In bone structure, which term is used for the spongy, porous type of bone tissue that is found mainly at the ends of long bones and inside flat bones?

Introduction / Context:
Human bones are not solid throughout; they contain different types of tissue that serve various functions. The outer regions of many bones are dense and strong, while the interior often contains a lighter, more porous tissue that helps reduce weight and store bone marrow. Understanding the terminology used for these different bone tissues is important in anatomy, orthopaedics, and radiology. This question asks for the correct term used for the spongy, porous bone tissue commonly found at the ends of long bones and inside flat bones.

Given Data / Assumptions:

• The tissue described is spongy and porous, not dense and compact.
• It is found mainly at the ends of long bones and in the interior of flat bones.
• Options list compact bone, bone fissure, yellow marrow, cancellous bone, and articular cartilage.
• We assume basic knowledge of bone structure and terminology.

Concept / Approach:
Bones typically have a dense outer layer called compact bone (cortical bone) that provides strength and protection. Inside many bones, especially at the ends of long bones and in flat bones like the pelvis and skull, there is a lighter, mesh like tissue known as cancellous bone or spongy bone. This tissue is made up of a network of bony struts called trabeculae, with spaces in between that often contain red bone marrow involved in blood cell production. The porous nature of cancellous bone reduces the overall weight of the skeleton while still providing structural support.

Step-by-Step Solution:
Step 1: Identify that the question is asking about spongy, porous bone tissue. Step 2: Recall that the dense outer portion of bone is called compact or cortical bone, not spongy bone. Step 3: Remember that the internal, porous network of bone at the ends of long bones is called cancellous or spongy bone. Step 4: Note that yellow marrow is a type of tissue inside bones, but it is not itself bone tissue; it stores fat. Step 5: Select cancellous (spongy) bone as the correct term for the described tissue.

Verification / Alternative check:
Anatomy diagrams of a long bone typically label three main features: a compact bone shell, cancellous (spongy) bone at the ends, and a medullary cavity containing marrow. The cancellous region is shown with a lattice like appearance, indicating spaces and trabeculae. In flat bones, such as the sternum, similar diagrams show compact bone layers on the outside and cancellous bone sandwiched in between. These visual representations consistently associate the spongy, porous interior bone tissue with the term cancellous bone.

Why Other Options Are Wrong:
Compact bone, the dense outer layer of bone: Compact bone is solid and dense, not spongy and porous. Bone fissure, a narrow slit in bone: A fissure is a type of opening or groove in bone, not a tissue type. Yellow bone marrow, which stores fat in the medullary cavity: Yellow marrow is soft tissue inside bones, not bone tissue itself. Articular cartilage covering the ends of bones at joints: Articular cartilage is a smooth cartilage that covers joint surfaces, not spongy bone tissue.

Common Pitfalls:
Students sometimes confuse cancellous bone with bone marrow or with compact bone because all appear together in diagrams. It helps to remember that cancellous bone refers to the bony framework made of trabeculae, whereas marrow is the soft tissue that fills the spaces. Another pitfall is assuming that all bone tissue is solid and heavy; in reality, the combination of compact and cancellous bone allows the skeleton to be strong yet relatively light. Keeping these distinctions in mind clarifies questions about bone structure.

Final Answer:
The spongy, porous type of bone tissue is called Cancellous (spongy) bone with many trabeculae and spaces.