|Embryology - 27 Apr 2017 Expand to Translate|
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- 1 Introduction
- 2 Some Recent Findings
- 3 Textbooks
- 4 Objectives
- 5 The Pharynx
- 6 Pharyngeal Arch Components
- 7 Early Face and Pharynx
- 8 Pharyngeal Arch Development
- 9 Arch Arteries
- 10 Arch Cartilage
- 11 Arch Muscle
- 12 Arch Nerve
- 13 Arch Pouches
- 14 Thyroid Gland
- 15 Anterior Pituitary
- 16 Face Development
- 17 Frontonasal Process
- 18 Head/Skull
- 19 Sensory Placodes
- 20 Head Growth
- 21 Palate
- 22 Ear Auricles
- 23 Tongue Development
- 24 Pharyngeal Arch Tables
- 25 Movies
- 26 References
- 27 Additional Images
- 28 Terms
- 29 External Links
- 30 Glossary Links
The head and neck is not really a "system", but structurally quite different in origin from the body. The head and neck are one of the most complicated structures that the embryo forms, with special intermediate structures (the pharyngeal arches) and contributions from all 3 embryonic layers (ectoderm, mesoderm, endoderm), and significantly, a major contribution from the neural crest. Neural crest contributes jaw skeletal elements,, connective tissues and tendons. The associated muscles derive mainly from cranial mesoderm. These components though will form different structures dependent upon which arch they are within. The cavity within the pharyngeal arches forms the pharynx.
The pharynx contributes to 2 endocrine organs, in the roof the pituitary (hypophysis) and the floor the thyroid. The thyroid gland being one of the first endocrine organs to be formed has an important role in embryonic development. The pharynx floor of all arches also contribute to the formation of the tongue.
Because the head contains many different structures also review notes on: Skull Development, Sensory (placodes, eye, ear, nose, taste), Respiratory (pharynx), Integumentary (teeth, hair) and Endocrine Development (pituitary, thyroid, parathyroid, thymus).
Some Recent Findings
|More recent papers|
This table shows an automated computer PubMed search using the listed sub-heading term.
References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability.
Ralf Janssen Gene expression reveals evidence for EGFR-dependent proximal-distal limb patterning in a myriapod. Evol. Dev.: 2017; PubMed 28444830
Carolyn Hayes, Debra Jackson, Patricia M Davidson, John Daly, Tamara Power Calm to chaos: engaging undergraduate nursing students with the complex nature of interruptions during medication administration. J Clin Nurs: 2017; PubMed 28445621
John Pang, Kathryn R Tringale, Viridiana J Tapia, William J Moss, Megan E May, Timothy Furnish, Linda Barnachea, Kevin T Brumund, Assuntina G Sacco, Robert A Weisman, Quyen T Nguyen, Jeffrey P Harris, Charles S Coffey, Joseph A Califano Chronic Opioid Use Following Surgery for Oral Cavity Cancer. JAMA Otolaryngol Head Neck Surg: 2017; PubMed 28445584
Sebastian Littin, Feng Jia, Kelvin J Layton, Stefan Kroboth, Huijun Yu, Jürgen Hennig, Maxim Zaitsev Development and implementation of an 84-channel matrix gradient coil. Magn Reson Med: 2017; PubMed 28444778
- The Developing Human: Clinically Oriented Embryology (8th Edition) by Keith L. Moore and T.V.N Persaud - Moore & Persaud Chapter Chapter 10 The Pharyngeal Apparatus pp201 - 240.
- Larsen’s Human Embryology by GC. Schoenwolf, SB. Bleyl, PR. Brauer and PH. Francis-West - Chapter 12 Development of the Head, the Neck, the Eyes, and the Ears pp349 - 418.
|You have access the following online Embryology textbooks through the UNSW Library.|
| Moore, K.L. & Persuad, T.V.N. (2008). The Developing Human: clinically oriented embryology (8th ed.). Philadelphia: Saunders.
The following chapter links only work with a UNSW connection.
- List the main structures derived from the pharyngeal arches, pouches and clefts.
- Know the stages and structures involved in the development of the face.
- Predict the results of abnormal development of the face and palate.
- Briefly summarise the development of the tongue.
The cavity within the pharyngeal arches forms the pharynx.
The pharynx contributes to 2 endocrine organs, in the roof the [endocrine7.htm pituitary] (hypophysis) and the floor the thyroid. The thyroid gland being one of the first endocrine organs to be formed has an important role in embryonic development. The pharynx floor of all arches also contribute to the formation of the [head6.htm tongue].
Pharyngeal Arch Components
Major features to identify for each: arch, pouch, groove and membrane. Contribute to the formation of head and neck and in the human appear at the 4th week. The first arch contributes the majority of upper and lower jaw structures.
Early Face and Pharynx
- Pharynx - begins at the buccopharyngeal membrane (oral membrane), apposition of ectoderm with endoderm (no mesoderm between)
Pharyngeal Arch Development
- branchial arch (Gk. branchia= gill)
- arch consists of all 3 trilaminar embryo layers
- ectoderm- outside
- mesoderm- core of mesenchyme
- endoderm- inside
- Mesenchyme invaded by neural crest generating connective tissue components
- cartilage, bone, ligaments
- arises from midbrain and hindbrain region
Each arch contains: artery, cartilage, nerve, muscular component
Arches and Phanynx Form the face, tongue, lips, jaws, palate, pharynx and neck cranial nerves, sense organ components, glands
- Humans have 5 arches - 1, 2, 3, 4, 6 (Arch 5 does not form or regresses rapidly)
- from in rostro-caudal sequence, Arch 1 to 6 from week 4 onwards
- arch 1 and 2 appear at time of closure of cranial neuropore
- Face - mainly arch 1 and 2
- Neck components - arch 3 and 4 (arch 4 and 6 fuse)
- externally separates each arch
- also called a cleft
- only first pair persist as external auditory meatus
- externally separates each arch
- internally separates each arch
- pockets from the pharynx
- ectoderm and endoderm contact regions
- only first pair persist as tympanic membrane
- Pharyngeal Arch 1 (Mandibular Arch) has 2 prominances
- smaller upper- maxillary forms maxilla, zygomatic bone and squamous part of temporal
- larger lower- mandibular, forms mandible
- Pharyngeal Arch 2 (Hyoid Arch)
- forms most of hyoid bone
- Arch 3 and 4
- neck structures
placental vein -> liver -> heart -> truncus arteriosus -> aortic sac -> arch arteries -> dorsal aorta -> placental artery
Human embryo (5mm, lateral view) showing pulmonary arteries
|Arch 5 Artery?|
|Carnegie Stage 14 human embryo.|
- Arch 1 - Meckel's cartilage, horseshoe shaped
- dorsal ends form malleus and incus
- midpart forms ligaments (ant. malleus, sphenomandibular)
- ventral part forms mandible template
- Arch 2 - Reichert's cartilage
- dorsal ends form stapes and Temporal bone styloid process
- ventral part ossifies to form hyoid bone components
- lesser cornu and superior body
- Arch 3- forms greater cornu and inferior part of hyoid
- Arch 4&6- form laryngeal cartilages, except epiglottis (from hypobranchial eminence)
- Arch 1 - muscles of mastication, mylohyoid, tensor tympanic, ant. belly digastric
- Arch 2 - muscles of facial expression, stapedius, stylohyoid, post. belly digastric
- Arch 3 - stylopharyngeus
- Arch 4&6 - crycothyroid, pharynx constrictors, larynx muscles, oesophagus (st. muscle)
Head and Heart Muscle On the left side of the body (right part of figure) the facial expression muscles have been removed to show the masticatory muscles.
- Arch 1 - CN V trigeminal, caudal 2/3 maxillary and mandibular, cranial 1/3 sensory nerve of head and neck, mastication motor
- Arch 2 - CN VII facial
- Arch 3 - CN IX glossopharyngeal
- Arch 4&6 - CN X vagus, arch 4- superior laryngeal, arch 6- recurrent laryngeal
- Arch 1 - elongates to form tubotympanic recess, tympanic cavity, mastoid antrum, eustachian tube
- Arch 2 - forms tonsillar sinus, mostly oblierated by palatine tonsil
- Arch 3 - forms inferior parathyroid and thymus
- Arch 4 - forms superior parathyroid, parafollicular cells of Thyroid
- not a pouch structure
- first endocrine organ to develop day 24
- from floor of pharynx
- descends thyroglossal duct (which closes)
- upper end at foramen cecum
- not a pouch structure
- boundary epitheilal ectoderm in the roof of the pharynx
- forms a pocket (Rathke's pouch) that comes into contact with the ectoderm of developing brain.
- Rathke's pouch is named after German embryologist and anatomist Martin Heinrich Rathke (1793 — 1860).
Begins week 4 centered around stomodeum, external depression at oral membrane
5 initial primordia from neural crest mesenchyme
- single frontonasal prominence (FNP) - forms forehead, nose dorsum and apex
- nasal placodes develop later bilateral, pushed medially
- paired maxillary prominences - form upper cheek and upper lip
- paired mandibular prominences - lower cheek, chin and lower lip
The frontonasal process (FNP) forms the majority of the superior part of the early face primordia. It later fuses with the maxillary component of the first pharyngeal arch to form the upper jaw. Failure of this fusion event during the embryonic period leads to cleft lip. Under the surface ectoderm the process mesenchyme consists of two cell populations; neural crest cells, forming the connective tissues; and the mesoderm forming the endothelium of the vascular network.
A chicken developmental model study has identified a specific surface region, the Frontonasal Ectodermal Zone (FEZ), initially induced by bone morphogenetic proteins that appears to regulate the future growth and patterning of the frontonasal process. The specific frontonasal ectodermal zone was located in the frontonasal process ectoderm flanking a boundary between Sonic hedgehog (Shh) and Fibroblast growth factor 8 (Fgf8) expression domains.
- During week 4 a series of thickened surface ectodermal patches form in pairs rostro-caudally in the head region.
- Recent research suggests that all sensory placodes may arise from common panplacodal primordium origin around the neural plate, and then differentiate to eventually have different developmental fates.
- These sensory placodes will later contribute key components of each of our special senses (vision, hearing and smell). Other species have a number of additional placodes which form other sensory structures (fish, lateral line receptor). Note that their initial postion on the developing head is significantly different to their final position in the future sensory system
in the stage 13/14 embryo (shown below) the otic placode has sunk from the surface ectoderm to form a hollow epithelial ball, the otocyst, which now lies beneath the surface surrounded by mesenchyme (mesoderm). The epithelia of this ball varies in thickness and has begun to distort, it will eventually form the inner ear membranous labyrinth.
lies on the surface, adjacent to the outpocketing of the nervous system (which will for the retina) and will form the lens.
- Links: Lens Development
has 2 components (medial and lateral) and will form the nose olfactory epithelium.
- continues postnatally - fontanelle allow head distortion on birth and early growth
- bone plates remain unfused to allow growth, puberty growth of face
Fetal head growth (circumference)
Chondrocranium - formed from paraxial mesoderm
- cranial end of vertebral column
- modified vertebral elements
- occipital and cervical sclerotome
- bone preformed in cartilage (endochondrial ossification)
Cranial Vault and Facial Skeleton - formed from neural crest
- muscle is paraxial mesoderm
- somitomeres and occipital somites
Calveria - bone has no cartilage (direct ossification of mesenchyme)
- bones do not fuse, fibrous sutures 1. allow distortion to pass through birth canal 2. allow growth of the brain
- 6 fontanelles, posterior closes at 3 months, anterior closes at 18 months
- Links: Skull Development
The palate has two key stages of development during embryonic and an early fetal involving the fusion of structures (epithelia to mesenchymal).
Secondary palate, fusion in the human embryo in week 9. This requires the early palatal shelves growth, elevation and fusion during the early embryonic period. The fusion event is to both each other and the primary palate. palatal shelf elevation | secondary palate
- Links: Palate Development
- form from 6 hillocks (week 5)
- 3 on each of arch 1 and 2
- Ectoderm of the first arch surrounding the stomodeum forms the epithelium lining the buccal cavity.
- Also the salivary glands, enamel of the teeth, epithelium of the body of the tongue.
- As the tongue develops "inside" the floor of the oral cavity, it is not readily visible in the external views of the embryonic (Carnegie) stages of development.
- Contributions from all arches, which changes with time
- begins as swelling rostral to foramen cecum, median tongue bud
- Arch 1 - oral part of tongue (ant 3/2)
- Arch 2 - initial contribution to surface is lost
- Arch 3 - pharyngeal part of tongue (post 1/3)
- Arch 4 - epiglottis and adjacent regions
- Tongue muscles originate from the somites.
- Tongue muscles develop before masticatory muscles and is completed by birth.
- Masticatory muscles originate from the somitomeres.
- These muscles develop late and are not complete even at birth.
- epithelial buds in oral cavity (week 6 to 7) extend into mesenchyme
- parotid, submandibular, sublingual
Pharyngeal Arch Tables
|Pharyngeal Arch||Nerve||Artery|| Neural Crest
|trigeminal (V)||maxillary artery (terminal branches)||mandible, maxilla, malleus, incus||muscles of mastication, mylohyoid, tensor tympanic, ant. belly digastric||ant lig of malleus, sphenomandibular ligament|
|facial (VII)|| stapedial (embryonic)
|stapes, styloid process, lesser cornu of hyoid, upper part of body of hyoid bone||muscles of facial expression, stapedius, stylohyoid, post. belly digastric||stylohyoid ligament|
|3||glossopharyngeal (IX)||common carotid, internal carotid arteries||greater cornu of hyoid, lower part of body of hyoid bone||stylopharyngeus|
|4||vagus (X) superior laryngeal branch||part of aortic arch (left), part right subclavian artery (right)||thyroid, cricoid, arytenoid, corniculate and cuneform cartilages||crycothyroid, soft palate levator veli palatini (not tensor veli palatini)|
|6||vagus (X) recurrent laryngeal branch||part of left pulmonary artery (left), part of right pulmonary artery (right)||thyroid, cricoid, arytenoid, corniculate and cuneform cartilages||larynx intrinsic muscles (not cricothyroid muscle)|
Structures derived from Pouches
Each pouch is lined with endoderm and generates specific structures.
||Overall Structure||Specific Structures|
||tubotympanic recess||tympanic membrane, tympanic cavity, mastoid antrum, auditory tube|
||intratonsillar cleft||crypts of palatine tonsil, lymphatic nodules of palatine tonsil|
||inferior parathyroid gland, thymus gland|
||superior parathyroid gland, ultimobranchial body|
||becomes part of 4th pouch|
Structures derived from Grooves
Only the first groove differentiates into an adult structure and forms part of the external acoustic meatus.
Structures derived from Membranes
At the bottom of each groove lies the membrane which is formed from the contact region of ectodermal groove and endodermal pouch. Only the first membrane differentiates into an adult structure and forms the tympanic membrane.
There are a number of movies representing development of different features of the head and face.
- Anthony Graham, Jo Richardson Developmental and evolutionary origins of the pharyngeal apparatus. Evodevo: 2012, 3(1);24 PubMed 23020903 | Evodevo.
- Jared Coffin Talbot, Stephen L Johnson, Charles B Kimmel hand2 and Dlx genes specify dorsal, intermediate and ventral domains within zebrafish pharyngeal arches. Development: 2010, 137(15);2507-17 PubMed 20573696
- Simon D Bamforth, Bill Chaudhry, Michael Bennett, Robert Wilson, Timothy J Mohun, Lodewyk H S Van Mierop, Deborah J Henderson, Robert H Anderson Clarification of the identity of the mammalian fifth pharyngeal arch artery. Clin Anat: 2013, 26(2);173-82 PubMed 22623372
- Rui Diogo, Robert G Kelly, Lionel Christiaen, Michael Levine, Janine M Ziermann, Julia L Molnar, Drew M Noden, Eldad Tzahor A new heart for a new head in vertebrate cardiopharyngeal evolution. Nature: 2015, 520(7548);466-73 PubMed 25903628
- Silvia Foppiano, Diane Hu, Ralph S Marcucio Signaling by bone morphogenetic proteins directs formation of an ectodermal signaling center that regulates craniofacial development. Dev. Biol.: 2007, 312(1);103-14 PubMed 18028903
Igor Adameyko, Kaj Fried The Nervous System Orchestrates and Integrates Craniofacial Development: A Review. Front Physiol: 2016, 7;49 PubMed 26924989
Shigeru Kuratani, Thomas Schilling Head segmentation in vertebrates. Integr. Comp. Biol.: 2008, 48(5);604-10 PubMed 20607135
| PMC2895339 | Integr Comp Biol. Armelle Grevellec, Abigail S Tucker The pharyngeal pouches and clefts: Development, evolution, structure and derivatives. Semin. Cell Dev. Biol.: 2010, 21(3);325-32 PubMed 20144910
Chong Pyo Choe, J Gage Crump Dynamic epithelia of the developing vertebrate face. Curr. Opin. Genet. Dev.: 2015, 32C;66-72 PubMed 25748249
Victoria Shone, Anthony Graham Endodermal/ectodermal interfaces during pharyngeal segmentation in vertebrates. J. Anat.: 2014, 225(5);479-91 PubMed 25201771
Hang Nguyen Thi Thu, Steven Fong Haw Tien, Siau Lin Loh, Jimmy So Bok Yan, Vladimir Korzh Tbx2a is required for specification of endodermal pouches during development of the pharyngeal arches. PLoS ONE: 2013, 8(10);e77171 PubMed 24130849
Hinrichsen K. The early development of morphology and patterns of the face in the human embryo. Berlin ; New York : Springer-Verlag, c1985
|Historic Disclaimer - information about historic embryology pages|
|Embryology History | Historic Embryology Papers)|
- Sinuses - a pharyngeal groove abnormality, when a portion of the groove persists and opens to the skin surface, located laterally on the neck.
- Fistula - a pharyngeal membrane abnormality, a tract extends from pharynx (tonsillar fossa) beween the carotid arteries (internal and external) to open on side of neck.
- Cysts -a cervical sinus abnormality, remants of the cervical sinus remains as a fluid-filled cyst lined by an epithelium.
- Vestiges - a cartilaginous or bony developmental remnants that lie under the skin on side of neck.
- Clefting - the way in which the upper jaw forms from fusion of the smaller upper prominence of the first pharyngeal arch leads to a common congenital defect in this region called "clefting", which may involve either the upper lip, the palate or both structures.
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- Essentials of Facial Growth Enlow and Hans
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Cite this page: Hill, M.A. 2017 Embryology Head Development. Retrieved April 27, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/Head_Development
- © Dr Mark Hill 2017, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G