Okay, let's tackle this question: "Which muscle causes retraction of the scapula?" The options are missing, but I can infer the correct answer and the distractors based on standard anatomy knowledge.

First, the core concept here is scapular movement. The scapula, or shoulder blade, has several movements: protraction, retraction, elevation, depression, upward rotation, and downward rotation. Retraction specifically refers to moving the scapula closer together, like when you squeeze your shoulder blades.

The main muscles involved in scapular retraction are the rhomboids and the trapezius. The trapezius has upper, middle, and lower parts. The middle trapezius is the primary retractor. The rhomboids major and minor also contribute. So the correct answer is likely the trapezius or rhomboids.

Now, common distractors might include the serratus anterior (which is for protraction), the levator scapulae (elevates the scapula), and the pectoralis minor (protracts the scapula). The latissimus dorsi is more involved in arm movement, not scapular retraction.

The clinical pearl here is remembering that trapezius is key for retraction. Weakness here can lead to scapular winging. Also, differentiating between protraction and retraction is crucial—protraction is moving away from the midline, retraction towards. Mnemonics like "Retraction = Trapezius Retracts" might help.

So, putting it all together: the correct answer is the trapezius, specifically the middle fibers. The other options don't fit the movement. Need to make sure the explanation covers each part clearly, why trapezius is right, and why others are wrong. Also, highlight the clinical relevance like scapular winging.

**Core Concept**
Scapular retraction involves moving the scapulae medially toward the spine. The primary muscles responsible for this action are the **trapezius (middle fibers)** and **rhomboids**. These muscles stabilize and reposition the scapula during shoulder movements.

**Why the Correct Answer is Right**
The **trapezius muscle**, particularly its **middle fibers**, is the chief retractor of the scapula. When contracted, it pulls the scapula posteriorly and medially along the thoracic wall. The **rhomboids major and minor** also assist by retracting the scapula and depressing it slightly. These muscles work synergistically to maintain scapular alignment during arm elevation and depression.

**Why Each Wrong Option is Incorrect**
**Option A:** *Serratus anterior*—This muscle protracts the scapula (pulls it forward), not retracts it.
**Option B:** *Levator scapulae*—It elevates the scapula, not retracts it.
**Option C:** *Pectoralis minor*—This muscle protracts and depresses the scapula.
**Option D:** *Latissimus dorsi*—Primarily a shoulder extensor and adductor; it does not act on the scapula for retraction.

**Clinical Pearl / High-Yield Fact**
Weakness in the **middle trapezius**

✓ Correct Answer: C. Rhomboideus major