Forebrain: From 1 Different Sources
n. the furthest forward division of the *brain, consisting of the *diencephalon and the two cerebral hemispheres.
Part of the forebrain (see BRAIN).... diencephalon
The small section of brain stem – excluding the pons and medulla – linking the hindbrain to the forebrain. (See BRAIN.)... mesencephalon
n. the enlarged and highly developed mass of nervous tissue that forms the upper end of the *central nervous system (see illustration). The average adult human brain weighs about 1400 g (approximately 2% of total body weight) and is continuous below with the spinal cord. It is invested by three connective tissue membranes, the *meninges, and floats in *cerebrospinal fluid within the rigid casing formed by the bones of the skull. The brain is divided into the hindbrain (rhombencephalon), consisting of the *medulla oblongata, *pons, and *cerebellum; the *midbrain (mesencephalon); and the forebrain (prosencephalon), subdivided into the *cerebrum and the *diencephalon (including the *thalamus and *hypothalamus). The brain is usually considered to be the site of the working of the mind, but to what extent the concepts of ‘brain’ and ‘mind’ are interchangeable is a matter of debate and of concern to anyone facing brain surgery. Anatomical name: encephalon.... brain
n. part of the forebrain, consisting of a narrow band of nerve tissue in the roof of the third ventricle (including the region where the choroid plexus is attached) and the *pineal gland. See also brain.... epithalamus
n. the region of the forebrain in the floor of the third ventricle, linked with the thalamus above and the *pituitary gland below (see brain). It contains several important centres controlling body temperature, thirst, hunger, and eating, water balance, and sexual function. It is also closely connected with emotional activity and sleep and functions as a centre for the integration of hormonal and autonomic nervous activity through its control of the pituitary secretions (see neuroendocrine system; pituitary gland). —hypothalamic adj.... hypothalamus
(mesencephalon) n. the small portion of the *brainstem, excluding the pons and the medulla, that joins the hindbrain to the forebrain.... midbrain
n. the forebrain.... prosencephalon
n. the region of the *midbrain below and in front of the *cerebral aqueduct. It contains the nuclei of several cranial nerves, the *reticular formation, and other ascending and descending nerve pathways linking the forebrain and the spinal cord.... tegmentum
n. (pl. thalami) one of two egg-shaped masses of grey matter that lie deep in the cerebral hemispheres in each side of the forebrain. The thalami are relay stations for all the sensory messages that enter the brain, before they are transmitted to the cortex. All sensory pathways, except that for the sense of smell, are linked to nuclei within the thalamus, and it is here that the conscious awareness of messages as sensations – temperature, pain, touch, etc. – probably begins.... thalamus
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