Clinical Case Study Look Out Below: A Case Study on Bone Tissue Structure and Re

Question

Clinical Case Study

Look Out Below: A Case Study on Bone Tissue Structure and Repair

Mrs. Debbie Morgan is a 45-year-old female who works as a stocking clerk for a local home improvement store. While she was at work today a large box of metal rivets fell from a 20-ft.-high overhead shelf, striking her outstretched arm and knocking her to the ground. The ambulance personnel reported that she had lost quite a bit of blood at the accident scene and was "knocked out" when they arrived. To minimize further hemorrhage, the paramedics applied a pressure bandage to her arm.

You meet the paramedics as they bring Mrs. Morgan into the emergency room and begin to assess her for injuries. She is awake and alert, but complaining of severe left arm and back pain, plus she has a "killer headache." To fully examine her injuries you remove four blood-soaked bandages from her arm. You notice a large open wound on her arm with what appears to be bone tissue sticking out of the skin. She also has bruises covering her left shoulder, left wrist, and lower back. To determine the extent of her injuries Mrs. Morgan undergoes several x-rays, which reveal the following:

fracture of the left humerus at the proximal diaphysis,
depressed fracture of the occipital bone,
fracture of the 3rd lumbar vertebral body.

Short Answer Questions

1.) Define the following terms, used in the case and also in associated questions:

hemorrhage
fracture
proximal
diaphysis

2.) One way bones are classified is by their shape. How would you classify the bones fractured by Mrs. Morgan?
The body of

3). 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.

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.

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?

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.

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.

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?

9).The extracellular matrix (ECM) of bone is considered to be a composite material made up of organic and inorganic matter. What makes up the organic and inorganic portions of the matrix? Describe the cellular mechanism involved in breaking down this matrix; include the bone cell required for the process.

Explanation / Answer

Q1. Hemorrhage: Loss of blood (bleeding).

Fracture: The term fracture represent the cracking or breaking of the bone tissue

Proximal: Depend upon the anatomical position of the body part, specific prefixes, suffixes are used to locate its position verbally, this terminology is very useful for remembering names and position of body organs.Proximal end of organs represent the closer end towards the point of attachment to the trunk. Eg: The wrist is proximal to the fingers. Shoulder is proximal to the wrist.

Diaphysis: The structure of long bones typically consists of epiphysis, diaphysis, metaphysis, medullary cavity and periosteum. The proximal and distal ends of a bone are called as epiphyses; diaphysis is the middle shaft of bone. The region between the epiphyses and diaphysis is known as metaphyses.

Q2.

Based on the shape of the bones, they are classified into five different types, namely long bones (Eg: femur, humerus), short bones (EG: ankle and wrist bones), flat bones (Eg: bones of sternum), irregular bones (Eg: bones of vertebra) and sesamoid bones (Eg: patella).

Long bones look more elongated with greater length than width, and they are curved at the middle that offers strength. These bones play a major role in body weight bearing.

3. The majority of the vertebral body is madeup of cencellous bone or spongy bone. Cancellous bone is light in weight with its porous appearance, it looks spongy (but its texture is not spongy) as it contains more spaces in its structure.

Vertebrates contain a characteristic supporting back bone called as “vertebral column (spinal cord),” which is made of several individual segments called “vertebra.” The average length of vertebral column in an adult male is about 71 cm and in females it is 61 cm.

The segments of vertebral column are flexible; they can rotate and move forward, backward, and sideways. This bony structure covers the spinal cord, and protects it. The main function of this strong flexible rod is to keep the skeleton in up straight position by supporting the head. Vertebral column also provides the sites of attachments for ribs, pelvic girdle, and to muscles of the upper limbs and back.

4. Compact bone is more crystalline with less spaces and is strongest than the spongy tissue. It is abundantly present beneath the periosteum of all bone types. The diaphysis of long bones mainly consists of compact bone, thus it offers bone strength. The structural unit of compact bone is “osteons.”

5. Rings of concentric lammelae (of canaliculi) are present around the central canal of each osteon. Bones receive nutrients through the blood supply. Blood vessels permeate the compact bone through the Volkmann’s canals (also known as perforating canals). Blood vessels first reach the central canal of the first osteon, and then to the central canal of second osteon through another perforating canal; the osteocytes of second osteon now receive blood supply through canaliculi.

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