Head And Neck Dev

Question 1

Somite primordia

Answer 1

1. Preotic somitomeres
2. Postotic somites
3. Somitic mesenchyme
4. Placodes

Question 2

Preotic somitomeres

Answer 2

Superior otic vesicle -> muscles of orbit

1. CN III
2. CN IV
3. CN VI

Question 3

Postotic somites

Answer 3

Become tongue tissues (CN XII)

Question 4

Somitic mesenchyme in head/neck dev

Answer 4

CN XI

Question 5

Placodes

Answer 5

Thickening ectoderm specific locations initiate differentiation -> special sensory

1. CN I
2. CN II
3. CN VII

Question 6

Pharyngeal apparatus

Answer 6

Arches + pouches + grooves
1. Groove = ectoderm
2. Pouch = endoderm
3. Arch originally mesoderm -> neural crest cells invade 
4. Arches -> viscerocranium bones (intermembranous)
  A. Face 
  B. Nasal cavity
  C. Mandible
  D. Endoderm -> epithelial lining 
    1. Middle ear
    2. Nasal cavity
    3. Oral cavity
    4. Pharynx/larynx

Question 7

Dev arches

Answer 7

Each have own

1. CN
2. Muscle group
3. Artery
4. Cartilage
5. Bone derivatives

Question 8

Arch 1

Answer 8

Jaw complex
1. CN V
2. Muscles
  A. Mastication
  B. Tensor tympani
  C. Tensor veli palatini
  D. Mylohyoid
  E. Anterior belly digastric
3. Artery: aspects of external carotid and maxillary a. 
4. Cartilage: meckel cartilage
  A. Incus and malleus
  B. Mandibular dev
5. Bone
  A. Maxillary prominence ->
    1. Maxilla
    2. Zygomatic
    3. Nasal
    4. Vomer
  B. Mandibular prominence -> 
    1. Mandible
    2. Squamous portion temporal

Question 9

Arch 2

Answer 9

1. CN VII
2. Muscles
   A. Facial expression
   B. Stapedius
   C. Stylohyoid
   D. Posterior digastric
3. Artery: stapedial a.
4. Cartilage: Reichert
   A. Stapes
   B. Styloid process
   C. Lesser Cornu of hyoid
   D. Superior body of hyoid

Question 10

Arch 3

Answer 10

1. CN IX
2. Muscles: stylopharyngeus
3. Artery: common carotid and internal carotid
4. Cartilage: greater Cornu and inferior aspect hyoid body

Question 11

Arches 4/6

Answer 11

Arch 5 degrades, 4 and 6 grow together
1. Nerve
  A. 4: bulk CN X
  B. 6: recurrent laryngeal branch
2. Muscles
  A. From 4: 
    1. Levator veli palatini
    2. Pharyngeal constrictors
    3. Cricothyroid
  B. From 6: 
    1. Intrinsic muscles larynx
3. Artery
  A. 4:
    1. Right: right subclavian a. 
    2. Left: aortic arch
  B. 6. 
    1. Right: right subclavian a.
    2. Left: left pulmonary a. And ductus arteriosus
4. Cartilage: laryngeal cartilages

Question 12

Grooves

Answer 12

1. First groove -> external acoustic meatus
2. Rest -> gills -> obliterate
3. Branchial cysts: can dev in grooves that don’t obliterate

Question 13

Pouches

Answer 13

1. First -> tympanic membrane
   A. CN IX
2. Second obliterated except palatine tonsillar fossa
   A. Form foramen cecum
3. Third -> inferior parathyroid glands and thymus
4. Fourth -> superior parathyroid glands

Question 14

Tongue dev

Answer 14

4th week lump forms anterior primordial pharynx rostral to foramen cecum
1. Series lingual swellings from first 2 pairs of arches -> mucosa
2. Copula and hypopharyngeal eminence forms from 3rd and 4th arch pairs
3. Muscles from postotic somites and migrate to tongue space
A. Pulls CN XII w/ it

Question 15

Salivary gland dev

Answer 15

1. CT and innervation from neural crest of relevant arch
2. Gland tissue dev from proliferation oral epithelium
3. Parotid gland: dev as buds from oral endodermal lining from 3rd arch
4. Submandibular and sublingual from 2nd arch