Okay, let's tackle this question. The patient has a straddle injury causing damage to the bulbar urethra, and the MRI shows extravasated urine and blood in the superficial perineal cleft. The question is about the fasciae that bound this space.

First, I need to recall the anatomy of the perineum. The perineum is divided into superficial and deep compartments. The superficial perineal space is bounded by different fascial layers. The key here is identifying the specific fasciae involved in the superficial perineal cleft.

The superficial perineal cleft is the area where structures like the bulbospongiosus and ischiocavernosus muscles are located. The fasciae involved would be the Colles' fascia superiorly and the superficial perineal fascia inferiorly. Wait, Colles' fascia is also known as the deep perineal fascia, right? Or is it the opposite?

Wait, let me clarify. The superficial perineal space is between the Colles' fascia (which is the deep fascia of the perineum) and the superficial fascia. Colles' fascia is the superior boundary, while the inferior boundary is the superficial perineal fascia. So the space between these two would contain the extravasated urine and blood in this injury.

Looking at the options, the correct answer would be the combination of Colles' fascia and the superficial perineal fascia. The other options might include other fasciae like the perineal membrane (which is part of the deep perineal space) or the Scarpa's fascia, which is more in the abdominal region. So the superficial perineal cleft is bounded by Colles' fascia superiorly and the superficial perineal fascia inferiorly. That makes sense because trauma here would lead to extravasation into that space.

**Core Concept**
The superficial perineal space is bounded by fascial layers that compartmentalize structures in the perineum. **Colles' fascia** (deep perineal fascia) forms its superior boundary, while **superficial perineal fascia** forms the inferior boundary. This space contains the bulbospongiosus and ischiocavernosus muscles and is a common site for extravasation in urethral injuries.

**Why the Correct Answer is Right**
In a straddle injury, the bulbar urethra tears, causing urine and blood to accumulate in the superficial perineal cleft. This space is enclosed by **Colles' fascia** superiorly and **superficial perineal fascia** inferiorly. These fasciae prevent spread of extravasated fluid into deeper pelvic structures but allow containment within the perineum, explaining the clinical localization seen on MRI.

**Why Each Wrong Option is Incorrect**
**Option A:** If incorrect, likely refers to **Scarpa’s fascia**, a superficial abdominal fascia not involved in perineal anatomy.
**Option B:** If incorrect, might reference the **perineal membrane** (deep perineal space boundary), which is deeper and unrelated to superficial cleft injuries.
**Option C:** If incorrect, could refer to **Buck’s fascia**, which covers the corpus spongiosum but lies within the deep perineal space.

✓ Correct Answer: C. Colles' fascia and external perineal fascia of Gallaudet