Final answer:
The almond-shaped opening between the eyelids is called the palpebral fissure. The orbit houses the eyeball and the muscles that move it and open the eyelid, while the lacrimal gland produces tears to keep the eye moist.
Step-by-step explanation:
The almond-shaped opening between the eyelids is called the palpebral fissure. It is an important structure for vision, as it allows light to enter the eye. Surrounding the eyeball and protecting it is the orbit, which is a bony socket within the skull. The orbit also contains muscles that are responsible for moving the eyeball and opening the upper eyelid. The lacrimal gland, situated above the orbit, secretes tears which flow over the eye, keeping it moist and removing foreign particles. This is a part of the broader lacrimal apparatus which includes the production and drainage of tears through structures like the lacrimal punctum and lacrimal sac.