Name
Western Governors University
D312 Anatomy and Physiology I with Lab
Prof. Name
Date
This section addresses questions related to the skeletal anatomy and the structure of bones, particularly those of the head and neck. Each question is followed by detailed explanations that clarify why the correct answer is accurate and why other options are incorrect. Where applicable, bone components are labeled to aid understanding.
Bone tissue contains several cell types, each with specific functions. Osteoclasts, large multinucleated cells, are responsible for breaking down old or damaged bone but are not embedded in the matrix. Osteogenic cells act as precursors to osteoblasts and reside in the periosteum and endosteum but are not trapped in the matrix. Osteoblasts are bone-forming cells that secrete the bone matrix but eventually become embedded as they mature. The correct answer is osteocytes, which are mature bone cells entrapped within the bone matrix, originating from osteoblasts that become trapped after secreting the matrix.
| Choice | Explanation |
|---|---|
| a. Osteoclast cells | Incorrect. These cells resorb bone but are not embedded in the matrix. |
| b. Osteogenic cells | Incorrect. Precursor cells not embedded in the matrix. |
| c. Osteoblast cells | Incorrect. Build matrix but not trapped within it. |
| d. Osteocyte cells | Correct. Mature bone cells entrapped in the bone matrix. |
| Label | Name |
|---|---|
| A | Spongy Bone |
| B | Bone Marrow |
| C | Compact Bone |
| D | Periosteum |
The diaphysis, or shaft of a long bone, is primarily composed of compact bone which provides strength and support. Cartilage is typically located at the bone’s ends (epiphyses) and is not part of the diaphysis. Spongy bone is also mainly found in the epiphyses, not the diaphysis.
| Choice | Explanation |
|---|---|
| a. The diaphysis is comprised of compact bone and cartilage. | Incorrect. Cartilage is found at epiphyses, not in the diaphysis. |
| b. The diaphysis is mostly compact bone. | Correct. Dense compact bone forms the diaphysis for strength. |
| c. The diaphysis is comprised of spongy bone and cartilage. | Incorrect. Spongy bone is in epiphyses, not diaphysis. |
| d. The diaphysis is mostly spongy bone. | Incorrect. Spongy bone is located in epiphyses, not diaphysis. |
Bone shapes are classified based on their form and function. Long bones are elongated and serve as levers, sesamoid bones develop within tendons, and flat bones are thin and broad. Irregular bones have complex shapes that do not fit into other categories and include bones like vertebrae and certain skull bones.
| Choice | Explanation |
|---|---|
| a. A – Long bones | Incorrect. Long bones are elongated, such as femur. |
| b. B – Sesamoid bones | Incorrect. Small bones within tendons, e.g., patella. |
| c. C – Flat bones | Incorrect. Thin, broad bones with spongy bone sandwiched between compact layers. |
| d. D – Irregular bones | Correct. Complex-shaped bones like vertebrae and certain skull bones. |
Bones labeled A have a long cylindrical shape with expanded ends. This structure characterizes long bones, which function primarily as levers during movement.
| Choice | Explanation |
|---|---|
| a. Irregular bones | Incorrect. Irregular bones have complex shapes, not cylindrical. |
| b. Short bones | Incorrect. Short bones are cube-shaped, like carpals, not long and cylindrical. |
| c. Long bones | Correct. Long bones have a long shaft and expanded ends, primarily compact bone. |
| d. Flat bones | Incorrect. Flat bones are thin and broad, unlike the labeled bone. |
The vertebrae protect the spinal cord and are categorized as irregular bones due to their complex shapes that do not fit into long, short, or flat bone categories.
| Choice | Explanation |
|---|---|
| a. Flat | Incorrect. Flat bones protect organs like the skull but do not surround the spinal cord. |
| b. Irregular | Correct. Vertebrae are irregular bones surrounding the spinal cord. |
| c. Short | Incorrect. Short bones are small, cube-like bones such as carpals. |
| d. Sesamoid | Incorrect. Sesamoid bones form within tendons, not around the spinal cord. |
Bones labeled A and B are characterized by their length and structure, fitting the description of long bones such as the humerus, radius, ulna, and femur.
| Choice | Explanation |
|---|---|
| a. Long bones | Correct. These bones are longer than wide and have a shaft with two ends. |
| b. Flat bones | Incorrect. Flat bones include skull bones, ribs, scapula, which do not match A and B. |
| c. Irregular bones | Incorrect. Irregular bones have unique shapes like vertebrae, not A and B. |
| d. Short bones | Incorrect. Short bones include carpals and tarsals, not represented here. |
The axial skeleton consists of the skull, vertebral column, and thoracic cage. It forms the central vertical axis of the body, providing support and protection for vital organs.
| Choice | Explanation |
|---|---|
| a. Thigh bones | Incorrect. These belong to the appendicular skeleton. |
| b. Vertebral column | Correct. It is a major component of the axial skeleton. |
| c. Foot bones | Incorrect. Part of the appendicular skeleton. |
| d. Shoulder bones | Incorrect. Belong to the appendicular skeleton. |
The appendicular skeleton includes all bones of the upper and lower limbs. It consists of 126 bones in total. Unlike the axial skeleton, it does not include bones of the trunk or head.
| Choice | Explanation |
|---|---|
| a. forms the vertical axis of the body | Incorrect. That describes the axial skeleton. |
| b. includes all bones of the body trunk and limbs | Incorrect. Trunk bones belong to the axial skeleton, limbs to the appendicular. |
| c. consists of 126 bones | Correct. This number specifically describes the appendicular skeleton. |
| d. is comprised of the bones of the lower and upper limbs | Correct but less specific than option c, which provides exact bone count. |
Marieb, E. N., & Hoehn, K. (2019). Human Anatomy & Physiology (11th ed.). Pearson.
Tortora, G. J., & Derrickson, B. (2017). Principles of Anatomy and Physiology (15th ed.). Wiley.
Kumar, V., Abbas, A. K., & Aster, J. C. (2020). Robbins Basic Pathology (10th ed.). Elsevier.
