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Transcript of Brain
The midbrain sits between the fore brain and the hind brain and is approximately 2 cm long. It forms a major part of the brainstem; the name given to the part of the brain which connects the spinal cord and the forebrain. The dorsal surface of the mid brain forms the tectum, meaning 'roof'. The ventral surface is characterised by two large fibre bundles, the cerebral peduncles, containing axons that travel between the cerebral cortex, the brainstem and the spinal cord. The cerebral } peduncles divide the brain into two halves. Each half is further divided into an anterior and posterior part by a band of grey matter, the substantial nigra.
The hindbrain extends from the spinal cord and is composed of the metencephalon and myelencephalon. The metencephalon contains structures such as the pons and cerebellum. These regions assists in maintaining balance and equilibrium, movement coordination, and the conduction of sensory information. The myelencephalon is composed of the medulla oblongata which is responsible for controlling such autonomic functions as breathing, heart rate, and digestion.
In Latin, the word pons literally means bridge. The pons is a portion of the hindbrain that connects the cerebral cortex with the medulla oblongata. It also serves as a communications and coordination center between the two hemispheres of the brain. As a part of the brainstem, the pons helps in the transferring of messages between various parts of the brain and the spinal cord.
function : The pons is involved in several functions of the
- body including:
- Controlling Autonomic Functions
- Relaying Sensory Information Between the Cerebrum
The medulla oblongata is a portion of the hindbrain that
controls autonomic functions such as breathing, digestion,
heart and blood vessel function, swallowing and sneezing.
Motor and sensory neurons from the midbrain and forebrain
travel through the medulla. As a part of the brainstem,
the medulla oblongata helps in the transferring of messages
between various parts of the brain and the spinal cord.
The medulla oblongata is involved in several functions of the body including:
- Control of Autonomic Functions
- Relay of Nerve Signals Between the Brain and Spinal Cord
- Coordination of Body Movements
About the size of a pearl, the hypothalamus directs a multitude of important functions in the body.It is the control center for many autonomic functions of the peripheral nervous system.
Connections with structures of the endocrine and nervous systems
enable the hypothalamus to play a vital role in maintaining homeostasis.
For example, blood vessel connections between the hypothalamus
and pituitary gland allow hypothalamic hormones to control pituitary
hormone secretion. As a limbic system structure, the hypothalamus also influences various emotional responses.
The frontal lobe is located at the front of the brain and is associated with reasoning, motor skills, higher level cognition, and expressive language. At the back of the frontal lobe, near the central sulcus, lies the motor cortex. This area of the brain receives information from various lobes of the brain and utilizes this information to carry out body movements. Damage to the frontal lobe can lead to changes in sexual habits, socialization, and attention as well as increased risk-taking.
The forebrain is the largest part of the brain, most of which is made up of the cerebrum. Other important structures found in the forebrain include the thalamus, the hypothalamus and the limbic system.
Parts of the Human Brain
The thalamus is located in the forebrain superior to the midbrain, near the center of the brain, with nerve fibers projecting out to the cerebral cortex in all directions. The medial surface of the thalamus constitutes the upper part of the lateral wall of the third ventricle, and is connected to the corresponding surface of the opposite
thalamus by a flattened gray band, the interthalamic adhesion.
In Latin, the word cerebellum means little brain. The cerebellum is the area of the hindbrain that controls motor movement coordination, balance, equilibrium and muscle tone. Like the cerebral cortex, the cerebellum is comprised of white matter and a thin, outer layer of densely folded gray matter. The folded outer layer of the cerebellum (cerebellar cortex) has smaller and more compact folds than those of the cerebral cortex. The cerebellum contains hundreds of millions of neurons for processing data. It relays information between body muscles
and areas of the cerebral cortex that are involved in motor control.
The cerebellum is involved in several functions of the body including:
Fine Movement Coordination, Balance and Equilibrium, Muscle Tone
The human brain has the same general structure as the brains of other mammals, but has a more developed cortex than any other. Large animals such as whales and elephants have larger brains in absolute terms, but when measured using the encephalization quotient which compensates for body size, the human brain is almost twice as large as the brain of the bottlenose dolphin, and three times as large as the brain of a chimpanzee. Much of the expansion comes from the part of the brain called the cerebral cortex, especially the frontal lobes, which are associated with executive functions such as self-control, planning, reasoning, and abstract thought. The portion of the cerebral cortex devoted to vision is also greatly enlarged in humans.
: The hypothalamus is involved in several functions of the body including :
1. Autonomic Function Control 2. Endocrine Function Control
3. Homeostasis 4. Motor Function Control
5.Food and Water Intake Regulation 6.Sleep-Wake Cycle Regulation
These structures form important connections between the cerebral cortex and the brainstem and spinal cord to control sensory processes such as vision and movement.
Functions of the mesencephalon include:
- Controlling Responses to Sight - Eye Movement
- Pupil Dilation - Body Movement
Location: Directionally, the medulla oblongata is inferior to the pons and anterior to the cerebellum.
Researchers have demonstrated that right-brain/left-brain theory is a myth, yet its popularity persists. Why? Unfortunately many people are likely unaware that the theory is outdated. Today, students might continue to learn about the theory as a point of historical interest to understand how our ideas about how the brain works have evolved and changed over time as researchers have learned more about how the brain operates.
Why do people still talk about right-brain, left-brain theory?
The parietal lobe is located in the middle section of the brain and is associated with processing tactile sensory information such as pressure, touch, and pain. A portion of the brain known as the somatosensory cortex is located in this lobe and is essential to the processing of the body's senses. Damage to the parietal lobe can result in problems with verbal memory, an impaired ability to control eye gaze and problems with language.
he temporal lobe is located on the bottom section of the brain. This lobe is also the location of the primary auditory cortex, which is important for interpreting sounds and the language we hear. The hippocampus is also located in the temporal lobe, which is why this portion of the brain is also heavily associated with the formation of memories. Damage to the temporal lobe can lead to problems with memory, speech perception, and language skills.
The occipital lobe is located at the back portion of the brain and is associated with interpreting visual stimuli and information. The primary visual cortex, which receives and interprets information from the retinas of the eyes, is located in the occipital lobe. Damage to this lobe can cause visual problems such as difficulty recognizing objects, an inability to identify colors, and trouble recognizing words.
The cerebrum, which develops from the front portion of the forebrain, is the largest part of the mature brain. It consists of two large masses, called cerebral hemispheres, which are almost mirror images of each other. They are connected by a deep bridge of nerve fibers .The surface of the cerebrum is marked by numerous ridges or convolutions which are also separated by grooves. A shallow groove is called a sulcus, and a very deep one is a fissure. A longitudinal fissure separates the right and left hemispheres of the cerebrum, and a transverse fissure separates the cerebrum from the cerebellum. Various sulci divide each hemisphere into lobes. The lobes are named for the skull bones under which they rest and are: (1) the frontal lobe, (2) the parietal lobe, (3) the temporal lobe, (4) the occipital lobe . The cerebrum is concerned with higher brain functions, interpreting sensory impulses and initiating muscle movements. It stores information and uses it to process reasoning. It also functions in determining intelligence and personality.
Controls Auditory and Visual Responses
The tectum is located in the dorsal region of the mesencephalon (mid brain). It consists of the superior colliculi (visual receptors) and inferior colliculi (auditory receptors).
- Controls Motor Functions
-Regulates Awareness and Attention
- Regulates Some Autonomic Functions
The tegmentum is the area within the brainstem that forms the base of the mesencephalon (mid brain). It consists of the cerebral aqueduct, periaqueductal gray, reticular formation, substantia nigra and the red nucleus.
- The cerebral peduncles are the part of the midbrain that link the remainder of the brainstem to the thalami and thereby, the cerebrum. They are the most anterior structure in the midbrain and contain the large ascending and descending tracts that run to and from the cerebrum.
- The peduncles form the walls of the fourth ventricle.
- The substantia nigra is located within the cerebral peduncles and considered
- The structure that separates the cerebral crus from the tegmentum.
The brainstem is the region of the brain that connects the cerebrum with the spinal cord. It consists of the midbrain, medulla oblongata, and the pons. Motor and sensory neurons travel through the brainstem allowing for the relay of signals between the brain and the spinal cord. The brainstem coordinates motor control signals sent from the brain to the body. The brainstem also controls life supporting autonomic functions of the peripheral nervous system.
Directionally, the brainstem is located at
the juncture of the cerebrum and the spinal
column. It is anterior to the cerebellum.
Function: The brainstem controls several important functions
of the body including:
- Alertness - Arousal
-Breathing - Blood Pressure
- Digestion - Heart Rate
- Other Autonomic Functions
- Relays Information Between
the Peripheral Nerves and Spinal Cord
to the Upper Parts of the Brain
By Kanokwan Sophan