Skeletal System

Bone tissue structure Bone is hierarchically organized. Zooming in the bone structure (Fig. 4a), we find the osteons or Haversian systems, which are the basic unit of structure of compact bone. Osteons consist of concentrically arranged layers, or lamellae, of compact bone tissue, that surround a central canal, the Haversian canal, where bone’s blood supplies and nerves can be found (Fig. 4b).

This type of joint allows for a good range of motion across two different axes. As we move further towards the distal end of the Phalanges we have another joint between the Proximal Phalanges and the Middle Phalanges. However, there are only four Middle Phalanges as the Big Toe or Hallux as it is also known consists of just a Proximal Phalanx and a Distal Phalanx. The joints between the Middle Phalanges and the Distal Phalanges are called the Proximal Interphalangeal Joints and these are the joints found in the middle of the toes. These joints are found on all toes with the exception of the Hallux or Big Toe which like the four other toes consists of the Distal Interphalangeal Joint which is the joint that is closest to the top of the toes hence the name Distal Interphalangeal Joint.

Stylohyoid ligament is attached to the lesser horn, the hyoid bone is suspended with long stylohyoid ligaments from the styloid process of the temporal bone of the outer skull base and maintains the position of the hyoid bone(4)(1). Anatomically the hyoid is composed of a body, two greater cornua and two lesser cornua. Each cornu is attached to the body by syn- chondrosis that calcifies with ageing. The tip of the cornu are directed postero-laterally. The important attachments of the hyoid are myelohyoid, omohyoid, thyorohyoid and stylohyoid(1).

A thick, triangular bone which is known as patella lies anterior surface between the femur and tibia. In each knee joint, there is two pieces of C-shaped cartilage which lies between the surfaces of the femur and tibia. The lateral side of the meniscus is known ad lateral meniscus while the medial side is known as medial meniscus. The major role of the menisci is to absorb the impact load between the femur and tibia and also to provide some degree of stabilization to

*The dorsal surface of the carapace has a median row of five vertebral shields, two lateral rows of costal shields or a marginal row of twenty four or twenty five marginal shields. *There are six pairs of shields, overlying the plastron. *These shields are gular, humeral, pectoral, abdominal, femoral and anal. B) Endoskeleton – i) Skull – *The skull is heavy and strong without temporal opening (anapsid condition). * All the skull bones except the lower jaw and the hyoid bone are immovably united together.

The Axial Skeleton is the central core of the human body and it protects all the vital organs. It consist of 80 bones in total, 29 bones in the head, 25 bones of the thorax and 26 bones in the vertebral column [8]. The best example for the support and protection function axial skeleton is your skull. There are eight bones in your skull called cranial bone they are thick and hard and lack the ability to move on their own. Their purpose is to protect your brain and its nerves and blood

It’s contributes to the multiple regions of the skull: anterior cranial fossa, middle cranial fossa, pterygopalatine fossa, infratemporal roof, , orbit, lateral wall of the cranial vault and roof and lateral wall of the nasal cavity, It’s articulates with the following bones: The ethmoid bone, the frontal bone, the zygomatic bones, the parietal bones, the temporal bones, the palatine bones, occipital bone and the vomer (Liebgott, 2011). It is consist from four main part : and three paired processes—greater wings, lesser wings and pterygoid processes (Tandon, 2009) 3.1.2 body of sphenoid bone• Its reprecent the central part and contains two sphenoidal air sinuses, It has multiple surfaces: Superior surface—bears a sulcus chiasmaticus and Dorsum sellae with two posterior clinoid processes lie posteriorly Inferior surface—has the rostrum, Two lateral surfaces—Each has a carotid sulcus for internal corotid artery. Anterior surface—presents sphenoidal crest in midline. On either side are openings of sphenoidal air sinuses and sphenoidal concha. Posterior surface fuses with basilar part of occipital bone by 25th year .

Results and Discussion The group viewed each specimen in the microscope, the members then observed four types of tissues. Each tissue was identified. The results are as follows: • Epithelial Tissue - The epithelial tissue covers majority of the body surface and also makes up the lining of some internal organs. This tissue is responsible for the protection of the body from dust, dirt, bacteria and other organisms that lie outside the body, it may also be changed/modified to glands that produce mucus, hormones, enzymes and etc. , also all epithelial cells are supported by a basement membrane underneath it.

Tendons are strong, tough bands of inelastic fibrous connective tissue that connects a muscle to a bone. They are sometimes referred to as sinews which are also tough bands of tissues capable of withstanding great amounts of tension and when talking about tensile strength, they’re the strongest among the other connective tissues. Tendons are consists of elongated collagenous cells and minimal ground substances. These tendons are closely packed together, parallel to the direction of the force (Brandt, 2004). But among these tendons in the body, only one muscles stood out not only as the largest, but also considered as the strongest; the Achilles’ tendon.

The lumbar spine has several distinguishing characteristics: The lower the vertebra is in the spinal column, the more weight it must bear. The five vertebrae of the lumbar spine (L1-L5) are the biggest unfused vertebrae in the spinal column, enabling them to support the weight of the entire