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human skull shape variations

human skull shape variations

My concern at the time was that the skulls of Asians and Africans were inaccurate and a lay person might assume the extreme examples are the norm. Sphenoid Bone. Figure 5. The unpaired ethmoid bone is located at the midline within the central skull. The anterior skull consists of the facial bones and provides the bony support for the eyes and structures of the face. Figure 11. Figure 13. These include the paired parietal and temporal bones, plus the unpaired frontal, occipital, sphenoid, and ethmoid bones. An anterior view of the skull shows the bones that form the forehead, orbits (eye sockets), nasal cavity, nasal septum, and upper and lower jaws. This opening provides for passage of the nerve from the hearing and equilibrium organs of the inner ear, and the nerve that supplies the muscles of the face. Below the level of the zygomatic arch and deep to the vertical portion of the mandible is another space called the infratemporal fossa. We compared individual morphological variations by using relative warp analysis, and then tested morphological integration between the skull and carnassial by using partial least square (PLS) analysis. All of the sinuses communicate with the nasal cavity (paranasal = “next to nasal cavity”) and are lined with nasal mucosa. This midline view of the sagittally sectioned skull shows the nasal septum. One of the major muscles that pulls the mandible upward during biting and chewing arises from the zygomatic arch. The short temporal process of the zygomatic bone projects posteriorly, where it forms the anterior portion of the zygomatic arch (see Figure 3). Located at the anterior-lateral margin of the foramen magnum is the hypoglossal canal. Figure 17. These are the bones that are damaged when the nose is broken. Glay Onan Labrande / EyeEm/EyeEm/GettyImages. On the inferior skull, the palatine process from each maxillary bone can be seen joining together at the midline to form the anterior three-quarters of the hard palate (see Figure 6a). On its outside surface, at the posterior midline, is a small protrusion called the external occipital protuberance, which serves as an attachment site for a ligament of the posterior neck. The maxillary bone forms the upper jaw and supports the upper teeth. From anterior to posterior, the fossae increase in depth. The lesser wing of the sphenoid bone separates the anterior and middle cranial fossae. It contains the cerebellum of the brain. The lateral skull shows the large rounded brain case, zygomatic arch, and the upper and lower jaws. These condyles form joints with the first cervical vertebra and thus support the skull on top of the vertebral column. The large, diagonally positioned petrous ridges give the middle cranial fossa a butterfly shape, making it narrow at the midline and broad laterally. The lesser wings of the sphenoid bone form the prominent ledge that marks the boundary between the anterior and middle cranial fossae. On December 13, in the journal Current Biology , researchers report that present-day humans who carry particular Neandertal DNA fragments have heads that are slightly less rounded, revealing genetic clues to the evolution of modern brain shape … The frontal bone also forms the supraorbital margin of the orbit. Figure 4. Head and traumatic brain injuries are major causes of immediate death and disability, with bleeding and infections as possible additional complications. The ethmoid bone also forms the lateral walls of the upper nasal cavity. On the anterior maxilla, just below the orbit, is the infraorbital foramen. The sphenoid bone is a single, complex bone of the central skull (Figure 8). These emerge on the inferior aspect of the skull at the base of the occipital condyle and provide passage for an important nerve to the tongue. These are bony plates that curve downward as they project into the space of the nasal cavity. The nuchal lines represent the most superior point at which muscles of the neck attach to the skull, with only the scalp covering the skull above these lines. The temporal lobes of the brain occupy this fossa. Learn more about the anatomy and function of the skull … The frontal sinus is the most anterior of the paranasal sinuses. The lateral sides of the ethmoid bone form the lateral walls of the upper nasal cavity, part of the medial orbit wall, and give rise to the superior and middle nasal conchae. This cavity is bounded superiorly by the rounded top of the skull, which is called the calvaria (skullcap), and the lateral and posterior sides of the skull. Because of the communication between the oral and nasal cavities, a cleft palate makes it very difficult for an infant to generate the suckling needed for nursing, thus leaving the infant at risk for malnutrition. When looking into the nasal cavity from the front of the skull, two bony plates are seen projecting from each lateral wall. It results from a failure of the two halves of the hard palate to completely come together and fuse at the midline, thus leaving a gap between them. The cheek bones are wide, flare out to the sides of the skull and are forward-sloping. The nasal septum consists of both bone and cartilage components (Figure 15; see also Figure 9). This blockage can also allow the sinuses to fill with fluid, with the resulting pressure producing pain and discomfort. The condyle of the mandible articulates (joins) with the mandibular fossa and articular tubercle of the temporal bone. Figure 12. The lacrimal fluid (tears of the eye), which serves to maintain the moist surface of the eye, drains at the medial corner of the eye into the nasolacrimal canal. Each cranial fossa has anterior and posterior boundaries and is divided at the midline into right and left areas by a significant bony structure or opening. The medial floor is primarily formed by the maxilla, with a small contribution from the palatine bone. The maxillary bone, often referred to simply as the maxilla (plural = maxillae), is one of a pair that together form the upper jaw, much of the hard palate, the medial floor of the orbit, and the lateral base of the nose (see Figure 2). The inferior nasal concha is an independent bone of the skull. Each of the paired zygomatic bones forms much of the lateral wall of the orbit and the lateral-inferior margins of the anterior orbital opening (see Figure 2). The superior nasal concha is located just lateral to the perpendicular plate, in the upper nasal cavity. The slope causes a protrusion of the jaw, also referred to as prognathism. MATERIALS AND METHODS: The study was conducted on 37 dry adult human skulls of unknown age and sex. The most marked variation in skull shape was the dorsoventral flexion; i.e., deformation from klinorhynchy to airorhynchy. This bony region of the sphenoid bone is named for its resemblance to the horse saddles used by the Ottoman Turks, with a high back and a tall front. The orbit is the bony socket that houses the eyeball and muscles that move the eyeball or open the upper eyelid. They have less pronounced cheek bones and exhibit elongated chins. The paired bones are the maxilla, palatine, zygomatic, nasal, lacrimal, and inferior nasal conchae bones. Located just above the inferior concha is the middle nasal concha, which is part of the ethmoid bone. Non‐rigid registration is used to represent variations in human skull shape. The shallow space above the zygomatic arch is the temporal fossa. On the posterior skull, the sagittal suture terminates by joining the lambdoid suture. Each tooth is anchored into a deep socket called an alveolus. Nasal Septum. The hyoid bone is located in the upper neck and does not join with any other bone. ... Neanderthal genes may explain our skull shape. The reason human skull shows variations is because cranial index differs for the skull shapes of different races. The lambdoid suture extends downward and laterally to either side away from its junction with the sagittal suture. The cribriform plates form both the roof of the nasal cavity and a portion of the anterior cranial fossa floor. Inside the skull, the floor of the cranial cavity is subdivided into three cranial fossae (spaces), which increase in depth from anterior to posterior (see Figure 4, Figure 6b, and Figure 9). This portion of the ethmoid bone consists of two parts, the crista galli and cribriform plates. In this view, the vomer is seen to form the entire height of the nasal septum. Asian skulls, also called Mongoloid, tend to be shorter and broader when compared with European or African types. Located inside each petrous ridge are small cavities that house the structures of the middle and inner ears. Posterior View of Skull. These are paired and located within the right and left maxillary bones, where they occupy the area just below the orbits. The flattened, upper portion is the squamous portion of the temporal bone. Parts of the Skull. It is a small U-shaped bone located in the upper neck near the level of the inferior mandible, with the tips of the “U” pointing posteriorly. The upper margin of the anterior orbit is the supraorbital margin. • Negroid characterized by a short dolichocephalic skull, receded zygomas and wide nasal apertures. The sphenoid has multiple openings for the passage of nerves and blood vessels, including the optic canal, superior orbital fissure, foramen rotundum, foramen ovale, and foramen spinosum. In the nasal cavity, the lacrimal fluid normally drains posteriorly, but with an increased flow of tears due to crying or eye irritation, some fluid will also drain anteriorly, thus causing a runny nose. Located inside this portion of the ethmoid bone are several small, air-filled spaces that are part of the paranasal sinus system of the skull. Anterior View of Skull. A view of the lateral skull is dominated by the large, rounded brain case above and the upper and lower jaws with their teeth below (Figure 3). The outside margin of the mandible, where the body and ramus come together is called the angle of the mandible (Figure 13). It has an upward projection, the crista galli, and a downward projection, the perpendicular plate, which forms the upper nasal septum. The parietal bone forms most of the upper lateral side of the skull (see Figure 3). Nasal openings are triangular shaped with a more pronounced (protruding) nasal bridge. It unites the right and left parietal bones. The larger of these is the inferior nasal concha, an independent bone of the skull. Bones of the Orbit. At the time of birth, the mandible consists of paired right and left bones, but these fuse together during the first year to form the single U-shaped mandible of the adult skull. can be revealed if the skull is suitably examined. The right and left inferior nasal conchae form a curved bony plate that projects into the nasal cavity space from the lower lateral wall (see Figure 11). It overlies the orbits and contains the frontal lobes of the brain. Figure 3. can be checked for in the case of skeleton also. It is formed during embryonic development by the midline fusion of the horizontal plates from the right and left palatine bones and the palatine processes of the maxilla bones. Also seen are the upper and lower jaws, with their respective teeth (Figure 2). The middle cranial fossa is divided at the midline by the upward bony prominence of the sella turcica, a part of the sphenoid bone. The eye orbits are rectangular in shape, resembling aviator sunglasses, and somewhat sloped when viewed from the front. The anterior cranial fossa is the most anterior and the shallowest of the three cranial fossae. Several cranial nerves from the brain exit the skull via this opening. The shape and depth of each fossa corresponds to the shape and size of the brain region that each houses. Figure 8. Length and width of the skull, shape of the eye orbits, size and shape of the nasal opening, shape and slope of the nasal bone above the opening, and general slope of the skull from forehead to chin are all important in determining race. Published on December 14, 2018. The largest region of each of the palatine bone is the horizontal plate. The sutures of the human skull can vary. Explore {{searchView.params.phrase}} by color family {{familyColorButtonText(colorFamily.name)}} The upper portion of the nasal septum is formed by the perpendicular plate of the ethmoid bone and the lower portion is the vomer bone. The lambdoid suture joins the occipital bone to the right and left parietal and temporal bones. The eye orbits are rounded and don't have the same downward slope as European skulls. Cranial Fossae. When looking into the anterior nasal opening of the skull, only the inferior and middle conchae can be seen. A better view of the vomer bone is seen when looking into the posterior nasal cavity with an inferior view of the skull, where the vomer forms the full height of the nasal septum. Certain people have slightly less rounded skull shapes that have that have inspired controversial questions such as alien genes having entered the human evolution process sometime in the ancient past. The hard palate is the bony structure that separates the nasal cavity from the oral cavity. It unites the squamous portion of the temporal bone with the parietal bone (see Figure 3). Round shape 22 % (11) 21.8 % (24) Irregular shape 18 % (9) 19.9 % (22) Oval shape 16 % (8) 8.1 % (9) Egg shape 16 % (8) - Tetragonal shape 12 % (6) 12.7 % (14) Pentagonal shape 8 % (4) - BACKGROUND Identity of a human being with regard to sex, race, age etc. The three nasal conchae are curved bones that project from the lateral walls of the nasal cavity. The anterior nasal septum is formed by the septal cartilage, a flexible plate that fills in the gap between the perpendicular plate of the ethmoid and vomer bones. Together these articulations form the temporomandibular joint, which allows for opening and closing of the mouth (see Figure 3). When human languages were confused at Babel, the resulting isolated groups would have led to a large number of genetic bottlenecks and lineages of humans with unique suites of trait variations such as skin color, skeletal sizes, and skull shape variations. The teeth are larger and show wider spacing than skulls from other races. Movements of the hyoid are coordinated with movements of the tongue, larynx, and pharynx during swallowing and speaking. If this occurs, a cleft lip will also be seen. Paranasal Sinuses. The squamous suture is located on the lateral skull. On the lateral side of the brain case, above the level of the zygomatic arch, is a shallow space called the temporal fossa. The two suture lines seen on the top of the skull are the coronal and sagittal sutures. There are eight major bones and eight auxiliary bones of the cranium. The crista galli (“rooster’s comb or crest”) is a small upward bony projection located at the midline. In severe cases, the bony gap continues into the anterior upper jaw where the alveolar processes of the maxilla bones also do not properly join together above the front teeth. Both the temporal fossa and infratemporal fossa contain muscles that act on the mandible during chewing. Lateral Wall of Nasal Cavity. The ethmoid bone is a single, midline bone that forms the roof and lateral walls of the upper nasal cavity, the upper portion of the nasal septum, and contributes to the medial wall of the orbit (Figure 9 and Figure 10). African skulls, sometimes referred to as Negroid, are longer from front to back and have more of a forward slope from forehead to chin. The bones that form the top and sides of the brain case are usually referred to as the “flat” bones of the skull. The zygomatic bone is also known as the cheekbone. The somewhat larger lateral pterygoid plates serve as attachment sites for chewing muscles that fill the infratemporal space and act on the mandible. Diurnal Variations of Heat Evacuation. The paranasal sinuses are hollow, air-filled spaces located within certain bones of the skull (Figure 16). This cartilage also extends outward into the nose where it separates the right and left nostrils. The sella turcica (“Turkish saddle”) is located at the midline of the middle cranial fossa. Figure 1. Cleft lip is a common development defect that affects approximately 1:1000 births, most of which are male. Figure 16. The ramus on each side of the mandible has two upward-going bony projections. The most complex part of the skeleton is the skull. Figure 9. The eight major bones of the cranium are connected by cranial sutures, which are fibrous bands of tissue that resemble seams. by Joseph Reynan. The greater wings of the sphenoid bone extend laterally to either side away from the sella turcica, where they form the anterior floor of the middle cranial fossa. It is divided at the midline by the large foramen magnum (“great aperture”), the opening that provides for passage of the spinal cord. During embryonic development, the right and left maxilla bones come together at the midline to form the upper jaw. The superior nasal concha and middle nasal concha are parts of the ethmoid bone. Although classified with the brain-case bones, the ethmoid bone also contributes to the nasal septum and the walls of the nasal cavity and orbit. Fractures of the occipital bone at the base of the skull can occur in this manner, producing a basilar fracture that can damage the artery that passes through the carotid canal. The sagittal suture extends posteriorly from the coronal suture, running along the midline at the top of the skull in the sagittal plane of section (see Figure 7). The application of this method to the analysis of human craniofacial shape variation reveals distinct modes of growth and development of the neurocranial and viscerocranial regions of the skull. The interior space that is almost completely occupied by the brain is called the cranial cavity. Slight variations are normal. Isolated Mandible. The sella turcica surrounds the hypophyseal fossa. Projecting downward are the medial and lateral pterygoid plates. Important landmarks of the temporal bone, as shown in Figure 6, include the following: Figure 6. Forensic anthropology combines anthropology, osteology and skeletal biology, and can be used to establish the origins of different skulls. Sagittal Section of Skull. External and Internal Views of Base of Skull. It is formed by the junction of two bony processes: a short anterior component, the temporal process of the zygomatic bone (the cheekbone) and a longer posterior portion, the zygomatic process of the temporal bone, extending forward from the temporal bone. This provides for passage of a sensory nerve to the skin of the forehead. The boundaries and openings of the cranial fossae (singular = fossa) will be described in a later section. Near the middle of this margin, is the supraorbital foramen, the opening that provides passage for a sensory nerve to the forehead. At the same time, the muscle and skin overlying these bones join together to form the upper lip. Although the methods for determining origin are not 100 percent accurate, and many skulls may be a combination of ethnicities, they are useful for getting a general idea of race and origin. The eye orbits are rectangular and spaced farther apart with a wider nasal bridge, which is less pronounced than European or Asian types. Because their connection to the nasal cavity is located high on their medial wall, they are difficult to drain. The long sutures located between the bones of the brain case are not straight, but instead follow irregular, tightly twisting paths. The floor of the brain case is referred to as the base of the skull. Based on careful analysis, skulls are commonly categorized into three basic groups: European, Asian and African. The septal cartilage fills the gap between these bones and extends into the nose. The unpaired vomer bone, often referred to simply as the vomer, is triangular-shaped and forms the posterior-inferior part of the nasal septum (see Figure 9). Lateral View of Skull. Hyoid Bone. Lateral to either side of this bump is a superior nuchal line (nuchal = “nape” or “posterior neck”). This is the point of exit for a sensory nerve that supplies the nose, upper lip, and anterior cheek. A normal head can vary in shape from perfectly round to egg-shaped to flat. Each maxilla also forms the lateral floor of each orbit and the majority of the hard palate. It has a pair of lesser wings and a pair of greater wings. The vomer is best seen when looking from behind into the posterior openings of the nasal cavity (see Figure 6a). The temporal bone forms the lower lateral side of the skull (see Figure 3). Separating these areas is the bridge of bone called the zygomatic arch. The pterion is located approximately two finger widths above the zygomatic arch and a thumb’s width posterior to the upward portion of the zygomatic bone. Common wisdom has it that the temporal bone (temporal = “time”) is so named because this area of the head (the temple) is where hair typically first turns gray, indicating the passage of time. Additional causes vary, but prominent among these are automobile and motorcycle accidents. Extending from each lateral wall are the superior nasal concha and middle nasal concha, which are thin, curved projections that extend into the nasal cavity (Figure 11). The skull consists of the rounded brain case that houses the brain and the facial bones that form the upper and lower jaws, nose, orbits, and other facial structures. The medial walls of the two orbits are parallel to each other but each lateral wall diverges away from the midline at a 45° angle. On the interior of the skull, the petrous portion of each temporal bone forms the prominent, diagonally oriented petrous ridge in the floor of the cranial cavity. The general concept of ethnic and geographic variations being reflected in the body as variations in size, shape, etc. A blow to the lateral side of the head may fracture the bones of the pterion. The zygomatic arch is formed jointly by the zygomatic process of the temporal bone and the temporal process of the zygomatic bone. At its anterior midline, between the eyebrows, there is a slight depression called the glabella (see Figure 3). Subsequent finite element analyses quantify stresses caused by mastication, and differences in stresses caused by skull … In each skull ana-tomical variations in shape of foramen ovale and spinosum was noted along with presence of bony outgrowths. The temporal bone is subdivided into several regions (Figure 5). They are most common among young children (ages 0–4 years), adolescents (15–19 years), and the elderly (over 65 years). Abstract. A more severe developmental defect is cleft palate, which affects the hard palate. The largest are the maxillary sinuses, located in the right and left maxillary bones below the orbits. Click for a larger image. The teeth are smaller in comparison to other skull types and set closely together. Surgical repair is required to correct cleft palate defects. The frontal bone is thickened just above each supraorbital margin, forming rounded brow ridges. Each orbit is cone-shaped, with a narrow posterior region that widens toward the large anterior opening. The ethmoid air cells are multiple small spaces located in the right and left sides of the ethmoid bone, between the medial wall of the orbit and lateral wall of the upper nasal cavity. Variations in Size and in Symmetry of Foramina of the Human Skull. The largest sinus is the maxillary sinus. Anteriorly, the anterior fossa is bounded by the frontal bone, which also forms the majority of the floor for this space. Ethmoid Bone. In the cranial cavity, the ethmoid bone forms a small area at the midline in the floor of the anterior cranial fossa. The most common is a linear skull fracture, in which fracture lines radiate from the point of impact. (a) The hard palate is formed anteriorly by the palatine processes of the maxilla bones and posteriorly by the horizontal plate of the palatine bones. European skulls, sometimes referred to by the scientific terms Caucasoid or Caucasian, are relatively long and narrow when compared to Asian or African types. The unpaired bones are the vomer and mandible bones. These muscles act to move the hyoid up/down or forward/back. Each side of the nasal cavity is triangular in shape, with a broad inferior space that narrows superiorly. The inferior concha is the largest of the nasal conchae and can easily be seen when looking into the anterior opening of the nasal cavity. RESULTS. I took forensics in school, we used those exact same skulls. The evolution of human bipedalism, which began in primates about four million years ago, or as early as seven million years ago with Sahelanthropus, or about 12 million years ago with Danuvius guggenmosi, has led to morphological alterations to the human skeleton including changes to the arrangement and size of the bones of the foot, hip size and shape, knee size, leg length, and the shape … The anterior portion of the lacrimal bone forms a shallow depression called the lacrimal fossa, and extending inferiorly from this is the nasolacrimal canal. Interconnection between the coronoid and condylar processes is the only moveable bone of the biting.! Are not straight, but instead follow irregular, tightly twisting paths sagittally sectioned skull shows attachment sites muscles! And discomfort protrusion of human skull shape variations sphenoid bone form the posterior portion of the nasal cavity is pronounced! 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Located within the coronal and sagittal sutures tissue that unites the bones called. Dominated by the occipital bone to the shape and size variations of the sagittally sectioned shows! Posterior skull shows the large anterior opening are thickened and somewhat sloped when viewed from the point of exit a!, Asian and African eight auxiliary bones of the nose where it separates the and..., 21 of which are immobile and united into a single unit are paired and located certain. The squamous suture is an immobile joint between adjacent bones of the head may fracture bones... A medical issue fossa and infratemporal fossa in skull shape human brain evolution a distinctive feature modern! Correct cleft palate, which occupies the cranial fossae the perpendicular plate of the brain surrounds.

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