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Lecture Notes under Development (notice removed when completed) This lecture is an introduction to the development of the head and face. In the early stages of embryonic development in the head region we saw only the brain covered by a thin surface epithelium. The first sign of the structures that will form the head and neck are a series of ventral and lateral ridge bulges appearin beneath the growing brain, the pharyngeal arches. Shown below is the web version of lecture slides from the Medicine lecture covering similar material to this current lecture. There is also text from powerpoint Lecture Slides. |
The Pharyngeal Arches |
(More? Carnegie Stages) |
Page Links: Introduction | Lecture Slides | Lectopia Audio | Lecture Objectives | UNSW Embryology | Comments | Online Books | Internet Links | Next | Glossary | Terms |
These links are to PDF versions of the Lecture slides: 1 slide/page viewing 48 pages | 4 slide/page printing 12 pages | 6 slide/page printing 8 pages
Lectopia Audio link to the audio recording of Lecture 15 Face
The online text Online Books and UNSW Embryology links listed on this page worth reviewing for this lecture.
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More: This current box is an additional note that appears beneath each "slide" and contains additional information and links (both internal and external) to the current site relevant to the slide above.
Links: Systems Notes - Head and Neck | Systems Notes - Hearing Lecture Slides (2004) ANAT2300 Head Development | Lecture Slides (2003) ANAM1006 Head Development
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More: Note the great change beween the middle of embryological development to the end.
Links: Embryo Stages | Stage Comparison | Stage 14 | Stage 23
More: Externally the pharyngeal arches are initially the most obvious external feature. Sensory placodes are present on the surface (but not obvious). By stage 14 the sensory placode that contributes to hearing (otic placode) has already been lots from the surface and now lies in the mesenchyme in the neck region. The cervical sinus is a surface landmark shwing the region where arch 2 is growing down over the
Links: Embryo Stages | Stage Comparison | Stage 14 | Stage 23
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More: The cranial neural crest therefore contributes much of the underlying structure of the face. Rhombomeres are the transient segmentation of the hindbrain.
Links: Neural Crest Notes |
More:
Links: Sadler Image Bank - Pharyngeal Arches | Sadler Image Bank - Pharyngeal Arch Arteries | Embryo Images - Aortic Arch Vessels |
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More:
Links: Embryo Stage 12 | Embryo Stage 13 | Embryo Images - Pharyngeal Arch 1 and 2 early | Embryo Images - Pharyngeal Arch 1 and 2 later | Dev Biol - Jaw structure in the fish, reptile, and mammal |
Pharyngeal Arch 2
Arch 3 and 4
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More: Hyoid bone ossified from six centres (2 body, 1 for each cornu). Ossiification - late fetal in the greater cornua, then in the body, then postnatally (1-2 years) in the lesser cornua.
Links: Embryo Stage 13 |
Arch |
Nerve |
Muscles |
Skeletal |
Artery |
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1 (maxillary/mandibular) |
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mastication (temporalis, masseter, medial pterygoid, lateral pterygoid) |
mandible model malleus, incus Meckel's cartilage |
maxillary (terminal branches) |
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(hyoid) |
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facial expression ( buccinator, platysma, stapedius, stylohyoid, digastric posterior belly) |
stapes, styloid process, lesser cornu of hyoid, upper part of body of hyoid bone Reichert's cartilage |
stapedial (embryonic) corticotympanic (adult)
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Stylopharyngeus |
greater cornu of hyoid, lower part of body of hyoid bone |
common carotid, internal carotid (root)
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intrinsic muscles of larynx, pharynx; levator palati |
thyroid, cricoid, arytenoid, corniculate and cuneform cartilages |
4 - aortic arch, right subclavian 6 - ductus arteriosus, pulmonary (roots) |
POUCH |
Overall Structure |
Specific Structures |
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tubotympanic recess |
tympanic membrane, tympanic cavity, mastoid antrum, auditory tube |
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intratonsillar cleft |
crypts of palatine tonsil, lymphatic nodules of palatine tonsil |
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inferior parathyroid gland, thymus gland |
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superior parathyroid gland, ultimobranchial body |
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becomes part of 4th pouch |
More: The above table is not for you to learn by heart but an indication of the structures formed from each arch.
It is easy to remember that:
1st arch - about the mouth (chewing, jaw) and the external and middle ear.
2nd arch - about the face, hyoid and external and middle ear.
3rd arch - about the neck and endocrine.
4th arch- about the neck and endocrine.
Links: Arch Derivatives | Dev Biol - Some derivatives of the pharyngeal arches |
More:
Links: Head and Neck Abnormalities | Hearing Abnormalities | Abnormal Development - Fetal Alcohol Syndrome | Abnormal Ultrasound - Cleft Lip |
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1 Frontonasal prominence - Nasal (medial, lateral)2 Maxillary |
More:
Links: Face Development | Sadler Image Bank - Frontal aspect of the face 5 week and 6 week embryo | Sadler Image Bank - Frontal aspect of the face 7 week embryo |
More: Cleft lip and palate develop between the 4th and 8th week of gestation and is dominated by changes resulting in the formation of the nose. Palatal development occurs between the 7th and 12th week of gestation and is divided into the formation of the primary palate (prolabium), premaxilla and cartilaginous septum) and formation of the secondary palate (hard and soft palate). The animation above shows the early fusion of the primary palate in the human embryo between stage 17 and 18, going from an epithelial seam to the mesenchymal bridge.
Links: Face Development - Primary Palate | Face Development Abnormalities | Abnormal Ultrasound - Cleft Lip |
Derived from all pharyngeal arches contributing different componentsSomites - tongue muscle cellsSomitomeres - muscles of mastication |
More: The tongue develops "inside" the floor of the oral cavity, therefre it is not readily visible in the external views of the embryonic (Carnegie) stages of development. Somitomeres are the unsegmented mesoderm found in the head region, in a similar location to that of somites in the body.
Movie of the human head covering the Carnegie stages from 15 to 22. Note the images are not to scale.
Quicktime movie 179 Kb in new window.
Movie of the human head covering the Carnegie stages from 16 to 18.
Movie of stage 13/14 pig embryo sections showing the head region of the nasal placodes.
Face Development Overview (300 Kb)
Fetal Development Overview (800 Kb)
Development of the Tongue (187Kb)
The following text is extracted and modified from lecture slides and should be used as a "trigger" to remind you of key concepts.
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The following links are to UNSW Embryology additional resources that provide further background information on the Lecture topics. Note that not all information found on these additional links is considered examinable and the lecture slides and laboratory classes should be used as your initial guide for course theory content. Links:Head and Neck Notes | Face | Stage 13/14 Embryo | Stage 13/14 (Pig) Overview | Stage 22 Embryo | High power (st22) | Primary Palate | Skull Development | Abnormalities | Face Abnormalities | Tongue | Systems | St22 Sets | Neck | St13/14 Sets The search window below allows a search within the UNSW Embryology website. |
Dr Mark Hill |
The head and face have complex origins and the associated structures have sensory, endocrine, gastrointestinal and structural roles. Some of these aspects will be covered elsewhere in the current course. This lecture will begin with the basic components that contribute to the face and neck, the pharyngeal arches. One aspect of how the face forms, maxillary arch fusion, contributes the visible feature of abnormal face development, clefting of the lip and palate. For this current course, I prefer the use of the term "pharyngeal" rather than "branchial" which may appear in some textbooks. These lecture pages are being updated for the current course, so it is worth coming back again later to see if any changes have occurred. Please let me know by email of broken links or content that is not clearly covered in this supporting online material. |
Developmental Biology 6th ed. Gilbert, Scott F. Sunderland (MA): Sinauer Associates, Inc.; c2000.
Below are listed links that relate to this Lecture from the textbook "Developmental Biology" which is available free online. You can either click the provided links or do your own search using the search link.
Molecular Biology of the Cell 4th ed. Alberts, Bruce; Bray, Dennis; Lewis, Julian; Raff, Martin; Roberts, Keith; Watson, James D. New York and London: Garland Publishing;
c2002.
Below are listed links that relate to this Lecture from the textbook "Molecular Biology of the Cell" which is available free online. You can either click the provided links or do your own search using the search link.
Course Homepage | Course Calendar | Course Handout 2008 - PDF Document (8 pages, 192Kb) | Textbooks | Journals
Online References
| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
buccal - (Latin, bucca = cheek) term used to relate to the mouth (oral cavity).
buccopharyngeal membrane - (oral membrane) (Latin, bucca = cheek) Forms the external upper membrane limit (cranial end) of the early gastrointestinal tract (GIT). This membrane is formed during gastrulation by ectoderm and endoderm without a middle (intervening) layer of mesoderm. The membrane lies at the floor of the ventral depression (stomadeum) where the oral cavity will open and will breakdown to form the initial "oral opening" of the gastrointestinal tract. The equivilent membrane at the lower end of the gastrointestinal tract is the cloacal membrane. (More? GIT Notes)
cleft - An anatomical gap or space occuring in abnormal development in or between structures. Most commonly associated with cleft lip and cleft palate. Term is also used to describe the groove that forms between each pharyngeal arch during their formation. (More? Face - Abnormalities | Face Notes | | Head Notes | Medline Plus - Cleft Lip and Palate)
cleft lip - An abnormality of face development leading to an opening in the upper lip. Clefting of the lip and or palate occurs with 300+ different abnormalities. Depending on many factors, this cleft may extend further into the oral cavity leading to a cleft palate. In most cases clefting of the lip and palate can be repaired by surgery. (More? Face - Abnormalities | Face Notes | | Head Notes | Medline Plus - Cleft Lip and Palate)
cleft palate - An abnormality of face development leading to an opening in the roof of the oral cavity between the mouth and the nose. Clefting of the lip and or palate occurs with 300+ different abnormalities. In most cases clefting of the lip and palate can be repaired by surgery. (More? Face - Abnormalities | Face Notes | | Head Notes | Medline Plus - Cleft Lip and Palate)
hard palate - the bony anterior portion of the palate formed by maxillary and palatine bones. The muscular posterior portion is called the soft palate.
palate - The roof of the mouth (oral cavity) a structure which separates the oral from the nasal cavity. Develops as two lateral palatal shelves which grow and fuse in the midline. Initally a primary palate forms with fusion of the maxillary processes with the nasal processes in early face formation. Later the secondary palate forms the anterior hard palate which will ossify and separate the oral and nasal cavities. The posterior part of the palate is called the soft palate (velum, muscular palate) and contains no bone. Abnormalities palatal shelf fusion can lead to cleft palate.
pharyngeal arch - (branchial arches, Greek, branchial = gill) These are a series of externally visible anterior tissue bands lying under the early brain that give rise to the structures of the head and neck. In humans, five arches form (1,2,3,4 and 6) but only four are externally visible on the embryo. Each arch has initially identical structures: an internal endodermal pouch, a mesenchymal (mesoderm and neural crest) core, a membrane (endoderm and ectoderm) and external cleft (ectoderm). Each arch mesenchymal core also contains similar components: blood vessel, nerve, muscular, cartilage. Though initially formed from similar components each arch will differentiate to form different head and neck structures. (More? Head Notes | Face Notes |Neural Crest Notes | Endocrine Notes)
pharyngeal arch artery - Each early developing pharyngeal arch contains a lateral pair of arteries arising from the aortic sac, above the heart, and running into the dorsal aorta. later in development these arch arteries are extensively remodelled to form specific components of the vascular system. Pharyngeal Arch 1 arteries are mainly lost and forms part of maxillary artery. Pharyngeal Arch 2 arteries remains to form the stapedial arteries. Pharyngeal Arch 3 arteries forms the common carotid arteries, internal carotid arteries in the neck. Pharyngeal Arch 4 arteries will form part of aortic arch (left arch artery) and part right subclavian artery (right arch artery) Pharyngeal Arch 6 arteries form part of left pulmonary artery (left arch artery) and part of right pulmonary artery (right arch artery). (More? Cardiovascular Notes)
pharyngeal arch cartilage - Each early developing pharyngeal arch contains a horseshoe shaped band of cartilage that acts as a template and contributes to the development of head and neck bony and cartilagenous features, including the middle ear bones. Pharyngeal Arch 1 cartilage (Meckel’s cartilage) dorsal ends form malleus and incus midpart forms ligaments (ant. malleus, sphenomandibular) ventral part forms mandible template. Pharyngeal Arch 2 cartilage (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. Pharyngeal Arch 3 cartilage forms hyoid components, greater cornu and inferior part of hyoid. Pharyngeal Arch 4 and 6 cartilage forms laryngeal cartilages except epiglottis (from hypobranchial eminence). (More? Middle Ear Notes | Head Notes | Face Notes)
pharyngeal arch nerve - Each early developing pharyngeal arch contains the developing cranial nerves, as a pair, within the arch mesenchyme. Each cranial nerve is numbered (roman numeral) in rostrocaudal sequence and also has a specific name. The cranial nerve within each arch often relates to the other structures formed from taht arch. Pharyngeal Arch 1 contains the trigeminal nerve (CN V, cranial nerve 5). Pharyngeal Arch 2 contains the facial nerve (CN VII, cranial nerve 7). Pharyngeal Arch 3 contains the glossopharyngeal nerve (CN IX, cranial nerve 9) Pharyngeal Arch 4 and 6 contains the Vagus (CN X cranial nerve 10), forming the adult superior laryngeal and recurrent laryngeal branches. (More? Neural Notes | Neural Crest Notes)
pharyngeal arch pouch - An out-pocketing of the endoderm lined pharynx occurring between each developing pharyngeal arch. Each of the pharyngeal arch pouches contributes different components of the head and neck, either cavities or endocrine tissues. Pharyngeal Arch 1 pouch elongates to form tubotympanic recess tympanic cavity, mastoid antrum and auditory tube (Eustachian tube). Pharyngeal Arch 2 pouch forms the tonsillar sinus and is later mostly oblierated by palatine tonsil. Pharyngeal Arch 3 pouch forms the inferior parathyroid and thymus. Pharyngeal Arch 4 pouch forms the superior parathyroid, parafollicular cells of Thyroid. (More? Middle Ear Notes | Thymus Notes | Parathyroid Notes | Thyroid Notes | Endocrine Notes | Head Notes | Face Notes)
soft palate - (velum, muscular palate) The muscular posterior portion of the palate forming the roof of the oral cavity. The bony anterior portion of the palate is called the hard palate, formed by maxillary and palatine bones.
Textbooks
Human Embryology (3rd ed.) Larson Chapter 12 pp 351-378
The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud Chapter 10 pp 201- 240
Online Textbooks
Developmental Biology (6th ed.) Gilbert, Scott F. Sunderland (MA): Sinauer Associates, Inc.; c2000. : Cranial neural crest cell migration in the mammalian head | Regions of the neural crest | Jaw structure in the fish, reptile, and mammal | Some derivatives of the pharyngeal arches |
Eurekah Bioscience Collection Chapters taken from the Eurekah Bioscience database. Eurekah.com and Landes Bioscience; 2003. : Cranial Neural Crest and Development of the Head Skeleton |
Clinical Methods (3rd ed.) Walker, H.K.; Hall, W.D.; Hurst, J.W.; editors Stoneham (MA): Butterworth Publishers; c1990 : 63. Cranial Nerves IX and X: The Glossopharyngeal and Vagus Nerves | The Tongue |
Anatomy of the Human Body Gray, H. Philadelphia: Lea and Febiger, 1918.
Molecular Biology of the Cell (4th ed.) Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter New York and London: Garland Science; c2002.
Online Resources
Embryo Images Unit: Embryo Images Online | Craniofacial Development | Cell Populations | Pharyngeal Arches | Tongue | Nose and Upper Lip | Palate Development
Journals: GI Motility online (2006) Anatomy and development of oral cavity and pharynx| The Cleft Palate Journal
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