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OBJECTIVES

Objectives

After studying this chapter, the student should be able to:

  • Outline the 5 embryonic vesicles and explain what they give rise to in the human brain.

  • Identify and define the major anatomic components of the forebrain derived from the telencephalon and diencephalon: the cerebral hemispheres, cerebral cortices, cerebral white matter, and subcortical structures.

  • Identify the major sulci and gyri, gray and white matter regions, organization of the cerebral cortex, and types of white matter tracts.

  • Describe the anatomy and explain the functions of the frontal, parietal, occipital, temporal, insular, and limbic lobes.

  • Describe the anatomy and explain the functions of the major forebrain subcortical areas: the amygdala, basal ganglia, thalamus, and hypothalamus.

  • Diagram the connections among the major cortical and subcortical structures.

OVERVIEW OF THE NERVOUS SYSTEM

The mammalian nervous system has 2 major divisions: the central nervous system (CNS) and the peripheral nervous system (PNS). The general structure of the nervous system and its cellular components were provided in Chapter 1. The CNS is composed of the brain and the spinal cord. Protected on the outside by bones and the meninges, the CNS is suspended in and contains cerebrospinal fluid (CSF) and is highly vascularized. Functionally, the CNS receives and processes sensory information from the PNS and special sense organs, integrates and stores that information, and sends instructions to coordinate and control responses, activities, and movements of the body. In addition, the CNS constructs emotion, perception, and cognition. The CNS can be generally divided into the forebrain, the midbrain, and the hindbrain, which form the brainstem and cerebellum, and the spinal cord. Derived from the embryonic telencephalon and diencephalon, the forebrain encompasses the cerebral hemispheres, including the cerebral cortex, cerebral white matter, and structures located within the white matter, including the basal ganglia, limbic system, thalamus, and hypothalamus. In this chapter, key anatomic and functional components of the forebrain are described. In the next chapter (Chapter 4), the anatomy and function of the brainstem, cerebellum, spinal cord, PNS, meninges, ventricular system, and vascular supply are further elaborated.

ANATOMIC REFERENCES & TERMS

For neuroanatomic descriptions, definitions of anatomic reference directions and terms are useful (Figure 3–1). In the human brain, anterior/rostral means toward the front of the brain and face, whereas posterior/caudal means toward the back of the cranial cavity or tail. In the brain, the direction pointing up is dorsal, and the direction pointing down is ventral. Below the midbrain and in the spinal cord, the direction pointing toward the back is dorsal, and the direction pointing toward the chest/stomach is ventral. The invisible line running down the middle of the nervous system is called the midline. Structures closer to the midline are medial; structures further away from the midline are lateral. A structure that is above a specific reference area is called superior, and one that is below is termed ...

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