**Question:** Which of the following is not a classification of humerus?

A. Neck
B. Head
C. Shaft
D. Epiphysis

**Core Concept:** The humerus is a long bone in the upper extremity of the human body, forming part of the shoulder joint (glenohumeral joint) and elbow joint (radiohumeral joint). It is classified into specific regions for better understanding and identification purposes during clinical examination or surgical intervention.

**Why the Correct Answer is Right:** D. Epiphysis (also known as a "epiphysis") is not a classification of the humerus. In contrast, A. Neck, B. Head, and C. Shaft are correct classifications, as they represent distinct sections of the bone with specific roles and features.

**Why Each Wrong Option is Incorrect:**

A. Neck: The neck is a transitional region between the shaft and the head of the humerus, where the bone tapers and articulates with the glenoid cavity of the scapula (shoulder blade) and the capitulum of the radius (forearm bone).

B. Head: The head of the humerus is the rounded part that articulates with the glenoid cavity of the scapula. It is the largest part of the humerus and is responsible for the majority of the joint surface area at the shoulder joint.

C. Shaft: The shaft is the central, cylindrical portion of the humerus, providing the mechanical support and strength for the bone. It connects the head and the condyles (Lateral and Medial condyles).

D. Epiphysis: Epiphyses are growth plates found in long bones of children and young adults, facilitating bone elongation during growth and development. They are not relevant to classifying the humerus in adults.

**Clinical Pearl:** Understanding the classifications of the humerus is crucial for medical professionals to accurately diagnose, treat, and communicate about bone abnormalities or injuries involving the humerus. For example, a fracture in the shaft or head of the humerus would require specific treatment strategies compared to a fracture in the neck or epiphysis.

**Correct Answer:** D. Epiphysis (epiphysis) is not a classification of the humerus. The correct classifications include neck, head, shaft, and condyles (Lateral and Medial condyles).