Difference Between Myotome and Dermatome

The key difference between myotome and dermatome is that dermatome is an area of skin that connects to a single spinal nerve, while myotome is a group of muscles that connect to a single spinal nerve.

The human body consists of 31 spinal nerves. Each spinal nerve carries out mixed functions to coordinate the movement of motor, sensory, and autonomic nerve impulses between the body and the spinal cord. Each spinal nerve originates from the nerve root. These nerve roots serve different regions of the body to coordinate information. Dermatome and myotome are two such regions of the body associated with a single spinal nerve for a specific function.

1. Overview and Key Difference
2. What is a Dermatome
3. What is a Myotome
4. Similarities – Myotome and Dermatome
5. Myotome vs Dermatome in Tabular Form
6. Summary – Myotome vs Dermatome

What is a Dermatome?

A dermatome is a particular area of skin that connects to a single spinal nerve or a single nerve root. The skin consists of many dermatomes, and each dermatome is unique to the type of single spinal nerve. Spinal nerves in the human body occur as pairs with two nerve roots. These two nerve roots are present on the left and right sides as ventral nerve root and dorsal nerve root.

The ventral nerve root is present on the anterior side of the body, while the dorsal nerve root is present on the posterior side of the body. These nerve roots innervate sensory functions through communication with the central nervous system (CNS). There are 31 spinal nerves in the body. Out of the 31 spinal nerves, 08 are cervical nerves, 12 are thoracic nerves, 5 are lumbar nerves, and the last one is a coccygeal nerve. Each spinal nerve consists of a dermatome except for the first cervical nerve (C1).

Figure 01: Dermatome

Dermatomes present in the thorax and abdomen are located as evenly spaced segments stacked on top of each dermatome. The map of dermatome distribution may differ from individual to individual. The clinical relevance of dermatomes is that it is an important aid in the diagnosis of diseases such as lumbar radiculopathy, pains from a visceral organ and Herpes zoster (shingles), and viral infections caused by the varicella-zoster virus.

What is a Myotome?

A myotome is a group of muscles that connect to a single spinal nerve or single nerve root. The human body consists of 31 spinal nerves, and out of that, 16 consists of a specific myotome. These myotomes control voluntary muscle movement. Most limb muscles receive innervation from more than one spinal nerve root and thereby consist of multiple myotomes. In the upper extremity of the body, C5 nerve root associated myotome is involved in shoulder abduction, C6 is involved in elbow flexion and wrist extension, C7 is involved in elbow extension, C8 is involved in thumb extension and wrist ulnar deviation, and T1 is involved in finger abduction.

Dermatome and Myotome - Side by Side Comparison

Figure 02: Myotome

Different types of spinal nerves associated myotomes control muscles in the chest wall, abdomen, and lower extremity of the body. Myotome testing is a common procedure to provide information about the level in the spine where a lesion may be present. It is a form of isometric resisted muscle testing.

What are the Similarities Between Myotome and Dermatome?

Dermatome and myotome are two types of anatomical structures.
They are present in the human body.
Moreover, they are associated with a single spinal nerve.
Both are associated with sensory, motor, and autonomic nerve impulses.
Both dermatome and myotome are important in the diagnosis of different diseases, most commonly spinal lesions.

What is the Difference Between Myotome and Dermatome?

A dermatome is an area of skin that connects to a single spinal nerve, while a myotome is a group of muscles that connect to a single spinal nerve. Thus, this is the key difference between dermatome and myotome. Dermatomes are involved in the coordination of sensory information, while myotome is responsible for the coordination of voluntary muscular movements. Moreover, dermatome is significantly related to a region of skin, while myotome is significantly related to a group of muscles.

The below infographic presents the differences between dermatome and myotome in tabular form for side-by-side comparison.

Summary – Myotome vs Dermatome

The human body has 31 spinal nerves, presenting mixed functions to coordinate the movement of motor, sensory, and autonomic nerve impulses between the body and the spinal cord. Dermatome and myotome are two types of anatomical structures associated with a single spinal nerve. The dermatome is an area of skin that connects to a single spinal nerve, while the myotome is a group of muscles that connect to a single spinal nerve. Dermatomes are involved in the coordination of sensory information, while myotome is responsible for the coordination of voluntary muscular movements. So, this summarizes the difference between myotome and dermatome.