What is the Difference Between Spinal Cord and Vertebrae

The main difference between spinal cord and vertebrae is that spinal cord is one of the two components of the central nervous system, extending from the brainstem to the lumber region whereas vertebrae are the individual components of the vertebral column, enclosing the spinal cord. Furthermore, the spinal cord is made up of nervous tissue while vertebrae are made up of bone and some hyaline cartilage.

Spinal cord and vertebrae are two structures that especially occur in vertebrates. Both occur in the dorsal region of the body.

Key Areas Covered

1. What is Spinal Cord
     – Definition, Anatomy, Role
2. What are Vertebrae
     – Definition, Anatomy, Role
3. What are the Similarities Between Spinal Cord and Vertebrae
     – Outline of common Features
4. What is the Difference Between Spinal Cord and Vertebrae
     – Comparison of Key Differences

Key Terms

Brainstem, Central Nervous System, Hyaline Cartilage, Spinal Cord, Vertebrae, Vertebral Column

What is Spinal Cord

The spinal cord is a long, thin, tubular structure that occurs inside the vertebral column or the spine. It starts at the medulla oblongata in the brainstem and extends to the level of the first or second lumbar vertebrae. Generally, it is 40 to 50 cm long and its diameter reduces with the length. The spinal cord connects the body to the brain. Usually, the brain sends motor messages through the spinal cord to the limbs in order to control movements. Moreover, it contains many reflex arcs, which can control reflexes independently from the brain, resulting in unconscious muscular movements.

Figure 1: Spinal Cord – Sectional Anatomy

Furthermore, the spinal cord is made up of both grey matter and white matter.  Additionally, the three regions of the spinal cord are the cervical, thoracic, and lumbar region. On each side of the spinal cord, two consecutive nerve roots of spinal nerves emerge. 31 pair of spinal nerves arise from the spinal cord. They include eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves.

What are Vertebrae

Vertebrae are the series of individual bony structures that form the vertebral column. Each vertebra in the column is separated by an intervertebral disk, which forms a fibrocartilaginous joint, allowing slight movement of vertebrae, acting as a ligament to hold the vertebrae together, and functioning as a shock absorber for the spine. Generally, 33 vertebrae incorporate to form the vertebral column. They include 24 presacral vertebrae (7 cervical, 12 thoracic, and 5 lumbar) followed by the sacrum (5 fused sacral vertebrae) and the coccyx (4 frequently fused coccygeal vertebrae).

Figure 2: Vertebrae – Anatomy

Although the size, shape, and the function of different types of vertebrae differ with the region, all follow a similar structural pattern. That means a typical vertebra will consist of a body, a vertebral arch, and seven processes. The main function of the body of the vertebra is to support the body weight of animals with upright posture. Furthermore, the size of the body of vertebrae increases while going down the vertebral column. On the other hand, the vertebral arch, which forms the posterior portion of the vertebra consists of four parts: the right and left pedicles and the right and left laminae. The vertebral foramen is the large opening of the vertebra through which the spinal cord runs.

Moreover, seven processes arise from the vertebral arch including a pair of transverse processes, a spinous process, and paired superior and inferior articular processes. Importantly, they are vital in the articulation of the vertebrae and attachment of muscles.

Similarities Between Spinal Cord and Vertebrae

• Spinal cord and vertebrae are two anatomical structures found in vertebrates.
• They occur in the dorsal region of the body.
• Moreover, they run from the brain to the back of the body.
• Also, both help in controlling the involuntary movements of the body.

Difference Between Spinal Cord and Vertebrae

Definition

Spinal cord refers to the cylindrical bundle of nerve fibers and associated tissue enclosed in the spine and connects nearly all parts of the body to the brain, with which it forms the central nervous system. Vertebrae refer to each of the series of small bones forming the backbone, having several projections for articulation and muscle attachment, and a hole through which the spinal cord passes.

Significance

Thus, the main difference between spinal cord and vertebrae is that spinal cord is one of the two components of the central nervous system while a series of vertebrae form the vertebral column.

Made up of

Additionally, the spinal cord is made up of nervous tissue while vertebrae are mainly made up of bones.

Function

Moreover, the spinal cord controls the involuntary muscular movements of the body while vertebrae enclose the spinal cord provide protection and sites for arising the spinal nerves. Thus, this is the functional difference between spinal cord and vertebrae.

Conclusion

The spinal cord is one of the two components of the central nervous system of vertebras while the second component is the brain. It is made up of nerve tissue and is responsible for controlling involuntary muscular movements of the body. On the other hand, vertebrae are the series of individual bony structures, forming the vertebral column or the spine. Here, the spine encloses the spinal cord, providing protection. Furthermore, spinal nerves arise from the vertebral column. Both the spinal cord and vertebral column are two characteristic features of a vertebrate. Thus, the main difference between spinal cord and vertebrae is their structure and function.

Reference:

1. Dafny, Nachum. “Chapter 3: Anatomy of the Spinal Cord.” Neuroscience Online, McGovern Medical School at UTHealth, Available Here.
2. “45 7.3 The Vertebral Column.” Anatomy and Physiology, OpenStax, 6 Mar. 2013, Available Here.

Image Courtesy:

1. “Spinal Cord Sectional Anatomy” By BruceBlaus – Own work (CC BY-SA 4.0) via Commons Wikimedia  
2. “718 Vertebra” By OpenStax College – Anatomy & Physiology, Connexions Web site.  Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia