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Encyclopedia > Human skull

Frontal bone Sphenoid bone Ethmoid bone Nasal bone Lagrimal bone Maxilla Mandible Parietal bone Occipital bone Zygomatic bone Temporal bone

In humans, the adult skull is normally made up of 22 bones. Except for the mandible, all of the bones of the skull are joined together by sutures, synarthrodial (immovable) joints formed by bony ossification, with Sharpey's fibres permitting some flexibility. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The mandible (from Latin mandibÅ­la, jawbone) or inferior maxillary bone is, together with the maxilla, the largest and strongest bone of the face. ... For other uses of Skull, see Skull (disambiguation). ... Side view of the skull. ... This article is about a joint in zootomical anatomy. ... Ossification is the process of bone formation, in which connective tissues, such as cartilage are turned to bone or bone-like tissue. ... Sharpeys fibres (bone fibres, or perforating fibres) are a matrix of connective tissue consisting of bundles of strong collagenous fibres connecting periosteum to bone. ...


Eight bones form the neurocranium (brain case), a protective vault of bone surrounding the brain and brain stem. Fourteen bones form the splanchnocranium, which comprises the bones supporting the face. Encased within the temporal bones are the six auditory ossicles of the middle ear. The hyoid bone, supporting the larynx, is usually not considered as part of the skull, as it is the only bone that does not articulate with other bones of the skull. The human brain controls the central nervous system (CNS), by way of the cranial nerves and spinal cord, the peripheral nervous system (PNS) and regulates virtually all human activity. ... The brain stem is the lower part of the brain, adjoining and structurally continuous with the spinal cord. ... The temporal bones (os temporales) are situated at the sides and base of the skull. ... The ossicles (also called auditory ossicles) are the three smallest bones in the human body. ... The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. ... The hyoid bone (Os Hyoideum; Lingual Bone) is a bone in the human neck, not articulated to any other bone; it is supported by the muscles of the neck and in turn supports the root of the tongue. ... The larynx (plural larynges), colloquially known as the voicebox, is an organ in the neck of mammals involved in protection of the trachea and sound production. ... Articulate is a board game manufactured by the company Drumond Park. ...


The skull also contains the sinus cavities, which are air-filled cavities lined with respiratory epithelium, which also lines the large airways. The exact functions of the sinuses are debatable; they contribute to lessening the weight of the skull with a minimal reduction in strength, they contribute to resonance of the voice, and assist in the warming and moistening of air drawn in through the nasal cavities. The paranasal sinuses are eight (four pairs) air-filled spaces, or sinuses, within the bones of the skull and face. ... Respiratory epithelium is another name for ciliated pseudostratified columnar epithelium with goblet cells. ...


The meninges are three layers of connective tissue surrounding structures of the central nervous system. From outermost to innermost layer, they are the dura mater, the arachnoid mater, and the pia mater. Each layer adds important protective and physiologic functions. The meninges (singular meninx) are the system of membranes that envelop the central nervous system. ... A diagram showing the CNS: 1. ... The dura mater (from the Latin hard mother), or pachymeninx, is the tough and inflexible outermost of the three layers of the meninges surrounding the brain. ... The Arachnoid mater is one of the three layers of the meninges, interposed between the dura mater and the pia mater and separated from the pia mater by the subarachnoid space. ... [www. ...


The anatomical position for the skull is the Frankfurt plane, where the lower margins of the orbits and the upper borders of the ear canals are all in a horizontal plane. This is the position where the subject is standing and looking directly forward. The Frankfurt plane may also be used to study the brains of other specifies, notably primates and hominids. However, this does not always equate to a natural posture in life. The anatomical planes The anatomical position is a schematic convention for describing the relative morphology of the human body. ... The Frankfurt plane (also called the auriculo-orbital plane) was established at the World Congress on Anthropology in Frankfurt, Germany in 1884, and decreed as the anatomical position of the human skull. ... In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. ... The ear canal (external auditory meatus, external acoustic meatus), is a tube running from the outer ear to the middle ear. ... In astronomy, geography, geometry and related sciences and contexts, a plane is said to be horizontal at a given point if it is locally perpendicular to the gradient of the gravity field, i. ... Families 15, See classification A primate is any member of the biological order Primates, the group that contains all the species commonly related to the lemurs, monkeys, and apes, with the latter category including humans. ... A hominid is any member of the biological family Hominidae (the great apes), including the extinct and extant humans, chimpanzees, gorillas, and orangutans. ...

Contents

Development of the skull

The skull is a complex structure; its bones are formed both by intramembranous and endochondral ossification. The bones of the splanchnocranium (face) and the sides and roof of the neurocranium are formed by intramembranous (or dermal) ossification, while the bones supporting the brain (the occipital, sphenoid, temporal, and ethmoid) are largely formed by endochondral ossification. Osteoblasts and osteoclasts on trabecula of lower jaw of calf embryo. ... Section of fetal bone of cat. ... The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoid in shape and curved on itself. ... The sphenoid bone (from Greek sphenoeides, wedgelike) is a bone situated at the base of the skull in front of the temporals and basilar part of the occipital. ... The temporal bones (os temporales) are situated at the sides and base of the skull. ... Your skull is in your back (this is obviously not true, I was just testing the website to see if it really works) The ethmoid bone (os ethmoidale) is a bone in the skull that separates the nasal cavity from the brain. ...


At birth, the human skull is made up of 45 separate bony elements. As growth occurs, many of these bony elements gradually fuse together into solid bone (for example, the frontal bone). The bones of the roof of the skull are initially separated by regions of dense connective tissue called "cranial sutures". There are five sutures: the frontal suture, sagittal suture, lambdoid suture, coronal suture, and squamosal suture. At birth these regions are fibrous and moveable, necessary for birth and later growth. This growth can put a large amount of tension on the "obstetrical hinge," which is where the squamous and lateral parts of the occipital bone meet. A possible complication of this tension is rupture of the great cerebral vein of Galen. Larger regions of connective tissue where multiple sutures meet are called fontanelles. The six fontanelles are: the anterior fontanelle, the posterior fontanelle, the two sphenoid fontanelles, and the two mastoid fontanelles. As growth and ossification progress, the connective tissue of the fontanelles is invaded and replaced by bone. The posterior fontanelle usually closes by eight weeks, but the anterior fontanelle can remain open up to eighteen months. The anterior fontanelle is located at the junction of the frontal and parietal bones; it is a "soft spot" on a baby's forehead. Careful observation will show that you can count a baby's heart rate by observing his or her pulse pulsing softly through the anterior fontanelle. The frontal bone (os frontale, TA: A02. ... Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, muscle, and nervous tissue. ... Side view of the skull. ... The frontal suture (sutura frontalis) is a dense connective tissue structure that divides the two halves of the frontal bone of the skull in infants and children. ... The sagittal suture (sutura sagittalis) is a dense, fibrous connective tissue joint between the two parietal bones of the skull. ... The lambdoid suture (sutura lambdoidea) is a dense, fibrous connective tissue joint that separates the parietal and temporal bones of the skull from the occipital bone. ... The coronal suture (sutura coronalis) is a dense, fibrous connective tissue joint that separates the frontal and parietal bones of the skull. ... The squamosal suture arches backward from the pterion and connects the temporal squama with the lower border of the parietal: this suture is continuous behind with the short, nearly horizontal parietomastoid suture, which unites the mastoid process of the temporal with the region of the mastoid angle of the parietal. ... The vein of Galen (VG), also known as the great cerebral vein, is one of the large blood vessels in the skull draining the cerebrum (brain). ... In human anatomy, a fontanelle (or fontanel) is one of two soft spots on a newborn humans skull. ...


Pathology

If the brain is bruised or injured it can be life-threatening. Normally the skull protects the brain from damage through its hard unyieldingness, but in some cases of head injury, there can be raised intracranial pressure through mechanisms such as a subdural haematoma. In these cases the raised intracranial pressure can cause herniation of the brain out of the foramen magnum ('coning') because there is no space for the brain to expand; this can result in significant brain damage or death unless an urgent operation is performed to relieve the pressure. This is why patients with concussion must be watched extremely carefully. Head injury is a trauma to the head, that may or may not include injury to the brain (see also brain injury). ... Intracranial pressure, (ICP), is the pressure exerted by the cranium on the brain tissue, cerebrospinal fluid (CSF), and the brains circulating blood volume. ... A subdural hematoma, also called a subdural hemorrhage, is a collection of blood between the dura (the outer protective covering of the brain) and the arachnoid (the middle layer of the meninges). ... Intracranial pressure, (ICP), is the pressure exerted by the cranium on the brain tissue, cerebrospinal fluid (CSF), and the brains circulating blood volume. ... In anatomy, in the occipital bone, the foramen magnum (Latin: great hole) is one of the several oval or circular apertures in the base of the skull (the foramina), through which the medulla oblongata (an extension of the spinal cord) enters and exits the skull vault. ... Brain damage or brain injury is the destruction or degeneration of brain cells. ... “Cerebral Concussion” redirects here. ...


Dating back to Neolithic times, a skull operation called trepanation was sometimes performed. This involved drilling holes in the cranium. Examination of skulls from this period reveals that the "patients" sometimes survived for many years afterward. It seems likely that trepanation was performed for ritualistic or religious reasons and not only as an attempted life-saving technique. Though some certain types of areas in the cranium, the bone can survive hard damage including metal, wood, and blows that can be severe if not for the skull surrounding the cranium. An array of Neolithic artifacts, including bracelets, axe heads, chisels, and polishing tools. ... 18th century French illustration of trepanation Trepanation (also known as trepanning, trephination, trephining or burr hole) is a form of surgery in which a hole is drilled or scraped into the skull, thus exposing the dura mater in order to treat health problems related to intracranial diseases, though in the...

An image of a skull by Leonardo da Vinci
An image of a skull by Leonardo da Vinci

Image File history File links View of a Skull (c. ... Image File history File links View of a Skull (c. ... “Da Vinci” redirects here. ...

Craniometry and morphology of human skulls

Like the face of a living individual, a human skull and teeth can also tell, to a certain degree, the life history and origin of its owner. Forensic scientists and archaeologists use metric and nonmetric traits to estimate what the bearer of the skull looked like. When a significant amount of bones is found, such as at Spitalfields in the UK and Jōmon shell mounds in Japan, osteologists can use traits, such as proportions of length, height, width, to know the relationships of population of the study, with living or extinct populations. The word forensic (from Latin: forensis - forum) refers to something of, pertaining to, or used in a court of law. ... Archaeology or sometimes in American English archeology (from the Greek words αρχαίος = ancient and λόγος = word/speech) is the study of human cultures through the recovery, documentation and analysis of material remains, including architecture, artefacts, biofacts, human remains, and landscapes. ... Metrics are a system of parameters or ways of quantitative and periodic assessment of a process that is to be measured, along with the procedures to carry out such measurement and the procedures for the interpretation of the assessment in the light of previous or comparable assessments. ... Christ Church, Spitalfields Spitalfields, an area in Tower Hamlets, east London near to Liverpool Street station and Brick Lane which gets its name from a contraction of hospital fields, as there used to be a major hospital in the area. ... Characters for Jōmon (Cord marks). The Jomon period ) is the time in Japanese pre-history from about 10,000 BC to 300 BC. Most scholars agree that by around 40,000 BC glaciation had connected the Japanese islands with the Asian mainland. ... It has been suggested that this article or section be merged with midden. ...


The German physician Franz Joseph Gall in around 1800 formulated the theory of phrenology, which attempted to show that specific features of the skull are associated with certain personality traits or intellectual capabilities of its owner. This theory is now considered to be obsolete. F.J. Gall Franz Joseph Gall (March 9, 1758 - August 22, 1828) was a neuroanatomist and physiologist who was a pioneer in the study of the localization of mental functions in the brain. ... Phrenology (from Greek: φρήν, phrēn, mind; and λόγος, logos, knowledge) is a theory which claims to be able to determine character, personality traits and criminality on the basis of the shape of the head (i. ...


The practice of craniometry has occasionally purported to reliably demonstrate racial or ethnic differences between skulls of different people. Occasionally this has been used as justification for ideas of racial supremacy. However, this theory is again obsolete. This article does not cite its references or sources. ...


Sexual dimorphism

In general, male skulls tend to be larger and more robust than female skulls, which are more gracile. Male skulls typically have more prominent supraorbital ridges, a more prominent glabella, and more prominent temporal lines. Male skulls on average have larger, broader palates, squarer orbits, larger mastoid processes, larger sinuses, and larger occipital condyles than those of females. Male mandibles typically have squarer chins and thicker, rougher muscle attachments than female mandibles. Supraorbital ridges seen in Australopithecus africanus The supraorbital ridge, supraorbital torus, superciliary ridge, arcus superciliaris, or brow ridge, refer to a bony ridge located above the eye sockets of all primates. ... The glabella is the space between the eyebrows and above the nose. ... The parietal bones (os parietale) are bones in the human skull and form, by their union, the sides and roof of the cranium. ... The palate is the roof of the mouth in humans and vertebrate animals. ... In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. ... The mastoid process (or mastoid bone) is a conical bump of the posterior portion of the temporal bone that is situated behind the ear in humans and many other vertebrates and serves as a site of neck muscle attachment (the Sternocleidomastoid, Splenius capitis, and Longissimus capitis). ... This article does not cite any references or sources. ... The occipital bone, a saucer-shaped membrane bone situated at the back and lower part of the cranium, is trapezoid in shape and curved on itself. ... This article is about the human bone. ...

Partial human skulls
Partial human skulls

All of these features vary considerably within human populations, making it difficult to identify the sex of a skull without knowledge of the population from which it came. Download high resolution version (1760x1164, 1116 KB)Public domain. ... Download high resolution version (1760x1164, 1116 KB)Public domain. ...


Ancestry

Although persons' descents are occasionally stereotyped as different from other ethnic groups on the basis of a variety of traits like eye, hair and skin color, all such characters are not discrete nor preserved in bones. Among archaeologists and forensic scientists, it is still sometimes stated that the most consistent and unique trait of ancestry in skeleton is skull shape (see craniometry). Archaeology or sometimes in American English archeology (from the Greek words αρχαίος = ancient and λόγος = word/speech) is the study of human cultures through the recovery, documentation and analysis of material remains, including architecture, artefacts, biofacts, human remains, and landscapes. ... A forensic scientist is a scientist who analyzes biological, chemical, or physical samples taken into evidence during a criminal investigation. ... This article does not cite its references or sources. ...


Additional images

Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links Gray190. ... Image File history File links Gray188. ...

See also

The following is a list of holes, or foramina, in the base of the skull and what goes through each of them. ... The base of the skull (lat. ...

References


  Results from FactBites:
 
Features of Human Cranium - Atlas of Human Skull Bones and Facial Bones (916 words)
The human cranium and the facial bones are the foundation for the soft tissues of the face and head.
The human skull also includes 14 facial bones that form the lower front of the skull and provide the framework for most of the face that is important to psychological research.
The reconstruction of this skull revealed a facial appearance that indicates he is a descendant of a more ancient migration from Asia than that which brought the ancestors of the Indians (Amerinds), who settled widely in the Americas before the arrival of Europeans.
Human skull - Wikipedia, the free encyclopedia (1201 words)
Except for the mandible, all of the bones of the skull are joined together by sutures, semi-rigid articulations formed by bony ossification, the presence of Sharpey's fibres permitting a little flexibility.
In humans, the anatomical position for the skull is the Frankfurt plane, where the lower margins of the orbits and the upper borders of the ear canals are all in a horizontal plane, or anatomical position.
The skull is a complex structure; its bones are formed both by intramembranous and endochondral ossification.
  More results at FactBites »

 
 

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