Neural Control and Coordination Test 14

There are a psir of solid club-shapted structures present on the anterior surface of cerebrum known as olfactory lobes. These lobes have an olfactory bulb and olfactory tract for relaying sense of smell to tempora lobes.

In the given figure, structures A and D are brain and spinal cord respectively, and these structures belong to central neural system. Structures 'B' and 'C' are the nerves arising from brain and spinal cord respectively and thus they belong to peripheral neural system.

In each segment of the spinal cord a spinal nerve arises from each side of the cord. Each spinal nerve connects with the cord through two nerve roots. The dorsal nerve root consists of a bundle of sensory axons (carrying afferent information) whose cell bodies are located in the dorsal root ganglion.

Arbor vitae is known as tree of life. Arbor vitae is a branching tree like arrangement of gre and white matter visible in the cross sectional area of cerebellar hemispheres.

Hypothalamus is a part of fore brain. It is the thermoregulatory centre of the brain. It keeps body temperature at roughly 37ºC by means of a complex thermostat system.

Both cerebral hemispheres are of the same size. Both function equally but left hemisphere is considered dominant because in majority of people Wernicke's and Broca's areas are located in the left hemisphere. Also majority of people are right-handed.

Each spinal nerve is a mixed nerve. It arises from the horns of the grey matter of spinal cord by two roots, purely sensory dorsal root and a purely motor ventral root. Therefore, the ventral root is composed of somatic motor and visceral motor fibres.

Broca's area is the motor speech area lying in the frontal lobe of cerebrum. It controls the movement of lips, tongue and larynx (vocal cords) to produce speech.

Corpus callosum is a broad of nervous tissue that connects two cerebral hemispheres. It consists of 300 million fibres and is present only in mammals.

Brain performs a number of activities like it controls the functions of our organs and also provides ualities of mind-learning, reasoning and memory. For all the activitites brain needs a large and constant supply of energy. The brain accounts for 20% of body's consumption of oxygen and 15% of consumption of blood glucose. If brain is deprived of oxygen for just 5 minutes, it becomes permanently damaged. Mental confusion occurs if brain is deprived of glucose.

Medulla oblongata is the posterior most part of the brain. It has respiratory centre to contro respiration and cardiac centre to control cardiac activity.

Sensory information like touch, temperature and pain from trunk and limbs is carried to sensory relay nuclei in thalamus. It is from the thalamus that the third order neuron goes to sensory cortex which is situated in the frontal lobe (fore brain).

The dorsal portion of the midbrain consists of four rounded lobes called quadrigemina.

Meninges are the three connective tissue membranes that enclose the brain and spinal cord. Piamater is the innermost membrane which is thin, delicate and vascular. The next membrane is arachnoid which is thin and webby. Duramater is the outermost membrane which is tough dense and fibrous in nature.

Pons is located in front of the cerebelum below the mid brain and above the medulla oblongata. It consists of nerve fibres that connect the two hemispheres of cerebellum.

Occipital lobes are primary visual areas of the brain. These are situated in the forebrain.

Epithalamus (roof of diencephalon) is thin and not formed of nervous tissue. Its anterior part is vascular and folded to form the anterior choroid plexus.

Hypothalamus is present at the floor of the diencephalon of the fore brain.

Piamater is the innermost membrane of the brain and arachnoid is the middle membrane. The space between arachnoid and piamater is called sub arachnoid space. This space is filled with cerebrospinal fluid.

The mid brain, pons varolli and medulla oblongata (both of which are parts of hind brain) are collectively termed as brain that connects the fore brain and spinal cord.

Corpora quadrigemina are euivalent to optic lobes (Corpora bigemina) of lower animals.

Comprehension of spoken and written words takes place in Wernicke's area located in the left temporal lobe.

Hypothalamus is a part of fore brain that controls the urge for eating and drinking.

Occipital lobe is concerned with decoding and interpretation of visual information, shape and colour. Thus, if occipital lobe is damaged, vision will be lost.

Broca's are a is the motor speech area and Wernicke's area plays role in understanding speech and speaking in coherent sentences.

The outer portion of cerebrum is called the cerebral cortex that makes up the grey matter of the cerebrum. It is 80% of the total brain mass.

Part 'C' is medulla oblongata that controls breathing.

Regulation of gastric secretion is also done by medulla oblongata.

Cerebellar hemispheres are the largest regions of the cerebellum. The cerebellar hemispheres are two divisions of the cerebellum on either side of the vermis. They are functionally subdivided into lateral and medial portions. It is a part of the hindbrain. The arborvitae is the cerebellar white matter, so-called for its branched, tree-like appearance. In resembles like a fern and is present in both cerebellar hemispheres. It brings sensory and motor information to and from the cerebellum.

(A) Medulla oblongata - (i) Involuntary breathing movements
(E) Cerebellum - (ii) Accurate voluntary movements
(D) Cerebral hemispheres - (iii) Seat of memory