Abstract
Neuroanatomy is a specific branch within neuroscience that deals with brain anatomy. Its broad area includes the brain structure, organization, and localization/networks of the nervous system. It also helps in understanding the sensorimotor systems, along with associated function like learning, behavior, vision, attention, language, and so on. In the present chapter, the author comprehensively discussed the brain basic morphology, architecture, and also some functional aspects of the brain. At the end of this chapter, the author included the tool and techniques used in the study of brain anatomy so that student can learn and understand the topic clearly.
TopChapter Outline
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Introduction
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Approaches used to study the brain region
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General organization of the brain
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Cerebrospinal fluid
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Choroid plexuses
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Blood-Brain Barrier
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Ventricles of the brain
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Brain anatomy at tissue level
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Brain anatomy at organ level
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Orientation in neuroanatomy
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Tool
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Conclusion
Learning Objectives
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Describing the approaches and tool to study brain.
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To describe the location of different brain region.
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Discussion about the Blood-Brain Barrier and blood supply system into brain.
Introduction
Brain is bilaterally symmetrical, soft, gelatinous structure weighting around 400 grams in infants and 1250-1450 grams in adults. The females have lesser brain weight than male. However, it does not mean that females are lesser intelligent than male since the relation between brain weight and intelligent is already disproved multiple studies. Brain is surrounded by meninges and then enclosed bya bony structure known as cranium. Brain is formed from five region namely telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalonfrom rostral to caudal region during embryogenesis. However these regions disappearwith development and new structure emerges in the adult brain.
Figure 1. a. Franz Josef Gall (1758-1828) portrait, b. Anphrenology chart
TopApproaches To The Study Of Brain Region
Brain is anatomically divided into multiple areas based on associated function. Hence it is essential to characterize the brain anatomically. Microscopic examination of animal specimens has been the basic foundation in neuroanatomy. Franz Josef Gall, a German neuroanatomist in the early 1800s, was the first person who tried to locate the brain function (Figure 1a). The studies of Gall gave birth of the new discipline called“phrenology”. Gall led down the basic tenets of phrenology: “1) brain is the organ of the mind; 2) The mind is composed of multiple distinct, innate faculties; 3) Because they are distinct, each faculty must have a separate seat or “organ” in the brain; 4). The size of an organ, other things being equal, is a measure of its power; 5). The shape of the brain is determined by the development of the various organs; 6). As the skull takes its shape from the brain, the surface of the skull can be read as an accurate index of psychological aptitudes and tendencies” (Figure 1b, britishlibrary.net). Soon, phrenology transformed itself from “anatomy” to “skull study”. Paul Broca in 1860s, successfully identified the brain region for language (Clower et al., 2001). Then experimentation on animals and humans (patients with focal brain lesions, behavioral studies, post-mortem anatomy, structural imaging, and functional imaging) are used to functionally characterize and ascribe the specific function to the specific brain area. Later, physiological response, tract-tracing, single-unit recordings, behavioral studies, pharmacology, etc. gave the foundation to modern neuroanatomy.
Key Terms in this Chapter
Cerebrospinal Fluid: Cerebrospinal fluid is a clear, colorless body fluid surrounding the hollow space present in brain and spinal cord. It is produced by ependymal cells, a specialized group of cells present in the choroid plexuses of the ventricles. It provides cushion to the brain from shocks, supports the venous sinuses, and also play an important role in the brain homeostasis and metabolism.
Neuroanatomy: Neuroanatomy is the study of brain organization and other functionally segregated structure present in nervous system. In vertebrates, it is divided into central nervous system and peripheral nervous system consisting brain and spinal cord and the nerves projection that connect it to the rest of the body.
Blood Brain Barrier: Blood brain barrier is a protective element with semipermeable architecture formed by extracellular fluid that separates the circulating blood from the brain and extracellular fluid in the central nervous system. Blood brain barrier system allows passage of small molecules including gases such as oxygen and carbon dioxide by passive diffusion; as well also promote the selective transportation of essential nutrients or molecules such as, water, glucose and amino acids, which cannot diffuse due to absence of required polarity.
Cortex: Cortex is a wrinkly structure of tightly packed neuron surrounding the brain. It is responsible for higher thought processes including speech, decision making process, writing, composing sentences, and problem-solving. It is divided into four different lobes namely frontal, parietal, temporal, and occipital lobe. Each lobe is responsible for processing different types of sensory information.
Brain Anatomy: The brain is divided into 3 parts namely cerebrum, brainstem, and cerebellum. Brain stem is placed at lowest position extending from upper cervical spinal cord to diencephalon of the cerebrum. Cerebrum is the largest part of the human brain, and associated with higher order of function such as thought and action. Cerebellum, also known as “little brain”, is divided into two highly folded hemispheres namely anterior and posterior lobe.
Brain: The brain is one of the largest, most vital and complex organs present in human body. It is made from more than 100 billion nerves that forms trillions of connections or projection subsequently called synapses. Synapses pass message from one location to another location via chemical transmission. It is located in the head, close to the sensory organs for senses such as vision.
Cerebrum: Cerebrum or telencephalon is the largest part of the brain. It is divided into approximately two symmetric halves, known as cerebral hemispheres. It controls emotions, thought, speech, hearing, vision, personality, reading, learning, etc.
Ventricle: It is a cerebrospinal fluid filled cavity present at brain parenchyma. The fluid is produced by choroid plexuses, which is located in the ventricles. It consists, two lateral ventricles, a third ventricle, cerebral aqueduct, and the fourth ventricle.