Main Difference – Brainstem vs Spinal Cord
Brain and spinal cord are the two components of the central nervous system that are responsible for generating both sensory and motor functions, encompassing the entire body. The brain can be divided into two main regions as the forebrain and the brainstem. Brainstem connects the spinal cord to the brain. Both brainstem and spinal cord are made up of nerve tissue. The three areas of the brainstem are midbrain, pons, and medulla oblongata. Both brainstem and spinal cord are involved in the transmission of nerve impulses from the body to the brain. The main difference between brain and spinal cord is that brainstem controls respiratory and cardiac functions whereas spinal cord controls the involuntary movements of the body.
Key Areas Covered
1. What is Brainstem
– Definition, Components, Function
2. What is Spinal Cord
– Definition, Structure, Function
3. What are the Similarities Between Brainstem and Spinal Cord
– Outline of Common Features
4. What is the Difference Between Brainstem and Spinal Cord
– Comparison of Key Differences
Key Terms: Brain, Brainstem, Cardiac and Respiratory Functions, Central Nervous System (CNS), Involuntary Movements, Spinal Cord
What is a Brainstem
Brainstem refers to the central trunk of the brain that continues to form the spinal cord. It is a tube-shaped mass made up of billions of nerves. It is located inferior to the cerebrum and superior to the spinal cord. The midbrain, pons, and medulla oblongata are the three main regions of the brainstem. The most-superior and the most complex region of the brainstem is the midbrain. The pons occurs inferior to the midbrain. The most inferior part is the medulla oblongata, and it connects to the spinal cord. The anatomy of the brainstem is shown in figure 1.
Figure 1: Brainstem
As brainstem is a component of the brain, its gray matter can be identified outside while its white matter can be identified inside. The gray matter of the brainstem controls the cardiac and respiratory functions of the body such as breathing, body temperature, blood pressure, heart rate, digestion of food, hunger and taste. The white matter of the brainstem connects the body via the spinal cord.
What is a Spinal Cord
Spinal cord refers to the cylindrical bundle of nerve fibers enclosed by the spine that connects all parts of the body to the brain. It is 40 to 50 cm long and 1 – 1.5 cm in diameter. The spinal cord can be divided into four regions as cervical, thoracic, lumbar, and sacral. The regions of the spinal cord are shown in figure 2.
Figure 2: Regions of Spinal Cord
As the spinal cord is also made up of nerve tissue, it is also composed of gray matter and white matter. However, gray matter occurs inside the spinal cord while white matter occurs outside the spinal cord. Two rows of consecutive nerve root pairs emerge on either side of the spinal cord. Each pair joins distally, forming 31 spinal nerve pairs. These nerves comprise both motor nerves and sensory nerves. Therefore, spinal nerves are referred to mixed nerves. The sensory axons pass through the dorsal root ganglion while the motor axons pass through the ventral roots. The sectional anatomy of the spinal cord is shown in figure 3.
Figure 3: Sectional Anatomy of the Spinal Cord
The spinal cord carries out two major functions. It connects most of the peripheral nerves to the brain. Therefore, the sensory information is transmitted to the brain through the spinal cord. Motor impulses are also transmitted to the effector organs through the spinal cord. The spinal cord is responsible for coordinating simple reflexes that create involuntary muscular movements.
Similarities Between Brainstem and Spinal Cord
- Both brainstem and spinal cord are two components of the central nervous system.
- Both brainstem and spinal cord are made up of nerve tissue.
- Both brainstem and spinal cord transmit nerve impulses to the brain.
Difference Between Brainstem and Spinal Cord
Definition
Brainstem: Brainstem is the central trunk of the brain that continues to form the spinal cord.
Spinal Cord: Spinal cord is the cylindrical bundle of nerve fibers enclosed by the spine that connects all parts of the body to the brain.
Significance
Brainstem: The brainstem is a part of the brain that connects the spinal cord to the brain.
Spinal Cord: The spinal cord runs through the vertebral column.
Components
Brainstem: The brainstem is composed of the midbrain, pons, and medulla oblongata.
Spinal Cord: The spinal cord is composed of 31 spinal nerves.
Gray/White matter
Brainstem: The outermost regions of the brainstem are made up of gray matter while the innermost regions of the brainstem are made up of white matter.
Spinal Cord: The outermost regions of the spinal cord is made up of white matter while the innermost region of the spinal cord is made up of gray matter.
Function
Brainstem: The brainstem controls the respiratory and cardiac functions of the body.
Spinal Cord: Spinal cord controls the involuntary movements of the body.
Conclusion
Brainstem and spinal cord are two components of the central nervous system. Both these structures are made up of nerve tissue. Both brainstem and spinal cord transmit nerve impulses from and to the brain. Moreover, the brainstem controls cardiac and respiratory functions of the body while the spinal cord coordinates simple reflexes. The main difference between brainstem and spinal cord is the role of each component in the coordination of the functions of the body.
Reference:
1. “Brain Stem.” Innerbody, Available here.
2. Anatomy of the Spinal Cord (Section 2, Chapter 3) Neuroscience Online: An Electronic Textbook for the Neurosciences | Department of Neurobiology and Anatomy – The University of Texas Medical School at Houston, Available here.
Image Courtesy:
1. “Diagram showing the brain stem which includes the medulla oblongata, the pons and the midbrain (2) CRUK 294″By Cancer Research UK – Original email from CRUK (CC BY-SA 4.0) via Commons Wikimedia
2. “Diagram of the spinal cord CRUK 046” By Cancer Research UK – Original email from CRUK (CC BY-SA 4.0) via Commons Wikimedia
3. “Spinal Cord Sectional Anatomy” By BruceBlaus – Own work (CC BY-SA 4.0) via Commons Wikimedia
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