In human skeletal anatomy, which of the following bones forms the largest superior portion of each coxal hip bone?

Introduction / Context:
The pelvic girdle supports the weight of the upper body, transfers it to the lower limbs, and protects pelvic organs. Each coxal or hip bone is formed by the fusion of three bones. Understanding which part forms the largest portion is useful in anatomy and clinical contexts. This question asks which bone makes up the largest superior part of the coxal bone.

Given Data / Assumptions:

• Each coxal bone is formed by fusion of ilium, ischium, and pubis.
• The ilium is located superiorly, the ischium posterior inferiorly, and the pubis anterior inferiorly.
• The question focuses on the largest portion of the coxal bone.
• Normal adult human anatomy is assumed.

Concept / Approach:
The ilium is the broad, flaring, superior part of the hip bone and forms the iliac crest that can be felt on the side of the waist. Ischium forms the lower posterior portion, including the ischial tuberosity on which we sit. Pubis forms the anterior inferior part and contributes to the pubic symphysis. Since the question asks for the largest portion of the coxal bone, the correct answer is ilium.

Step-by-Step Solution:
Step 1: Recall that the coxal bone consists of ilium, ischium, and pubis fused together in adults. Step 2: Remember that the ilium is the uppermost and widest part, forming the iliac crest. Step 3: Recognize that the ischium is smaller and forms the lower posterior region, while the pubis forms the anterior inferior portion. Step 4: Compare all options and identify which bone is described as the largest superior portion. Step 5: Conclude that the ilium is the largest portion of the coxal bone.

Verification / Alternative check:
Visualizing or examining diagrams of the pelvis clearly shows that the ilium occupies most of the superior area, forming the broad, wing like region of the hip bone. Palpation of the lateral hip region in a living person reveals the iliac crest, which is part of the ilium, confirming its size and position.

Why Other Options Are Wrong:
Option B, ischium, contributes to the lower posterior part and the sitting bones but is not the largest portion. Option C, pubis, is anterior inferior and smaller in area. Option D, sacrum, is a separate bone in the vertebral column that articulates with the coxal bones but is not part of the coxal bone itself. Option E, femur, is the thigh bone and also not part of the coxal bone.

Common Pitfalls:
Students sometimes confuse the names ilium and ileum, the latter being part of the small intestine. Another pitfall is to think of the entire hip region as the femur or sacrum rather than distinguishing individual bones. Remember that the coxal bone is a fusion of ilium, ischium, and pubis.

Final Answer:
The largest superior portion of the coxal bone is formed by the Ilium.