
A
- arch cartilage
- arch cranial nerve
- arch artery
- skeletal muscle
7
Q
What structure that is found within the pharyngeal arch is NOT developed from the arch itself? What is it developed from?
A
arch cranial nerve is developed from neuroectoderm and grows in to the arch
8
Q
What is the largest and most active pharyngeal arch?
A
first arch
9
Q
What is another name for the 1st arch?
A
(mandibular arch)
10
Q
What nerve supplies the 1st arch?
A
mandibular nerve (CN V3)
11
Q
What muscles arise from the 1st arch?
A
MASS MATT
- Muscles of mastication
- Mylohyoid
- Ant. Belly of digastric
- Tensor tympani
- Tensor veli palatini
12
Q
What skeletal/cartilage structures arise from the 1st arch?
A
-malleus
-incus (both from middle ear)
-mandible
-maxilla
-zygomatic
-part of temporal
(builds most of facial bone structure)
13
Q
What type of cells do the skeletal/cartilage structures that arise from pharyngeal arches arise from?
A
neural crest cells
14
Q
What is the aortic arch component of pharyngeal arch 1?
A
very small arteries that he said not to worry about :)
15
Q
What is the other name for the second pharyngeal arch?
A
hyoid arch
16
Q
What nerve supplies the 2nd arch?
A
Facial (CN VII)
17
Q
What muscles arise from the 2nd arch?
A
(muscles of facial expression)
- stapedius
- stylohyoid
- posterior belly of digastric
18
Q
What skeletal/cartilage structures arise from the 2nd arch?
A
- stapes (middle ear)
- styloid process
- lesser horn of hyoid
- upper body of hyoid
19
Q
What is the aortic arch component of pharyngeal arch 2?
A
very small arteries that he said not to worry about :)
20
Q
What nerve supplies the 3rd arch?
A
glossopharyngeal nerve (CN IX)
21
Q
What is interesting about the 3rd arch?
A
only arch to develop only 1 muscle!
22
Q
What muscle arises from the 3rd arch?
A
stylopharyngeus
23
Q
What skeletal/cartilage structures arise from the 3rd arch?
A
- greater horn of the hyoid
- lower part of the body of the hyoid
24
Q
What is the aortic arch component of pharyngeal arch 3?
A
right and left common and internal carotid arteries
25
From what primary germ layer do the aortic arches arise?
mesoderm
26
What is the nerve supply to the 4th arch?
superior laryngeal branch of the vagus (CN X)
27
What muscles arise form the 4th arch?
- caricothyroid
- levator veli palatini (soft palate)
- 5 pharyngeal muscles
28
What skeletal/cartilage structures arise from the 4th arch?
thyroid cartilage
29
What is the aortic arch component of pharyngeal arch 4?
right: subclavian
left: aortic arch between left subclavian and left common carotid
30
What is the nerve supply to the 5th arch?
trick question! there is no 5th arch! hehe
31
What is the nerve supply to the 6th arch?
recurrent laryngeal branch of vagus (CN X)
32
What muscles arise from the 6th arch?
laryngeal muscles
| striated muscles of the esophagus
33
What skeletal/cartilage structures arise from the 6th arch?
laryngeal cartilages
34
What is the aortic arch component of pharyngeal arch 6?
- right and left pulmonary arteries
| - ductus arteriosus (from left side)
35
What are the 3 major actions of the vagus nerve (meaning what are the function of its muscles)?
- vocalization
- swallowing (5 out of 6)
- "Ahh" (all but 1 uvula muscle)
36
What innervates the 7 muscles of the orbit?
CN III, IV, and VI
37
What innervates muscles of the tongue?
CN XII
38
What do the muscles of the orbit and tongue develop from?
mesoderm of somitomeres (upper occipital somites)
39
A neural crest cell migration defect of the 1st arch results in what (general)? Name 2 specific symdromes.
major face malformation
1) Treacher Collins syndrome
2) Pierre Robin sequence
40
What type of motor fibers do CN V, VII, IX, and X contain?
BE fibers!
41
What is formed by pharyngeal pouch 1?
epithelial lining of auditory tube and middle ear (tympanic) cavity
42
What is formed by pharyngeal pouch 2?
epithelial lining of crypts of palatine tonsil
43
What is formed by pharyngeal pouch 3?
inferior parathyroid gland (ventral) and thymus (dorsal)
44
What is formed by pharyngeal pouch 4?
superior parathyroid gland (ventral) and ultimobranchial body (dorsal)
45
What is the ultimobranchial body?
"last pouch"- neural crest cells migrate into this to form parafollocular (C) cells of the thyroid--which make calcitonin
46
What is unique about the 3rd and 4th pharyngeal pouches?
they have dorsal and ventral extensions
47
True or false, pouch derivatives from the 3rd arch migrate further than the 4th arch.
true!
48
Why are ectopic thymic tissue and parathyroid glands common?
because the thymus must descend to the mediastinum and the 3rd and 4th arches migrate (in general)
49
What is the only pharyngeal groove that forms an adult structure? What is this structure?
1st cleft forms external auditory canal
50
What happens with the other 3 pharyngeal grooves? Why is this important?
the 2nd pharyngeal arch grows down to cover the 3rd and 4th arches, this closes off grooves 2-4 so that we do not have gills
51
What is formed by the overgrowth of the 2nd pharyngeal arch over the grooves?
lateral cervical sinus
52
What is the common fate of the lateral cervical sinus?
usually obliterates and closes off
53
What happens if the lateral cervical sinus does not close off? Where is this commonly identified in adults?
cervical cyst (found along the SCM muscle)
54
Why is the ear said to be of "dual development"?
outer ear is formed from ectoderm
| middle ear is formed from 1st pouch endoderm
55
Name the 3 glands that are of "dual development".
1) adrenal gland
2) pituitary gland
3) thyroid gland
56
What is the origin of the adrenal gland?
```
cortex= mesoderm
medulla= neural crest cells
```
57
What is the origin of the pituitary gland?
anterior: ectoderm (of Rathke's pouch)
posterior: neural crest cells
58
Does the thyroid gland develop from pouch endoderm?
NO!
59
Describe the development of the thyroid gland.
thickening of midline floor endoderm at foramen cecum (thyroid diverticulum) and vertical descent
neural crest cells develop parafollecular (C) cells of the thyroid too!
60
What connects the thyroid gland to the foramen cecum that usually obliterates in adulthood?
thyroglossal duct
61
What is it called when ectopic remnants of the thyroglossal duct are left in the path of descent from the foramen cecum?
thyroglossal cysts
62
Where are thyroglossal cysts usually found in patients?
midline of neck!
63
What is the fate of the foramen cecum?
gets terminated into tongue and divides it into anterior 2/3 and posterior 1/3
64
What is Pierre Robin sequence?
first arch syndrome (of neural crest cells) that results in:
- poor mandibular growth
- cleft palate
- posteriorly placed tongue
65
What is Treacher Collins syndrome?
first arch syndrome (of neural crest cells) that results in:
- mandibular hypoplasia
- zygomatic hypoplasia
- malformed ears
- etc.
66
What is DiGeorge sequence?
pharyngeal pouches 3 and 4 fail to differentiate into the parathyroid glands and thymus (neural crest cell defect)
67
The first arch forms what components of the developing tongue?
- lateral lingual swelling
| - median lingual swelling (tongue bud)
68
The second arch forms what components of the developing tongue?
copula and facial nerve to taste buds
69
The third arch forms what components of the developing tongue?
hypopharyngeal eminence (with a little help from 4?)
70
The 4th arch froms what components of the developing tongue?
epiglottis
71
What do the lateral lingual swellings form in the adult tongue?
anterior 2/3 of tongue (why innervation is via V3)
72
What does the hypoharyngeal eminence form in the adult tongue?
posterior 1/3 (major)
73
What does arch 2 contribute to in the developed tongue?
taste buds on anterior 2/3 of tongue (via CN VII) because the copula degrades
74
Where do the 5 facial prominences arise from? What tissues?
first arch (mesoderm and neural crest)
75
Name the 5 facial prominences.
1) frontonasal prominence
2&3) two maxillary prominences
4&5) two mandibular prominences
76
What forms the "mouth part" of the developing face? How does this happen?
oropharyngeal membrane breaks down by end of the 4th week
77
The nasal placodes form in what facial prominence? When?
by 5th week, nasal placodes begin to thicken in the lower portion of the frontonasal prominence
78
The frontonasal prominence forms what?
forehead and cranium
| bridge of nose too!
79
The mandibular prominences fuse to form what?
lower jaw and lip
80
What is formed by the fusion of the medial nasal placode and the maxillary prominences?
philtrum of upper lip
81
What is formed by the fusion of the lateral nasal placode and the maxillary process?
lateral part of the mouth
82
The medial nasal prominences form what?
philtrum of upper lip, tip of nose, intermaxillary process
83
The lateral nasal prominences form what?
ala of nose
84
The maxillary prominence forms what?
central face, lower eyelid, and lateral upper lip
85
Cleft lip occurs when what two facial components fail to fuse?
maxillary prominence and medial nasal prominence
86
What are the 2 portions of the hard palate?
1) primary palate
| 2) secondary palate
87
What is the primary palate? What is the source of this?
intermaxillary segment (via medial nasal prominence)
88
What is the secondary palate? What is the source of this?
palatine shelves (from maxillary processes)
89
What is more anterior palatine shelves or intermaxillary segment?
intermaxillary segment
90
Explain the formation of the secondary palate.
palatine shelves fuse and zip up the midline
91
What are the 2 causes of cleft palate?
1) secondary palates fail to fuse with primary palate
| 2) secondary palates fail to fuse with each other
