Bony Orbit and Soft Tissues
Seven bones form the boundaries of the orbit (see Figs 1-1 through 1-3 in BCSC Section 7, Oculofacial Plastic and Orbital Surgery). They are the ethmoid, frontal, lacrimal, maxillary, palatine, sphenoid, and zygomatic bones.
The orbital cavity contains the globe, lacrimal gland, muscles, tendons, fat, fasciae, vessels, nerves, ciliary ganglion, and cartilaginous trochlea. Inflammatory and neoplastic processes that increase the volume of the orbital contents lead to proptosis (protrusion) of the globe and/or displacement (dystopia) from the horizontal or vertical position. The degree and direction of ocular displacement help localize the position of the mass.
The lacrimal gland is situated anteriorly in the superotemporal quadrant of the orbit. The gland is divided into orbital and palpebral lobes by the lateral portion of the aponeurosis of the levator palpebrae superioris muscle. The lacrimal gland is an eccrine gland, and the acini are round and composed of cuboidal epithelium. The nucleus is located toward the outer edge of the acinus. The ducts, which lie within the fibrovascular stroma, are lined by 2 layers: an inner, low cuboidal epithelium and an outer layer of low, flat myoepithelial cells. The histologic appearance of the lacrimal gland is very similar to that of the salivary glands. See BCSC Section 2, Fundamentals and Principles of Ophthalmology, and Section 7, Oculofacial Plastic and Orbital Surgery, for additional discussion.
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.