DEVELOPMENT OF HEAD AND NECK. Vývoj hlavy, krku pharyngeal arches Carnegie 13 (28 – 32 days) 4 – 6 mm, 30 somites

DEVELOPMENT DEVELOPMENT OF HEAD AND OF HEAD AND

NECKNECK

Vývoj hlavy, krku

pharyngeal arches

Carnegie 13 (28 – 32 days)Carnegie 13 (28 – 32 days)4 – 6 mm, 30 somites4 – 6 mm, 30 somites

• lips

• oral cavity– oral vestibule

• teeth

• tongue

• hard palate

• soft palate

• pharynx

• larynx

• parotid gland

• submandibular gland

• sublingual gland

• thyroid gland

• parathyroid gland– 4 bodies

• thymus

http://www.mayoclinic.com/images/image_popup/pthyroid.jpg

Development of the digestive tubeDevelopment 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

Origin of mesenchymeOrigin 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)

Pharyngeal apparatusPharyngeal 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

Pharyngeal arches (Pharyngeal arches (arcus pharyngeiarcus 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)

Pharyngeal arches (Pharyngeal arches (arcus pharyngeiarcus 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

Aortic archesAortic arches((Aa. arcuum pharyngeorumAa. arcuum pharyngeorum))

Derivatives of aortic archesDerivatives of aortic arches

• 1st pair – arteria maxillaris + a. carotis externa• 2nd pair – arteria stapedia

• 3rd pair – proximally - arteria carotis communis

– distally - arteria carotis interna

Derivatives of aortic archesDerivatives 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

Derivatives of aortic archesDerivatives 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

arch nerve muscles skeletal structures ligaments arteries1. mandibular (maxillary

and mandibular process)

n. trigeminus muscles of mastication(m. temporalis, m. masseter, m. pterygoideus medialis et lateralis)m. mylohyoideus, venter anterior m. digastricim. tensor tympanim. 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

2. hyoid n. facialis muscles of facial expression (m. buccinator, mm. auriculares, m. frontalis, platyzma, m. orbicularis oris et oculi)m. stapediusm. stylohyoideus, venter posterior m. digastrici

stapes,processus styloideus, cornua minora et corpus ossis hyoidis (upper part)

lig. stylohyoideum a. stapedia

3. arch n.glossopharyngeus m. stylopharyngeus cornua majora etcorpus ossis hyoidis (lower part)

a. carotis communisa. carotis interna (proximal part of pars cervicalis)

4. left n. laryngeus superior (n.X)

m. cricothyroideus, m. levator veli palatini, m. constrictor pharyngis med. et inf.,intrinsic muscles of larynxstriated muscles of the oesophagus

5th arch is missingcartilaginous parts of the 4th and 6th arch merge into a common base of the cartilages of the larynxcartilago thyroidea,cricoidea, arytenoidea, corniculata, cuneiformis

arcus ortae from a. carotis communis sin. to a. subclavia sin

right prox. part of a.subclavia dx.

6. left n. laryngeus recurrens (fibres from n. accessorius using n. vagus)

a.pulmonalis sin., ductus arteriosus

right a.pulmonalis dx.

First pharyngeal archFirst pharyngeal arch ( (arcus pharyngeus primus)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


Second pharyngeal archSecond pharyngeal arch ( (arcus pharyngeus secundus)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


Third pharyngeal archThird pharyngeal arch• cornua majora + caudal part of corpus ossis hyoidei• innervation: n. IX

Fourth pharyngeal archFourth 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.)

Fifth pharyngeal archFifth pharyngeal arch• does not arise in human at all

• merges with 4th arch

• muscles of larynx

• innervation: n.X (n. laryngeus recurrens)

• containing fibres from n.XI

Sixth pharyngeal archSixth pharyngeal arch

Pharyngeal pouches (Pharyngeal pouches (sacci pharyngeisacci pharyngei))

• human embryo has 5 pouches

• their endoderm gives rise to branchiogenic organs


First pharyngeal pouchFirst 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)

Second pharyngeal pouchSecond pharyngeal pouch

• base of palatine tonsil (tonsilla palatina)

• fossa supratonsillaris

http://biology.clc.uc.edu/fankhauser/labs/microbiology/strep_detection/strep_test.htm

Third pharyngeal pouchThird pharyngeal pouch

• dorsal part– inferior parathyroid bud

• ventral part– thymic bud

• bases migrate caudally

Fourth pharyngeal pouchFourth 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)

Pharyngeal grooves (Pharyngeal grooves (Sulci pharyngeiSulci 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

Lateral cervical fistulaLateral cervical fistula

http://www.ultratwistersgym.com/Resources/Head/Head%20and%20Neck.htmlhttp://journals.tums.ac.ir/full_text.aspx?org_id=59&culture_var=en&journal_id=4&issue_id=1293&manuscript_id=11415&segment=en

Innervation of tongueInnervation of tongue

• n. V3 – n. lingualis

• n. VII – chorda tympani

• n. IX• n. X

Development of tongueDevelopment 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)

Development of tongueDevelopment of tongue


Congenital defects of tongueCongenital 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

AnkyloglossiaAnkyloglossia

http://www.ghorayeb.com/TongueTie.html

Macroglossia - MicroglossiaMacroglossia - Microglossia

http://www.consultantlive.com/display/article/10162/43839 http://dentallecnotes.blogspot.cz/2011/08/developmental-disturbances-of-tongue.html

Development of the thyroid glandDevelopment 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

Congenital defects of thyroid glandCongenital 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

Thyroglossal duct cystsThyroglossal duct cysts

http://www.learningradiology.com/archives06/COW%20231-Thyroglossal%20Duct%20Cyst/tgdccorrect.html

http://www.surgical-tutor.org.uk/default-home.htm?tutorials/thyroglossal.htm~right

Processus pyramidalis Processus pyramidalis glandulae thyroideaeglandulae thyroideae

• the most common congenital defect

• along the course of the descent

• 40 %

http://www.anatomyatlases.org/AnatomicVariants/OrganSystem/Images/82.shtml

DiGeorge syndromeDiGeorge syndromeAplasia thymoparathyroideaAplasia thymoparathyroidea

microdeletion 22q11.21:3000

Development of faceDevelopment of facefacial 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

Development of faceDevelopment of face


Development of faceDevelopment 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

Development of Development of oral and nasal cavityoral and nasal cavity

stomodeum• a pit lined with ectodermboundaries: • 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

Development of palateDevelopment of palate• 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 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)

Development of palateDevelopment of palate


Separation of oral and nasal cavitySeparation of oral and nasal cavity


Cleft malformations of face and palateCleft 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


• 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


http://www.craniofacial.net/cleft-lip-cleft-palate-only

http://blog.johnrchildress.com/2011/06/07/real-leadership-and-hope/



http://www.rodina.cz/clanek3188.htm

beforebefore

afterafter

Development of salivary glandsDevelopment 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

Development of teethDevelopment 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)

Development of teethDevelopment of teeth• production of dentine

– 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

Development of teethDevelopment of teeth


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DEVELOPMENT OF HEAD AND NECK. Vývoj hlavy, krku pharyngeal arches Carnegie 13 (28 – 32 days) 4 – 6 mm, 30 somites