Chapter 2: The Brain and Nervous System
Before diving into the organization of the nervous system and introducing brain structures, we present some important anatomical terms for visualizing and navigating the brain. The brain is a three-dimensional (3-D) structure that can be visualized in two-dimensional (2-D) slices. There are three standard anatomical planes for visualizing the brain: 1) the coronal or frontal plane; 2) the sagittal plane; and 3) the horizontal or axial plane (Figure 1). The coronal or frontal plane is a vertical plane and splits the brain into front and back sections. The sagittal plane is a vertical plane which splits the brain into left and right sections. The horizontal or axial plane is a horizontal plane which splits the brain into upper and lower sections.
Conventional terms describe locations and directions in the brain and are helpful for navigating around the brain. Anterior means toward the front of the brain; Posterior means toward the back of the brain. Rostral means toward the front or the “beak”; Caudal means toward the tail end. Superior means toward the top; Inferior means toward the bottom. Dorsal means toward the top or back (think dorsal fin); and ventral means toward the belly. Medial means toward the middle; and Lateral toward the side. Contralateral means on the opposite (left/right) side; Ipsilateral means on the same side. You’ll hear these terms a lot as you learn about the brain.
- Slices of the human brain © Wikimedia is licensed under a CC BY-NC-SA (Attribution NonCommercial ShareAlike) license