Embryology of the head and neck Flashcards
Describe the differences in the mesoderm found in the Trunk and in the head.
T:
Segmental nature
somites
derivatives
H:
Occipital somites
Pre-otic/auricular/orbital mesoderm
mesoderm brachial arches
Which structures do the neural crest cells produce?
Cranial and sensory ganglia and nerves
Adrenal medulla
Melanocytes
Phyrangeal pouch cartilage
meninges
bulbar and conal ridges
cranial mesenchyme
Which gene controls the neural crest migration to the pharyngeal pouches?
Hox
Which structures make up the pharyngeal arches?
Striated muscle
cartilage
artery
nerve
Which structures arise from pharyngeal arch 1?
maxilla
mandible
squamous temporal
malleus and incus
mastication
mylohyoid
anterior digastric
Tensor tympani
Tensor veli palatini
Trigenimal nerve
External carotid artery, maxillary artery.
Which structures arise from pharyngeal arch 2?
Stapes
styloid process
lesser horn and body of hyoid
facial expression
stapedius
stylohyoid
posterior digastric
facial nerve and stapedial aa
Which structures arise from the pharyngeal arch 3?
greater horn and body of hyoid
stylopharyngeus
Glossophyrangeal
Common carotid
Which structures arise from pharyngeal arch 4 and 6?
larynx
pharynx
levator of palate
oesophagus
Vagus
Right subclavian
Which structures arise from pharyngeal arch 5?
Rudimentary, haha!
What is form by pouch 1?
Eustachian tube
What form by pouch 2?
palatine tonsils
What form by pouch 3?
upper derivative forms thymus
and lower forms inferior parathyroid
What form by pouch 4?
Superior parathyroid
C cells of thyroid
What form by pouch 5?
c cells of the thyroid gland
Explain the development of the 2nd cleft.
Downward growth covering arches 2-4.
Forms the platysma muscle.
initially forms the sinus of his when the arch combines with the third and fourth cleft.
Eventually forms the cervical sinus
Describe the development of the thyroid gland.
originates between the 1st and 2nd pharyngeal pouches near the base of the tongue.
it then descends through the foramen cecum of the tongue to its position by the larynx forming a thyroglossal duct.
The duct will close.
Describe the development of the parathyroid gland.
3rd pouch gives rise to the inferior parathyroid and the 4th pouch gives rise to the superior parathyroid.
Both of them descend from to the thyroid, however, the inferior parathyroid descends further hence it is lower than the superior parathyroid pouch
Describe the development of the tongue.
Anterior part 2/3 develops from the first arch
There is lateral and medial (tuberculum impar) lingual swelling
the lateral swelling fuses and forms the median sulcus.
forming the fungiform posterior and the filiform and foliate more anteriorly
posterior part 1/3 from the 3rd arch
A hypopharyngeal eminence component forms
this grows up forming a terminal sulcus, which is prominent after fusion.
There is an outgrowth of circumvallate papillae.
they migrate forward into the fungiform region, which drags the nerve supply with them.
Describe the development of the face.
Frontonasal prominence
- nasal placode- gives rise to the nasolateral process and nasomedial process. This then undergoes merging. A nasolacrimal groove also forms that houses the tear ducts.
Maxillary and mandibular prominences
the processes fuse across the midlines.
then it approaches the frontonasal process (ascends)
the external acoustic meatus also develops inferior and then ascends to its position.
Describe the development of the hard palate.
Primary palate- median palatine process from the intermaxillary segment of the maxilla
Secondary- 2 lateral palatine process- maxillary prominences
Elevates
horizontal growth
once the tongue becomes smaller and moves inferiorly there is midline contact and eventually fusion.
