1. The development of the head and neck

2. Vývoj hlavy, krku Carnegie 13 (28 – 32 days) 4 – 6 mm, 30 somites
pharyngeal arches

3. lips oral cavity teeth tongue hard palate soft palate pharynx larynx
vestibule
teeth
tongue
hard palate
soft palate
pharynx
larynx

4. parotid gland
submandibular gland
sublingual gland

5. thyroid gland parathyroid gland thymus 4 bodies

6. Development of the digestive tube
primitive gut
formed during the 4th week, as the head, tail and lateral folds incorporate a part of the yolk sack into the embryo
foregut (preentereon) – separated from the stomodeum (primitive mouth) by membrana oropharyngea, protrusion of the base of the lower respiratory tract
midgut (mesenteron) – distally from the liver bud to ductus vitellinus
hindgut (metenteron) – further, separated from proctodeum (anal pit) by membrana cloacalis

7. Origin of the mesenchyme
paraaxial mesoderm (non-segmented)
bones of the base of the skull and some of the bones of calvaria
all the skeletal muscles
dermis and fibrous tissue on the dorsal part of the head
ectomesenchyme (from the neural crest)
skeleton of the face and pharyngeal arches
ectodermal placodes (thickened areas of ectoderm)
pharyngeal arches
occipital segments (basis et condyli ossis occipitalis)

8. Thomas W. Sadler, Langman´ Medical embryology, 10th edition
Pharyngeal apparatus
pharyngeal arches (arcus pharyngei)
pharyngeal pouches (sacci pharyngei)
pharyngeal grooves (sulci pharyngei)
pharyngeal membranes (membranae pharyngeae)
Thomas W. Sadler, Langman´ Medical embryology, 10th edition

9. Pharyngeal arches (arcus pharyngei)
paired structures
begin to develop in the 4th-5th week
separation of the columns of the mesenchyme:
there are pharyngeal grooves on the outer side (depressions in the ectoderm)
there are pharyngeal pouches on the inner side (formed by the endoderm of the primitive larynx)
grooves and pouches never merge (no gills form)
the mesenchyme of neural crest cells is streaked by paraaxial mesoderm and in each pharyngeal arch gives rise to muscles
cartilages and skeleton of the arches are differentiated from the ectomesenchyme
each arch is innervated by a cranial nerve and has its own artery (aa. arcuum pharyngeorum = aortic arches)
5th arch does not arise

11. Aortic arches (Aa. arcuum pharyngeorum)

12. Derivatives of the pharyngeal arch arteries I
1st pair – arteria maxillaris + carotis externa
2nd pair – arteria stapedia
3rd pair – proximally - arteria carotis communis
- distally - arteria carotis interna

13. Derivatives of the pharyngeal arch arteries II
4th pair –
left – part of arcus aortae
right – a. subclavia dx.
distal part of a. subclavia dx. comes from aorta dorsalis dextra
a. subclavia sin. is not a derivative of arcus aortae, but of the 7th intersegmental artery

14. Derivatives of the pharyngeal arch arteries III
5th pair - Ø
6th pair –
left prox. arteria pulmonalis sinistra
dist. ductus arteriosus (Botali)
right prox. arteria pulmonalis dextra
dist. Ø

17. (maxillary and mandibular process) n. trigeminus
arch
nerve
muscles
skeletal structures
ligaments
arteries
mandibular
(maxillary and mandibular process)
n. trigeminus
muscles of mastication
(m. temporalis, m. masseter, m. pterygoideus medialis et lateralis)
m. mylohyoideus, venter anterior m. digastrici
m. tensor tympani
m. tensor veli palatini
premaxilla, maxilla, os palatinum, os zygomaticum, squama ossis temporalis, Meckel´s cartilage, mandibula, malleus, incus
lig. mallei ant.,
lig. sphenomandibulare
a. maxillaris
hyoid
n. facialis
muscles of facial expression
(m. buccinator, mm. auriculares, m. frontalis, platyzma, m. orbicularis oris et oculi)
m. stapedius
m. stylohyoideus, venter posterior m. digastrici
stapes,
processus styloideus, cornua minora et corpus ossis hyoidis (upper part)
lig. stylohyoideum
a. stapedia
n.glossopharyngeus
m. stylopharyngeus
cornua majora et
corpus ossis hyoidis (lower part)
a. carotis communis
a. carotis interna (proximal part of pars cervicalis)
left
n. laryngeus superior (n.X)
m. cricothyroideus, m. levator veli palatini, m. constrictor pharyngis med. et inf.,
intrinsic muscles of larynx
striated muscles of the oesophagus
5th arch is missing
cartilaginous parts of the 4th and 6th arch merge into a common base of the cartilages of the larynx
cartilago thyroidea,
cricoidea, arytenoidea, corniculata, cuneiformis
arcus ortae from a. carotis communis sin. to a. subclavia sin
right
prox. part of a.subclavia dx.
n. laryngeus recurrens (fibres from n. accessorius using n. vagus)
a.pulmonalis sin., ductus arteriosus
a.pulmonalis dx.

18. First pharyngeal arch (arcus pharyngeus primus)
2 processes
maxillary (cranially)
mandibular (caudally)
contains the Meckel´s cartilage (gives rise to malleus and incus)
formation of the lower jaw
merging of the right and left mandibular process, subsequent membranous ossification
Thomas W. Sadler, Langman´ Medical embryology, 10th edition

19. Second pharyngeal arch (arcus pharyngeus secundus)
cartilage (= Reichert´s cartilage)
by merging of the right and left arch in the midline a part of the body and lesser horns of a hyoid bone are formed
Thomas W. Sadler, Langman´ Medical embryology, 10th edition

20. Fourth pharyngeal arch
Third pharyngeal arch
cornua majora + caudal part of corpus ossis hyoideum
innervation: n. IX
Fourth pharyngeal arch
merges with the 6th arch
cartilago cricoidea + thyroidea
muscles of larynx, palate (apart from m. tensor veli palatini), pharynx (apart from m. stylopharyngeus)
innervation: n. X (n. laryngeus sup.)

21. Fifth pharyngeal arch Sixth pharyngeal arch does not arise in human
merges with the 4th arch
muscles of larynx
innervation: n.X (n. laryngeus recurrens – contains the fibres from n.XI)

22. Pharyngeal pouches (sacci pharyngei)
human embryo has 5 pouches
their endoderm gives rise to branchiogenic organs
Thomas W. Sadler, Langman´ Medical embryology, 10th edition

23. First pharyngeal pouch
recessus tubotympanicus (tubotympanic recess)
blind recess (toward the 1st pharyngeal groove)
its end is broaden into the primitive tympanic cavity
medial part remains straight
tuba auditiva Eustachii
together with the 1st pharyngeal groove participates in formation of an eardrum (membrana tympanica)

24. Second pharyngeal pouch
base of the palatine tonsil (tonsilla palatina)
fossa supratonsillaris

25. Third pharyngeal pouch
dorsal part
inferior parathyroid bud
ventral part
thymic bud
bases migrate caudally

26. Fourth pharyngeal pouch
dorsal part
superior parathyroid bud
ventral part
rudimentary
ultimopharyngeal body (corpus ultimopharyngeum / ultimobranchiales)
cells from the neural crest
differentiate into the parafolicular C-cells of the thyroid gland (calcitonin)

27. Pharyngeal grooves 4 paires of grooves are formed within the 5th week
dorsal part of the 1st groove persists as the external acoustic meatus (meatus acusticus externus)
epithelium on the floor creates the outer surface of an eardrum (membrana tympanica)
other grooves come to lie in a depression  sinus cervicalis (cervical sinus)
sinus cervicalis is obliterated as the neck develops, lateral cervical cysts may persist  fistulae

28. Lateral cervical fistula

29. Tongue - innervation n. V3 n. VII n. IX. n. X. n. lingualis
chorda tympani
n. IX.
n. X.

30. Development of the tongue I
4th week: on the inner side of the pharyngeal pouches (primordia lingualia)
1st arch: tuberculum impar (wears off) + 2 tubercula lingualia lateralia  apex + dorsum linguae (n.V3)
2nd arch: copula (wears off) - n.VII - chorda tympani (taste)
3rd-4th arch: eminentia hypobranchialis  radix linguae (n.IX, n.X)
sulcus terminalis (separates the body and the root of the tongue)
4th arch epiglottis (n. X)
muscles:
from myotomes of the occipital somites (n. XII)
from the 4th arch (n. X - m. palatoglossus)

31. Development of the tongue II
Thomas W. Sadler, Langman´ Medical embryology, 10th edition

32. Congenital abnormalities of the tongue
cysts and fistulae – remnants of the thyroglossal duct
ankyloglossia (tongue-tie)
short frenulum linguae
macroglossia
microglossia
glossoschissis (= cleft tongue)
rare, incomplete cleft

33. Ankyloglossia

34. Macroglossia x Microglossia

35. Development of the thyroid gland
the growth of the epithelium between tuberculum impar and copula (later location of foramen caecum)
growths in front of the pharynx in a caudal direction
within the descent is connected to the tongue thanks to ductus thyroglossus
progressive descent in front of the hyoid bone and the cartilages of the larynx
within the 7th week gets to its final place in front of the trachea
gets functional at the end of the 3rd month

36. Congenital abnormalities of the thyroid gland
thyroglossal duct cysts
may form anywhere along the course of it during the descent of the thyroid gland from the tongue
thyroglossal duct fistulae
communication of the cysts with the outer space
ectopic thyroid gland
along the course of the descent
most often at the root of the tongue
this tissue may be functional

37. Thyroglossal duct cysts

38. Processus pyramidalis glandulae thyroideae
the most common congenital abnormality
along the course of the descent
40 %

39. DiGeorge‘s syndrome Aplasia thymoparathyroidea
microdeletion 22q11.2
1:3000

40. Development of the face I
facial primordia appear at the end of the 4th week (neural crest ectomesenchyme of the 1st pharyngeal arch) around the stomodeum
maxillary prominences laterally
mandibular prominences caudally
frontonasal prominence cranially
on each side develop bilateral oval thickenings of the surface ectoderm  nasal placodes
they depress within the 5th week  nasal pits
pits are bordered by horseshoe-shaped elevations = medial and lateral nasal prominences

41. Development of the face II
Thomas W. Sadler, Langman´ Medical embryology, 10th edition

42. Development of the face III
maxillary prominences enlarge (cheeks and upper jaw) and growth medially – pressing medial nasal prominences to the midline, then they merge
upper lip is formed by the maxillary prominences and medial nasal prominences
lower lip and jaw are formed by mandibular prominences that merge in the midline
nose arises from 5 sources:
frontonasal prominence, 2 medial nasal prominences, 2 lateral nasal prominences

43. Development of the oral and nasal cavity
stomodeum
a pit lined with ectoderm
boundaries:
lower processes of the 1st pharyngeal arch – mandibula
on sides upper processes of the 1st pharyngeal arch – maxilla
frontonasal prominence with nasal placodes from above ( pits, vesicles, open into the primitive oral cavity), medial and lateral nasal prominences
membrana oropharyngea (buccopharyngea) breaks up on the 26th day

44. Development of the palate I
primary palate
from intermaxillary segment (by merging of both medial nasal prominences)
lip component  philtrum
component for the upper jaw (carries 4 incisors)
palatine component (forms the primary palate)
passes continuously into the nasal septum (from the frontonasal prominence)
secondary palate
by merging of the palatine processes of the maxillary process (6th week)
fusion with the primary palate (os incisivum) in front

45. Development of the palate II
Thomas W. Sadler, Langman´ Medical embryology, 10th edition

46. Separation of the oral and nasal cavity
Thomas W. Sadler, Langman´ Medical embryology, 10th edition

47. Cleft malformations of the face and the palate I
lack of fusion of the structures (1:550)
anterior palate clefts (cheiloschisis, cheilognathoschisis)
lateral cleft lip, clet upper jaw, cleft between the primary and secondary palates
partial or complete lack of fusion of the maxillary prominence with the medial nasal prominence on one or both sides
posterior palate clefts (palatoschisis)
cleft secondary palate, cleft uvula
combination of clefts lying anterior as well as posterior to the incisive foramen (cheilo-gnatho-palatoschisis)
oblique facial clefts
failure merging of the maxillary prominence with its corresponding lateral nasal prominence
median (midline) cleft lip
rare abnormality
incomplete merging of the two medial nasal prominences in the midline

48. Cleft malformations of the face and the palate II
Thomas W. Sadler, Langman´ Medical embryology, 10th edition

49. Cleft malformations of the face and the palate III
before
before
after
after

50. Development of the salivary glands
epithelial pouches of the oral cavity (6th – 8th week)
the intergrowth into the adjacent ectomesenchyme  its connective tissue comes from the neural crest
parenchyme ( secretion) comes from the proliferating oral epithelium
ectoderm  gl. parotis
endoderm  gl. submandibularis et sublingualis

51. Development of the teeth I
6th week: proliferation of the oral epithelium (ectoderm) into the surrounding ectomesenchyme
dental lamina (parallell to labiogingival crest)
ectoderm → enamel organ
outer enamel epithelium
stratum intermedium, stellate reticulum
inner enamel epithelium - ameloblasts
ectomesenchyme → dental papilla - odontoblasts

52. Development of the teeth II
production of the dentin
odontoblasts: procollagen - predentin - dentin
with thickening of the dentin layer, odontoblasts retreat into the dental papilla, leaving a thin cytoplasmic processes – dental processes (Tomes´ fibres)
production of the enamel
basal surface of the ameloblasts is becoming secretory:
enamel matrix (organic - mineralisation)
development of the roots
dental epithelial layers penetrate into the underlying mesenchyme  root sheath, mesenchymal cells on the outside of the tooth and in contact with dentin of the root differentiate into cementoblasts
permanent teeth
secondary dental lamina is located lingually to the primary one

53. Development of the teeth III
Thomas W. Sadler, Langman´ Medical embryology, 10th edition