Mammalian Brain
(Anatomical study For Classes 10 and 12 CBSE)
The mammalian brain is the most evolved of all is subdivided into three basic regions. (i) Forebrain (ii) Midbrain and (iii) Hind Brain
* Forebrain
This region contains the telencephelon and diencephelon.
* A variety of functions are centered here . Among these are conscious , thoughts , emotions , control of many basic body functions and control of endocrine systems.
* Telencephelon
* This is the forward most region of the vertebrate brain.It can be explained broadly as (i) cerebral hemisphere and (ii) olfactory lobes.
(i) Cerebral Hemispheres
* The two cerebral hemispheres can be seen in telencephelon, separated by a deep longitudinal Median Fissure.
* They are so large in mammals that they overlap the diencephelon and midbrain and almost touch the cerebellum behind. They form nearly 2/3 of the entire brain.
* A shallow lateral ,somewhat oblique Sylvian Fissure divides each hemisphere into larger frontal lobe and smaller posterolateral temporal lobe.
* Ventrally, longitudnal Rhinal Fissure demarcates the olfactory tract, while another longitudnal Hippocampal Sulcus or fissure demarcates the hippocampal lobe.
* Connecting the two hemispheres internally is a broad transverse band of nerve tissue, the Corpus Callosum, which is characteristics of Placental mammals.
* Inner cavity of each hemisphere is called II Ventricle or Lateral Ventricle or Paracoel. The two paracoels are connected with each other and with the diacoel through a a passage called the foramen of Monro.
* The roof of Paracoels are formed by the Corpus Callosum, while the lateral walls and floor by Corpus Striatum.
Functions
* The cerebral hemispheres are the seat of highly complicated activities such as thought, reasoning,memory , intelligence etc. they are not well developed in lower vertebrates having low faculties.
(ii) Olfactory lobes
* The sense of smell is controlled by the olfactory lobes.
* The narrow cavity of each olfactory lobe is called the
I Ventricle or Rhinocoel. It opens posterioly into the cerebral hemisphere of its side.
Diancephelon
* The small and depressed diancephelon lies covered below the backward extension of cerebral hemispheres. Its narrow internal cavity is known as the III Venticle or diacoel. The roof of diacoel is epithalamus, floor is hypothalamus and the lateral thickened walls are optic thalami.
* Dorsally, from roof of diancephelon, arises a slender pineal stalk carrying a small rounded pineal body, which is an endocrine gland.
* Ventrally , the floor of diancephelon (hyphothalamus) projects into a median rounded infundibulum. Its lower end carries an oval Ratheke's pouch or hypophysis, behind which attached a small rounded body , the Corpus Albicans.
* Infundibulum and hypophysis together constitute the pituitary body. Just in front of the infundibulum lies the crossing of the two optic nerves, called optic chiasma.
* Functions of Hypothalamus
- it provides anatomical connection between the nervous system and endocrine system by its relationship to the pituitary gland.
- It acts as a thermo regulatory center.
- It controls growth, sexual behavioral other behavioral activities.
- Appetite, thirst and satiety centers are located in the hypothalamus.
- It also influences respiration and heart beat.
(To Be Continued....Midbrain and Hind brain in detail)
(Anatomical study For Classes 10 and 12 CBSE)
The mammalian brain is the most evolved of all is subdivided into three basic regions. (i) Forebrain (ii) Midbrain and (iii) Hind Brain
* Forebrain
This region contains the telencephelon and diencephelon.
* A variety of functions are centered here . Among these are conscious , thoughts , emotions , control of many basic body functions and control of endocrine systems.
* Telencephelon
* This is the forward most region of the vertebrate brain.It can be explained broadly as (i) cerebral hemisphere and (ii) olfactory lobes.
(i) Cerebral Hemispheres
* The two cerebral hemispheres can be seen in telencephelon, separated by a deep longitudinal Median Fissure.
* They are so large in mammals that they overlap the diencephelon and midbrain and almost touch the cerebellum behind. They form nearly 2/3 of the entire brain.
* A shallow lateral ,somewhat oblique Sylvian Fissure divides each hemisphere into larger frontal lobe and smaller posterolateral temporal lobe.
* Ventrally, longitudnal Rhinal Fissure demarcates the olfactory tract, while another longitudnal Hippocampal Sulcus or fissure demarcates the hippocampal lobe.
* Connecting the two hemispheres internally is a broad transverse band of nerve tissue, the Corpus Callosum, which is characteristics of Placental mammals.
* Inner cavity of each hemisphere is called II Ventricle or Lateral Ventricle or Paracoel. The two paracoels are connected with each other and with the diacoel through a a passage called the foramen of Monro.
* The roof of Paracoels are formed by the Corpus Callosum, while the lateral walls and floor by Corpus Striatum.
Functions
* The cerebral hemispheres are the seat of highly complicated activities such as thought, reasoning,memory , intelligence etc. they are not well developed in lower vertebrates having low faculties.
(ii) Olfactory lobes
* The sense of smell is controlled by the olfactory lobes.
* The narrow cavity of each olfactory lobe is called the
I Ventricle or Rhinocoel. It opens posterioly into the cerebral hemisphere of its side.
Diancephelon
* The small and depressed diancephelon lies covered below the backward extension of cerebral hemispheres. Its narrow internal cavity is known as the III Venticle or diacoel. The roof of diacoel is epithalamus, floor is hypothalamus and the lateral thickened walls are optic thalami.
* Dorsally, from roof of diancephelon, arises a slender pineal stalk carrying a small rounded pineal body, which is an endocrine gland.
* Ventrally , the floor of diancephelon (hyphothalamus) projects into a median rounded infundibulum. Its lower end carries an oval Ratheke's pouch or hypophysis, behind which attached a small rounded body , the Corpus Albicans.
* Infundibulum and hypophysis together constitute the pituitary body. Just in front of the infundibulum lies the crossing of the two optic nerves, called optic chiasma.
* Functions of Hypothalamus
- it provides anatomical connection between the nervous system and endocrine system by its relationship to the pituitary gland.
- It acts as a thermo regulatory center.
- It controls growth, sexual behavioral other behavioral activities.
- Appetite, thirst and satiety centers are located in the hypothalamus.
- It also influences respiration and heart beat.
(To Be Continued....Midbrain and Hind brain in detail)
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