BGD Lecture - Face and Ear Development

From Embryology
Embryology - 18 Nov 2017    Facebook link Pinterest link Twitter link  Expand to Translate  
Google Translate - select your language from the list shown below (this will open a new external page)

العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt    These external translations are automated and may not be accurate. (More? About Translations)

Introduction

Face animation.gif

Face Development Movie

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.

2017 Lecture

Lecture Archive  
2017 PDF |

2016 | 2015 | 2014 | 2014 PDF | 2013 | 2012 | 2009 | Face and Ear Practical | DB

Lecture Objectives

To introduce the developmental embryology of both the face and ear, and their associated abnormalities.
  1. To understand the formation and contribution of the pharyngeal arches to face and neck development.
  2. To know the main structures derived from components of the pharyngeal arches (groove, pouch and arch connective tissue).
  3. To know the 3 major parts (external, middle and inner) of hearing development and their embryonic origins.
  4. To briefly understand some abnormalities associated with face and hearing development.
One-minute.gif

1 Minute Embryology
UNSW theBox

Textbooks  
Embryo logo Hill, M.A. (2017). UNSW Embryology (17th ed.) Retrieved November 18, 2017, from https://embryology.med.unsw.edu.au
Head Links: Introduction | Medicine Lecture | Medicine Lab | Science Lecture | Lecture Movie | Science Lab | Craniofacial Seminar | Mouth | Palate | Tongue | Placodes | Skull Development | Head and Face Movies | Abnormalities | Category:Head
Historic Head Embryology  
1910 Skull | 1910 Skull Images | 1912 Nasolacrimal Duct | 1921 Human Brain Vascular | 1923 Head Subcutaneous Plexus | 1919 21mm Embryo Skull | 1920 Human Embryo Head Size | 1921 43 mm Fetal Skull | Historic Disclaimer
Palate Links: Palate Development | Cleft Lip and Palate | Cleft Palate | Head Development | Category:Palate


Hearing Links: Introduction | Science Lecture | Lecture Movie | Medicine Lecture | Inner Ear | Middle Ear | Outer Ear | Balance | Hearing - Neural Pathway | Stage 22 | Abnormalities | Neonatal Diagnosis - Hearing | Hearing test | Sensory Introduction | Placodes | Student project

Categories: Hearing | Outer Ear | Middle Ear | Inner Ear

Historic Hearing Embryology 
Historic Embryology: 1880 Platypus cochlea | 1902 Development of Hearing | 1906 Membranous Labyrinth | 1910 Auditory Nerve | 1913 Tectorial Membrane | 1918 Human Embryo Otic Capsule | 1918 Cochlea | 1918 Grays Anatomy | 1922 Human Auricle | 1922 Otic Primordia | 1931 Internal Ear Scalae | 1932 Otic Capsule 1 | 1933 Otic Capsule 2 | 1936 Otic Capsule 3 | 1933 Endolymphatic Sac | 1934 Otic Vesicle | 1934 Membranous Labyrinth | 1938 Stapes - 7 to 21 weeks | 1938 Stapes - Term to Adult | 1942 Stapes - Embryo 6.7 to 50 mm | 1943 Stapes - Fetus 75 to 150 mm | 1948 Stapes - Fetus 160 mm to term | 1959 Auditory Ossicles | 1963 Human Otocyst | Historic Disclaimer
The Developing Human, 10th edn.jpg Moore, K.L., Persaud, T.V.N. & Torchia, M.G. (2015). The developing human: clinically oriented embryology (10th ed.). Philadelphia: Saunders. (links only function with UNSW connection)

Chapter 9 Pharyngeal Apparatus, Face, and Neck

Chapter 18 Development of Eyes and Ears

The Developing Human: Clinically Oriented Embryology (10th edn) 
The Developing Human, 10th edn.jpg

UNSW Students have online access to the current 10th edn. through the UNSW Library subscription (with student Zpass log-in).


APA Citation: Moore, K.L., Persaud, T.V.N. & Torchia, M.G. (2015). The developing human: clinically oriented embryology (10th ed.). Philadelphia: Saunders.

Links: UNSW Embryology Textbooks | Embryology Textbooks | UNSW Library
  1. Introduction to the Developing Human
  2. First Week of Human Development
  3. Second Week of Human Development
  4. Third Week of Human Development
  5. Fourth to Eighth Weeks of Human Development
  6. Fetal Period
  7. Placenta and Fetal Membranes
  8. Body Cavities and Diaphragm
  9. Pharyngeal Apparatus, Face, and Neck
  10. Respiratory System
  11. Alimentary System
  12. Urogenital System
  13. Cardiovascular System
  14. Skeletal System
  15. Muscular System
  16. Development of Limbs
  17. Nervous System
  18. Development of Eyes and Ears
  19. Integumentary System
  20. Human Birth Defects
  21. Common Signaling Pathways Used During Development
  22. Appendix : Discussion of Clinically Oriented Problems
Larsen's human embryology 5th ed.jpg Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R., Francis-West, P.H. & Philippa H. (2015). Larsen's human embryology (5th ed.). New York; Edinburgh: Churchill Livingstone.(links only function with UNSW connection)


Chapter 17 Development of the Pharyngeal Apparatus and Face

Chapter 18 Development of the Ears

Larsen's Human Embryology (5th edn) 
Larsen's human embryology 5th ed.jpg
UNSW students have full access to this textbook edition through UNSW Library subscription (with student Zpass log-in).


APA Citation: Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R., Francis-West, P.H. & Philippa H. (2015). Larsen's human embryology (5th ed.). New York; Edinburgh: Churchill Livingstone.

Links: UNSW Embryology Textbooks | Embryology Textbooks | UNSW Library
  1. Gametogenesis, Fertilization, and First Week
  2. Second Week: Becoming Bilaminar and Fully Implanting
  3. Third Week: Becoming Trilaminar and Establishing Body Axes
  4. Fourth Week: Forming the Embryo
  5. Principles and Mechanisms of Morphogenesis and Dysmorphogenesis
  6. Fetal Development and the Fetus as Patient
  7. Development of the Skin and Its Derivatives
  8. Development of the Musculoskeletal System
  9. Development of the Central Nervous System
  10. Development of the Peripheral Nervous System
  11. Development of the Respiratory System and Body Cavities
  12. Development of the Heart
  13. Development of the Vasculature
  14. Development of the Gastrointestinal Tract
  15. Development of the Urinary System
  16. Development of the Reproductive System
  17. Development of the Pharyngeal Apparatus and Face
  18. Development of the Ears
  19. Development of the Eyes
  20. Development of the Limbs
Head Movies  
Face 001 icon.jpg
 ‎‎Face Development
Page | Play
Palate 001 icon.jpg
 ‎‎Palate (oral view)
Page | Play
Palate 002 icon.jpg
 ‎‎Palate (front view)
Page | Play
Tongue 001 icon.jpg
 ‎‎Tongue
Page | Play
Postnatal human mandible growth icon.jpg
 ‎‎Mandible Growth
Page | Play
Endoderm 002 icon.jpg
 ‎‎Endoderm
Page | Play
Stage16-18 face 02.jpg
 ‎‎Face Stage 16-18
Page | Play
Stage15to22 head icon.jpg
 ‎‎Head Stage 15-22
Page | Play
Stage23 MRI S01 icon.jpg
 ‎‎Sagittal Head
Page | Play
Fetal week 10 palate icon.jpg
 ‎‎Fetal Palate
Page | Play
Mouse cranial neural crest migration 01.jpg
 ‎‎Cranial Neural Crest
Page | Play
Mouse face microCT icon.jpg
 ‎‎Mouse Face
Page | Play

Week 3

Buccopharyngeal Membrane and Pharynx  

Buccopharyngeal Membrane

These images of the Week 4 embryo (23 - 26 days, Stage 11) show the breakdown of the buccopharyngeal (oral) membrane.

The Pharynx

Head arches cartoon.jpg Stage13 B2 excerpt.gif Pharynx cartoon.jpg

The cavity within the pharyngeal arches forms the pharynx.

  • begins at the buccopharyngeal membrane (oral membrane), apposition of ectoderm with endoderm (no mesoderm between)
  • expands behind pharyngeal arches
  • narrows at glottis and bifurcation of gastrointestinal (oesophagus) and respiratory (trachea) systems
  • regions on roof, walls and floor have important contributions to endocrine in oral and neck regions
  • also contributes to tongue development

Week 4

Week 4 (stage 12)
Week 4 - Arches (stage 11)  
Stage11 sem81.jpg

Pharyngeal Arch Components

Pharyngeal arch structure cartoon.gif

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.

Pharyngeal Arch Development

  • branchial arch (Greek. branchia = gill)
  • arch consists of all 3 trilaminar embryo layers
  • ectoderm- outside surface and core neural crest
  • mesoderm- core of mesenchyme
  • endoderm- inside pharynx
Pharynx Week 4 (stage 13)
Stage13 oral cavity floor02.jpg

Neural Crest

neural crest migration
  • Mesenchyme invaded by neural crest generating connective tissue components
  • cartilage, bone, ligaments
  • arises from midbrain and hindbrain region
Neural Crest Migration  
Chicken Embryo - DiI-labelled neural crest cells towards the branchial arches.

White rings indicate migration of individual cells. Each image represents 10 confocal sections separated by 10 microns.

Mouse cranial neural crest migration 01.jpg

Mouse Embryo - GFP-labelled cranial neural crest cells in embryonic mouse (E9.5).

Chicken-neural-crest-migration-01.jpg
 ‎‎Neural Crest 1
Page | Play
Mouse cranial neural crest migration 01.jpg
 ‎‎Cranial Neural Crest
Page | Play

Arch Features

Stage13 B2 excerpt.gif
Pharyngeal arches Week 5 (Stage 14 sensory)

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)
  • form 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)


  • arch
  • groove - (cleft) externally separates each arch (only first pair persist as external auditory meatus)
  • pouch - internally separates each arch (pockets out from the pharynx)
  • membrane - ectoderm and endoderm contact regions (only first pair persist as tympanic membrane )

Pharyngeal Arch 1 (Mandibular Arch) has 2 prominences

  • 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
Arch Arteries  
  • Arch 1 - mainly lost, form part of maxillary artery
  • Arch 2 - stapedial arteries
  • Arch 3 - common carotid arteries, internal carotid arteries
  • Arch 4 - left forms part of aortic arch, right forms part right subclavian artery
  • Arch 6 - left forms part of left pulmonary artery , right forms part of right pulmonary artery

Embryo Blood Flow - placental vein -> liver -> heart -> truncus arteriosus -> aortic sac -> arch arteries -> dorsal aorta -> placental artery

Gray0473.jpg
Arch Cartilage  
  • 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)
Pharyngeal arch cartilages.jpg

Pharyngeal arch cartilages Meckel.jpg

Merkel's cartilage (first pharyngeal arch)

Arch Muscle  
  • Arch 1 - muscles of mastication, mylohyoid, tensor tympani, ant. belly digastric
  • Arch 2 - muscles of facial expression, stylohyoid, stapedius, post. belly digastric
  • Arch 3 - stylopharyngeus
  • Arch 4&6 - cricothyroid, pharynx constrictors, larynx muscles, oesophagus (st. muscle)
Arch Nerve  
  • Arch 1 - CN V trigeminal, caudal 2/3 maxillary (V2) and mandibular (V3), 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 Pouches  
  • 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
Pharyngeal Arch - Summary Table
Pharyngeal Arch Nerve Artery Neural Crest
(Skeletal Structures)
Muscles Ligaments
1
(maxillary/mandibular)
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
2
(hyoid)
facial (VII) stapedial (embryonic)

corticotympanic (adult)

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)

Endocrine

The arch pouches contribute to endocrine organ development, except for the thyroid and pituitary. Note endocrine development will be covered in detail in a later BGD lecture.

Thyroid Gland Anterior Pituitary
  • 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

Thyroid-development-cartoon.jpg

  • 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).

Historic-pituitary.jpg

Face Development

Begins week 4 centered around stomodeum, external depression at oral membrane

5 initial primordia from neural crest mesenchyme (week 4)

  • 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

Week 4 onward | Week 6-7

Week 8

  • End of the embryonic period.
  • MRI scan through the stage 23 embryo head from left to right. Identify head, neural and sensory structures.
Stage23 MRI S01-ear.jpg Stage23 MRI S01-cortex.jpg Stage23 MRI S01-vesicles.jpg
External ear (left) Cortex and eye Secondary brain vesicles
Stage23 MRI S01 icon.jpg
 ‎‎Sagittal Head
Page | Play

Head/Skull

Fetal skull (week 12)
Adult skull
  • Cranium (Neurocranium) surrounds brain.
    • dermatocranium (membranous) - skull calvarial vault develops from intramembranous ossification
    • chondrocranium (cartilaginous) - skull base develops from endochondral ossification
    • 8 bones - occipital, 2 parietals, frontal, 2 temporals, sphenoidal, ethmoidal.
  • Face (Viscerocranium) development of the facial bones
    • 14 bones - 2 nasals, 2 maxillæ, 2 lacrimals, 2 zygomatics, 2 palatines, 2 inferior nasal conchæ, vomer, mandible.
Fetal head growth circumference

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

Head Growth

Fetal Head (12 weeks) showing bone and cartilage
  • continues postnatally - fontanelle allow head distortion on birth and early growth
  • bone plates remain unfused to allow growth, puberty growth of face


Links: Skull Development

Sensory Placodes

Stage 14 sensory placodes
  • 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

Otic Placode

  • Carnegie stage 12 still visible on embryo surface.
  • Carnegie 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.

Lens Placode

  • (optic placode) lies on the surface, adjacent to the outpocketing of the nervous system (which will for the retina) and will form the lens.

Nasal Placode

  • Has 2 components (medial and lateral) and will form the nose olefactory epithelium.

Hearing Development

Adult hearing embryonic origins.jpg

Inner Ear

Week 5 Week 8
Stage13 otocyst.jpg

Otocyst (Week 5, Stage 13)

Stage22 ear.jpg

Inner Ear (Week 8, Stage 22)

  • Inner Ear Labyrinth
    • Cochlea - Otic vesicle - Otic placode (ectoderm)
    • Semicircular canals - Otic vesicle - Otic placode (ectoderm)
    • Saccule and utricle - Otic vesicle - Otic placode (ectoderm)
  • Cranial Nerve VIII
    • Auditory component - Otic vesicle and neural crest (ectoderm)
    • Vestibular component - Otic vesicle and neural crest (ectoderm)

Middle Ear

  • Middle Ear Ossicles
    • Malleus and incus - Pharyngeal Arch 1 cartilage Neural crest (ectoderm)
    • Stapes - Pharyngeal Arch 2 cartilage Neural crest (ectoderm)
  • Middle Ear Muscles
    • Tensor tympani - Pharyngeal Arch 1 (mesoderm)
    • Stapedius - Pharyngeal Arch 2 (mesoderm)
  • Middle ear cavity - Pharyngeal Arch 1 pouch (endoderm)
Pharyngeal arch cartilages.jpg

Pharyngeal arch cartilages

External Ear

External ear stages 14-23 and adult (not to scale)
  • Auricle - Pharyngeal Arches 1 and 2 (ectoderm, mesoderm)
    • form from 6 hillocks (week 5) 3 on each of arch 1 and 2
  • External Auditory Meatus - Pharyngeal Arch 1 groove or cleft (ectoderm)
  • Tympanic Membrane - Pharyngeal Arch 1 membrane (ectoderm, mesoderm, endoderm)

Postnatal Changes

Eustacian tube angle.jpg Adult - longer (twice as long), wider and runs at approximately 45 degrees to the horizontal, tube is opened by two separate muscles (tensor palati and levator palati)


At birth - shorter (17-18 mm), narrower and runs almost horizontal, tube is opened by a single muscle (tensor palati muscle)

  • Auditory tube = Eustachian, otopharyngeal or pharyngotympanic tube.
  • Connects middle ear cavity to nasopharynx portion of pharynx
  • Ventilation - pressure equalization in the middle ear
  • Clearance - allow fluid drainage from the middle ear Tube is normally closed and opened by muscles


Links: Hearing Development

Palate

Embryonic

Primary palate, fusion in the human embryo between week 6-7 (stage 17 and 18, GA Week 8-9), from an epithelial seam to the mesenchymal bridge.

Stage17-18 Primary palate.gif

Stage18 em11.jpg

Fetal

Stage 22 image 061.jpg

Secondary 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

Tongue1.png Tongue2.png Tongue3.png

  • 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 development animation

Tongue Muscle

tongue muscle
  • 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.

Salivary Glands

  • epithelial buds in oral cavity (wk 6-7) extend into mesenchyme
  • parotid, submandibular, sublingual

Abnormalities

Cleft Lip and Palate

Cleft_palate.jpg Unilateral cleft palate.jpg Bilateral cleft palate.jpg
cleft palate unilateral cleft lip and palate bilateral cleft lip and palate
  • 300+ different abnormalities, different cleft forms and extent, upper lip and ant. maxilla, hard and soft palate

Victoria

The ten most frequently reported birth defects in Victoria between 2003-2004.

  1. Hypospadias
  2. Obstructive Defects of the Renal Pelvis or Obstructive Genitourinary Defects
  3. Ventricular Septal Defect
  4. Congenital Dislocated Hip
  5. Trisomy 21 or Down syndrome
  6. Hydrocephalus
  7. Cleft Palate
  8. Trisomy 18 or Edward Syndrome - multiple abnormalities of the heart, diaphragm, lungs, kidneys, ureters and palate 86% discontinued.
  9. Renal Agenesis/Dysgenesis - reduction in neonatal death and stillbirth since 1993 may be due to the more severe cases being identified in utero and being represented amongst the increased proportion of terminations (approximately 31%).
  10. Cleft Lip and Palate - occur with another defect in 33.7% of cases.
Statistics  
USA Selected Abnormalities (CDC National estimates for 21 selected major birth defects 2004–2006)
Birth Defects Cases per Births (1 in ...) Estimated Annual Number of Cases
Anencephaly 4,859 859
Spina bifida without anencephaly 2,858 1,460
Encephalocele 12,235 341
Anophthalmia/microphthalmia 5,349 780
Common truncus 13,876 301
Transposition of great arteries 3,333 1,252
Tetralogy of Fallot 2,518 1,657
Atrioventricular septal defect 2,122 1,966
Hypoplastic left heart syndrome 4,344 960
Cleft palate without cleft lip 1,574 2,651
Cleft lip with and without cleft palate 940 4,437
Esophageal atresia/tracheoesophageal fistula 4,608 905
Rectal and large intestinal atresia/stenosis 2,138 1,952
Reduction deformity, upper limbs 2,869 1,454
Reduction deformity, lower limbs 5,949 701
Gastroschisis 2,229 1,871
Omphalocele 5,386 775
Diaphragmatic hernia 3,836 1,088
Trisomy 13 7,906 528
Trisomy 21 (Down syndrome) 691 6,037
Trisomy 18 3,762 1,109
Links: Human Abnormal Development | CDC Birth Defects - Data & Statistics | USA Statistics | Victoria 2004 | USA 2006 | Europe 2010

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.


Palate Links: Palate Development | Cleft Lip and Palate | Cleft Palate | Head Development | Category:Palate

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

FASface.jpg

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 Pouches

Each pouch is lined with endoderm and generates specific structures.


POUCH
Overall Structure Specific Structures
1
tubotympanic recess tympanic membrane, tympanic cavity, mastoid antrum, auditory tube
2
intratonsillar cleft crypts of palatine tonsil, lymphatic nodules of palatine tonsil
3
inferior parathyroid gland, thymus gland
4
superior parathyroid gland, ultimobranchial body
5
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

Search

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‚Äôs cartilage) dorsal ends form malleus and incus midpart forms ligaments (ant. malleus, sphenomandibular) ventral part forms mandible template. Pharyngeal Arch 2 cartilage (Reichert‚Äôs 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)
Hearing Terms  
Hearing and Balance Development
  • altricial animal - Term used to describe an animal born in a helpless state, with incomplete development of sensory systems at birth. For example rats and mice are born with incomplete development of visual and auditory systems. (More? Animal Development)
  • ampulla - Term used to describe an anatomical dilation of a tube or canal lumen. Anatomical description of the opening end of the uterine tube lying above the ovary and the enlarged initial segmeny of the semicircular canals of the inner ear vestibular system. (More? Inner Ear)
  • aneurism - (Greek, aneurysma = a widening, aneurysm) A term used to describe an abnormal widening of a vessel or anatomical tubal structure.
  • aquaeductus vestibuli - see vestibular aqueduct (More? Inner Ear)
  • auditory neuropathy - (AN) abnormality of transmission of sound information to the brain.
  • auditory tube - (eustachian tube) between the middle ear and oral cavity, has a bony (tympanic 1/3) and cartilaginous (pharyngeal 2/3) portion. The main role is equalization of pressure and fluid drainage in the middle ear. (More? Middle Ear)
  • auricular hillock - see hillock (More? Middle Ear)
  • atresia - narrowing, usually of an anatomical tube or cavity.
  • autophagocytosis - (Greek, auto = self, phagy = eating, also called autophagy) a cell death mechanism that uses the cell's own lysosomes to self digest.
  • border cells - columnar cells within the organ of Corti on the medial portion of the basilar membrane. (More? Inner Ear)
  • canalis reuniens - (ductus reuniens, canaliculus reuniens, canalis reuniens, Hensen's canal, Hensen's duct, uniting canal, canalis reuniens of Hensen) short narrow canal connecting the cochlea duct to the saccule. (Victor Hensen, 1835-1924) (More? Inner Ear)
  • cerumen - (ear wax) produced by glands in the skin of the outer portion of the ear canal. (More? Outer Ear)
  • chondrified - the developmental differentiation of cartilage from mesenchye, an embryonic connective tissue.
  • cristae ampullaris - located in the ampulla of the membranous semicircular canals a region with both supporting and hair cells. The hair cell cilia are embedded in the gelatinous cupula. (More? Inner Ear)
  • claudius cells - (cells of Claudius) columnar cells with microvilli overlying the basilar membrane and extend from Hensen's cells to the spiral prominence. Barrier cells that lie external to the organ of corti in endolymph. (More? Inner Ear)
  • cochlear sac - embryonic structure, which will form the coiled cochlear duct and contribute to the saccule. (More? Inner Ear)
  • cochlear aqueduct - a bony channel containing the fibrous periotic duct. It connects the basal turn of the cochlea perilymphatic space with the subarachnoid space of the posterior cranial cavity. (More? Inner Ear)
  • cochlin - major constituent of the inner ear extracellular matrix. (More? Inner Ear)
  • collagen type II - major constituent of the inner ear extracellular matrix. (More? Inner Ear)
  • conductive loss - term used to describe one of the two major classes of hearing loss involving external and middle ear abnormalities (other form is Sensorineural loss).
  • connexins - channel proteins of the gap junctions that allow rapid communication between adjacent cells. The two connexins Cx26 and Cx30 are the major proteins of cochlear gap junctions.
  • connexin 26 - A strikingly high proportion (50%) of congenital bilateral nonsyndromic sensorineural deafness cases have been linked to mutations in the GJB2 coding for the connexin26
  • cupular deposits - basophilic material on the cupulae of the semicircular ducts, an postnatal ageing phenomenon seen in some vestibular labyrinth. (More? Inner Ear)
  • clinical weeks - taken from last menstrual period (LMP) and therefore approximately two weeks before fertilization occurs.
  • Deiters' cells - (outer phalangeal cells)
  • discoidin domain receptor 1 - (DDR1) a tyrosine kinase receptor activated by native collagen, expressed in the basement membrane and with fibrillar collagens. Found in basal cells of the stria vascularis, type III fibrocytes, and cells lining the basilar membrane of the organ of Corti. {Meyer zum Gottesberge, 2008 #1877}
  • ductus utriculosaccularis - (More? Inner Ear)
  • endochondral ossification - the process of bone formation from a pre-existing cartilage template. (More? Middle Ear)
  • endoderm - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.
  • endolymphatic fluid - (endolymph, Scarpa's fluid) fluid that fills all the membranous labyrinth of the inner ear, except for the cochlea scala tympani and scala vestibuli which are filled with perilymph.
  • endolymphatic sac - inner ear structure that has anatomically both an intraosseous and extraosseous component. Th e sac has functions regulating endolymph that are both secretory and absorptive. Also the site of endolymphatic sac tumors either sporadical occurring or associated with the autosomal-dominant von Hippel-Lindau (VHL) disease, due to a germ line mutation. (More? Inner Ear)
  • embryological weeks - taken from the time of fertilization which typically occurs around the middle (day 14), or just after, of the typical 28 day menstrual cycle. (More? Embryonic Development)
  • Emx2 - homeobox gene affecting middle ear and inner ear development.
  • eustachian tube - (auditory tube) A cavity linking the pharynx to the middle ear, which develops from the first pharyngeal pouch. Named after Bartolomeo Eustachi (1500 - 1574) an Italian anatomist. (More? Middle Ear)
  • external auditory meatus - (ear canal) develops from the first pharyngeal cleft. (More? Outer Ear)
  • ear wax - see cerumen. (More? Outer Ear)
  • espins - calcium-resistant actin-bundling proteins enriched in hair cell stereocilia and sensory cell microvilli and spiral ganglion neurons (SGNs)
  • eustachian tube - (auditory tube) between the middle ear and oral cavity, equalization of pressure in the middle ear. (More? Middle Ear)
  • external auditory meatus - (EAM, ear canal) cavity connecting the external ear to the tympanic membrane. The adult human ear canal is about 2.5 cm long and 0.7 cm in diameter. (More? Outer Ear)
  • fenestra ovalis - (oval window) separates the tympanic cavity from the vestibule of the osseous labyrinth. (More? Inner Ear)
  • fenestra rotunda - (round window) separates the tympanic cavity from the scala tympani of the cochlea. (More? Inner Ear)
  • fetus - (foetus) term used to describe human development after the 8th week (10th clinical week, LPM) and covers the developmental periods of second and third trimester.
  • fibroblast growth factor 1 - (Fgf-1) a growth factor released from cochlea sensory epithelium which stimulates spiral ganglion neurite branching.
  • fibroblast growth factor 8 - (Fgf-8) a growth factor released by inner hair cells which regulates pillar cell number, position and rate of development.
  • fibroblast growth factor receptor 3 - (Fgfr-3) a tyrosine kinase receptor with a role in the commitment, differentiation and position of pillar cells in the organ of corti
  • fundamental frequency - (natural frequency) the lowest frequency in a harmonic series, for the female voice this is about 225 Hz.
  • helicotrema - term used to describe the cochlear apex. (More? Inner Ear)
  • Hes - (hairy and enhancer of split) family of factors, which has been shown to be a general negative regulator of neurogenesis (Zheng, 2000).
  • hillock - a small hill, used to describe the six surface elevations on pharyngeal arch one and two. (More? Outer Ear)
  • Incus - (anvil) auditory ossicle (More? Middle Ear)
  • inner phalangeal cells - in the cochlea a single row of cells, that along with and three rows of outer phalangeal cells (Deiter's cells), are the hair cell supporting cells. (More? Inner Ear)
  • inner pillar cells - organ of Corti cells arranged in rows and form a boundary between the single row of inner hair cells and three rows of outer hair cells. These cells have surface-associated microtubule bundles. (More? Inner Ear)
  • inner sulcus - area of the cochlear duct. (More? Inner Ear)
  • internal auditory meatus - (internal acoustic meatus, IAM) Anatomical canal in which CN VII and CN VIII ganglia reside and pass through to the brainstem. This bony canal lies between the posterior surface of the petrous pyramid and the bony labyrinth within the dense petrous bone. Also associated clinically with the site where acoustic neuromas may occur. (More? Inner Ear)
  • kinocilium - inner ear hair cell specialised type of cilium on the cell apex.
  • Kolliker's organ - (Kollicker's organ, greater epithelial ridge) Developing cochlear structure consisting of columnar-shaped supporting cells filling the inner sulcus and lying directly under the tectorial membrane. This transient organ regresses and generates the space of the inner sulcus. Rudolph Albert von Kolliker (1817-1905)?? (More? Inner Ear)
  • lateral semicircular duct
  • limbus -
  • LMP - acronym for last menstrual period, used to clinically measure gestation.
  • malleus - (hammer) auditory ossicle (More? Middle Ear)
  • mastoid process - of temporal bone (More? Middle Ear)
  • Math1 - homolog of the Drosophila proneural gene atonal, necessary and sufficient for the production of hair cells in the mouse inner ear. Negatively regulated by Hes1 and Hes5
  • meatal plug - temporary blockage of the external auditory meatus which forms at the end of the embryonic period and remains present until the seventh month.
  • meatus - anatomical opening, cavity or space (external acoustic meatus, internal auditory meatus)
  • mechano-electrical transduction - (MET) occurs within the cochlear hair cells hair bundle. A mechanical stimulus of the hair bundle causes the tip-links to be tensioned, opening ion channels, resulting in the generation of the cell receptor potential. (More? Inner Ear)
  • Meckel's cartilage - first pharyngeal ach cartilage, located within the mandibular prominence. This cartilage first appears at stage 16, stage 20 the beginning of membranous ossification. Named after Johann Friedrich Meckel, (1781 - 1833) a German anatomist. (http://www.whonamedit.com/doctor.cfm/1840.html) (More? Middle Ear)
  • membranous labyrinth - (More? Inner Ear)
  • mucopolysaccharidosis - (MPS IIIB, Sanfilippo Syndrome type B) abnormality caused by a deficiency in the lysosomal enzyme N-acetyl-glucosaminidase (Naglu). Children with MPS IIIB develop abnormal hearing, and mental functioning culminating in early death.
  • netrin-1 - secreted growth factor, expressed in the organ of Corti and spiral ganglion cells, role in process outgrowth. (More? Inner Ear)
  • otoacoustic emissions testing - (OET) hearing test measures sounds generated by the outer hair cells of the cochlea in response to clicks or tone bursts emitted and recorded by a tiny microphone placed in the infant’s external ear canal. (More? Hearing test)
  • olivocochlear - brainstem cholinergic and GABAergic efferent system that innervates sensory cells and sensory neurons of the inner ear.
  • organ of Corti - (More? Inner Ear)
  • organ of Corti protein II - (OCP-II) cytosolic protein or transcription factor? (More? Inner Ear)
  • otolithic membrane - extracellular matrix that cover the sensory epithelia of the inner ear. (More? Inner Ear)
  • ossicle - (small bone) the individual bone of the three middle ear bones (auditory ossicles), which reduce vibrational amplitude but increase force to drive fluid-filled inner ear. (More? Middle Ear)
  • ossify - (More? Middle Ear)
  • otic capsule -
  • otic cup -
  • otic placode - Embryonic ectodermal epithelium giving rise to inner ear structures. (More? Inner Ear | Placodes)
  • otic vesicle - (More? Inner Ear)
  • otoconin - inner ear biominerals required for vestibular apparatus function. (More? Inner Ear)
  • otogelin - (Otog) an inner ear specific glycoprotein expressed in cochlea cells at different developmental times. (More? Inner Ear)
  • otolithic membrane - a membrane within the utricle and saccule containing embedded hair cell cilia and small crystalline bodies of calcium carbonate (otoliths). Functions to detect head motion.
  • otoliths - small crystalline bodies of calcium carbonate found within the otolitic membrane of the utricle and saccule. (More? Inner Ear)
  • ototoxic - compound or drug causing temporary or permanent hearing loss.
  • outer hair cells - (OHCs) three rows of hair cells that function to increase basilar membrane motion through a local mechanical feedback process within the cochlea, the " cochlear amplifier".
  • outer pillar cells - arranged in rows and form a boundary between the single row of inner hair cells and three rows of outer hair cells. (More? Inner Ear)
  • paratubal musculature - muscles lying beside the auditory (Eustachian) tube. The tensor veli, palatini (TVP) and tensor tympani muscles. (More? Middle Ear)
  • perilymph - perilymphatic space - Periotic Capsule - petrous portion - of temporal bone
  • pejvakin gene - in humans, two missense mutations in this gene cause nonsyndromic recessive deafness (DFNB59) by affecting the function of auditory neurons.
  • pharyngeal arch - (More? Outer Ear) pharyngeal pouch pharyngeal membrane Pharynx
  • pillar cells - (PC) form an inner and outer row of support cells that form a boundary between inner and outer hair cells. (More? Inner Ear)
  • preyer reflex - ear flick in mouse in response to sound.
  • presbyacusis
  • prestin - a motor protein structurally similar to the anion transporter family expressed in cochlear outer hair cells. (More? Inner Ear)
  • preauricular tag - skin tags located in front of the external ear opening, are common in neonates and in most cases are normal, though in some cases are indicative of other associated abnormalities.
  • protocadherin 15 - (Pcdh15) required for initial formation of stereocilia bundles and changes in the actin meshwork within hair cells. The Ames waltzer (av) mouse mutant has both auditory and vestibular abnormalities from a mutation in this gene.
  • Reichert's cartilage - pharyngeal ach 2 cartilage, named after Karl Bogislaus Reichert (1811 - 1883) a German anatomist.
  • Reissner's membrane - (vestibular membrane, vestibular wall) is a membrane located inside the cochlea separating the scala media from scala vestibuli. Named after Ernst Reissner (1824-1878) a German anatomist. It primarily functions as a diffusion barrier, allowing nutrients to travel from the perilymph to the endolymph of the membranous labyrinth.
  • rhombomere -
  • saccular macula -
  • Saccule - (Latin, sacculus = a small pouch)
  • sacculocollic reflex -
  • scala tympani - one of the three Cochlea cavities, it is filled with perilymph.
  • Scarpa's ganglion - (vestibular ganglion) primary afferent vestibular neuron ganglion of the vestibular nerve. Located within the internal auditory meatus. (More? Inner Ear)
  • semicircular canals - series of fluid-filled loops of the inner ear required for balance and sensing acceleration. (More? Inner Ear)
  • sensorineural - term used to describe one of the two major classes of hearing loss involving the central pathway from the cochlear (other form is conductive loss).
  • space of Nuel - within the cochlea, an organ of Corti space between the outer pillar cells and the phalangeal and hair cells. Named after Jean-Pierre Nuel (1847-1920) a Belgian ophthalmologist. (More? Inner Ear)
  • spiral ganglion neurons - (SGN) innervate the inner (Type I) and outer (Type II) hair cells of the cochlea. (More? Inner Ear)
  • stapedius muscle - (innervated by CN VII tympanic branch) one of the two muscles in the middle ear, contraction of this muscle pulls the stapes and dampens auditory ossicle movement. (More? Middle Ear)
  • stapes - (stirrup) a middle ear auditory ossicle (bone) (More? Middle Ear)
  • stapes footplate - (More? Middle Ear)
  • startle response -
  • stereocilia -finger-like projections from the apical surface of sensory hair cells forming the hair bundle in the cochlea. Formed by tightly cross-linked parallel actin filaments in a paracrystalline array with cell surface specializations (tip links, horizontal top connectors, and tectorial membrane attachment crowns).
  • stratified squamous epithelia - classification of epithelium which transiently forms a plug in external ear canal to the outer eardrum.
  • stria vascularis - forms the outer wall of the cochlear duct of the mammalian cochlea is composed primarily of three types of cells. Marginal cells line the lumen of the cochlear duct and are of epithelial origin. Basal cells also form a continuous layer and they may be mesodermal or derived from the neural crest. Intermediate cells are melanocyte-like cells, presumably derived from the neural crest, and are scattered between the marginal and basal cell layers. The stria forms endolymph and also contains a rich supply of blood vessels. (More? Inner Ear)
  • sulcus -
  • synostotically - anatomically normally separate skeletal bones fused together. (More? Middle Ear)
  • tectorial membrane - within the cochlea an extracellular matrix produced by interdental cells, that covers the sensory epithelial hair cells of the organ of corti. (More? Inner Ear)
  • alpha-tectorin and beta- (TECTA, TECTB) major non-collagenous protein component of the tectorial membrane forming a striated-sheet matrix. Synthesized as glycosylphosphatidylinositol-linked, membrane bound precursors.
  • temporal bone - (More? Middle Ear)
  • tensor tympani - (innervated by CN V mandibular nerve) one of the two muscles in the middle ear, contraction of this muscle pulls the malleus and tenses the tympanic membrane, dampening auditory ossicle movement. The muscle arises from auditory tube (cartilaginous portion) and is inserted into the malleus (manubrium near the root).
  • teratogens -
  • tonotopy - term describing the mapping along the tectorial membrane within the cochlea of the different sound frequencies. (More? Inner Ear)
  • tympanic membrane - (ear drum)
  • utricle -
  • vacuolization -
  • vesicle -
  • vestibular apparatus -
  • vestibular evoked myogenic potential (VEMP) test
  • vestibular ganglion - (Scarpa's ganglion) primary afferent vestibular neuron ganglion of the vestibular nerve. Located within the internal auditory meatus. (More? Inner Ear)
  • vestibular membrane - (Reissner's) extends from the spiral lamina to the outer wall and divides the cochlea into an upper scala vestibuli, a lower scala tympani. (More? Inner Ear)
  • Vestibulocochlear Nerve - Cranial Nerve VIII
  • Whirlin - A PDZ scaffold protein expressed in hair cells at the stereocilia tips, essential for the stereocilia elongation process. The DFNB31 gene mutations cause hearing loss in human and mouse. This protein can interact with membrane-associated guanylate kinase (MAGUK) protein, erythrocyte protein p55 (p55). (More? Inner Ear)
  • Wnt7a - signaling through the Wnt pathway regulates the development of hair cell unidirectional stereociliary bundle orientation. (More? Inner Ear)
Other Terms Lists  
Terms Lists: ART | Birth | Bone | Cardiovascular | Cell Division | Gastrointestinal | Genetic | Hearing | Heart | Immune | Integumentary | Neural | Oocyte | Palate | Placenta | Renal | Respiratory | Spermatozoa | Ultrasound | Vision | Historic | Glossary

External Links

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.
Embryo Images Unit: Embryo Images Online | Craniofacial Development | Cell Populations | Pharyngeal Arches | Tongue | Nose and Upper Lip | Palate Development



BGDsmall.jpg
BGDB: Lecture - Gastrointestinal System | Practical - Gastrointestinal System | Lecture - Face and Ear | Practical - Face and Ear | Lecture - Endocrine | Lecture - Sexual Differentiation | Practical - Sexual Differentiation | Tutorial


Glossary Links

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 | Numbers | Symbols



Cite this page: Hill, M.A. 2017 Embryology BGD Lecture - Face and Ear Development. Retrieved November 18, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/BGD_Lecture_-_Face_and_Ear_Development

What Links Here?
© Dr Mark Hill 2017, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G