Embryology of the Head and Neck

Question 1

What is the disease associated with premature fusion of coronal suture?

Answer 1

Apert syndrome

Question 2

Describe the Development of the Face.

Answer 2

The stomodeum is surrounded by five facial swelling of the 1st branchial arch. they are formed by mounds of mesenchyme and their overlying ectoderm

facial swelling include:
frontonasal prominence
maxiallary prominence arch 1: move forward, corner of orbit
mandibular prominence of arch 1: at chin cleft

Question 3

The frontal prominence will form the ______, and the _______ and ___ of _____.

Answer 3

forehead

dorsum and apex of the nose

Question 4

Describe the nasal placodes.

Answer 4

a portion of the skin ectoderm in this region thickens to form the nsal placodes.

Question 5

The _____ ______ are formed by the proliferation of the mesenchyme beneath the medial and lateral edges of the nasal placodes.

Answer 5

nasal prominences

Question 6

The ______ ____ ____ forms the alae of the nose

Answer 6

lateral nasal prominence

Question 7

The ______ ___ _______ will form the middle part of nose, medial upper lib, and philtrum.

Answer 7

medial nasal prominence

Question 8

what forms the primary palate?

Answer 8

the posterior (palatal) portion of the intermaxillary segment form the primary palate. The nasal septum is a midline down growth of the fused medial nasal prominences

Question 9

Describe the nasopharynx opening to the oropharynx.

Answer 9

the nasal placodes invaginate to form nasal pits. these pits enlarge into the nasal sacs. The remaining membrane between the developing nasal sac(primitive nasal cavities) and the oral cavity is called the oronasal membrane

Question 10

describe the nasolacrimal groove?

Answer 10

Nasolacrimal groove: oblique furrow created between the lateral nasal prominence and the maxillary prominence. The ectoderm in the floor of the groove thickens to form a cord. The cord separates from the surface and canalizes to form the nsaolacrimal duct

Question 11

How does a oblique facial cleft?

Answer 11

oblique facial cleft is due to the failure of the lateral nasal prominences and the maxillary prominences to fuse. often associated with cleft chin, and a partial fusion of teh mandibular prominences

Question 12

What does the maxillary prominences form?

Answer 12

lateral parts of the upper lip and jaw, and the secondary palate or palatine shelves
nasolacrimal
mimetic muscles
muscles of mastication

Question 13

Describe the mimetic muscle.

Answer 13

mesenchyme from Arch II invades into the maxillary and mandibular swellings (arch I) , and form the muscles of facial expression

these muscles are innervated by SVE fibers from the facial n.. Special visceral efferent fibers innervate muscles of branchiomeric origin

Question 14

Describe the development of muscles of mastication.

Answer 14

derived from the mesenchyme of Arch I. They are innervated by SVE fibers from the mandibular division of the trigeminal nerve.

Question 15

Describe the formation of the pharyngeal arches?

Answer 15

arches form in craniocaudal sequences during the weeks 4-5 (day 24: arches I and II are formed)

arches form in craniocaudal sequence during weeks 4-5 (day 27 arches I (maxillary and mandibular), II, and III)

Day 31: all pharyngeal arches are formed, corresponding development of pharyngeal pouches

Question 16

The ______ membrane separates the nasal sacs from the primitive oral cavity.

Answer 16

oronasal membrane

it break down to form the primitive choanae. The definitive choanae await the development of the palate and nasal septum

Question 17

The secondary palate fuses and separates the ______ cavity from the _____ cavity.

Answer 17

nasal cavity from the oral cavity

Question 18

Olfactory epithelium is derived from _____

Answer 18

entoderm (SVA)

Question 19

Congenital Malformations of the Face

Answer 19

Anterior cleft deformity: results from a failure of the medial nasal and maxillary swellings to fuse

posterior cleft deformity: palatine shelves do not fuse during development

Question 20

What muscles, nerve, skeletal structure, artery arise from the 1st branchial arch?

Answer 20

Muscles: Mastication, anterior digastric, tensor tympani and tensor palati
Nerve: trigeminal n.
Skeletal structure: maxilla, incus, malleus
Artery: degenerates

tympanic membrane
external auditory meatus

Question 21

What muscles, nerve, skeletal structure, artery arise from the 2nd branchial arch?

Answer 21

Muscles: mimetic ms., posterior digastric, stapedius, stylohyoid
Nerve: Facial n.
Skeletal structure: stapes, hyoid (lesser Cornu)
Artery: degenerates

Question 22

What muscles, nerve, skeletal structure, artery arise from the 3rd branchial arch?

Answer 22

Muscles: stylopharyngeus 
Nerve: glossopharyngeal n. 
Sketetal structures: hyoid (body and great cornu) 
Artery: stem of internal carotids
Artery: stem of internal carotids

Question 23

What muscles, nerve, skeletal structure, artery arise from the 4th branchial arch?

Answer 23

Muscles: pharyngeal mm, and laryngeal mm.
Nerve: vagus n.
Skeletal structures: laryngeal cartilages
Artery: left: aortic arch, rt: subclavian

Question 24

First arch syndrome

Answer 24

Treacher Collins Syndrome (mandibulofacial dysostosis)
impaired growth of the midface
malar and mandibular hypoplasia
conductive hearing loss due to underdevelopment of ossicles and usually affects the hearing in both ears equally