A 40 year old man presents to ohopedics emergency with the following deformity. He is daily wage laborer by profession and this problem occurred following lifting heavy load. Usg reveals following finding: Which of the following structure is affected?

**Core Concept**
The patient's presentation suggests a possible injury to a structure in the lower back, likely related to lifting a heavy load, which is a common cause of musculoskeletal injuries. The underlying concept being tested is the anatomy and function of the structures in the lumbar spine.

**Why the Correct Answer is Right**
The patient's symptoms and history are suggestive of a lumbar disc herniation, which is a common cause of lower back pain and radiculopathy. The structure most likely affected is the **annulus fibrosus**, a tough, fibrous outer layer of the intervertebral disc that can rupture or herniate, causing pain and neurological symptoms. This is often seen in individuals who engage in heavy lifting or bending, as in this patient's case.

**Why Each Wrong Option is Incorrect**
* **Option A:** The **intervertebral disc** is affected, but the specific structure within the disc that is most likely injured is the annulus fibrosus.
* **Option B:** The **facet joints** are not the primary structure affected in this scenario, although they can be involved in lumbar disc herniation.
* **Option C:** The **ligamentum flavum** is not typically injured in a lumbar disc herniation, although it can be involved in other types of spinal injuries.

**Clinical Pearl / High-Yield Fact**
In patients presenting with acute lower back pain and radiculopathy, it is essential to consider the possibility of a lumbar disc herniation, particularly in individuals with a history of heavy lifting or bending.

**Correct Answer:** A.