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DEVELOPMENT
OF HEAD AND
NECK
Carnegie 13 (28 – 32 days)
4 – 6 mm, 30 somites
Vývoj hlavy, krku
pharyngeal
arches
• 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 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 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 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 (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)
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
Aortic arches
(Aa. arcuum pharyngeorum)
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
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
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
arch
1. mandibular
(maxillary
and
mandibular
process)
nerve
n. trigeminus
muscles
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
skeletal structures
premaxilla, maxilla, os
palatinum, os
zygomaticum, squama
ossis temporalis,
Meckel´s cartilage,
mandibula, malleus,
incus
ligaments
lig. mallei ant.,
lig.
sphenomandibulare
arteries
a. maxillaris
2.
hyoid
n. facialis
stapes,
processus styloideus,
cornua minora et
corpus ossis hyoidis
(upper part)
lig. stylohyoideum
a. stapedia
3.
arch
n.glossopharyngeus
muscles of facial
expression
(m. buccinator, mm.
auriculares, m. frontalis,
platyzma, m. orbicularis
oris et oculi)
m. stapedius
m. stylohyoideus, venter
posterior m. digastrici
m. stylopharyngeus
4.
left
n. laryngeus superior
(n.X)
6.
right
left
right
m. cricothyroideus, m.
levator veli palatini, m.
constrictor pharyngis
med. et inf.,
n. laryngeus recurrens intrinsic muscles of
larynx
(fibres from n.
striated muscles of the
accessorius using n.
oesophagus
vagus)
cornua majora et
corpus ossis hyoidis
(lower part)
a. carotis communis
a. carotis interna
(proximal part of pars
cervicalis)
5th arch is missing
cartilaginous parts of the
4th and 6th arch merge
into a common base of
the cartilages of the
larynx
arcus ortae from a.
carotis communis sin. to
a. subclavia sin
cartilago thyroidea,
cricoidea, arytenoidea,
corniculata,
cuneiformis
prox. part of a.subclavia dx.
a.pulmonalis sin., ductus
arteriosus
a.pulmonalis dx.
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
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
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.)
Fifth 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
Pharyngeal pouches (sacci
pharyngei)
• human embryo has 5 pouches
• their endoderm gives rise to branchiogenic
organs
Thomas W. Sadler, Langman´ Medical embryology, 10th edition
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)
Second 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 pouch
• dorsal part
– inferior parathyroid bud
• ventral part
– thymic bud
• bases migrate caudally
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)
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
Lateral cervical fistula
http://www.ultratwistersgym.com/Resources/Head/Head%20and%20Neck.html
http://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 tongue
• n. V3
– n. lingualis
• n. VII
– chorda tympani
• n. IX
• n. X
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)
Development of tongue
Thomas W. Sadler, Langman´ Medical embryology,
10th edition
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
Ankyloglossia
http://www.ghorayeb.com/TongueTie.html
Macroglossia - Microglossia
http://www.consultantlive.com/display/article/10162/43839
http://dentallecnotes.blogspot.cz/2011/08/developmental-disturbances-of-tongue.html
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
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
Thyroglossal duct cysts
http://www.surgical-tutor.org.uk/defaulthome.htm?tutorials/thyroglossal.htm~right
http://www.learningradiology.com/archives06/COW%20231Thyroglossal%20Duct%20Cyst/tgdccorrect.html
Processus pyramidalis
glandulae thyroideae
• the most common congenital defect
• along the course of the descent
• 40 %
http://www.anatomyatlases.org/AnatomicVariants/OrganSystem/Images/82.shtml
DiGeorge syndrome
Aplasia thymoparathyroidea
microdeletion 22q11.2
1:3000
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
Development of face
Thomas W. Sadler, Langman´ Medical embryology, 10th edition
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
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
Development 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 palate
Thomas W. Sadler, Langman´ Medical embryology, 10th edition
Separation of oral and nasal cavity
Thomas W. Sadler, Langman´ Medical embryology, 10th edition
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
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
Cleft malformations of face and palate
http://blog.johnrchildress.com/2011/06/0
7/real-leadership-and-hope/
Thomas W. Sadler, Langman´ Medical embryology, 10th edition
http://www.craniofacial.net/cleft-lip-cleft-palate-only
Cleft malformations of face and palate
http://www.rodina.cz/clanek3188.htm
before
before
after
after
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
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)
Development 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 teeth
Thomas W. Sadler, Langman´ Medical embryology, 10th edition