Sinonasal Embryology and Anatomy

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Sinonasal Embryology and Anatomy

Rhinology
Author Credentials 

Taha Mur, MD
Elina Toskala, MD, PhD, MBA
Professor
Otolaryngology Head and Neck Surgery
Temple University Hospital
Philadelphia, PA

Module Summary

Understanding the embryology of the sinonasal pathway is crucial in appreciating its anatomy and pathophysiology. Congenital anomalies occur because of errors during embryogenesis. Depending on the affected period during prenatal development, different structures and malformations may be observed. The abnormalities may range from full absence of development to a mild malformation, easily reparable. Given the complexity of the sinonasal procedures, it is imperative to truly understand the anatomy prior to operating.

Module Learning Objectives 
  1. Describe the basic embryology of the sinonasal tract.
  2. Recognize the most common embryologic abnormalities of the sinonasal tract.
  3. Explain the anatomic relationships of the sinonasal tract in the setting of the head and neck
  4. Cite the origins of anatomic variants of the nasal system
  5. Describe the variants of the frontal sinus anatomy

Embryology

Learning Objectives 
  1. Understand the normal embryologic development of the sinuses and the nose and the different germ cell layers associated with their development.
  2. Know the window span of development and the roles of the branchial arches, branchial pouches and the primitive gut in the development of the sino-nasal tract.
  3. Know the origin of the stomodeum and the significance of this orifice as well as the surrounding embryologic structures.
  4. Understand what the nasal placodes and embrylogic middle meatus ultimately develop into.
  5. Know that the frontonasal prominence gives rise to inferior mesodermic projections, ultimately dividing the nose into two cavities.
  6. Know that projections arise from the lateral wall of the nose, serving as the beginning of the development of paranasal sinuses. These projections consist of an anterior, inferior and superior form, each developing into a unique structure.
  7. Understand how the small lateral diverticula invaginate into the primitive choana to form the meati of the nose.
  8. Understand the development of the sinuses. Know that the frontal sinus may develop as a result of two different process. The first is through direct continuation of the embryonic infundibulum and frontal recess. The other is by upward migration of anterior ethmoidal air cells to penetrate the inferior aspect of the frontal bone.
  9. Know that pneumatization of the frontal bone will begin when the child is about 2 years of age and will continue till the child is 9 years old.
  10. Know that the frontal sinus is the most variable in development.
  11. Know that with age, the maxillary sinus will expand as the child’s maxillary teeth are lost and that it will reach its final size at variable times.
  12. Understand how the superior, middle and inferior concha develop as elevations on the lateral nasal wall of each nasal cavity.
References 
  1. Johnston MC, Bronsky PT. Prenatal craniofacial development: new insights on normal and abnormal mechanisms. Crit Rev Oral Biol Med. 1995;6(4):368-422.
  2. Tessier P. Anatomical classification facial, cranio-facial and latero-facial clefts. J Maxillofac Surg. 1976 Jun;4(2):69-92.
  3. Wake M, Takeno S, Hawke M. The Early Development of Sino-Nasal Mucosa. Laryngoscope. 1994 Jul;104(7):850-5.

Anatomy

Learning Objectives 
  1. Understand the anatomy of the nose and the different segments of the nose in relation to one another. 
  2. Understand the location of each of the turbinates in relation to the nasal wall and the septum.
  3. Know the major surgical landmarks in the nose.
  4. Understand the different vessels within the nose and the routes that they take.
  5. Know the different vascular plexuses within the nose and the vessels that make them up.
  6. Familiarize yourself with the location and shape of each of the sinuses, as well as their ostia.
References 
  1. Lang J. Clinical anatomy of the nose, nasal cavity, and paranasal sinuses. Stuttgart, Germany: Thieme Medical Publishers. 1989.
  2. Kubal WS. Sinonasal anatomy. Neuroimaging Clin N Am. 1998 Feb;8(1):143-56.
  3. Baryam M, Sirikci A, Bayazit YA. Important anatomic variations of the sinonasal anatomy in light of endoscopic surgery: a pictorial review. Eur Radiol. 2001;11:1991-97.

Pathogenesis

Learning Objectives 
  1. Understand the different kinds of embryologic abnormalities of the sinonasal tract
  2. Know the manifestations and complications of each of these pathologies
  3. Know that failure of the anterior posterior fusion can result in bifid uvula
  4. Understand how failure of fusion between maxillary process and premaxilla can cause cleft lip
  5. Know that failure of rupture of the oronasal membrane can result in choanal atresia.
  6. Failure of olfactory placode development can result in complete or partial absence of the nose.
References 
  1. Hengerer AS, Oas RE. Congenital anomalies of the nose: Their embryology, diagnosis, and management (SIPAC). Alexandria, VA: American Academy of Otolaryngology. 1987.
  2. Leclerc JE, Fearon B. Choanal atresia and associated anomalies. Int J Pediatr Otorhinolaryngol. 1987 Oct;13(3):265-72.
  3. Albernaz VS, Castillo M, Mukherji SK, et al.Congenital arhinia. AJNR Am J Neuroradiol. 1996 Aug;17(7):1312-4.

Incidence

Learning Objectives 

Know the incidence of common embryologic abnormalities

References 
  1. Denoyelle F, Ducroz V, Roger G, Garabedian EN. Nasal dermoid sinus cysts in children. Laryngoscope. 1997 Jun;107(6):795-800.
  2. Brown OE, Pownell P, Manning SC. Choanal atresia: a new anatomic classification and clinical management applications. Laryngoscope. 1996 Jan;106(1 Pt 1):97-101.

Genetics

Learning Objectives 

Be familiar with the possible role of genetics in developmental abnormalities of the sinonasal passages.

Imaging

Learning Objectives 
  1. Be familiar with the normal anatomy of the sinonasal tract in an MRI or CT image.
  2. Be familiar with imaging of embryological abnormalities.
References 
  1. Scuderi AJ, Harnsberger HR, Boyer RS. Pneumatization of the paranasal sinuses: normal features of importance to the accurate interpretation of CT scans and MR images. AJR Am J Roentgenol. 1993 May;160(5):1101-4.
  2. Slovis TL, Renfro B, Watts FB, Kuhns LR, Belenky W, Spoylar J.  Choanal atresia: precise CT evaluation. 1985 May;155(2):345-8.
  3. Arslan H, Aydinlioglu A, Bozkurt M, Egeli E.  Anatomic variations of the paranasal sinuses: CT examination for endoscopic sinus surgery, Auris Nasus Larynx. 1999 Jan;26(1):39-48.

Surgical Therapies

Learning Objectives 
  1. Be familiar with surgical techniques in the repair of common embryologic abnormalities.
  2. Know when surgical therapy should be postponed in patients with embryologic abnormalities of the sinonasal tract.
References 
  1. Gargano F, Szymanski K, Bosman M et al. Tessier 1-13 Atypical Craniofacial Cleft. Eplasty. 2015; 15: ic32.
  2. McGlone L. Congenital arhinia. J Paediatr Child Health. 2003 Aug;39(6):474-6.
  3. Shikowitz MJ. Congenital nasal pyriform aperture stenosis: diagnosis and treatment. Int J Pediatr Otorhinolaryngol. 2003 Jun;67(6):635-9.

Case Studies

  1. A 2 day old female patient with mild shortness of breath, foul-smelling secretions from the left nare. The patient is also reported to be cyanotic upon breastfeeding, which seems to resolve when the infant is crying. On quick physical exam, the patient appears to have ear abnormalities and a reported abnormal heart murmur. The otolaryngologist attempts to pass a catheter through each side of the nose, only passing successfully through the right. Endoscopy of the left nare demonstrates a posterior blockage of the nasal passageway. What further testing if any is necessary? How would you elect to treat this patient?
  2. A newborn child presents with a median nasal cleft, marked hypertelorism and pronounced separation of the nostrils. The physician observes a large furrow involving the medial canthus and ipsilateral alum. What is the patient’s diagnosis? What embryologic error causes this malformation? When is reconstruction warranted for such abnormalities?

Complications

Learning Objectives 

Know the complications of the surgical treatment of these embryologic abnormalities.

Review

Review Questions 
  1. List the paranasal sinuses and where each opens up into the nasal cavity.
  2. Describe the embryologic origin of the hard and soft palate.
  3. What vessels compose Kiesselbach’s Plexus?
  4. How do midline structures like the nose and nasal cavities form?
  5. What is the nasolacrimal groove and what does it give rise to.
  6. How long does it take for complete development of the frontal sinus?
  7. How common are embryologic abnormalities?
Resources 

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  1. Annual Meeting Webcasts (AMW):
  2. ENT Exam Series (Xs):
  3. ENT for the PA-C:
  4. Sinus and Nasal Anatomy