Question

Craniocaudally the parts of colon in ox are
(A). Proximal loop
(B). Spiral colon
(C). Distal loop
(D). Transverse colon
Choose the correct answer from the options given below:

• A. (A), (B), (C), (D).
• B. (A), (C), (B), (D).
• C. (B), (A), (D), (C).
• D. (C), (B), (D), (A).

Hint:

To remember the sequence of the ruminant ascending colon, use the abbreviation PSD: Proximal loop $\rightarrow$ Spiral colon $\rightarrow$ Distal loop.
This is followed immediately by the Transverse colon as it crosses the midline.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The colon of ruminants (like the ox) is highly specialized to accommodate fermentation.
Its ascending colon is elongated and modified into three distinct, continuous segments before joining the transverse colon.

Step 2: Detailed Explanation:
The anatomical path of the colon in the ox, from the ileocecocolic junction (cranial/proximal) to the rectum (caudal/distal), is as follows:
1. Proximal loop of the colon (ansa proximalis) (A): This S-shaped segment connects the cecum to the spiral colon. It runs cranially and then caudally.
2. Spiral colon (ansa spiralis) (B): This is the hallmark of the ruminant colon, arranged in a flat, double-coiled disc with centripetal (inward) coils and centrifugal (outward) coils.
3. Distal loop of the colon (ansa distalis) (C): The centrifugal coils emerge to form this loop, which runs caudally, then turns cranially to join the transverse colon.
4. Transverse colon (D): This segment crosses from right to left across the midline, cranial to the cranial mesenteric artery, and continues as the descending colon.
Thus, the craniocaudal anatomical sequence of the colon is Proximal loop $\rightarrow$ Spiral colon $\rightarrow$ Distal loop $\rightarrow$ Transverse colon.

Step 3: Final Answer:
This sequence matches (A), (B), (C), (D), which corresponds to option (A).