Visual Accessory Organs

Each eye, lacrimal gland, and associated extrinsic muscles are housed within the pear-shaped orbital cavity of the skull. The orbit, which is lined with the periosteums of various bones, also contains fat, blood vessels, nerves, and connective tissues.

Each eyelid (palpebra) is composed of four layers— skin, muscle, connective tissue, and conjunctiva. The skin of the eyelid, which is the thinnest skin of the body, covers the lid's outer surface and fuses with its inner lining near the margin of the lid (fig. 12.23).

The muscles that move the eyelids include the orbicularis oculi and the levator palpebrae superioris. Fibers of the orbicularis oculi encircle the opening between the lids and spread out onto the cheek and forehead. This muscle acts as a sphincter that closes the lids when it contracts.

Blood VeselsPictures Accessory Organs The Eye
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  • John
    What are the visual accessory organs?
    6 years ago
  • Angela
    Where are the visual accessory organs housed?
    5 years ago

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