Nasal bridge
The nasal bridge is the upper part of the nose, where the nasal bones and surrounding soft tissues provide structural support. While commonly discussed in human anatomy, nasal bridges exist in various forms across many vertebrates, particularly mammals. The shape, size, and function of the nasal bridge are influenced by evolutionary adaptations, playing a key role in respiration, sense of smell, and thermoregulation.
Anatomy
[edit]Humans
[edit]In humans, the nasal bridge is the elevated region of the nose between the eyes. It is primarily formed by the two small, oblong nasal bones, which meet at the midline to form the internasal suture. The nasal bridge extends from the nasal root, where the nose meets the forehead, to the lower edge of the nasal bones. Laterally, it reaches the inner canthi, the medial corners of the eyes, creating a saddle-shaped contour across the upper nose.[1]
The height and shape of the nasal bridge vary among individuals and populations, reflecting genetic diversity and environmental adaptations. A high nasal bridge, often associated with a proportionally elongated nasal passage, is observed with greater frequency in populations indigenous to cold climates. This morphology is hypothesized to enhance the conditioning of inhaled air through increased surface area for heat and moisture exchange, which mitigates the physiological stress of frigid, desiccating atmospheric conditions. By contrast, a lower nasal bridge is more prevalent in populations originating from warm, humid environments, where airflow efficiency may be prioritized. However, this morphology is a polygenic trait shaped by complex genetic, developmental, and environmental factors, leading to substantial variation within and between populations.[2][3]
The procerus muscle, a small pyramidal muscle in the glabella, creates horizontal wrinkles on the nasal bridge. It is involved in facial expressions such as frowning and those associated with attentional control, and it indirectly helps shield the eyes from bright light. Because it contributes to wrinkle formation, it is often targeted in non-surgical facial rejuvenation treatments, such as botulinum toxin injections.[4]: 558
Animals
[edit]The nasal bridge, or its analogous, varies widely across animal species. In canines, the nasal bridge is typically elongated, supporting extensive nasal passages, though brachycephalic breeds exhibit a notably shortened structure due to selective breeding.[5][6]: 187 In birds, the nasal bones are often fused with the skull.[7][8]
Association with epicanthic folds
[edit]Low-rooted nasal bridges are closely associated with epicanthic folds. A lower nasal bridge is more likely to cause an epicanthic fold, and vice versa.[9]
Dysmorphology
[edit]A lower or higher than average nasal bridge in humans can be a sign of various genetic disorders, such as fetal alcohol syndrome. A flat nasal bridge can be a sign of Down syndrome (Trisomy 21), Fragile X syndrome, 48,XXXY variant Klinefelter syndrome,[10] or Bartarlla-Scott syndrome. A broad nasal bridge can be a sign of Snijders Blok–Campeau syndrome.[11]
An appearance of a widened nasal bridge can be seen with dystopia canthorum, which is a lateral displacement of the inner canthi of the eyes.[12] Dystopia canthorum is associated with Waardenburg syndrome.[13]
See also
[edit]- Aquiline nose – Human nose with a prominent bridge
- Bridge piercing – Facial piercing through the skin on the nasal bridge
References
[edit]- ^ "Anatomy of the Nose". Elements of Morphology: Human Malformation Terminology. National Human Genome Research Institute. Archived from the original on January 24, 2025. Retrieved March 9, 2025.
- ^ De Jaime-Soguero A, Aulicino F, Ertaylan G, Griego A, Cerrato A, Tallam A, et al. (March 2017). "Wnt/Tcf1 pathway restricts embryonic stem cell cycle through activation of the Ink4/Arf locus". PLOS Genetics. 13 (3): e1006682. doi:10.1371/journal.pgen.1006616. PMC 5378138. PMID 28346462.
- ^ Noback ML, Harvati K, Spoor F (August 2011). "Climate-related variation of the human nasal cavity". American Journal of Physical Anthropology. 145 (4): 599–614. doi:10.1002/ajpa.21523. PMID 21660932.
- ^ Hopkins C (2016). "Chapter 33. Nose, nasal cavity and paranasal sinuses". In Standring S (ed.). Gray's Anatomy: The Anatomical Basis of Clinical Practice (41st ed.). Elsevier. ISBN 9780702052309.
- ^ Craven BA, Paterson EG, Settles GS (June 2010). "The fluid dynamics of canine olfaction: unique nasal airflow patterns as an explanation of macrosmia". Journal of the Royal Society, Interface. 7 (47): 933–943. doi:10.1098/rsif.2009.0490. PMC 2871809. PMID 20007171.
- ^ Colville TP, Bassert JM (2016). "Chapter 7. The Skeletal System". Clinical Anatomy and Physiology for Veterinary Technicians. Elsevier. ISBN 9780323227933 – via Google Books.
- ^ Plateau O, Foth C (April 2020). "Birds have peramorphic skulls, too: anatomical network analyses reveal oppositional heterochronies in avian skull evolution". Communications Biology. 3 (1): 195. doi:10.1038/s42003-020-0914-4. PMC 7181600. PMID 32332847.
- ^ Gussekloo SW, Berthaume MA, Pulaski DR, Westbroek I, Waarsing JH, Heinen R, et al. (May 2017). "Functional and evolutionary consequences of cranial fenestration in birds" (PDF). Evolution; International Journal of Organic Evolution. 71 (5): 1327–1338. doi:10.1111/evo.13210. PMID 28230246.
- ^ Montagu A (1989). Growing Young. N.Y.: McGraw Hill. p. 40.
- ^ "Klinefelter Syndrome Clinical Presentation". Archived from the original on July 4, 2018. Retrieved March 27, 2018.
- ^ Drivas TG, Li D, Nair D, Alaimo JT, Alders M, Altmüller J, et al. (October 2020). "A second cohort of CHD3 patients expands the molecular mechanisms known to cause Snijders Blok-Campeau syndrome". European Journal of Human Genetics. 28 (10): 1422–1431. doi:10.1038/s41431-020-0654-4. PMC 7608102. PMID 32483341.
- ^ Shen J, Deskin RW (March 17, 2004). Quinn Jr FB, Ryan MW (eds.). "Genetic Hearing Loss". UTMB, Dept. of Otolaryngology. Archived from the original on February 17, 2013.
- ^ Tagra S, Talwar AK, Walia RL, Sidhu P (2006). "Waardenburg syndrome". Indian Journal of Dermatology, Venereology and Leprology. 72 (4): 326. doi:10.4103/0378-6323.26718. PMID 16880590.