N3 Anatomy and Physiology (1st Sem AY 2022-2023)

1. Watch this video to view a rotating and exploded skull with color-coded bones. Which bone (yellow) is centrally located and joins with most of the other bones of the skull? 

The bone that is colored yellow from the video represents the sphenoid bone. It is one of the 6 major cranial bones and has a shape which resembles a figure of a butterfly or bat with full extension of its wings. Its purpose is to provide support for the facial muscles and other bones of the skull since it is situated quite in the middle of them. 

2. What are the two mechanisms by which the bones of the body are formed and which bones are formed by each mechanism?

Based on the video, there are two mechanisms which allow bone formation in prenatal stages of human development: the intramembranous and endochondral ossification

Intramembranous ossification occurs within the fibrous connective tissue membranes within mesenchyme cells. This then spearheads to the subsequent development processes of having ossification center, calcification, trabeculae formation and periosteum formation. During intramembranous ossification, flat bones such as the skull, mandible and clavicle are formed. 

Endochondral ossification accounts for bones which develop from hyaline cartilages originating from mesenchyme cells. It is the mechanism which develops the majority of the body’s bones like the femur, humerus, tibia, and many more. This starts with the development of a cartilage model where mesenchymal cells crowd together to form chondroblasts. This then transcends to chondrocytes which accounts for the lengthening and thickening of the developing bone followed by the establishment of the primary ossification center which forms spongy bones and medullary cavity. After such, secondary ossification centers further develop the epiphyses which ends up in developing the articular cartilages and epiphyseal line. 

3. What are the synovial joints being described in the video?

Based on the video, there are 6 different synovial joints being described and demonstrated which are located in different articulations of our skeletal system. 

• • Ball and socket joints (shoulders)

  • Pivot joints (1st and 2nd vertebrae)

  • Plantar joints (carpals)

  • Saddle joints (thumb and wrist)

  • Hinge joints (elbow and knee)

  • Condyloid joints (lumbar vertebrae)

4. Which type of synovial joint allows for the widest ranges of motion?

Among the six synovial joints, the ball and socket joints allow the widest ranges of motion. It allows all types of motion except gliding and this joint is usually found in shoulders and hips.