DEVELOPMENT OF HEAD AND NECK

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1 DEVELOPMENT OF 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
oral 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 stomodeum (primitive mouth) by membrana oropharyngea, protrusion of base of lower respiratory tract midgut (mesenteron) – aborally from liver bud to Cannon-Böhm point hindgut (metenteron) – further, separated from proctodeum (anal pit) by membrana cloacalis

7 Origin of mesenchyme paraaxial mesoderm (non-segmented)
bones of skull base and some of bones of calvaria all skeletal muscles dermis and fibrous tissue on the dorsal part of head ectomesenchyme (from the neural crest) skeleton of 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 columns of mesenchyme: pharyngeal grooves on external side (depressions in ectoderm) pharyngeal pouches on internal side (formed by endoderm of primitive larynx) grooves and pouches never merge (no gills form)

10 Pharyngeal arches (arcus pharyngei)
mesenchyme of neural crest cells is streaked by para-axial mesoderm and in each pharyngeal arch gives rise to muscles cartilages and skeleton of arches are differentiated from ectomesenchyme each arch is innervated by a cranial nerve and has its own artery (aa. arcuum pharyngeorum = aortic arches) 5th arch does not arise

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12 Aortic arches (Aa. arcuum pharyngeorum)

13 Derivatives of aortic arches
1st pair – arteria maxillaris + a. carotis externa 2nd pair – arteria stapedia 3rd pair – proximally - arteria carotis communis – distally - arteria carotis interna

14 Derivatives of aortic arches
4th pair left – part of arcus aortae right – arteria subclavia dx. distal part of a. subclavia dx. arises from aorta dorsalis dextra a. subclavia sin. is not derived from aortic arch but from the 7th intersegmental artery

15 Derivatives of aortic arches
5th pair – Ø 6th pair left proximally: arteria pulmonalis sinistra left distally: ductus arteriosus (Botali) right proximally: arteria pulmonalis dextra right distally: Ø

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18 (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.

19 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

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

21 Fourth pharyngeal arch
Third pharyngeal arch cornua majora + caudal part of corpus ossis hyoidei innervation: n. IX Fourth pharyngeal arch merges with 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.)

22 Fifth pharyngeal arch Sixth pharyngeal arch
does not arise in human at all Sixth pharyngeal arch merges with 4th arch muscles of larynx innervation: n.X (n. laryngeus recurrens) containing fibres from n.XI

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

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

25 Second pharyngeal pouch
base of palatine tonsil (tonsilla palatina) fossa supratonsillaris

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

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

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

30 Lateral cervical fistula

31 Innervation of tongue n. V3 n. VII n. IX n. X n. lingualis
chorda tympani n. IX n. X

32 Development of tongue 4th week: primordia lingualia appear on inner side of pharyngeal pouches 1st arch: tuberculum impar (fades out) + 2 tubercula lingualia lateralia  apex + dorsum linguae (n.V3) 2nd arch: copula (wears off) – n.VII – chorda tympani (taste) 3rd-4th arch: eminentia hypopharyngea  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 occipital somites (n. XII) from 4th pharyngeal arch (n. X – only m. palatoglossus)

33 Thomas W. Sadler, Langman´ Medical embryology, 10th edition
Development of tongue Thomas W. Sadler, Langman´ Medical embryology, 10th edition

34 Congenital defects of tongue
cysts and fistulae – remnants of the thyroglossal duct ankyloglossia (t= ongue-tie) short frenulum linguae macroglossia microglossia glossoschissis (= cleft tongue) rare, incomplete cleft

35 Ankyloglossia

36 Macroglossia - Microglossia

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

38 Congenital defects of thyroid gland
thyroglossal duct cysts may develop anywhere along the course of descent of thyroid gland from the tongue thyroglossal duct fistulae communication of cysts with external space ectopic thyroid gland along the course of descent most often at root of tongue this tissue may be functional

39 Thyroglossal duct cysts

40 Processus pyramidalis glandulae thyroideae
the most common congenital defect along the course of the descent 40 %

41 DiGeorge syndrome Aplasia thymoparathyroidea
microdeletion 22q11.2 1:3000

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

43 Thomas W. Sadler, Langman´ Medical embryology, 10th edition
Development of face Thomas W. Sadler, Langman´ Medical embryology, 10th edition

44 Development of face 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

45 Development of oral and nasal cavity
stomodeum a pit lined with ectoderm boundaries: lower processes of 1st pharyngeal arch – mandibula on sides upper processes of 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 26th day

46 Development of palate primary palate secondary 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 nasal septum (from frontonasal prominence) secondary palate by merging of palatine processes of maxillary process (6th week) ventrally fusion with primary palate (future os incisivum)

47 Thomas W. Sadler, Langman´ Medical embryology, 10th edition
Development of palate Thomas W. Sadler, Langman´ Medical embryology, 10th edition

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

49 Cleft malformations of face and palate
impaired fusion of structures (1:550) anterior palate clefts (cheiloschisis, cheilognathoschisis) lateral lip, upper jaw cleft, cleft between the primary and secondary palates partial or complete lack of fusion of maxillary prominence with medial nasal prominence on one or both sides posterior palate clefts (palatoschisis) secondary palate cleft, uvula cleft

50 Cleft malformations of face and palate
combination of clefts lying anterior as well as posterior to incisive foramen (cheilo-gnatho-palatoschisis) oblique facial clefts failure in merging of maxillary prominence with its corresponding lateral nasal prominence median (midline) lip cleft rare abnormality incomplete merging of two medial nasal prominences in the midline

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

52 Cleft malformations of face and palate
before before after after

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

54 Development of teeth 6th week: proliferation of oral epithelium (ectoderm) into 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)

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

56 Thomas W. Sadler, Langman´ Medical embryology, 10th edition
Development of teeth Thomas W. Sadler, Langman´ Medical embryology, 10th edition

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