A flat facial profile, or craniofacial flatness, describes a deviation from typical facial or skull curvature that can range from a minor cosmetic difference to a sign of underlying developmental issues. This appearance is broadly categorized into two distinct types: flatness caused by external, mechanical pressure on the skull bones, and flatness resulting from the intrinsic underdevelopment of the midface structure. Understanding the difference between these two primary origins is the first step in determining the cause, which can stem from something as common as an infant’s sleeping position or as complex as a genetic syndrome. The etiology of a flatter facial profile is highly varied, involving a complex interplay of mechanical forces, inherited traits, and functional habits that shape the bones of the skull and face.
Positional and Deformational Causes in Infancy
The most common cause of a flattened head shape in infants is external pressure exerted on the soft, pliable bones of the skull. This condition is often referred to as deformational head shape, which does not involve the premature fusion of skull sutures. Deformational plagiocephaly is characterized by an asymmetrical flattening on one side of the back of the head, causing the ear on the affected side to appear pushed forward.
Prolonged time spent in the supine, or back-sleeping, position is the primary driver of this type of flattening, largely increasing in prevalence following the “Back to Sleep” campaign aimed at reducing Sudden Infant Death Syndrome (SIDS). Deformational brachycephaly, conversely, presents as a symmetrical flattening across the entire back of the head, resulting in a widened skull shape. This bilateral flatness is typically seen in infants who spend significant periods lying on their backs without preferential head turning.
Restrictive positioning, even before birth, such as in-utero constraint due to breech presentation or multiple births, can also contribute to a flatter head shape at birth. A condition known as congenital muscular torticollis, which involves tightness in the neck muscles, can further exacerbate the issue. Torticollis causes the infant to hold their head in a preferred position, leading to consistent pressure on a single area of the skull.
Interventions for these deformational conditions focus on relieving pressure from the flattened area while the skull is still rapidly growing. Repositioning techniques, such as encouraging the infant to face away from the flattened side, are commonly employed during waking hours. Supervised “tummy time” while awake is promoted to strengthen neck muscles and remove pressure from the back of the head entirely. For moderate to severe cases, a custom-molded cranial orthotic helmet may be used to gently redirect skull growth.
Genetic Syndromes and Inherited Structural Traits
A fundamentally different cause of a flatter facial profile involves intrinsic factors, where the underlying facial bone structure is underdeveloped or malformed due to genetic programming. This structural flatness often involves midface hypoplasia, which is the decreased growth of the central facial bones, including the upper jaw (maxilla), cheekbones, and eye sockets. In these cases, the appearance is not due to external pressure, but rather an inherent lack of forward projection of the midface.
Genetic syndromes frequently involve midface hypoplasia. Conditions like Trisomy 21, also known as Down Syndrome, are a well-known example. Individuals with Down Syndrome often exhibit a characteristic flatter facial profile and a smaller midface, which can contribute to a recessed nasal bridge. Other conditions, such as Apert syndrome and Crouzon syndrome, involve premature fusion of the skull sutures, a process called craniosynostosis.
Craniosynostosis restricts the growth of the skull perpendicular to the fused suture, forcing compensatory growth in other directions. When certain sutures fuse early, the development of the midface and orbits is constrained, leading to a structurally flat face and shallow eye sockets. The general shape of an individual’s face, including the projection of the maxilla, is also influenced by normal, inherited genetic variation. Some people may simply inherit a facial structure that naturally appears less convex or forward-growing than others, independent of any syndrome.
Craniofacial Development and Functional Influences
Beyond genetics and infant positioning, the development of the face is continuously shaped by functional and environmental forces throughout childhood. This concept highlights the influence of soft tissues, such as muscles and the tongue, on the underlying bone structure, a process often studied through the lens of epigenetics. The way a person breathes, swallows, and chews can significantly influence the growth direction of the jawbones and midface.
A key factor is the difference between chronic mouth breathing and proper nasal breathing, often due to airway obstruction from allergies or enlarged adenoids. When the mouth is habitually open to facilitate breathing, the tongue drops from its proper resting position on the palate. This low tongue posture removes the internal, gentle, outward-and-forward pressure the tongue normally exerts on the upper jaw.
The constant inward pressure from the cheeks, unopposed by the tongue’s force, can lead to a narrow, high-arched palate and a maxilla that grows downward and backward, contributing to a flatter midface profile. This altered growth pattern often results in an increased lower facial height and a jaw that appears recessed.
Furthermore, the modern shift toward softer, processed diets provides insufficient stimulation for robust jaw growth. The action of chewing tough, textured foods generates mechanical forces that stimulate bone apposition and promote the development of wider, stronger jawbones. Without this necessary resistance, the bones of the maxilla and mandible may not reach their full genetic potential for forward and lateral expansion. This lack of functional stimulation contributes to a higher incidence of narrow dental arches and less projected midface structures in contemporary populations compared to historical groups with tougher diets.