Chapter 17 – Anatomical Terminology

Figure 17.1

A side profile of the head and spinal cord (left) and a top-down view of the brain (right) define directional terms. On the head profile, orange arrows show that along the brain’s axis, rostral points toward the face and caudal points toward the back of the head, while dorsal points to the top of the brain and ventral points to the bottom. Blue arrows show that along the spinal cord’s axis, rostral points up toward the brain and caudal points down, while dorsal points toward the back of the body and ventral points toward the front. Black arrows outside the body mark body-wide axes: anterior to posterior (front to back) and superior to inferior (top to bottom). On the top-down brain view, medial points toward the midline and lateral points outward, while rostral/caudal and anterior/posterior both point front-to-back and align with each other. The key distinction: dorsal/ventral and rostral/caudal shift direction between the brain and spinal cord, but superior/inferior, anterior/posterior, and medial/lateral stay consistent throughout the body.

Figure 17.2

Three rows compare anatomical planes, each showing a side-view brain diagram marking the cut (left) and the resulting section (right). Frontal/coronal plane: a vertical line runs top to bottom, medial to lateral; the section shows both hemispheres side by side with ventricles near the center. Sagittal plane: a horizontal line runs the length of the brain, front to back; the section shows a single hemisphere from the side, with the corpus callosum, brainstem, and cerebellum visible. Horizontal plane: a horizontal line in a similar position but representing a cut parallel to the ground; the section shows both hemispheres from above, with ventricles visible near the center.

Figure 17.3

Two body outlines compare the divisions of the nervous system. Left: “Central nervous system: Brain & spinal cord,” with the brain and spinal cord highlighted in blue down the center of the back. Right: “Peripheral nervous system: Cranial & spinal nerves,” with the brain and spinal cord in gray and the cranial and spinal nerves highlighted in orange, branching into the limbs. Flanking arrows show afferent information traveling up toward the brain and efferent information traveling down away from it.

Figure 17.4

A coronal brain section shows the folded cortical surface. One arrow labeled “White matter (axons)” points to the lighter, unfolded region in the center. Two arrows labeled “Gray matter (cell bodies)” point to the outer cortical surface and to a smaller, irregular structure deeper within the white matter, representing a subcortical gray matter region.

Chapter 18 – External Brain Anatomy

Figure 18.1

A side view of the brain shows the cerebrum (blue), bracketed and labeled as the largest structure, covering most of the image with its folded surface. Arrows point to a single gyrus (ridge) and sulcus (groove) on the frontal region. Posterior and inferior to the cerebrum sits the cerebellum (purple, textured). The brainstem (brown) connects the cerebrum to the spinal cord (yellow), extending from the ventral side of the brain below the cerebellum.

Figure 18.2

A side view of the brain shows the frontal lobe highlighted in blue, occupying the most anterior third of the cerebrum. Within it, a darker blue strip marks the precentral gyrus, labeled as the primary motor cortex. One arrow identifies the frontal lobe; a second points to the precentral gyrus specifically.

Figure 18.3

A side view of the brain shows the parietal lobe highlighted in pink, on the top of the brain caudal to the frontal lobe. The central sulcus, marking the boundary between the two lobes, is shown as a dark groove with its own arrow. Within the parietal lobe, a darker pink strip marks the postcentral gyrus, labeled as the primary somatosensory cortex, sitting just caudal to the central sulcus.

Figure 18.4

A side view of the brain shows the temporal lobe highlighted in green along the lower lateral surface. The lateral fissure, marking the boundary between the temporal lobe and the frontal and parietal lobes above it, is identified with an arrow. A second arrow labels the temporal lobe itself.

Figure 18.5

A side view of the brain shows the occipital lobe highlighted in orange, occupying the most posterior portion of the cerebrum, caudal to the parietal and temporal lobes. An arrow labels the occipital lobe.

Figure 18.6

A side view of the brain shows the cerebral cortex unlabeled and uncolored, directing attention to the structures below it. The cerebellum (purple, textured) is labeled posterior and inferior to the cerebrum. The brainstem (brown) sits ventral to the cerebellum and connects to the spinal cord (yellow), each identified with an arrow.

Figure 18.7

A top-down view of the brain shows the left and right cerebral hemispheres bracketed and labeled, separated at the midline by the longitudinal fissure. The frontal lobe (blue) occupies the rostral portion of each hemisphere, the parietal lobe (pink) the middle portion, and the occipital lobe (orange) the caudal portion. The central sulcus is marked at the boundary between the frontal and parietal lobes. Within the frontal lobe, the precentral gyrus is labeled as the primary motor cortex; within the parietal lobe, the postcentral gyrus is labeled as the primary somatosensory cortex, sitting just caudal to the central sulcus.

Figure 18.8

A bottom-up view of the brain shows the frontal lobe (blue) at the rostral end, divided at the midline by the longitudinal fissure. The temporal lobes (green) flank the brainstem on either side. At the center, the pons and medulla (brown) connect the cerebrum to the spinal cord (yellow), which extends caudally. The cerebellum (purple, textured) is visible on either side of the brainstem, caudal to the temporal lobes.

Figure 18.9

A ventral view of the brain highlights midline and brainstem structures against an uncolored cerebral cortex. The olfactory nerve (magenta) runs rostral to caudal along the midline and converges at the optic chiasm, where the two optic tracts cross. Just caudal to the chiasm, the hypothalamus (tan) is labeled, with the mammillary bodies (two small tan protrusions) identified separately just caudal to it. Cranial nerves (orange) emerge laterally from the brainstem, with a bracket identifying the group.

Chapter 19 – Internal Brain Anatomy

Figure 19.1

A midsagittal section of the brain shows all four cerebral lobes: frontal (blue) and parietal (pink), divided by the central sulcus; occipital (orange) at the posterior end; and temporal (dark green) below the lateral fissure, near the brainstem. Wrapping around the corpus callosum (tan, C-shaped) is the cingulate gyrus (maroon), extending through the medial frontal and parietal lobes. Below the cerebrum, the midbrain (bracketed, containing the tegmentum and tectum) sits superior to the pons (brown), which connects to the medulla and then the spinal cord (yellow). The cerebellum (purple, textured) sits posterior to the brainstem.

Figure 19.2

A midsagittal brain section highlights the diencephalon and brainstem against an unlabeled cortex. The lateral ventricle (lavender) and fornix (purple) sit superior to the thalamus (green) and anterior commissure (magenta), which mark the anterior and superior borders of the diencephalon. The hypothalamus (salmon) sits inferior to the thalamus, with the optic chiasm (cyan) at its base and the mammillary body labeled just posterior to it. In the brainstem, the superior and inferior colliculi (blue) sit posterior to the thalamus, and the reticular formation (brown, dashed) runs through the length of the brainstem. The fourth ventricle (gray) lies between the brainstem and cerebellum.

Figure 19.3

A coronal section taken at the level of the amygdala shows the longitudinal fissure dividing the hemispheres at the top, with the corpus callosum arching above the lateral and third ventricles. The lateral sulcus marks the border between the temporal lobe and the lobes above it. The amygdala (orange) sits in the medial temporal lobe on each side, inferior to the lateral ventricle. The basal ganglia are visible as the striatum (caudate and putamen, blue) and globus pallidus (blue), lateral to the ventricles.

Figure 19.4

A coronal section taken at the level of the hippocampus shows the longitudinal fissure dividing the hemispheres at the top, with the corpus callosum arching above the lateral and third ventricles. The lateral sulcus marks the border between the temporal lobe and the lobes above it. The hippocampus (purple) sits in the medial temporal lobe on each side. The basal ganglia are visible in more detail here than in the amygdala-level section: the striatum (caudate and putamen, blue) sits lateral to the thalamus, with the globus pallidus (blue) shown as two adjacent segments. The substantia nigra (purple) and subthalamic nucleus, both labeled with arrows, sit inferior to the thalamus and basal ganglia.

Chapter 20 – Brainstem and Spinal Cord

Figure 20.1

A ventral view of the brainstem and diencephalon shows the thalamus (blue) at the top, flanking the optic chiasm at the midline. Below the thalamus, the hypothalamus (magenta) surrounds the infundibulum (tan) and mammillary body (orange), with the optic tract labeled entering from the thalamus toward the chiasm. The pons (brown, ridged) sits inferior to the diencephalon, followed by the medulla (brown), which narrows and transitions into the spinal cord (yellow) at the bottom. White nerve roots emerge laterally from the pons and medulla.

Figure 20.2

A ventral view of the brainstem shows the twelve cranial nerves color-coded by function, with a key at bottom right: purple for sensory (afferent), yellow for motor (efferent), and blue for mixed (both). The optic nerve (CN II, purple) enters at the top near the thalamus. The oculomotor nerve (CN III, yellow) exits from the midbrain at the midline. The trochlear nerve (CN IV, yellow) exits laterally, also from the midbrain. The trigeminal nerve (CN V, blue) exits from the pons. The abducens (CN VI, yellow), facial (CN VII, mixed colors), and vestibulocochlear (CN VIII, purple) nerves exit at the pons-medulla junction. The glossopharyngeal (CN IX, blue), vagus (CN X, blue), spinal accessory (CN XI, yellow), and hypoglossal (CN XII, yellow) nerves exit from the medulla. The olfactory nerve (CN I) is not shown, as it enters the forebrain rather than the brainstem.

Figure 20.3

A side view of the vertebral column, shown alongside the brain and brainstem at the top, is divided into four color-coded regions with representative spinal cord cross-sections to the right of each. The cervical region (green, C1-C8) is most rostral, followed by the thoracic region (purple, T1-T12), the largest division. The lumbar region (blue, L1-L5) follows, and the sacral region (orange, S1-S5) is most caudal. Each cross-section shows the gray matter (shaded butterfly shape) proportionally larger or smaller depending on the region: the cervical and lumbar cross-sections show larger gray matter, reflecting the greater motor and sensory input/output to the limbs, while the thoracic cross-section shows comparatively less.

Figure 20.4

A cross-section of the spinal cord (salmon) is shown with a key distinguishing central nervous system tissue (salmon) from peripheral nervous system tissue (blue, dashed). The spinal cord itself, including its gray matter (darker salmon, butterfly-shaped) and surrounding white matter, is entirely central nervous system tissue. On each side, a dashed blue line represents the spinal nerve, which splits as it approaches the cord: one branch connects near a small blue dot (representing the dorsal root ganglion) before entering dorsally, and the other enters ventrally, both marking the transition from peripheral to central nervous system tissue at the point where the fibers meet the cord.

Figure 20.5

A cross-section of the spinal cord shows two labeled tissue types. White matter (unshaded) forms the outer region of the cord, with an arrow pointing to it. Gray matter (shaded, butterfly-shaped) occupies the center of the cord, with an arrow labeled “cell bodies & terminals” pointing to it. Outside the cord, the peripheral nerve roots and a small ganglion (shaded circle) are also shown, unlabeled in this figure, illustrating that peripheral fibers are largely axonal (comparable to white matter) except at the ganglion, where cell bodies cluster.

Figure 20.6

A cross-section of the spinal cord labels the subdivisions of white and gray matter. The white matter is divided into three columns: the dorsal column at the top, the ventral column at the bottom, and the lateral column on the side, between them. The gray matter, shaded in the same butterfly shape, is divided into three horns: the dorsal horn projects toward the dorsal column, the ventral horn projects toward the ventral column, and the lateral horn projects toward the lateral column. On the right side of the figure, the dorsal root is labeled entering the dorsal horn, with the dorsal root ganglion (shaded circle) shown along its path. The ventral root is labeled exiting from the ventral horn. Both roots merge to form the spinal nerve.

Figure 20.7

A cross-section of the spinal cord shows the path of afferent and efferent fibers, drawn in red over the gray and white matter outline. On the left, an afferent fiber (labeled “ex: sensory”) enters through the sensory cell body in the dorsal root ganglion, then continues into the dorsal horn, where it synapses onto an interneuron. The interneuron’s short axon crosses toward the ventral horn on the opposite side and synapses onto a motor cell body. On the right, an efferent fiber (labeled “ex: motor”) originates at this motor cell body in the ventral horn and exits via the ventral root. Arrows label the interneurons, the sensory and motor cell bodies, and the afferent and efferent fibers at the points where they enter and exit the cord.