Chapter 3. Cranial nerves
cranial nerves origin, components, and functions
Figure 3.1 is a schematic dorsal view of the brainstem, in which the motor and parasympathetic cranial nerve nuclei are shown on the right and the somatosensory and special sensory nuclei are shown on the left. Lateral views showing the anatomical relations of the motor and parasympathetic nuclei, and of the somatosensory and special sensory nuclei, are found in figures 3.2 and 3.3, respectively.
The origin, components, and function ofthe individual cranial nerves are listed in table 3.1. Figure 3.4 provides a synoptic view of the sites of emergence of all 12 cranial nerves from the brainstem, their functional components, and their peripheral sites of origin and termination. All 12 cranial nerves are seen in the figure, from I (olfactory nerve) to XII (hypoglossal nerve); it should be borne in mind, however, that the second cranial "nerve" - the optic nerve - is actually not a peripheral nerve at all, but rather a tract of the central nervous system.
Recall that spinal nerve fibers can be classified as somatic afferent, somatic efferent, vegetative afferent, and vegetative efferent.
The classification of cranial nerve fibers is a little more complicated, for two reasons. Some of the cranial nerve fibers are special sensory fibers arising from the sense organs of the head (vision, hearing, taste, smell). Furthermore, some of the efferent cranial nerve fibers arise in nuclear areas that are embryologically derived from the branchial arches; these fibers innervate muscles of branchial origin.
Глава 3. Черепные нервы
происхождение, строение и функции
На рис. 3.1 схематично изображен ствол головного мозга, в котором двигательные и парасимпатические ядра черепных нервов показаны на правой, а соматосенсорные и специальные сенсорные ядра - на левой стороне. Вид сбоку показывает анатомическое соотношение двигательных и парасимпатических ядер, а также соматосенсорных и специальных сенсорных ядер (представлены на рис. 3.2 и 3.3 соответственно).