Muskosceletal Physiology

1. Define the following terms, used in the case and also in associated questions: 
 a. Hemorrhage
Associated with a large loss of blood. In the case it is the extreme amount of blood lost from her arm wound. Hemorrhage’s can be internal or external b. Fracture
A fracture is a break, in this case a break in the patients humerus, occipital bone and 3rd Lumbar vertebral body c. Proximal
Closer to the origin of the body. In this case the fracture at the proximal diaphysis means the part of the shaft closer to the origin of the humerus (the shoulder) d. Diaphysis

The shaft of the bone which surrounds the medullary cavity. In this patients case the diaphysis (shaft) of the humerus has been fractured
2. One way bones are classified is by their shape. How would you classify the bones fractured by Mrs. Morgan? 
 Humerus: Classified as a long bone (longer than it is wide and contains a diaphysis, epiphysis and Endosteum) Occipital Bone: Classified as a flat bone

3rd Lumbar Vertebral body: Classified as an irregular bone

3. The body of Mrs. Morgan’s vertebra is fractured. What type of bone tissue makes up the majority of the vertebral body? Describe the structure and function of this type of bone. The cavity of the vertebral body consists of cancellous (spongy) bone tissue and is surrounded by a protective layer of compact bone. Spongy bone contains the osteocytes, which are responsible for new bone formation and it has a honeycomb appearance. The bone matrix contains a latticework of trabuclaue and there is often fat, marrow and blood vessels contained within the latticework Compact bone makes up the hard outer shell and gives bone its shape

4. The diaphysis of Mrs. Morgan’s humerus is fractured. What type of bone makes up the majority of the diaphysis of long bones like the humerus? Describe the layers of bone tissue found here. Compact (cortical) bone makes up the majority of the diaphysis of long bones like in the humerus of the patient. Long bone forms around cancellous bone and the medullary cavity, which is the site of bone marrow. It protects the inside of the bone and is rigid which helps keep the body upright. Compact bone contains Haversian Systems, which are in concentric circles called lamellae. Haversian system contains a blood supply and the periosteum is located on the outside

5. Most connective tissue, including bone, is highly vascular. Which anatomical structures in Mrs. Morgan’s compact bone house blood vessels? What sign or symptom in Mrs. Morgan’s case is directly related to disruption of these structures by her bone fractures? How is the sign or symptom related to these anatomical structures? The Haversian system houses the blood vessels in Mrs. Morgan’s compact bone. The bone tissue sticking out the skin, the bruising and the extensive bleeding from the arm are the signs and symptoms related to the disruption of these structures by her bone fractures. The bleeding and the bone tissue sticking out of the skin shows how the blood vessels within the Haversian system, such as the periosteal arteries supplying the outer area and the nutrient artery which supplies the inner part of bone have been disrupted. The disruption of these arteries within the Haversian system will then make Mrs Morgan’s humerus susceptible to avascular necrosis.

6. Within days after a fracture, a “soft callus” of fibrocartilage forms. What fibers are found in this type of cartilage? Identify the cells required for fibrocartilaginous callus formation and list their functions. Soft Callus cartilage is formed 1-3 weeks after a fracture. Fibroblasts, osteoblasts and capillaries move into the wound to produce granulation tissue before the formation of the soft callus in the procallus phase. The fibroblasts produce collagen fibers, which are the fibers found in soft callus fibrocartilage. This is then followed by the callus phase, which involves the osteoblasts depositing disorganized clumps of primitive bone matrix called woven bone (which forms the soft callus). The cells required for fibrocartilaginous callus formation include: Osteoblasts: build new bone from matrix containing collagen and minerals Fibroblasts: produce collagen fibers and then become chondroblasts which make cartilage Chondroblasts: make cartilage at site of repair

7. As a fracture is repaired, new bone is added to the injury site. What term is used to describe the addition of new bone tissue? Identify which bone cell is responsible for this process and explain how it occurs. 
 Ossification is the term used to describe the addition of new bone. Osteoblasts are responsible for this addition of new bone and they do this by lining the resorption cavity and laying down new bone. They produce matrix which consist of collagen and ground substance to make the new bone and repair the fracture

8. In the final stage of bone repair, some of the osseous tissue must be broken down and removed. What term is used to define the breaking down of osseous tissue? Which bone cell would be best suited for this task? Bone resorption is the process of breaking down osseous tissue. The osteoclasts, which are derived from macrophages, are the bone cells best suited for this task. They remove the excess bone tissue that is no longer needed when repair of the bone has been completed.