In the
human skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...
, the zygomatic bone (from grc, ζῠγόν, zugón, yoke), also called cheekbone or malar bone, is a paired
irregular bone which articulates with the
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...
, the
temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex.
The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. ...
, the
sphenoid bone
The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of the occipital bone. The sphenoid bone is one of the seven bones that articulate to form the o ...
and the
frontal bone
The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, ...
. It is situated at the upper and lateral part of the face and forms the prominence of the
cheek
The cheeks ( la, buccae) constitute the area of the face below the eyes and between the nose and the left or right ear. "Buccal" means relating to the cheek. In humans, the region is innervated by the buccal nerve. The area between the insi ...
, part of the lateral wall and floor of the
orbit
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...
, and parts of the
temporal fossa
The temporal fossa is a fossa (shallow depression) on the side of the skull bounded by the temporal lines and terminating below the level of the zygomatic arch.
Boundaries
* Medial: frontal bone, parietal bone, temporal bone, and sphenoid bon ...
and the
infratemporal fossa. It presents a malar and a temporal surface; four
processes
A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic.
Things called a process include:
Business and management
*Business process, activities that produce a specific se ...
(the frontosphenoidal, orbital, maxillary, and temporal), and four borders.
Etymology
The term ''zygomatic'' derives from the
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...
, ''zygoma'', meaning "yoke". The zygomatic bone is occasionally referred to as the
zygoma, but this term may also refer to the
zygomatic arch
In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygo ...
.
Structure
Surfaces
The ''malar surface'' is convex and perforated near its center by a small aperture, the
zygomaticofacial foramen
The zygomaticofacial foramen is a small aperture. It perforates the malar surface of the convex zygomatic bone near its center, for the passage of the zygomaticofacial nerve and vessels. Below this foramen
In anatomy and osteology, a foramen ( ...
, for the passage of the zygomaticofacial nerve and vessels; below this foramen is a slight elevation, which gives origin to the
zygomaticus muscle.
The ''temporal surface'', directed posteriorly and medially, is concave, presenting medially a rough, triangular area, for articulation with the maxilla (articular surface), and laterally a smooth, concave surface, the upper part of which forms the anterior boundary of the
temporal fossa
The temporal fossa is a fossa (shallow depression) on the side of the skull bounded by the temporal lines and terminating below the level of the zygomatic arch.
Boundaries
* Medial: frontal bone, parietal bone, temporal bone, and sphenoid bon ...
, the lower a part of the infratemporal fossa. Near the center of this surface is the zygomaticotemporal foramen for the transmission of the
zygomaticotemporal nerve.
The ''orbital surface'' forms the lateral part and some of the inferior part of the bony orbit. The
zygomatic nerve passes through the zygomatic-orbital foramen on this surface. The lateral palpebral ligament attaches to a small protuberance called the orbital tubercle.
Processes
Each zygomatic bone is diamond-shaped and composed of three processes with similarly named associated bony articulations: frontal, temporal, and maxillary. Each process of the zygomatic bone forms important structures of the skull.
The orbital surface of the frontal process of the zygomatic bone forms the anterior lateral orbital wall, with usually a small paired foramen, the zygomaticofacial foramen opening on its lateral surface. The temporal process of the zygomatic bone forms the zygomatic arch along with the zygomatic process of the temporal bone, with a paired zygomaticotemporal foramen present on the medial deep surface of the bone. The orbital surface of the maxillary process of the zygomatic bone forms a part of the infraorbital rim and a small part of the anterior part of the lateral orbital wall.
Orbital process
The orbital process is a thick, strong plate, projecting backward and medialward from the orbital margin. Its ''antero-medial surface'' forms, by its junction with the orbital surface of the
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...
and with the great wing of the
sphenoid, part of the floor and lateral wall of the orbit. On it are seen the orifices of two canals, the
zygomatico-orbital foramina; one of these canals opens into the
temporal fossa
The temporal fossa is a fossa (shallow depression) on the side of the skull bounded by the temporal lines and terminating below the level of the zygomatic arch.
Boundaries
* Medial: frontal bone, parietal bone, temporal bone, and sphenoid bon ...
, the other on the malar surface of the bone; the former transmits the
zygomaticotemporal, the latter the
zygomaticofacial nerve.
* Its ''postero-lateral surface,'' smooth and convex, forms parts of the temporal and infratemporal fossae.
* Its ''anterior margin,'' smooth and rounded, is part of the circumference of the orbit.
* Its ''superior'' ''margin,'' rough, and directed horizontally, articulates with the frontal bone behind the zygomatic process.
* Its ''posterior margin'' is serrated for articulation, with the great wing of the sphenoid and the orbital surface of the maxilla.
At the angle of junction of the sphenoidal and maxillary portions, a short, concave, non-articular part is generally seen; this forms the anterior boundary of the inferior orbital fissure: occasionally, this non-articular part is absent, the fissure then being completed by the junction of the maxilla and sphenoid, or by the interposition of a small sutural bone in the angular interval between them.
Borders
The ''antero-superior'' or ''orbital'' border is smooth, concave, and forms a considerable part of the circumference of the orbit.
The ''antero-inferior'' or ''maxillary'' border is rough, and bevelled at the expense of its inner table, to articulate with the maxilla; near the orbital margin it gives origin to the
quadratus labii superioris
The levator labii superioris (pl. ''levatores labii superioris'', also called quadratus labii superioris, pl. ''quadrati labii superioris'') is a muscle of the human body used in facial expression. It is a broad sheet, the origin of which exten ...
.
The ''postero-superior'' or ''temporal'' border, curved like an italic letter ''f,'' is continuous above with the commencement of the temporal line, and below with the upper border of the
zygomatic arch
In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygo ...
; the temporal fascia is attached to it.
The ''postero-inferior'' or ''zygomatic border'' affords attachment by its rough edge to the
masseter.
Articulations
The zygomatic bone articulates with the
frontal bone
The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, ...
,
sphenoid bone
The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of the occipital bone. The sphenoid bone is one of the seven bones that articulate to form the o ...
, and paired
temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebral cortex.
The temporal bones are overlaid by the sides of the head known as the temples, and house the structures of the ears. ...
s, and
maxillary bones.
Development
The zygomatic bone is generally described as
ossifying from three centers—one for the malar and two for the orbital portion; these appear about the eighth week and fuse about the fifth month of fetal life.
Mall describes it as being ossified from one center which appears just beneath and to the lateral side of the orbit.
After birth, the bone is sometimes divided by a horizontal suture into an upper larger, and a lower smaller division.
In some
quadrumana the zygomatic bone consisted of two parts, an orbital and a malar.
Society and culture
Zygomatic arches, also known as high cheek bones, are considered
physically attractive
Physical attractiveness is the degree to which a person's physical features are considered aesthetically pleasing or beautiful. The term often implies sexual attractiveness or desirability, but can also be distinct from either. There are many ...
in some cultures, in both males and females.
Ancient
Chinese sculptures of goddesses typically have a "broad forehead, raised
eyebrows, high cheekbones, and large, sensuous mouth".
Similarly, many depictions of Qin warriors in the
Terracotta Army
The Terracotta Army is a collection of terracotta sculptures depicting the armies of Qin Shi Huang, the first emperor of China. It is a form of funerary art buried with the emperor in 210–209 BCE with the purpose of protecting the emperor ...
are depicted with "broad
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 ...
s, high cheekbones, large eyes, thick eyebrows, and stiff
beards
A beard is the hair that grows on the jaw, chin, upper lip, lower lip, cheeks, and neck of humans and some non-human animals. In humans, usually pubescent or adult males are able to grow beards.
Throughout the course of history, societal at ...
."
For this reason some individuals undergo
cheek augmentation, a form of
cosmetic surgery
Plastic surgery is a surgical specialty involving the restoration, reconstruction or alteration of the human body. It can be divided into two main categories: reconstructive surgery and cosmetic surgery. Reconstructive surgery includes cranio ...
.
Other animals
The zygomatic is
homologous to the
jugal bone of other
tetrapods
Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct therapsi ...
.
Non-mammalian vertebrates
In non-
mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...
ian vertebrates, the zygomatic bone is referred to as the
jugal bone, since these animals have no zygomatic arch. It is found in most
reptile
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates ( lizards and snakes) and rhynchocephalia ...
s,
amphibian
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...
s, and
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s. It is connected to the
quadratojugal The quadratojugal is a skull bone present in many vertebrates, including some living reptiles and amphibians.
Anatomy and function
In animals with a quadratojugal bone, it is typically found connected to the jugal (cheek) bone from the front and ...
and
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...
, as well as other bones, which may vary by species.
This bone is considered key in the determination of general traits of the skull, as in the case of creatures, such as
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
s in
paleontology
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
, whose entire skull has not been found. In
coelacanth
The coelacanths ( ) are fish belonging to the order Actinistia that includes two extant species in the genus ''Latimeria'': the West Indian Ocean coelacanth (''Latimeria chalumnae''), primarily found near the Comoro Islands off the east coast ...
s and early
tetrapod
Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct t ...
s the bone is relatively large. Here, it is a plate-like bone forming the lower margin of the orbit and much of the side of the face. In
ray-finned fish
Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species.
The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...
es it is reduced or absent, and the entire cheek region is generally small. The bone is also absent in living
amphibian
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arbo ...
s.
With the exception of
turtle
Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...
s, the jugal bone in
reptile
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates ( lizards and snakes) and rhynchocephalia ...
s forms a relatively narrow bar separating the orbit from the inferior
temporal fenestra, of which it may also form the lower boundary. The bone is similarly reduced in
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s. In mammals, it takes on broadly the form seen in humans, with the bar between the orbit and fenestra vanishing entirely, and only the lower boundary of the fenestra remaining, as the zygomatic arch.
[
]
Additional images
See also
* Treacher Collins syndrome
* Zygoma fracture
* Zygomatic arch
In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygo ...
* Zygomatic complex fracture
* Zygomatic fossa
References
External links
*
{{Authority control
Bones of the head and neck
Facial features
Irregular bones
Vertebrate anatomy