A Detailed Exploration of the Human Brain Part 1: The Cerebrum

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Introduction

Hello All. I am going to be trying something different for the time being. Instead of writing in the format that I normally do (write one blog post about a topic that I find intriguing). I am going to make a multi-post series on a topic that interests me the most: The Human Brain. Over the next few weeks I am going to explore different aspects of the brain such as functionality, memories, diseases involving the brain, and other interesting topics. Today we will explore the different parts of the brain.

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The Various Parts of the Brain

There are 3 main parts of the brain. The brainstem, cerebrum, and cerebellum. In this blog post we will focus primarily on the Cerebrum.

  1. The Cerebrum – The Cerebrum is the largest part of the brain, and consists of the left and right hemispheres. The cerebrum controls “higher functions” such as the interpretation of the senses, as well as emotions and “fine movement”.
  • The Brainstem – The brainstem connects the cerebrum and cerebellum to the spinal cord. Automatic functions such as breathing, and digestion are performed by the brainstem
  • The Cerebellum – The Cerebellum is in charge of muscle movements. It is located underneath the Cerebrum, and also controls balance as well as posture.
The Human Brain

The Cerebrum

As previously mentioned, the Cerebrum consists of a left and right hemisphere. The two hemispheres are connected by Corpus Callosum, a bundle of fibers which transmit messages between the two sides. According to Mayfields Clinic, “In general, the left hemisphere controls speech, comprehension, arithmetic, and writing. The right hemisphere controls creativity, spatial ability, artistic, and musical skills. The left hemisphere is dominant in hand use and language in about 92% of people.” Each hemisphere is comprised of 4 lobes (frontal, occipital, temporal, and parietal)

The following information regarding the lobes, is taken directly from https://mayfieldclinic.com/pe-anatbrain.htm

Frontal lobe

  • Personality, behavior, emotions
  • Judgment, planning, problem solving 
  • Speech: speaking and writing (Broca’s area) 
  • Body movement (motor strip) 
  • Intelligence, concentration, self awareness 

Parietal lobe

  • Interprets language, words 
  • Sense of touch, pain, temperature (sensory strip) 
  • Interprets signals from vision, hearing, motor, sensory and memory
  • Spatial and visual perception 

Occipital lobe

  • Interprets vision (color, light, movement)

Temporal lobe

  • Understanding language (Wernicke’s area) 
  • Memory
  • Hearing 
  • Sequencing and organization

Broca’s area: lies in the left frontal lobe (Fig 3). If this area is damaged, one may have difficulty moving the tongue or facial muscles to produce the sounds of speech. The person can still read and understand spoken language but has difficulty in speaking and writing (i.e. forming letters and words, doesn’t write within lines) – called Broca’s aphasia. 

Wernicke’s area: lies in the left temporal lobe (Fig 3). Damage to this area causes Wernicke’s aphasia. The individual may speak in long sentences that have no meaning, add unnecessary words, and even create new words. They can make speech sounds, however they have difficulty understanding speech and are therefore unaware of their mistakes.

Areas of the brain affected by Alzheimer's and other dementias

Cortex

The Cerebrum’s surface is called the cortex. The brain consists of 86 billion neurons, 16 of which are located in the cortex. Underneath the cortex exist axons. These axons connect various parts of the brain together. The cortex consists of various deep structures.

A chart of Deep Structures is provided by https://mayfieldclinic.com/pe-anatbrain.htm

Hypothalamus: is located in the floor of the third ventricle and is the master control of the autonomic system. It plays a role in controlling behaviors such as hunger, thirst, sleep, and sexual response. It also regulates body temperature, blood pressure, emotions, and secretion of hormones. 

Pituitary gland: lies in a small pocket of bone at the skull base called the sella turcica. The pituitary gland is connected to the hypothalamus of the brain by the pituitary stalk. Known as the “master gland,” it controls other endocrine glands in the body. It secretes hormones that control sexual development, promote bone and muscle growth, and respond to stress. 

Pineal gland: is located behind the third ventricle. It helps regulate the body’s internal clock and circadian rhythms by secreting melatonin. It has some role in sexual development. 

Thalamus: serves as a relay station for almost all information that comes and goes to the cortex. It plays a role in pain sensation, attention, alertness and memory. 

Basal ganglia: includes the caudate, putamen and globus pallidus. These nuclei work with the cerebellum to coordinate fine motions, such as fingertip movements.

Limbic system: is the center of our emotions, learning, and memory. Included in this system are the cingulate gyri, hypothalamus, amygdala (emotional reactions) and hippocampus (memory).

This Post was written by Yash Banga

Sources

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