Recommended
Recommended
More Related Content
Similar to Crânio | cranio
Similar to Crânio | cranio (20)
More from DiogoSantos462
More from DiogoSantos462 (13)
Recently uploaded
Recently uploaded (20)
Crânio | cranio
- 3. Cabeça óssea
- 7. CALVARIUM ESQUELETO DA FACE Viscerocranium - Forms facial framework - Provide cavities for the sense organs of sight, taste, and smell - Provide openings for passage of air and food - Secure the teeth - Anchor facial muscles of expression Neurocranium -Encloses brain -Protects organs of hearing and balance
- 8. Development of Viscerocranium Cartilagenous VC: malleus, incus, stapes, styoid process Membranous VC: maxilla, zygomatic, mandible Development of Neurocranium Cartilagenous NC: base of skull Membranous NC: frontal, parietals, squamous temporal bone, interparietal occipital squama
- 11. Sutures (Restricted to the skull)
- 16. Suture closure –PF 3-6mo –AF 9-18mo –C,S,L sutures 40years
- 23. • Skull growth mainly secondary to brain growth • – 40% adult size at term – 90% adult size by 1y – 95% adult size by 6y
- 25. Plano orbitomeatal (de Frankfurt)
- 31. CrAnio e face
- 32. 8 20 The skull has 22 bones, excluding the ossicles of the ear
Editor's Notes
- Cabeça óssea – caveira
- Cabeça óssea= crânio+mandibula
- Vesalius
- FUNCTIONS: Protection The head houses and protects the brain and all the receptor systems associated with the special senses-the nasal cavities associated with smell, the orbits with vision, the ears with hearing and balance, and the oral cavity with taste. Trepanation is perhaps the oldest surgical procedure for which there is archaeological evidence A detail from "The Extraction of the Stone of Madness", a painting by Hieronymus Bosch depicting trepanation (c.1488-1516) Trepanated skull, Iron age. The perimeter of the hole in the skull is rounded off by ingrowth of new bony tissue, indicating that the patient survived the operation.
- Divisão calote-base do crânio
- The skull has two major functional and anatomical components: the neurocranium and viscerocranium. The neurocranium is composed of the skull vault and skull base; it surrounds and protects the brain and the special sense organs of olfaction, vision, hearing and balance. The viscerocranium forms the skeleton of the face, palate and pharynx, and mediates the functions of feeding, breathing and facial expression; it also protects the tongue and forms the middle ear and the bony external acoustic meatus.
- Ossificação mista Development of Cranium The cranium (skull) develops from mesenchyme around the developing brain. The growth of the neurocranium (bones of cranium enclosing the brain) is initiated from ossification centers within the desmocranium mesenchyme, which is the primordium of the cranium. The cranium consists of the: • Neurocranium, the bones of the cranium enclosing the brain (brain box • Viscerocranium, the bones of the facial skeleton derived from the pharyngeal arches Cartilaginous Neurocranium Initially, the cartilaginous neurocranium or chondrocranium consists of the cartilaginous base of the developing cranium, which forms by fusion of several cartilages (Fig. 14-8A to D). Later, endochondral ossification of the chondrocranium forms the bones in the base of the cranium. The ossification pattern of these bones has a definite sequence, beginning with the occipital bone, body of sphenoid, and ethmoid bone Membranous Neurocranium Membranous ossification (intramembranous ossification) occurs in the head mesenchyme at the sides and top of the brain, forming the calvaria (skullcap). During fetal life, the flat bones of the calvaria are separated by dense connective tissue membranes that form fibrous joints, the sutures of the calvaria artilaginous ViscerocraniumMost mesenchyme in the head region is derived from the neural crest. Neural crest cells migrate into the pharyngeal arches and form the bones and connective tissue of craniofacial structures. Homeobox (Hox) genes regulate the migration and subsequent differentiation of the neural crest cells, which are crucial for the complex patterning of the head and face. These parts of the fetal cranium are derived from the cartilaginous skeleton of the first two pairs of pharyngeal arches (see Chapter 9).• The dorsal end of the first pharyngeal arch cartilage forms two middle ear bones, the malleus and incus.• The dorsal end of the second pharyngeal arch cartilage forms the stapes of the middle ear and the styloid process of the temporal bone. Its ventral end ossifies to form the lesser horn or cornu and superior part of the body of the hyoid bone.• The third, fourth, and sixth pharyngeal arch cartilages form only in the ventral parts of the arches. The third arch cartilages form the greater horns of the hyoid bone and the inferior part of the body of the hyoid bone.• The fourth pharyngeal arch cartilages fuse to form the laryngeal cartilages, except for the epiglottis (see Chapter 9).Membranous ViscerocraniumMembranous ossification occurs in the maxillary prominence of the first pharyngeal arch (see Chapter 9), and subsequently forms the squamous temporal, maxillary, and zygomatic bones. The squamous temporal bones become part of the neurocranium. The mesenchyme in the mandibular prominence of the first pharyngeal arch condenses around its cartilage and undergoes membranous ossification to form the mandible. Some endochondral ossification (formation of osseous tissue by the replacement of calcified cartilage) occurs in the median plane of the chin and the mandibular condyle
- Crescimento Sutures are restricted to the skull. In a suture, the two bones are separated by a layer of membrane-derived connective tissue. The sutural aspect of each bone is covered by a layer of osteogenic cells (cambial layer) overlaid by a capsular lamella of fibrous tissue which is continuous with the periosteum on both the endo- and ectocranial surfaces. The area between the capsular coverings contains loose fibrous connective tissue and decreases with age so that the osteogenic surfaces become apposed. On completion of growth, many sutures synostose and are obliterated. Synostosis occurs normally as the skull ages: it can begin in the early twenties and continues into advanced age. A schindylesis is a specialized suture in which a ridged bone fits into a groove on a neighboring element, e.g. where the cleft between the alae of the vomer receives the rostrum of the sphenoid
- As suturas podem ser planas, serreadas, denteadas, escamosas (os bordos são talhados em bisel) e a sutura esquindileza (entre as asas do vómer e o rostrum do esfenóide). As suturas permitem manter a união entre os osso do crânio e a função primordial das suturas é o crescimento dos ossos do crânio. Sutures are restricted to the skull. In a suture, the two bones are separated by a layer of membrane-derived connective tissue. On completion of growth, many sutures synostose and are obliterated. Synostosis occurs normally as the skull ages. The sutural aspect of each bone is covered by a layer of osteogenic cells (cambial layer) overlaid by a capsular lamella of fibrous tissue which is continuous with the periosteum on both the endo- and ectocranial surfaces. The area between the capsular coverings contains loose fibrous connective tissue and decreases with age so that the osteogenic surfaces become apposed. On completion of growth, many sutures synostose and are obliterated. Synostosis occurs normally as the skull ages: it can begin in the early twenties and continues into advanced age.A schindylesis is a specialized suture in which a ridged bone fits into a groove on a neighboring element, e.g. where the cleft between the alae of the vomer receives the rostrum of the sphenoid. During birth the skull is moulded by slow compression. Fontanelles and the openness and width of the sutures allow bones of the cranial vault some overlap. The majority of bones in the skull are held together firmly by fibrous joints termed sutures: in the developing skull sutures allow for growth. The three main sutural morphologies are dependent upon the magnitude of strains placed upon them. Thus the margins of adjacent bones of a suture may be smooth and meet end-to-end, giving a simple (butt-end) suture (e.g. median palatine suture); bevelled, so that the border of one bone overlaps the other (e.g. parietotemporal suture); or present numerous projections that interlock, giving a serrated appearance (e.g. sagittal suture). The complexity of serrated sutures increases from the inner to the outer surface. Fusion across sutures (synostosis) can start early in the
- a Sagitbl suture: scaphocephaly (long, narrow slwll) b Coronal suture: oxycephaly (pointed skull) c Frontal suture: trigonocephaly (triangular skull) d Asymmetrical suture closure, usually
- Scaphocephaly. Boy, 4 months of age. a Side view with posteriorly elongated skull. b View from above shows posterior synostosis in the sagittal suture
- Metopic ridge. a The ridge extends from the site of anterior fontanelle to the radix of the nose. b The ridge is visualized only in upper part of the forehead. Both represent minimal alterations caused by metopic closure. Sometimes the metopic ridge is formed after birth. No treatment is required.
- Postnatal growth of the skull is characterized by changing proportions of its components. Growth of the brain continues to be extremely rapid in the first 2 years; in addition to continuing growth of the frontal and parietal bones, the squamous temporal bone increases in size so that it contributes a greater proportion of the skull vault in the adult than in the neonate (Fig. 35.21). The inner ear and the petrous temporal bone around it grow very little after birth, so the increasing breadth of the skull draws the petrous temporal bone out laterally, creating the bony external acoustic meatus. The tympanic ring (with the tympanic membrane) lies at the surface of the meatus in the neonatal skull; it remains at the proximal end of the deepening canal. Use of the sternocleidomastoid muscle to lift the head results in formation of the mastoid process of the temporal bone, which develops air-filled spaces that are continuous with the middle ear cavity. The paranasal sinuses begin to form in late fetal life as diverticula from the nasal cavity which gradually invade the maxilla, frontal, ethmoid and sphenoid bones. At birth they fill with air when the amniotic fluid drains from them. Thickening of the skull bones is accompanied by increasing size of the sinuses, and by a change in form of the sutures, from straight to wavy lines and finally to the complex interdigitations seen in the adult. After growth ceases, the skull sutures contain inert connective tissue and some cartilage; in old age some of them are completely replaced by bone (natural synostosis).
- Pontos craniometricos
- IDENTIFICATION FROM THE SKULL There are many ways of identifying an individual: in physical and forensic anthropology the most important concern biological and personal identity. Biological identity pertains to those features that allow an individual to be classified in relation to features present in other individuals e.g. sex, age, race and stature, whereas personal identity establishes criteria that are characteristic and discriminatory for a particular individual e.g. DNA, fingerprints and dental information. The skull is a useful source of information for the establishment of both biological and personal identity. It is probably the most studied aspect of the skeleton. The foundation of this obsession has many historical roots, but fundamentally it has arisen from the importance that humans place in the concept that the skull is the repository of ‘self', and that it is the means by which interpersonal communication is effected. Our face is our primary means of recognition and communication and therefore it plays a pivotal role in establishing and reconstructing the identity of an individual. SEX The determination of sex from a juvenile skull is notoriously unreliable. While sexual differences have been detected in measurements of the mandible, orbits, tooth size and pattern of dental eruption, they do not reach a level of discrimination that will allow accurate and reliable assessment. It is equally difficult to assign sex to the face of a child because the faces of prepubertal boys and girls are comparable: perceivable sexual dimorphism is not manifest until secondary sexual changes are completed. Growth in the female face ceases in advance of the male, and consequently female sex-related characteristics are more paedomorphic. The defining characteristics of sex in an adult skull are therefore male in orientation and reflect the effects of the increased mass of the muscles of mastication, which attach to the mandible, and the muscles associated with maintaining the erect head. It is reported that using the skull alone, sex can be predicted with over 80% accuracy in the adult. This is extremely encouraging because research has shown that the correct sex can usually be predicted from the adult living face with around 96% accuracy. Generally speaking, the male skull is more robust and the female more gracile, although there are obvious genetic, and therefore racial, variations which must be considered when attempting to assign sex from a skull. The female forehead is generally higher, more vertical and more rounded than the male, and there is a clear retention of the frontal eminences in the female. The male mandible is more robust and larger than that of the female: it generally displays a greater height in the region of the symphysis menti, the chin is more square, the condyles are larger, the muscle attachments are more pronounced and the gonial angle is generally less than 125°. A male skull has thicker and more rounded orbital margins, pronounced supra-orbital ridges, and often a well-defined glabella that occupies the midline above the root of the nose. The temporal lines are more pronounced in the male and the supramastoid crest generally extends posterior to the external auditory meatus. Other sites of muscle attachment on the skull reflect the biomechanical requirement to keep the more robust male head erect. They include the mastoid process for sternocleidomastoid, which is generally more robust in the male and more gracile in the female, and the nuchal lines, especially the external occipital protuberance for the attachment of the ligamentum nuchae. The cranial base in the male is generally more robust and the bone is thicker, which means that this area of the skull survives inhumation particularly well and is therefore of great value in sex identification from fragmentary remains.
- AGE DETERMINATION Age is a continuous variable: to establish chronological age from a skull requires that structures change with age at a relatively constant and predictable rate. The relationship between chronological age and skeletal maturity is closest in the juvenile years, and therefore greater accuracy is achieved in the prediction of age from the juvenile than from the adult skull. The neonatal skull has been described above. Examples of additional features that allow reliable age determination throughout the subadult years are: development of the nasal spine (by year 3), completion of the hypoglossal canal (by year 4), formation of the foramen of Huschke (by year 5), ossification of the dorsum sellae (by year 5) and fusion of the different parts of the occipital bone (by year 7). The fontanelles are usually all closed by the middle of the second year: the posterolateral is the first to close in the first two months after birth, and the anterior fontanelle is the last to close around the middle of the second year. The mastoid process appears in the second year and the metopic suture between the two frontal bones will close by year 4. The spheno-occipital synchondrosis will fuse between 11 and 16 years in the female and 13 and 18 years in the male, while the vomer and the ethmoid will fuse between 20 and 30 years of age. The last part of the skull to show active age-related growth is the jugular growth plate, a small triangular area sited posterolateral to the jugular foramen in the occipitotemporal suture. Fusion here does not begin until 22 years of age, and bilateral fusion may not be completed before 34 years; in a small proportion of individuals, the plate may remain unfused beyond 50 years. Closure of the cranial sutures is age-related but the correlation is not strong and displays strong genetic variation. Thus, while it can be said that suture closure may begin in the early part of the third decade, and it is likely that many of the sutures will be obliterated with advancing age, it is not a reliable means of establishing the age of an individual. The most accurate means for determining age from the skull (of both a living and a deceased individual) is by assessment of dental maturation. Tooth development can be studied throughout the entire juvenile age span (from the early embryo to the adolescent), and importantly dental age and chronological age have been shown to exhibit a stronger correlation than skeletal and chronological age. Further, the teeth tend to survive inhumation successfully and are remarkably resilient to fire and explosion, ensuring their value in forensic investigations. The chronological pattern of dental maturation is well documented and is an extremely important tool for age evaluation. Tooth development can be separated into a number of well defined stages: deciduous mineralization (crown and root), deciduous emergence and maturation, deciduous root resorption, shedding of deciduous teeth, mineralization (crown and root) of permanent dentition, emergence and maturation of deciduous dentition and attrition of permanent crowns (see Ch. 30). These stages do not occur in a linear fashion: while some of the deciduous teeth are emerging, permanent teeth are already being formed. For example, mineralization of the deciduous central incisor commences around the 15th week post fertilization, and this is the first tooth to emerge within the first 5 months after birth. All deciduous teeth are in occlusion by around 3 years of age. The first deciduous teeth to be shed are generally the central and lateral incisors around 7 years of age, when the permanent incisors emerge. The last deciduous tooth to be shed is generally the second molar in the 10th year. The first permanent tooth to show mineralization is the first molar, which occurs around the time of birth (sometimes earlier and sometimes later): it is also the first permanent tooth to emerge at around 6 years of age, and it will reach occlusion by the end of the 7th year. The last permanent tooth to emerge is the third molar: the variability of this occurrence makes it of restricted value for age prediction. While the patterns of mineralization, emergence and shedding are extremely useful, there are other methods available for determining age from the dentition. These include tooth length, cementum apposition, secondary dentine formation, incremental enamel lines, attrition rates, root translucency and dentine transparency.
- RACE DETERMINATION The determination of racial or genetic origin is particularly difficult to achieve although it is something that both physical and forensic anthropologists insist on trying to do. The traditional view of race is that it is ‘one of the major zoological subdivisions of mankind, regarded as having a common origin and exhibiting a relatively constant set of physical traits’ (Bamshad & Olson 2003). Classifying groups on this basis is rather restrictive and, in our migrant modern world, somewhat artificial. It is still useful to be able to attempt to assign a ‘most likely’ racial group, especially when dealing with unidentified forensic remains, but there are enormous areas of overlap between the characteristics, and within any racial group there is often a full spectrum of representation. Yet we persist in classification on the basis of visual characteristics, and the area of the body that is most often analysed in this way is the skull. Early anthropologists classified man largely through geographical origins and recognized physical traits. The four traditional races of man were: (1) Caucasoid – geographically from Europe, North Africa, Middle East, Indian subcontinent and parts of Central Asia. Classically the Caucasoid skull has a rounded to long shape (dolicocephalic) with a narrow nasal aperture, moderately developed supraorbital ridging, a prominent nasal spine, a steeple shaped nasal root, little prognathism and a narrow interorbital distance. The forehead is steep, the chin is prominent, the palate is long and narrow, the cheek bones are not overly prominent and there is a tendency to maxillary protrusion or mandibular retrusion. (2) Negroid – geographically represented by sub-Saharan and West African groups. The Negroid skull is also long with a wide nasal aperture, strong alveolar prognathism, low nasal root, guttering of the nasal aperture and a wide interorbital distance. The forehead is rounder, the palate is wider and the teeth are larger. (3) Mongoloid – geographically represented by groups in East Asia, South East Asia, Central Asia, Americas, Greenland, Inuit, Polynesia, South Asia and Eastern Europe. The Mongoloid skull is generally described as round with a nasal aperture of medium width, well developed and high cheek bones, moderate prognathism, a tented nasal root, short nasal spine and shovel shaped incisors. The palate is foreshortened, the forehead is vertical, the nasal bridge is low and there is a tendency for a forward rotation of the mandible. (4) Australoid – geographically represented by Australian Aborigines, Maori, Pacific Islanders, Fijians and Papuans. This skull of this rather heterogeneous group is generally represented by a broad nasal aperture, well developed supraorbital ridging and glabella, and a wide palate with large teeth. There is a current resurgence in research into racial determination which is largely centred on genetic markers: skeletal indicators now play a significantly reduced role in this task. The archaeological record in Mesoamerica is further complicated by the practice of skull mutilation and modification carried out after the death of the subject, to fashion "trophy skulls" and the like of captives and enemies. This was a widespread tradition, illustrated in pre-Columbian art that occasionally depicts rulers adorned with or carrying the modified skulls of their defeated enemies, or of the ritualistic display of sacrificial victims. Several Mesoamerican cultures used a skull-rack (known by its Nahuatl term, tzompantli ), on which skulls were impaled in rows or columns of wooden stakes. Even so, some evidence of genuine trepanation in Mesoamerica (i.e., where the subject was living) has survived.
- SKULL The skull has 22 bones, excluding the ossicles of the ear. Except for the mandible, which forms the lower jaw, the bones of the skull are attached to each other by sutures, are immobile, and form the cranium. The cranium can be subdivided into: an upper domed part (the calvaria), which covers the cranial cavity containing the brain; a base that consists of the floor of the cranial cavity; and a lower anterior part-the facial skeleton (viscerocranium). The bones forming the calvaria are mainly the paired temporal and parietal bones, and parts of the unpaired frontal, sphenoid, and occipital bones. The bones forming the base of the cranium are mainly parts of the sphenoid, temporal, and occipital bones. The bones forming the facial skeleton are the paired nasal bones, palatine bones, lacrimal bones, zygomatic bones, maxillae, inferior nasal conchae, and the unpaired vomer. The mandible is not part of the cranium nor part of the facial skeleton.
- Superior view The frontal bone, parietal bones, and occipital bone are seen in a superior view of the skull (Fig. 8.21). These bones make up the superior part of the calvaria or the calva (skullcap). In an anterior to posterior direction: the unpaired frontal bone articulates with the paired parietal bones at the coronal suture; the two parietal bones articulate with each other in the midline at the sagittal suture; the parietal bones articulate with the unpaired occipital bone at the lambdoid suture. The junction of the sagittal and coronal sutures is the bregma, and the junction of the sagittal and lambdoid sutures is the lambda. The only foramen visible in this view of the skull may be the paired parietal foramina, posteriorly, one on each parietal bone just lateral to the sagittal suture (Fig. 8.21). The bones making up the calvaria (Fig. 8.22) are unique in their structure, consisting of dense internal and external tables of compact bone separated by a layer of spongy bone (the diploë).