2011 Lab 6 - Abnormalities

From Embryology
2011 Lab 6: Introduction | Trilaminar Embryo | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment

Pharyngeal Abnormalities

The four different types of pharyngeal abnormalities are relatively rare.

Sinuses - a pharyngeal groove defect, when a portion of the groove persists and opens to the skin surface, located laterally on the neck.

Fistula - a pharyngeal membrane defect, a tract extends from pharynx (tonsillar fossa) beween the carotid arteries (internal and external) to open on side of neck.

Cysts - a cervical sinus defect, remants of the cervical sinus remains as a fluid-filled cyst lined by an epithelium.

Vestiges - cartilaginous or bony developmental remnants lies under the skin on side of neck.

First Arch Syndrome

There are 2 major types of genetic first arch syndrome, Treacher Collins and Pierre Robin, both result in extensive facial abnormalites.

Treacher Collins syndrome (TCS)

  • a rare autosomal dominant craniofacial disorder (1:50.000)
  • caused by frameshift deletions or duplications in the TCOF1 gene.
  • hypoplasia of the mandible and zygomatic complex
  • down-slanting palpebral fissures
  • coloboma of the lower eyelid
  • absence of eyelashes medial to the defect
  • external and middle ear malformation
  • conductive hearing loss
Links: Medline Plus - Pierre Robin Syndrome | Medline Plus - Treacher Collins Syndrome

Embryo Cleft Lip and Palate

Human embryo primary palate cleft (Carnegie stage 16, 18 and 19, images not to scale, Kyoto collection)

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).

300+ different abnormalities different cleft forms and extent upper lip and ant. maxilla hard and soft palate

Fetal Cleft Ultrasound Movies

Cleft lip 01.jpg

<Flowplayer height="460" width="604" autoplay="true">Cleft_lip_01.flv‎</Flowplayer> Movie shows a cleft lip in an 18 week fetus. Fetal facial clefting can be detected by ultrasound scans. A common form of facial abnormality is that of cleft lip and palate. This is associated with the way in which the maxillary processes of the first pharyngeal arch must grow and fuse.

A measurement of the facial cleft of 4.8 mm (between the 2 plus marks + +)

Links: Quicktime version | Quicktime | Flash

A second movie shows a cleft lip in an 13 week (LMP 15 weeks) fetus. Quicktime | Flash


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.

Cleft Lip and Palate Classification

unilateral incomplete - cleft on one side of the lip that does not extend into the nose. unilateral complete - cleft on one side of the lip that extends into the nose. bilateral complete - cleft that involves both sides of the lip and extends into and involves the nose.

Cleft Lip

Bilateral cleft palate International Classification of Diseases code 749.1 for isolated cleft lip and 749.2 for cleft lip with cleft palate
  • Australian national rate (1982-1992) 8.1 - 9.9 /10,000 births.
  • Of 2,465 infants 6.2% were stillborn and 7.8% liveborn died during neonatal period.
  • rate similar in singleton and twin births.

Cleft Palate

Cleft palate International Classification of Diseases code 749.0
  • Australian national rate (1982-1992) 4.8 - 6 /10,000 births.
  • Of 1,530 infants 5.5% were stillborn and 11.5% liveborn died during neonatal period.
  • slightly more common in twin births than singleton.

(Data: Congenital Malformations Australia 1981-1992 P. Lancaster and E. Pedisich ISSN 1321-8352)

Fetal Alcohol Syndrome (FAS)


The following facial features may be associated with FAS

  • Microcephaly - leads to small head circumference
  • Palpebral fissure - short opening of eye
  • Epicanthal folds - fold of skin at inside of corner of eye
  • Midface - flat
  • Nasal Bridge - low
  • Philtrum - Indistinct, vertical grooves between nose and mouth
  • Upper Lip - thin
  • Micrognathia - small jaw
  • Ears - curve at top part of outer ear is underdeveloped and folded over parallel to curve beneath. Gives the appearance of a "railroad track"
Fetal Alcohol Syndrome face appearance

Auricular Abnormalities

Pre-auricular fistulae and appendage locations.jpg

Cephalic Disorders

Cephalic (Greek, kephale = head) are a group of abnormalities that relate to a wide range of skeletal (skull) and neural (brain) associated defects. Listed below are some selected skull defects.

Acephaly (absence of head) Exencephaly (brain outside skull) Macrocephaly (large head) Micrencephaly (small brain) Otocephaly (absence of lower jaw) Brachycephaly (premature fusion of coronal suture) Oxycephaly (premature fusion of coronal suture + other) Plagiocephaly (premature unilateral fusion of coronal or lambdoid sutures) Scaphocephaly (premature fusion of sagittal suture)

Additional Information

The following links cover abnormalities of these systems in more detail.

Links: Head Abnormalities | Skull Abnormal Synostosis | Hearing Abnormalities | Vision Abnormalities

2011 Lab 6: Introduction | Trilaminar Embryo | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment

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Cite this page: Hill, M.A. (2024, May 29) Embryology 2011 Lab 6 - Abnormalities. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2011_Lab_6_-_Abnormalities

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G