The brain is considered to be the most complex organ and system of the human body. It averages, according to Neurosurgery Today, 2.7 pounds for women and 3 pounds for men. The brain is the seat of all interpretive sensory experience, thought and intelligence, physiological function, and behavior and emotions. Protected by the bony structure of the skull, it can be divided anatomically into three main sections: the forebrain, midbrain and hindbrain.
Forebrain
The forebrain, the largest region the brain, is the most specialized and contains the cerebrum. The cerebrum, the center of cognitive functions, is further divided into halves or hemispheres.
The left hemisphere is associated with logic, detailed analytical and mathematical information; also, Broca's area for speech is located here. The hypothalamus, another major brain structure, regulates many homeostatic mechanisms. It controls autonomic nervous system functions and is involved in the physiological stress response which includes regulating neural and endocrine hormone secretions. Also, the hypothalamus regulates metabolic processes, body temperature, hunger, thirst and sexual impulse processes. The hippocampus is responsible for memory and spatial awareness, while the thalamus is a relay station for sensory information such as touch, pressure and pain from the spinal cord to the brain.
The right hemisphere is creativity-based with imagination, symbolic and artistic functions as well as spatial perception. Buried deep in the cerebrum is the significant limbic system, also known as the emotional brain, which collectively consists of the thalamus, hypothalamus, amygdala, and hippocampus. The limbic system is responsible for controlling and regulating emotion, and is salient to the survival function by the emotions of anger and fear; also, it is involved in memory storage of powerfully emotional or traumatic events where fear and anger are triggered. It is referred to as the "reward system" in that it produces pleasant sensations for certain behaviors such as eating and sex. Thus, the limbic system plays a major role in addictions.
Midbrain
The midbrain, the upper part of the brain stem, controls many eye, head and trunk movements. Furthermore, it is divided into two main areas known as the tectum and the tegmentum, both of which directly feed into the spinal cord for faster processing of sensory information.
The tectum is involved with visual and auditory reflexes. The tectum is further divided into two parts, the inferior and the superior colliculi. The superior colliculi regulates visual stimuli and eye movement. The inferior colliculi processes data related to auditory sensations and transmits the data to the cerebral cortex. The midbrain also transmits motor impulses from the cortex to the spinal cord.
Hindbrain
The hindbrain is the at the very back of the skull and contains the vital brainstem. The brainstem controls reflex functions such as breathing, heart rate and blood pressure. Also, the pons regulates swallowing, bladder control, respiration and facial expressions. The cerebellum, the second largest area of the brain, is the brain region primarily responsible for integrating information from the senses for coordination of movement and motor activities.
