BGD Lecture - Face and Ear Development: Difference between revisions
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Portions of the ear appear very early in development as specialized region (otic placode) on the embryo surface that sinks into the mesenchyme to form a vesicle (otic vesicle = otocyst) that form the inner ear. | Portions of the ear appear very early in development as specialized region (otic placode) on the embryo surface that sinks into the mesenchyme to form a vesicle (otic vesicle = otocyst) that form the inner ear. | ||
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Revision as of 14:56, 7 May 2015
Introduction
The face is the anatomical feature which is truly unique to each human, though the basis of its general development is identical for all humans and similar to that seem for other species. The face has a complex origin arising from a number of head structures and sensitive to a number of teratogens during critical periods of its development. The related structures of upper lip and palate significantly contribute to the majority of face abnormalities.
Head The head and neck structures are more than just the face, and are derived from pharyngeal arches 1 - 6 with the face forming from arch 1 and 2 and the frontonasal prominence. Each arch contains similar Arch components derived from endoderm, mesoderm, neural crest and ectoderm. Because the head contains many different structures also review notes on Special Senses), Respiratory, Integumentary (Teeth), Endocrine (thyroid, parathyroid, pituitary, thymus) and Ultrasound- Cleft lip/palate. Hearing We use the sense of balance and hearing to position ourselves in space, sense our surrounding environment, and to communicate. Importantly hearing is linked into postnatal neurological development (milestones) involved with language and learning. Portions of the ear appear very early in development as specialized region (otic placode) on the embryo surface that sinks into the mesenchyme to form a vesicle (otic vesicle = otocyst) that form the inner ear.
Lecture ObjectivesTo introduce the developmental embryology of both the face and ear, and their associated abnormalities.
Week 3Buccopharyngeal MembraneThese images of the Stage 11 embryo show the breakdown of the buccopharyngeal membrane. The PharynxThe cavity within the pharyngeal arches forms the pharynx.
Week 4Pharyngeal Arch ComponentsMajor 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. Pharyngeal Arch Development
Neural Crest
Arch FeaturesEach 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
Pharyngeal Arch 1 (Mandibular Arch) has 2 prominences
Pharyngeal Arch 2 (Hyoid Arch)
Arch 3 and 4
Arch Arteries
placental vein -> liver -> heart -> truncus arteriosus -> aortic sac -> arch arteries -> dorsal aorta -> placental artery Arch Cartilage
Arch Muscle
Arch Nerve
Arch Pouches
EndocrineNote endocrine development will be covered in detail in a later BGD lecture. Thyroid Gland
Anterior Pituitary
Face DevelopmentBegins week 4 centered around stomodeum, external depression at oral membrane 5 initial primordia from neural crest mesenchyme (week 4)
Head/Skull
Calveria - bone has no cartilage (direct ossification of mesenchyme)
Sensory Placodes
Otic Placode
Lens Placode
Nasal Placode
Hearing DevelopmentExternal Ear
Middle Ear
Inner Ear
Postnatal Changes
Head Growth
PalateEmbryonic
FetalSecondary palate, fusion in the human embryo in week 9 (GA week 11). 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 Tongue Development
Tongue Muscle
Salivary Glands
AbnormalitiesCleft Lip and Palate
VictoriaThe ten most frequently reported birth defects in Victoria between 2003-2004.
|
Cleft Palate
- Cleft palate has the International Classification of Diseases code 749.0.
- In Australia the national rate (1982-1992) for this abnormalitity in births was 4.8 - 6/10,000 births, which represented 1,530 infants 5.5% were stillborn and 11.5% liveborn died during neonatal period and slightly more common in twin births than singleton.
Cleft Lip
- The International Classification of Diseases code 749.1 for isolated cleft lip and 749.2 for cleft lip with cleft palate.
- In Australia the national rate (1982-1992) for this abnormalitity was 8.1 - 9.9 /10,000 births. Of 2,465 infants 6.2% were stillborn and 7.8% liveborn died during neonatal period and the rate was similar in singleton and twin births.
- Links: Palate Development
First Arch Syndrome
- There are 2 major types of associated first arch syndromes, Treacher Collins (Mandibulofacial dysostosis) and Pierre Robin (Pierre Robin complex or sequence), both result in extensive facial abnormalites.
Treacher Collins Syndrome
Pierre Robin Syndrome
- Hypoplasia of the mandible, cleft palate, eye and ear defects.
- Initial defect is small mandible (micrognathia) resulting in posterior displacement of tongue and a bilateral cleft palate.
DiGeorge Syndrome
- absence of thymus and parathyroid glands, 3rd and 4th pouch do not form
- disturbance of cervical neural crest migration
Cysts
- Many different types
Facial Clefts
- extremely rare
- Holoprosencephaly
- shh abnormality
Maternal Effects
- Retinoic Acid - present in skin ointments
- 1988 associated with facial developmental abnormalities
Fetal Alcohol Syndrome
Due to alcohol in early development (week 3+) leading to both facial and neurological abnormalities
- lowered ears, small face, mild+ retardation
- Microcephaly - leads to small head circumference
- Short Palpebral fissure - opening of eye
- Epicanthal folds - fold of skin at inside of corner of eye
- Flat midface
- Low nasal bridge
- Indistinct Philtrum - vertical grooves between nose and mouth
- Thin upper lip
- Micrognathia - small jaw
Exposure of embryos in vitro to ethanol simulates premature differentiation of prechondrogenic mesenchyme of the facial primordia (1999)
- Links: Fetal Alcohol Syndrome
Table - Structures derived from Arches
Arch | Nerve | Skeletal Structures | Muscles | Ligaments |
1 (maxillary/mandibular) | trigeminal (V) | mandible, maxilla, malleus, incus | ant lig of malleus, sphenomandibular ligament | |
2 (hyoid) | facial (VII) | stapes, styloid process, lesser cornu of hyoid, upper part of body of hyoid bone | stylohyoid ligament | |
3 | glossopharyngeal (IX) | greater cornu of hyoid, lower part of body of hyoid bone | ||
4 & 6 | superior laryngeal and recurrent laryngeal branch of vagus (X) | thyroid, cricoid, arytenoid, corniculate and cuneform cartilages |
Structures derived from Arches
Arch | Nerve | Skeletal Structures | Muscles | Ligaments |
1 (maxillary/mandibular) | trigeminal (V) | mandible, maxilla, malleus, incus | ant lig of malleus, sphenomandibular ligament | |
2 (hyoid) | facial (VII) | stapes, styloid process, lesser cornu of hyoid, upper part of body of hyoid bone | stylohyoid ligament | |
3 | glossopharyngeal (IX) | greater cornu of hyoid, lower part of body of hyoid bone | ||
4 & 6 | superior laryngeal and recurrent laryngeal branch of vagus (X) | thyroid, cricoid, arytenoid, corniculate and cuneform cartilages |
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.
References
Online Textbooks
- Developmental Biology by Gilbert, Scott F. Sunderland (MA): Sinauer Associates, Inc.; c2000 Figure 1.3. Pharyngeal arches | Table 13.2. Some derivatives of the pharyngeal arches | The Cranial Neural Crest
- Madame Curie Bioscience Database Chapters taken from the Madame Curie Bioscience Database (formerly, Eurekah Bioscience Database) Cranial Neural Crest and Development of the Head Skeleton | Neural Crest Cells and the Community of Plan for Craniofacial Development: Historical Debates and Current Perspectives
Search
- Bookshelf pharyngeal arch | head development | face development
- Pubmed pharyngeal arch | head development | face development |
External Links
Embryo Images Unit: Embryo Images Online | Craniofacial Development | Cell Populations | Pharyngeal Arches | Tongue | Nose and Upper Lip | Palate Development
Research Labs: tzahor lab
Terms
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 of palatal shelf fusion can lead to cleft palate. (More? Palate Development | Head | Head Abnormalities)
palatogenesis
- The process of palate formation, divided into primary and secondary palate development. (More? Palate Development | Head | Head Abnormalities)
pharyngeal arch
- (branchial arch, 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. Each arch though initially formed from similar components will differentiate to form different head and neck structures. (More? | Head Development | Endocrine | Neural Crest)
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? | Head Development | Cardiovascular)
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? Head Development | Middle Ear)
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? | Head Development | Neural | Neural Crest)
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 | Thyroid | Parathyroid | Thymus | Endocrine | Head Development
pharyngotympanic tube
- (auditory tube, eustachian tube, otopharyngeal tube) A narrow canal connecting the middle ear space to the back of the oral cavity. The tube allows ventilation, protection and clearance for the middle ear cavity. Ventilation is the pressure equalization in the middle ear. Clearance is to allow fluid drainage from the middle ear. Embryonic origin is from the first pharyngeal pouch. In development, the canal is initially both horizontal, short and very narrow leading to poor drainage and easy blockage. (More? Middle Ear | Hearing | Hearing Abnormalities)
pharynx
- (throat) Forms the initial segment of the upper respiratory tract divided anatomically into three regions: nasopharynx, oropharynx, and laryngopharynx (hypopharynx). Anatomically extends from the base of the skull to the level of the sixth cervical vertebra. (More? Respiratory System Development)
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Cite this page: Hill, M.A. (2024, March 28) Embryology BGD Lecture - Face and Ear Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGD_Lecture_-_Face_and_Ear_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G