The nasal bridge is the upper part of the

nose A nose is a sensory organ and respiratory structure in vertebrates. It consists of a nasal cavity inside the head, and an external nose on the face. The external nose houses the nostrils, or nares, a pair of tubes providing airflow through the ...

, where the

nasal bone The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...

s and surrounding

soft tissue Soft tissue connective tissue, connects and surrounds or supports internal organs and bones, and includes muscle, tendons, ligaments, Adipose tissue, fat, fibrous tissue, Lymphatic vessel, lymph and blood vessels, fasciae, and synovial membranes.� ...

s provide structural support. While commonly discussed in

human anatomy Human anatomy (gr. ἀνατομία, "dissection", from ἀνά, "up", and τέμνειν, "cut") is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross ...

, nasal bridges exist in various forms across many

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

s, particularly

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s. The shape, size, and function of the nasal bridge are influenced by evolutionary

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the p ...

s, playing a key role in

respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellul ...

sense of smell The sense of smell, or olfaction, is the special sense through which smells (or odors) are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste. In humans, it ...

, and

thermoregulation Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...

Anatomy

Humans

In humans, the nasal bridge is the elevated region of the

between the eyes. It is primarily formed by the two small, oblong

s, which meet at the midline to form the

internasal suture The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...

. The nasal bridge extends from the nasal root, where the nose meets the

forehead In human anatomy, the forehead is an area of the head bounded by three features, two of the skull and one of the scalp. The top of the forehead is marked by the hairline, the edge of the area where hair on the scalp grows. The bottom of the fo ...

, to the lower edge of the nasal bones. Laterally, it reaches the inner

canthi The canthus (: canthi, palpebral commissures) is either corner of the eye where the upper and lower eyelids meet. More specifically, the inner and outer canthi are, respectively, the medial and lateral ends/angles of the palpebral fissure. The ...

, the medial corners of the eyes, creating a

saddle A saddle is a supportive structure for a rider of an animal, fastened to an animal's back by a girth. The most common type is equestrian. However, specialized saddles have been created for oxen, camels and other animals. It is not know ...

-shaped contour across the upper nose. The height and shape of the nasal bridge vary among individuals and populations, reflecting

genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...

and environmental

s. A high nasal bridge, often associated with a proportionally elongated

nasal passage The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal c ...

, is observed with greater frequency in populations indigenous to cold climates. This

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

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. The

procerus muscle The procerus muscle (or pyramidalis nasi) is a small pyramidal muscle in the glabella. It is involved in facial expressions such as frowning and those associated with attentional control, and it indirectly helps shield the eyes from bright ligh ...

, a small pyramidal muscle in the

glabella The glabella, in humans, is the area of skin between the eyebrows and above the nose. The term also refers to the underlying bone that is slightly depressed, and joins the two brow ridges. It is a cephalometric landmark that is just superior ...

, creates horizontal wrinkles on the nasal bridge. It is involved in

facial expression Facial expression is the motion and positioning of the muscles beneath the skin of the face. These movements convey the emotional state of an individual to observers and are a form of nonverbal communication. They are a primary means of conveying ...

s such as

frown A frown (also known as a scowl) is a facial expression in which the eyebrows are brought together, and the forehead is wrinkled, usually indicating displeasure, sadness or worry, or less often confusion or concentration. The appearance of a fr ...

ing and those associated with

attentional control Attentional control, commonly referred to as concentration, refers to an individual's capacity to choose what they pay attention to and what they ignore. It is also known as endogeny, endogenous attention or executive functions, executive attenti ...

, 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 Facial rejuvenation is a cosmetic treatment (or series of cosmetic treatments), which aims to restore a youthful appearance to the human face. Facial rejuvenation can be achieved through either surgical and/or non-surgical options. Procedures can v ...

treatments, such as

botulinum toxin Botulinum toxin, or botulinum neurotoxin (commonly called botox), is a neurotoxic protein produced by the bacterium ''Clostridium botulinum'' and related species. It prevents the release of the neurotransmitter acetylcholine from axon en ...

injections.

Animals

The nasal bridge, or its analogies, varies widely across animal species. In canines, the nasal bridge is typically elongated, supporting extensive nasal passages, though

brachycephalic Brachycephaly (derived from the Ancient Greek '' βραχύς'', 'short' and '' κεφαλή'', 'head') is the shape of a skull shorter than average in its species. It is perceived as a cosmetically desirable trait in some domesticated dog and ...

breeds exhibit a notably shortened structure due to

selective breeding Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant m ...

. In

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s, the nasal bones are often fused with the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

Association with epicanthic folds

Low-rooted nasal bridges are closely associated with

epicanthic fold An epicanthic fold or epicanthus is a skin fold of the upper eyelid that covers the inner corner (medial canthus) of the Human eye, eye. However, variation occurs in the nature of this feature and the presence of "partial epicanthic folds" or " ...

s. A lower nasal bridge is more likely to cause an epicanthic fold, and vice versa.

Dysmorphology

A lower or higher than average nasal bridge in humans can be a sign of various

genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosome abnormality. Although polygenic disorders ...

s, such as

fetal alcohol syndrome Fetal alcohol spectrum disorders (FASDs) are a group of conditions that can occur in a person who is exposed to alcohol during gestation. FASD affects 1 in 20 Americans, but is highly misdiagnosed and underdiagnosed. The several forms of the ...

. A flat nasal bridge can be a sign of Down syndrome (Trisomy 21),

Fragile X syndrome Fragile X syndrome (FXS) is a genetic neurodevelopmental disorder. The average IQ in males with FXS is under 55, while affected females tend to be in the borderline to normal range, typically around 70–85. Physical features may include a lo ...

, 48,XXXY variant

Klinefelter syndrome Klinefelter syndrome (KS), also known as 47,XXY, is a chromosome anomaly where a male has an extra X chromosome. These complications commonly include infertility and small, poorly functioning testicles (if present). These symptoms are often n ...

, or

Bartarlla-Scott syndrome Xylosyltransferase 1 is an enzyme that in humans is encoded by the ''XYLT1'' gene. Xylosyltransferase (XT; EC 2.4.2.26) catalyzes the transfer of UDP-xylose to serine residues within XT recognition sequences of target proteins. Addition of this ...

. A broad nasal bridge can be a sign of Snijders Blok–Campeau syndrome. An appearance of a widened nasal bridge can be seen with

dystopia canthorum Telecanthus, or dystopia canthorum, refers to increased distance between the inner corners of the eyelids (medial canthi), while the inter-pupillary distance is normal. This is in contrast to hypertelorism, in which the distance between the who ...

, which is a lateral displacement of the inner

of the eyes. Dystopia canthorum is associated with

Waardenburg syndrome Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes (or Heterochromia iridum, one blue eye and one brown ey ...

References