Sixth cranial nerve palsy of left eye causes
**Core Concept**
Sixth cranial nerve palsy, also known as abducens nerve palsy, involves the paralysis of the lateral rectus muscle, which is responsible for outward gaze (abduction) of the eye. This condition is characterized by the inability to move the affected eye laterally.
**Why the Correct Answer is Right**
The sixth cranial nerve palsy leads to a weakness or paralysis of the lateral rectus muscle, resulting in an inability to abduct the affected eye. The affected eye may also show a medial deviation (esotropia) due to unopposed action of the medial rectus muscle. This condition can be caused by various factors, including trauma, aneurysm, tumor, or inflammation affecting the abducens nerve.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant as sixth cranial nerve palsy specifically affects the lateral rectus muscle, not the superior rectus muscle.
* **Option B:** While third cranial nerve palsy affects the superior, inferior, and medial rectus muscles, as well as the inferior oblique muscle, it does not primarily affect the lateral rectus muscle.
* **Option C:** Seventh cranial nerve palsy affects the muscles of facial expression, not the extraocular muscles, and therefore is not related to sixth cranial nerve palsy.
**Clinical Pearl / High-Yield Fact**
In cases of sixth cranial nerve palsy, the affected eye may show a characteristic "down and out" position due to the unopposed action of the medial rectus muscle and the gravity's effect on the affected eye.
**Correct Answer: B. Third cranial nerve palsy**