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). Sequential concentric lamellae have alternate fiber orientations with each other, spiralling around the central canal [12].

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).

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.

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.

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.

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

The four components of the axial skeleton are: SKULL (consists of 28 bones that include the cranium, which encloses and protects the brain and facial bones). VERTEBRAL COLUMN (supports the skull and protect the spinal cord). RIBS ( 12 pairs of bow shaped bones that protect the organs in the body cavities of the trunk). STERNUM ( aka breastbone and supports the collar bones).

The objective of the virtual lab on bones consisted of identifying the major bones of the human body. We had to place the major bones of the body in the correct anatomical position. The key terms included the axial skeleton which includes the skull and the bones that support it, such as, the vertebral column, ribs, and sternum. The appendicular skeleton includes the bones of the limbs and the structures that support them such as, the scapula and pelvic bones.

The cranium size can be analyzed by comparing the size of the overall cranium with the size of the overall face. The cranium shape can be determined by analyzing the height and width of the overall skull. The degree of prognathism can be examined by looking at the profile of the skull and determined how much the face projects outward. By looking at the back of the skull and analyzing the morphology of the occipital and nuchal region the shape of occipital and nuchal region can be determined. When determining canine size and diastema, one should analyze and compare the canine to other teeth and the space between the canine and the premolars.

The phalanges are not separately mobile, being bound by ligaments, so the claws from one functional whole. Its muscles work by means of contraction. They contain more retractor muscles than the extensor muscles. A retractor muscle, in sloth makes them cling onto the branches of a tree in a long period of time; they lack extensor muscles thus making it hard for