Difference Between Cranial and Spinal Nerves

The key difference between Cranial and Spinal Nerves is that the cranial nerves originate from the brain and carry nerve impulses to the eyes, mouth, face and other parts of the head region while the spinal nerves originate from the spinal cord and carry nerve impulses to the other parts of the body.

The nervous system of human and other vertebrates are more or less the same and can be categorized into two main categories. They are, Central nervous system and Peripheral nervous system. Furthermore, the nervous system is basically made up of neurons and nerve fibres, which collectively control and regulate body activities by conducting nerve impulse throughout the body. Basically, the brain and the spinal cord make up the central nervous system, while their branches make up the peripheral nervous system. Therefore, depending on the originating place (either brain or spinal cord) of the nerves, peripheral nervous system nerve cells can be classified into two categories namely, cranial nerves and spinal nerves. Along with these two types of nerves that arise from the brain and spinal cord, the central nervous system communicates successfully with the rest of the body parts.

CONTENTS

1. Overview and Key Difference
2. What are Cranial Nerves
3. What are Spinal Nerves
4. Similarities Between Cranial and Spinal Nerves
5. Side by Side Comparison – Cranial vs Spinal Nerves in Tabular Form
6. Summary

What are Cranial Nerves?

The brain is situated inside the cranium. Hence, the nerves originating from the brain are cranial nerves. They mainly associate with the head and neck (with the exception of the vagus nerve) and involve in the transmission of both sensory and motor information to and from the brain to the head, neck and face regions.

There are 12 pairs of cranial nerves, and these pairs have a number and a name where the name may associate with its function. For example, the name of the olfactory nerve is cranial nerve I, and it is responsible for vision. The optic-spinal nerve, which is cranial nerve II, is responsible for vision/eyesight. Except for olfactory, optic, and vestibulocochlear nerves, all other cranial nerves are mixed nerves, where they consist of both sensory and motor fibres. Olfactory, optic, and vestibulocochlear nerves consist only a sensory fibre; hence they pick only the stimuli and bring to the brain.

What are Spinal Nerves?

Nerves that are originating from the spinal cord are spinal nerves. There are 31 pairs of spinal nerves that are named in relation to their location on the spinal cord. All of them are mixed nerves so that each nerve consists of both ventral (motor) and dorsal root (sensory) components. These nerves mainly carry nerve impulse to and from the spinal cord to all parts of the body.

Spinal nerves either go directly to a particular body segment or form a network with adjacent spinal nerves and veins called a plexus. There are four main spinal nerve plexus is present in the body, namely; cervical plexus, brachial plexus, lumber plexus, and sacral plexus.

What are the Similarities Between Cranial and Spinal Nerves?

• Cranial and Spinal Nerves are part of the peripheral nervous system.
• They extend from the central nervous system.
• Also, both consist of sensory as well as motor neurons.
• Furthermore, they exist as pairs.
• And, both transmit nerve impulses.

What is the Difference Between Cranial and Spinal Nerves?

Cranial nerves and spinal nerves are two types of nerves of the peripheral nervous system. The key difference between cranial and spinal nerves is that the cranial nerves come from the brain while the spinal nerves come from the spinal cord. Another difference between cranial and spinal nerves is that there are 12 cranial nerve pairs while there are 31 spinal nerve pairs in mammals. In addition, we can also identify a difference between cranial and spinal nerves based on their functions. That is, the cranial nerves coordiante the activities associated with the head and neck whereas, the spinal nerves coordinate the activities associated with all the body parts, below the neck. The two nerves also differ in the way of numbering and naming.

The below infographic on difference between cranial and spinal nerves shows a detailed side by side comparison of the two nerves.

Summary – Cranial vs Spinal Nerves

Nerve or a neuron is the basic structural and functional unit of the nervous system. Nerves mainly facilitate communication and signal transmission throughout the body. Thus, there are around several billions of nerves in our body. Furthermore, the brain is one of the major parts of the central nervous system that locates inside the cranium. Hence, cranial nerves are the nerves that come from the brain. There are 12 pairs of cranial nerves. Moreover, the spinal code is the second major part of the central nervous system, and the spinal nerves are the nerves that come from the spinal cord. There are 31 pairs of spinal nerves. Both the cranial and spinal nerves collectively make the peripheral nervous system. Hence, this is the difference between cranial and spinal nerves.

Reference:

1.Mandal, Ananya. “What Is the Nervous System?” News-Medical.net, News Medical, 23 Aug. 2018. Available here  
2.“Test Your Cranial Nerves.” Neuroscience For Kids – Brain vs. Computer. Available here 

Image Courtesy:

1.”1320 The Cranial Nerves”By OpenStax (CC BY 4.0) via Commons Wikimedia
2.”Nervous system diagram-en”By Medium69, Jmarchn  (CC BY-SA 4.0) via Commons Wikimedia