Major Anatomical Divisions of the Human Skull - Term Paper Example

Human skull Human skull Major anatomical divisions of human skull Human skull has two major parts: neurocranium and viscerocranium.Neurocranium represents the part of the brain while viscerocranium represents the face part of the brain. The cranium has the role of protecting the brain against trauma. Sutures join the cranium bones (Hitoshi et al., 2013). These sutures include sagittal suture (acts as the key joint of the parietal bones), lambdoidal suture (acts as the joint between occipital and parietal bones), squamous suture (joins the temporal and parietal bones) and coronal suture (joins parietal and frontal bone). Coronal acts as the last bone to form a fusion among these. Cranium has occipital, sphenoid and ethmoid bones on the base. As such, the cranium base has three distinct regions, which are anterior, posterior and middle fossae. Further, the cranium has holes on its base, which are called foramina. These holes facilitate in allowing nerves and blood vessels to leave and enter cranium successfully (Sharifi et al., 2013). The largest foramen is at the occipital bone, which is regarded as foramen magnum. Thus, the spinal cord moves via the large opening, which makes it to have a connection with the brain via the medulla oblongata. Laterally to the foramen magnum, hypoglossal canals, which establish pathways for hypoglossal nerves, exist. Jugular foramina exist at the end of the temporal bones. These canals and foramen facilitates in hosting nerves and blood vessels in the cranium. The skull has 14 facial bones and 8 cranial bones. These bones facilitate in the provision of protection to brain and support of nerves and organs, such as smell, vision, equilibrium, hearing and taste (Sharifi et al., 2013). Further, the bones offer an attachment for muscles, which aid in the control of chewing and facial expressions and allowing the movement of the head. Embryonic tissue origin and bone formation. The skull has a total of 22 bones. Immobile joints regarded as sutures unite the separate bones of the cranial part of the skull. These joint are held by the sutural ligaments. The cranium is linked to the mandible by the mobile synovial joint, which is the temporomandibular joint. Diploe is a spongy bone layer, which separates the internal and external tables of skull bones (Hitoshi et al., 2013). The internal table is brittle and thinner in comparison to the external table, but the inner and outer surfaces of the bones are covered by the periosteum. The bones of skull have two divisions, which are cranium bones and face bones. Cranium has the following bones frontal bone (1), ethmoid bone (1), sphenoid bone (1), occipital bone (1), parietal bones (2) and temporal bones (2) (Sheikh et al., 2014). Such indicates that the cranium only has two bones, which are paired. Face bones include mandible (1), vomer (1), zygomatic bones (2), maxillae (2), nasal bones (2), inferior conchae (2), palatine bones (2) and lacrimal bones (2). Thus, the face has only two bones, which are not paired. The frontal bone is responsible for the formation of forehead, which curves and ends downwards by having upper orbit margins. It articulates with nasal and maxillae bones medially and with the zygomatic bone laterally. Key features of the fronta bone are the supraorbital notches and superciliary arches and frontal air sinuses. The spaces create room for nose communication, as well as voice resonation. The orbit represents the bony cavity, which houses the eyeball. Its margin is formed by maxilla (inferiorly), frontal bone (superiorly), processes of frontal and maxilla bone (medially) and zygomatic bone (laterally) (Gawlikowska-Sroka et al., 2013). The two nasal bones create the nose bridge where the anterior borders with nasal aperture and the lower borders with maxillae. The two maxillae bones form hard palate anterior part, upper jaw, orbital cavity floors and nasal cavity lateral walls. Zygomatic bone forms lateral floor and wall of the orbital cavity and the cheek. The mandible is the lower jaw, which consists of two vertical rami and horizontal body. Bone formation occurs from the replacement of a tissue, which was in existence. For the long bones, the tissue in existence was hyaline cartilage, which makes the process have the name endochondral ossification. When the tissue in existence is of the embryonic mesenchyme material, flat bones emerge, which are evident for the skull bones (Martínez-Abadías et al., 2012). These result from the process of intramembranous ossification. The processes for bone formation are the same since the same chemical reactions and cells are involved; what differs is the material, which is replaced. Endochondral ossification begins with the differentiation of the cartilage cells into osteoblasts, which eventually secrete bony collar adjacent to the diaphysis of the hyaline cartilage model. The second step is the opening of a primary ossification center, whichs facilitates calcifying of the cartilage. Further, blood vessels grow in the internal cavities where fibroblasts differentiate to form osteoblasts that secrete spongy bone matrix in the diaphysis. This ends with the bone remodeling after epiphysis ossification to form the final form. Some of the hyaline cartilage remains, which forms epiphyseal and articular cartilage that separates diaphysis and epiphysis. Intramembranous ossification begins when an ossification center develops in the embryonic tissus in which clustering of mesenchymal cells occurs. These, then differentiate to osteoblasts that secrete bone matrix. Blood vessels then develop, which supply the matric and cells with nutrients and oxygen and eventually they are trapped in the developing bone, which becomes spongy. Remodeling occurs that forms compact bone. Methods for determining osteogenesis and tissue origins of bones Autografting is a key procedure, which is often adopted in the process of studying bone tissues. Such a method involves harvesting a donor bone and transplanting the same to a defect site. This entails spinal fusion procedures, which aid in massive autologous grafting of the bone. Bone formation in vitro is a strategy, which focuses on cellular function and differentiation, which occurs during embryonic development. In this method, scaffold exists, which creates logistic and structural template for the tissue that is developing and has the impact of influencing cell behavior (Sheikh et al., 2014). Porous scaffolds support this bone formation method, which include those that are made from synthetic and native polymers, ceramics and composite materials. Essential scaffold properties for bone formation are pores shape, distribution and size, scaffold structure, presence of sites for cell attachment and surface roughness. Bioreactor or culture system is another essential feature of bone tissue engineering. The design of these systems focuses on the control of oxygen and nutrients transport to the cells and enhancing biological stimuli support in different regions of the graft (Martínez-Abadías et al., 2012). Further, system designs for the bioreactor support physiological designs for cell microenvironment through conditioning and perfusion of culture medium. Scientific and clinical utility for tissue engineering is reliant on the potential of individuals to predict cell division in temporally and spatially defined patterns. Noninvasive methods for bone tissue investigation exist. Such include the DEXA scanning technique, which facilitates in the comprehension of bone mineral content (BMC) and bone mineral density (BMD) (Freire et al., 2013). Thus, DEXA scans represent the common tests for BMC and BMD measurement and they facilitate in the diagnosis of osteoporosis or osteopenia. The other nondestructive methods for bone tissue investigation are standard radiography, QCT and ultrasound. These techniques offer noninvasive methods for investigation of the bone tissue without the destruction of the properties of the bone. Impact of these factors on clinical scenarios, such as tissue engineering and bone healing A typical clinical scenario is the injury of the brain. In such a case, intracranial pressure increases, this results in brain herniation from foramen magnum. Such occurs since the brain lacks space for expansion and the condition may result in an intensified brain damage or death. However, such a situation can be reversed by conducting a quick operation, which aids in the relieving of pressure for the brain (Gawlikowska-Sroka et al., 2013). High regenerative bone capacity indicates that most of the bone fractures can heal effectiiveelyy without a need for major intervention. However, large bone defects, which are evident after nonunion fractures and bone tumor reactions leads to a need for intensified surgical intervention. Transplanting of the autologous bone contributes in the attainment of the best clinical outcomes. However, there is a reduction in the supply and challenges in donor site morbidity. Tissue-engineered bone constructs are able to eliminate the demand, which emerges from allograft and autograft materials for bone healing augmentation (Freire et al., 2013). The technologies also facilitate in the discovery of the biological potential of different cell types. Moreover, the use of the noninvasive methods for bone tissue investigation facilitates in the comprehension bone related issues and enhancement of quick healing, as well as support of the tissue engineering processes. Such ensures that clinical scenarios, which involve healing of individuals with bone related problems, occur effectively. This is because noninvasive technologies aid in identification of the bone problem and the best treatment procedure to ensure that the patient recovers quickly. As such, noninvasive technologies facilitate in the attainment of better results in the clinical scenarios, at all times. References Freire A, Rossi A, de Oliveira V, Prado F, Caria P, & Botacin P (2013). Emissary Foramens of the Human Skull: Anatomical Characteristics and its Relations with Clinical Neurosurgery. International Journal Of Morphology, 31: 287-292. Gawlikowska-Sroka AA, Stocki ŁŁ, Dąbrowski PP, Kwiatkowska BB., Szczurowski J J, & Czerwiński F F (2013). Topography of the mental foramen in human skulls originating from different time periods. HOMO - Journal Of Comparative Human Biology, 6-44: 286-295. Hitoshi F, Evins AI, Burrell JC, Koichi I, Stieg PE, & Bernardo A (2013). The Meningo-Orbital Band: Microsurgical Anatomy and Surgical Detachment of the Membranous Structures through a Frontotemporal Craniotomy with Removal of the Anterior Clinoid Process. Journal Of Neurological Surgery. Part B. Skull Base, 75-2: 125-132. Martínez-Abadías N, Esparza M, Sjøvold T, González-José R, Santos M, Hernández M, & Klingenberg C (2012). PERVASIVE GENETIC INTEGRATION DIRECTS THE EVOLUTION OF HUMAN SKULL SHAPE. Evolution, 66-4: 1010-1023. Sharifi S, Mohagheghi S, Ghasemi I, Kavoosi M, Mohagheghi A, Feyz A, & Masserat V (2013). Analysis of the Accuracy of Linear Measurements on CBCT in Comparison with the Anatomic Measurements Obtained from Dry Human Skull. (English). Jundishapur Scientific Medical Journal, 12-5: 497-507. Sheikh E, NasrW, & Shahat Ibrahim A (2014). Anatomical variations of supraorbital notch and foramen: a study on human adult Egyptian skulls. European Journal Of Plastic Surgery, 37-3: 135-140. Read More