The development of the head and neck. Vývoj hlavy, krku pharyngeal arches Carnegie 13 (28 – 32 days) 4 – 6 mm, 30 somites

The development The development of the head and neckof the head and neck

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

– 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 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

Origin of the mesenchymeOrigin 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)

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 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

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

Derivatives of the pharyngeal arch arteries IDerivatives 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

Derivatives of the pharyngeal arch arteries IIDerivatives 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

Derivatives of the pharyngeal arch arteries IIIDerivatives of the pharyngeal arch arteries III• 5th pair - Ø• 6th pair –

– left prox. arteria pulmonalis sinistradist. ductus arteriosus (Botali)

– right prox. arteria pulmonalis dextradist. 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 the right and left arch in the

midline a part of the body and lesser horns of a hyoid bone are formed


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

Fourth pharyngeal archFourth 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.)

Fifth pharyngeal archFifth 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)

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 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)

Second pharyngeal pouchSecond pharyngeal pouch• base of the 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

/ ultimobranchiales) • cells from the neural crest• differentiate into the parafolicular C-cells of the thyroid

gland (calcitonin)

Pharyngeal groovesPharyngeal 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

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

Tongue - Tongue - innervationinnervation

• n. V3 – n. lingualis

• n. VII – chorda tympani

• n. IX.• n. X.

Development of the tongue IDevelopment 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)

Development of the tongue IIDevelopment of the tongue II


Congenital abnormalities of the tongueCongenital 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

AnkyloglossiaAnkyloglossia

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

Macroglossia x MicroglossiaMacroglossia x 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• 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

Congenital abnormalities ofCongenital abnormalities ofthe thyroid glandthe 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

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 glandulae Processus pyramidalis glandulae thyroideaethyroideae

• the most common congenital abnormality• along the course of the descent• 40 %

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

DiGeorge‘s syndromeDiGeorge‘s syndromeAplasia thymoparathyroideaAplasia thymoparathyroidea

microdeletion 22q11.21:3000

Development of the face IDevelopment 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

Development of the face IIDevelopment of the face II


Development of the face IIIDevelopment 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

Development of the Development of the oral and nasal cavityoral and nasal cavity

stomodeum• a pit lined with ectodermboundaries: • 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

Development of the palate IDevelopment 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

Development of the palate IIDevelopment of the palate II


Separation of the oral and nasal cavitySeparation of the oral and nasal cavity


Cleft malformations of the Cleft malformations of the face and the palate Iface 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

Cleft malformations of the Cleft malformations of the face and the palate IIface and the palate II

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

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


Cleft malformations of the Cleft malformations of the face and the palate IIIface and the palate III

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

beforebefore

afterafter

Development of the salivary glandsDevelopment 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

Development of the teeth IDevelopment 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

Development of the teeth IIDevelopment 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

Development of the teeth IIIDevelopment of the teeth III


Documents

The development of the head and neck. Vývoj hlavy, krku pharyngeal arches Carnegie 13 (28 – 32 days) 4 – 6 mm, 30 somites