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