Short Notes For Neet Hindbrain

The human brain is divided into three major parts: Forebrain, Midbrain and Hindbrain. It is the control centre of all bodily functions and information processing.

Hindbrain Structure

The Hindbrain, also known as the rhombencephalon, is the lower part of the human brain located near the brain stem.

During embryonic development, the anterior end of the neural tube differentiates into three bulges: hindbrain, midbrain, and forebrain. These bulges differentiate further and develop into the adult brain.

The Hindbrain subdivides into Metencephalon and Myelencephalon. The Metencephalon gives rise to the Cerebellum and Pons, whereas Myelencephalon gives rise to the Medulla.

The hindbrain of an adult comprises the Cerebellum, Pons, and Medulla oblongata.

Human Brain

Pons

The pons is a part of the brain stem located below the midbrain and above the medulla. It consists of neural tracts which interconnect different parts of the brain.

The Pons plays an important role in the transmission of signals from the brain to the medulla and cerebellum, as well as carrying sensory signals to the thalamus. Additionally, it assists in relaying information between the cerebellum and the forebrain.

It carries nuclei for four cranial nerves, namely trigeminal (V), abducens (VI), facial (VII), and vestibulocochlear (VIII).

The brainstem’s network of neurons is responsible for regulating alertness and the sleep-wake cycle.

Cerebellum

The cerebellum is located posterior to the pons and is characterized by its convoluted surface, which provides more surface area for neurons. It is rich in Purkinje fibres and granule cells.

It is an important part of motor control, as it receives sensory signals from the spinal cord and other parts of the brain.

Purkinje fibres play an important role in the coordination, precision, and fine-tuning of motor responses. Additionally, the cerebellum plays a key role in motor learning, with short granule cells being integral to this process.

The cerebellum is responsible for equilibrium, posture and muscle tone. It is also known to store unconscious memories and motor skills like swimming, cycling, etc.

Injury to the cerebellum can lead to uncoordinated muscle movements, making activities that require more precision, such as threading a needle, more difficult to perform.

Medulla

The medulla oblongata is the posterior part of the brain, which continues to the spinal cord. It forms the brain stem along with the midbrain and pons, and its cavity is known as the fourth ventricle, which is connected to the spinal cavity.

The thick wall of the medulla consists of a bundle of axons forming nerve tracts, which connect the spinal cord to various parts of the brain.

The medulla is an important part of the body, as it helps to regulate many life processes, including respiration, blood pressure, heartbeat, and gastric secretions. Additionally, it houses the centers for reflex actions, including vomiting, coughing, and swallowing.

Activities Controlled by the Hindbrain

The main functions regulated by the hindbrain are:

  • Respiration
  • Cardiovascular reflexes
  • Motor activities
  • Sleep-wake cycle, etc.

Pons - It is responsible for controlling the sleep-wake cycle and generating dreams.

The Pneumotaxic Centre, located in the Pons, regulates the transition from Inhalation to Exhalation.

The four cranial nerves (V-VIII) with nuclei in the pons region regulate respiration, involuntary actions, bladder control, hearing, posture, maintaining equilibrium, chewing, swallowing, taste, eye movement, facial expressions, and sensation.

Injury to the pons region may lead to difficulty with walking, touch, swallowing, and other functions.

Cerebellum: It is responsible for the coordination and fine-tuning of motor activity, aiding in the precision of muscle movements, as well as regulating equilibrium, posture, and muscle tone.

It is also known to store implicit memories and motor skills such as swimming, cycling, etc.

Medulla: It controls various autonomic functions such as breathing, digestion, and heart rate.

It regulates respiration. This is done by chemoreceptors, which sense the change in the blood pH.

It regulates cardiovascular reflexes and heartbeat.

It regulates reflexes such as swallowing, vomiting, coughing, etc.

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