Lacrimal punctum of upper and lower eyelids are ?
**Core Concept**
The lacrimal puncta are small openings located at the medial canthus of the upper and lower eyelids, serving as the entry points for tears to drain into the lacrimal canaliculi.
**Why the Correct Answer is Right**
The lacrimal puncta are situated at the medial canthus, allowing tears to flow from the ocular surface into the nasolacrimal apparatus. The puncta are connected to the lacrimal canaliculi, which then merge to form the lacrimal sac and ultimately empty into the nasal cavity through the nasolacrimal duct. The location of the puncta is crucial for proper tear drainage and maintenance of ocular health.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not specify the location of the lacrimal puncta.
**Option B:** This option is incorrect as it mentions the lacrimal sac, which is a structure located further downstream in the nasolacrimal apparatus.
**Option C:** This option is incorrect as it mentions the eyelid margin, which is not the correct location for the lacrimal puncta.
**Clinical Pearl / High-Yield Fact**
The lacrimal puncta are often disrupted in conditions such as ectropion, entropion, or trauma, leading to impaired tear drainage and potential ocular complications.
**Correct Answer: D. The medial canthus of the upper and lower eyelids.**