Corona Radiata
Corona Radiata is a collection of nerve fibers present in the brain that carries messages between the brain cells of the cerebral cortex and the brain stem. Both brain stem and cerebral cortex play a role in motor function and sensation and it is the corona radiata that links both sensory and motor nerve pathways between these structures.
Neuron Structure
A neuron is defined as the functional unit of the body system called the nervous system. It is significant in transmitting signals that include receiving and sending the signals from a portion of the brain. The neurons are considered specialized cells in terms of their structure.
Afferent Neurons
Neurons are electrically excitable cells in the body specialized for receiving and transmitting information. They are referred to as the structural units of the nervous system. The important parts of a neuron include the cell body, dendrites, and axons.
Motor Homunculus
The term homunculus is Latin and is referred to as ‘little man’. In neuroanatomy, the cortical homunculus is either the motor or sensory distribution along the cerebral cortex of the brain. It was discovered by the great scientist ‘Wilder Penfield and Edwin Boldrey in the year 1937. It is a map that corresponds body part to touch sensitivity. The proportion of the sensory cortex to the size of the body region is irregular. For example, a small area is devoted to sensations that are arising from the trunk, and a large cortical area is devoted to the face and lips.
Nervous System
The nervous system is the portion of an animal's body that controls and transmits signals between various parts of the body. The central nervous system (CNS) and the peripheral nervous system (PNS) are the two primary components of the nervous system in vertebrates. The brain and spinal cord are housed in the CNS. The PNS is made up primarily of nerves, which are long fibers that link the CNS to every other part of the body, but it also includes peripheral ganglia, sympathetic and parasympathetic ganglia, and the enteric nervous system, which is a semi-independent part of the nervous system that regulates the gastrointestinal system.
Which of the following is part of the ventricular system associated with the mesencephalon?
a. fourth ventricle
b. third ventricle
c. subarachnoid space
d. cerebral aqueduct
d. lateral ventricle
The ventricular system is a set of fluid-filled interconnected spaces that are filled with cerebrospinal fluid. These altogether form a fluid-filled cavity for the brain. These are four in number. The two which are present in the cerebrum are larger and forms lateral ventricles. The third is present in the diencephalon of the brain and the fourth one is found on the medulla oblongata of the hindbrain. All these four systems are function together to produce CSF and also helps in its circulation.
In the above-mentioned problem, option a is the fourth ventricle, which is an associated ventricular space present at the cerebellum and pons which are embryologically known as metencephalon. Hence, the option is incorrect.
Option b claims that the third ventricle shows an association with mesencephalon but it is not true as the third ventricle is found associated with diencephalon. Hence, option b is also incorrect.
Option c states that subarachnoid is associated with mesencephalon but it is not a direct part of the ventricular system and can not be the answer. It is a space filled with CSF, located between arachnoid space and pia mater.
Option d states that lateral ventricles are associated with mesencephalon but these are the largest ventricles which are associated with telencephalon or forebrain, hence is an incorrect option.
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