ANTHROPOMETRIC COMPARISM OF CEPHALIC INDICES BETWEEN YORUBA AND BENIN ETHNIC GROUPS RESIDING IN OKADA TOWN, EDO STATE.
ANTHROPOMETRIC COMPARISM OF CEPHALIC INDICES BETWEEN
YORUBA AND BENIN ETHNIC GROUPS RESIDING
IN OKADA TOWN, EDO STATE.
1.1 BACKGROUND OF STUDY
Anthropometry (from Greek anthropos, “man” andmetron, “measure”) refers to the measurement of the human individual.Anthropometry involves the systematic measurement of the physical properties of the human body, primarily dimensional descriptions of body size and shape,it is the study of the measurement of the human body in terms of the dimensions of bone, muscle, and adipose (fat) tissue. Actual stature, weight, and body measurements (including skinfolds and circumferences) will be collected for purposes of assessing growth, body fat distribution, and for the provision of reference data. Anthropometry is the single most universally applicable, inexpensive, and non-invasive method available to assess the size, proportions, and composition of the human body. Today, anthropometry plays an important role in industrial design, clothing design, ergonomics and architecture where statistical data about the distribution of body dimensions in the population are used to optimize products. Changes in lifestyles, nutrition, and ethnic composition of populations lead to changes in the distribution of body dimensions (e.g. obesity epidemic), and require regular updating of anthropometric data collections.` Cephalic index is a useful anthropometric parameter utilized in the determination of racial variations.It is also used to determine sexual differences especially in individuals whose identities are unknown. It is one of the clinical anthropometric parameters recognized in the investigation of craniofacial skeletal deformities and brain development because of its validity and practicality.Cephalic index is the most frequently investigated craniofacial parameter as it utilizes the length and breadth of the head which are useful indices in the study of secular trend, it is used to measure the size of the head,cephalic index gives an idea of how genetic characters are transmitted between parents, offspring, and siblings. It is inherited in a unitary fashion,isolated or syndromiccraniosynostosis, primary microcephaly, and hydrocephalus are pathological disorders which manifest with abnormal cephalic indices in addition to other features.Several studies have been carried out to classify head shapes based on cephalic index into four internationally acceptable categories that include DOLICHOCEPHALIC(<74.9),MESOCEPHALIC (75–79.9), BRACHYCEPHALIC (80.0–84.9), and HYPERBRACHYCEPHALIC (85.0–89.9). A study has shown that the people of Gurung community of Nepal of India are brachycephalic with cephalic index of 80.42.Bhils and Barelas are mesocephalic (76.98 & 79.80). The Iranian people are predominantly brachycephalic and hyperbrachycephalic. The research aimed at comparing the cephalic index between the two genders in a selected population and at determining a baseline value of cephalic index which could be vital in forensic, anthropological, and clinical studies. Cephalic index is an important parameter useful in establishing racial and sexual dimorphism, data obtained from such measurements have been very useful in differentiating people of different ethnic backgrounds, nutritional status, and gender. Several measurable anthropometric parameters or variables have been developed over the years for establishing possible differences amongst different groups.Cephalic index is one of such very useful measurable anthropometric variables used in physical anthropology to determine geographical gender, age, and racial and ethnic variations. Comparison of changes in cephalic index between parents, offspring, and siblings gives clues to genetic transmission of inherited characters or traits which play a role in forensic science.
Arguably, Cephalometry continues to be the most versatile technique in the investigation of the craniofacial skeleton because of its validity and practicality.Cephalometry is associated with the morphological study of all the structures present in the human head. Cephalometry is the scientific measurement of the dimensions of the head usually through the use of standardized lateral skull radiographs. Based on the above factors, anthropometric studies are conducted on the age, sex, and social or ethnic groups in certain geographical zones.Several studies have been conducted on the age, sex, and racial or ethnic groups in different geographical zones. These authors have sited various categories of cranium on the basis of head length, breadth, and index and described seven groups of crania.Okupe et al. , in a comparative study of biparietal diameter (BPD) foetuses of some of the Nigerian ethnic groups and Caucasians, showed statistically significant differences until near term when the Nigerian foetuses showed consistently longer BPD.Cussenot et al. (1990) reported that skeletal measurements were made as the basis of foetal anthropometry and age determination. In a related study, cephalic index varied with advancing gestational age with the highest and lowest being 81.5 and 78.0 at weeks 14 and 28, respectively.A study has shown that the people of Gurung community of Nepal of India are brachycephalic with cephalic index of 80.42.Bhils and Barelas are mesocephalic (76.98 & 79.80). The Iranian people are predominantly brachycephalic and hyperbrachycephalic.Besides being a predictor of fetal death, early transvaginal measurement of cephalic index had been used for the determination of Down syndrome foetuses
GROSS ANATOMY OF THE SKULL
Thehuman skull is the bonystructure that forms the head in the human skeleton. It supports the structures of the face and forms a cavity for the brain . Like the skulls of other vertebrates, it protects the brain from injury.The skull consists of two parts, of differentembroyologicalorigin—theneurocranium and the facial skeleton (also called the viscerocranium). The neurocranium (or braincase) forms the protective cranial vault that surrounds and houses the brain andbrainstem. The facial skeleton is formed by the bones supporting the face.Except for the mandible,all of the bones of the skull are joined together by sutures (immovable) joints formed by bony ossification. The neurocranium has a dome-like roof called the Calvaria(skull cap and a floor or cranial base(Basicranium).
The neurocranium in adults is formed by a series of 8 bones;4 singular bones centered on the midline(Frontal,Ethmoidal,Sphenoidal and Occipital) and 2 sets of bones occurring as bilateral pairs(Temporal and Parietal). The bones forming the Calvaria are primarily flat bones (Frontal,Temporal and Parietal) formed by intramemebranous ossification of head mesenchyme from the neural crest. The bones contributing to the cranial base are primarily irregular bones with substantial flat portions (Sphenoidal and Temporal) formed by endochrondial ossification of cartilage (Chrondocranium) or from more than one type of ossification.
The Ethmoid Bone
The ethmoid bone is a singular porous bone that makes up the middle area of the viscerocranium and forms the midfacial region of the skull. It contributes to the moulding of the orbit, nasal cavity, nasal septum and the floor of the anterior cranial fossa.
The bone consists of a perpendicular plate and two ethmoidal labyrinths parts which are all superiorly attached to the cribriform plate. A smaller orbital part extends towards the orbit.
The ethmoid labyrinths lie on both lateral sides and contain numerous little cavities with ethmoidal cells which are referred to as the ethmoidal sinus. The labyrinths form two of the biggest structures in the nasal cavity: the superior and middle nasal concha. The hiatus semilunaris separates the ethmoid bulla and the uncinate process. It constitutes the connection between the frontal and maxillary sinuses to the anterior ethmoidal cells.
The perpendicular plate is a thin lamina which runs horizontally from the cribriform plate. Inferiorly it attaches to the septal cartilage of the nose and hereby forms part of the nasal septum.
The cribriform plate (Latin “cribriform” = perforated) lies within the ethmoidal notch of the frontal bone and forms the roof of the nasal cavity. As the name suggests it comprises numerous openings through which the olfactory fibers from the nasal cavity pass through to the anterior cranial fossa. The falxcerebri is attached to the crista galli (Latin “crista galli” = crest of the cock), a small vertical protrusion on top of the plate. The olfactory bulbs lie on two grooves lateral to the crista galli.