Brain connected to spinal cord

What Connects the Brain to the Spinal Cord?

The spinal cord is perhaps one of the most impressive and important structures in the body. It transmits signals from touch receptors to the brain as well as signals from the brain to other parts of the body to allow movements to be made.

Signals from the brain that are responsible for things such as heart rate, breathing and blood pressure are also transmitted through the spinal cord. The spinal cord also acts as support frame that helps us remain upright.

In layman’s terms, explaining the brain in relation to the spinal cord can be achieved with this effective analogy:

Think of the brain as a postal office, sending and receiving mail from places around the world. On the other hand, the spinal cord is like the mail trucks, which are responsible for carrying the mail to and from the postal office.

The brain is connected to the spinal cord by the brain stem, which consists of three distinct parts: the midbrain, the medulla oblongata, and the pons.

The Central Nervous System

In short, our bodies would not be able to function without a complex network known as the nervous system. This is split into two parts, the central and the peripheral nervous system.

The central nervous system basically comprises of the brain and the spinal cord, both of which are protected by three membranes and cerebrospinal fluid. In addition to this, the brain is covered by the hard bone of the skull and the spinal cord is protected by 33 vertebrae which run down the centre of back.

  • The body has billions of nerves in it with 13.5 million in the spinal cord alone
  • The basic constituent of the nervous system is the neuron which has long cables called axons and short cables called dendrites that are used to transmit messages to and from the brain and spinal cord
  • There are 4 different types of neuron or nerve cell depending on their function: sensory, motor, receptors, and interneurons (which send messages to other neurons)
  • In some cases, the speed of transmission across a nerve can reach as much as 246 mph
  • The brain uses 20% of the energy produced by our bodies and most of this is used in the transmission of signals

The Brain Stem

Brain stem
The brain stem
Credit: OpenStax, 1311 Brain StemCC BY 4.0

The brain and the spinal cord are seen as two separate entities and are connected by an area of the body called the brain stem. This has a number of functions including to control the flow of messages between the brain and the rest of the body. It’s also involved in controlling basic functions that we take for granted such as our blood pressure, swallowing and breathing.

The brainstem is divided into three regions:

  • The midbrain or mesencephalon which helps with important functions relating to motor movement
  • The pons or metencephalon which connects the medulla to the cerebellum
  • The medulla oblongata or myelencephalon which merges with the spinal cord at the base of the skull

The brain stem has some very important neural responsibilities when it comes to the body and even a small amount of damage can have dramatic consequences. For instance, damage to this area can often cause speech impairments as well as mobility and movement coordination problems.

What is the Difference Between the Brainstem and the Spinal Cord?

While both the spinal cord and the brainstem are made up of nerve tissue and are involved in transmitting signals to and from the brain, there are some subtle differences between the two.

  • The main one is that the brain stem is involved in controlling functions such respiration and heartbeat. The spinal cord, apart from its role as an information highway, plays a big role in involuntary movements.
  • The brain stem consists of just three parts while the spinal cord is split into 33 different segments.
  • There is a difference between the way white and grey matter is distributed in each. Grey matter is basically the collection of neuron cell bodies while white matter comprises the long cords that stretch out from the cells. In the brain stem, white matter is on the inside and grey matter on the outside. In the spinal cord, this is reversed.

Summary

Our central nervous system is a biological masterpiece, responsible for so much of what the body is able to do. The brain is the powerhouse that drives everything but the brain stem and the spinal cord are also vital for the full functioning of the body.  

While they share common characteristics, they also have their own set of functions. Any damage to these two areas can have a catastrophic impact on how we process and send signals to other parts of the body.