The accompanying aery with axillary nerve in the quadrangular space is:
**Core Concept**
The quadrangular space is an anatomical region in the shoulder that contains the axillary nerve and a accompanying artery. This space is bounded by the teres minor, teres major, triceps brachii, and the humerus.
**Why the Correct Answer is Right**
The posterior circumflex humeral artery accompanies the axillary nerve in the quadrangular space. This artery is a branch of the axillary artery, which is the continuation of the subclavian artery. The posterior circumflex humeral artery supplies blood to the shoulder region.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct accompanying artery.
**Option B:** This option is incorrect because it is not related to the quadrangular space.
**Option C:** This option is incorrect because it refers to a different artery.
**Option D:** This option is incorrect because it is not the accompanying artery of the axillary nerve.
**Clinical Pearl / High-Yield Fact**
The quadrangular space is a significant anatomical landmark, and knowledge of its contents is crucial for understanding the neurovascular supply of the shoulder region.
**Correct Answer:** D. Posterior circumflex humeral artery.