CHAPTER 1
Neuro-Ophthalmic Anatomy
Medical practice in general—and surgical subspecialties in particular—are exercises in applied anatomy. Although an adequate understanding of physiology and, increasingly, molecular genetics is important in understanding disease and potential treatments, anatomy is the foundation. Important anatomical topics for the ophthalmologist include the anatomy of the globe (both the anterior and posterior segments), the orbit and adnexal structures, and the afferent and efferent visual pathways with their intracranial projections. The anatomy of the globe and adnexal structures is covered in more detail in BCSC Section 2, Fundamentals and Principles of Ophthalmology; Section 7, Orbit, Eyelids, and Lacrimal System; and Section 8, External Disease and Cornea. The material in this book is not intended to substitute for detailed anatomy texts; rather, it focuses on tracing the important anatomical connections that underlie visual function. Accordingly, this chapter outlines the intracranial pathways subserving the afferent and efferent visual pathways. It also briefly discusses the sensory and motor anatomy of the face and the autonomic nervous system as applied to the eye and visual system.
Bony Anatomy
Skull Base
The skull base has an intimate relationship with visually essential structures (Fig 1-1). The skull base is connected to the lower facial skeleton by 3 sets of pillars formed by the maxillary and zygomatic bones anteriorly and the pterygoid process of the sphenoid bone posteriorly. Superiorly, the vault of the skull is made up of the parietal bones, which meet at the sagittal suture; the frontal bone, which adjoins them at the coronal suture; as well as the occipital bone, which meets the parietal bones at the lambdoid suture.
Figure 1-1 Bony anatomy of the skull base. A, General view of the skull base. The cavernous sinuses are located on each side of the sella turcica. Several important openings within the skull base are the cribriform plate (transmits branches of the olfactory nerve, CN I); optic canal (transmits the optic nerve, CN II); foramen ovale (transmits the mandibular division [V3] of the trigeminal nerve, CN V); foramen rotundum (transmits the maxillary division [V2] of CN V); superior orbital
fissure (transmits the oculomotor, CN III; trochlear, CN IV; abducens, CN VI; and CN V [ophthalmic division, V1]); and the foramen spinosum (transmits the middle meningeal artery, a branch of the external carotid artery). B, View of the parasellar bony anatomy demonstrates the relationship of the pituitary fossa to the cavernous sinus, including the foramina of the skull base. The foramen lacerum is filled with cartilage and contains the artery of pterygoid canal, nerve of pterygoid canal, and venous drainage structures. The carotid artery enters the skull base through the carotid canal.
(Courtesy of Alb ert L. Rhoton, Jr, MD.)
The sella turcica, located posteriorly and medially to the 2 orbits, is a skull-based depression within the body of the sphenoid bone. The lesser wing of the sphenoid bone is pierced by the optic
canal, which allows the optic nerves to exit from the orbit. The superior orbital fissure, which transmits the ocular motor nerves (cranial nerves [CNs] III, IV, and VI), the first division of the sensory trigeminal nerve (CN V1), the sympathetic fibers, and the superior ophthalmic vein (Fig 1-2), represents the gap between the lesser and greater wings of the sphenoid bone. The parasellar region is connected laterally to the petrous and temporal bones and inferiorly to the clivus, extending to the foramen magnum and the exit of the spinal cord. The posterior skull base is enclosed by the occipital bones.
