Difference Between Cervical and Thoracic Vertebrae

Main Difference – Cervical vs Thoracic Vertebrae

The vertebral column or the backbone is a part of the axial skeleton in all vertebrates. In chordates, the notochord is found inside the vertebral column. The vertebral column consists of a segmented series of bones known as vertebrae. The human vertebral column consists of thirty-three vertebrae. The upper twenty four vertebrae are articulated by intervertebral discs. Spinous process, laminae, facets, transverse process, foramina, and the vertical body are the main structural components of typical vertebrae. Based on the region, these vertebrae can be categorized as cervical (C1-C7), thoracic (T1-T12), lumber (L1-L5), sacrum (S1-S5), and coccyx (fused) vertebrae. The main difference between cervical and thoracic vertebrae is that the cervical vertebrae are small whereas thoracic vertebrae are comparatively large.

Key Areas Covered

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

Key Terms: Cervical Vertebrae, Facet, Foramina, Laminae, Spinous Process, Thoracic Vertebrae, Transverse Process, Vertebral Body

What are Cervical Vertebrae

The cervical vertebrae refer to the seven cylindrical bones that provide structure and support for the cervical spine. The seven cervical vertebrae can be found in the neck region of the vertebral column. They are abbreviated from C1 to C7 from top to bottom. The main function of the cervical vertebrae is to protect the brain stem as well as the spinal cord. They also support the skull and allow a wide range of head movement. The position of the cervical vertebrae is shown in figure 1.

Figure 1: Cervical Vertebrae (red)

The C1 vertebra that holds the skull is known as the atlas. It is a ring-shaped vertebra, supporting the skull. The C2 is known as the axis. It consists of a blunt, tooth-like structure known as odontoid, projecting upward into the atlas. The C1 and C2 vertebrae are responsible for the turning and the rotation of the head. The rest of the cervical vertebrae (C3 to C7) are box-shaped. The anatomy of the human cervical vertebrae is shown in figure 2.

Figure 2: A Human Cervical Vertebra

The vertebral body of the cervical vertebrae is thin and surrounded by the vertebral foramen and transverse foramina. The spinal cord and its meninges pass through the neck via the vertebral foramina of the cervical vertebrae. Carotid arteries and jugular veins that supply blood to the brain pass through the transverse foramina. The lateral view of the cervical vertebrae is shown in figure 3.

Figure 3: Cervical Vertebrae – Lateral View

The spinous process and the transverse processes of the cervical vertebrae are small. They serve as connection points to the muscles such as the trapezius and spinalis muscles.

What are Thoracic Vertebrae

The thoracic vertebrae refer to the twelve bones to which the ribs are attached. The first thoracic vertebra occurs just below the last cervical vertebra. The twelve thoracic vertebrae occur in the thoracic region of the body. They are abbreviated from T1 to T12 from top to bottom. In addition to protecting the spinal cord and support, the thoracic vertebrae provide attachment sites for the ribs. Therefore, the thoracic vertebrae are more stable than the cervical and lumber vertebrae. The position of the thoracic vertebrae is shown in figure 4.

Figure 4: Thoracic Vertebrae (red)

The vertebral body of the thoracic vertebrae is heart-shaped. It is broad in both antero-posterior and the transverse directions. The anatomy of the human thoracic vertebrae is shown in figure 5.

Figure 5: A Human Thoracic Vertebra

On either side of the vertebral body of the T1-T10 vertebrae, a single costal and two demi-facets can be observed near the root of the pedicle. The superior facets are known as demi-facets while the inferior facets are known as costal facets. They articulate with the tubercles and the heads of the ribs respectively. The lateral view of the thoracic vertebrae is shown in figure 6.

Figure 6: Thoracic Vertebrae – Lateral View

The spinous process of the thoracic vertebrae is long and slant inferiorly, increasing the protection of the spinal cord. The intervertebral disks joint the adjacent vertebral bodies. This type of cartilaginous joints is known as symphysis. The vertebral arches join each other through the superior and inferior articular processes in a synovial type joint.

Similarities Between Cervical and Thoracic Vertebrae

• Cervical and thoracic vertebrae are two types of upper vertebrae in the vertebral column.
• Both cervical and thoracic vertebrae consist of a vertebral body, foramina, spinous process, transverse process, laminae, and articulate facets.
• In between each of the cervical and thoracic vertebrae, an intervertebral disk is present.
• The main function of both cervical and thoracic vertebrae is to protect the spinal cord.
• Both cervical and thoracic vertebrae provide stiffening for the body.
• Both cervical and thoracic vertebrae provide sites for the attachment of muscles.
• In bipeds, both cervical and thoracic vertebrae transmit body weight in standing and walking.

Difference Between Cervical and Thoracic Vertebrae

Definition

Cervical Vertebrae: The cervical vertebrae are the seven cylindrical bones that provide structure and support to the cervical spine.

Thoracic Vertebrae: The thoracic vertebrae are the twelve bones to which the ribs are attached.

Region

Cervical Vertebrae: Cervical vertebrae is found in the neck, immediately below the skull.

Thoracic Vertebrae: Thoracic vertebrae is found in the middle segment of the vertebral column between the cervical and lumber vertebrae.

Number of Vertebrae

Cervical Vertebrae: There are seven cervical vertebrae (C1-C7) in the vertebral column.

Thoracic Vertebrae: There are twelve thoracic vertebrae (T1-T12) in the vertebral column.

Size

Cervical Vertebrae: The cervical vertebrae are small.

Thoracic Vertebrae: The thoracic vertebrae are comparatively large.

Vertebral Body

Cervical Vertebrae: The vertebral body of the cervical vertebrae is small and oval-shaped.

Thoracic Vertebrae: The vertebral body of the thoracic vertebrae is large and heart-shaped.

Vertebral Foramen

Cervical Vertebrae: The vertebral foramen of the cervical vertebrae is large and triangular.

Thoracic Vertebrae: The vertebral foramen of the thoracic vertebrae is comparatively small and circular.

Other Foramina

Cervical Vertebrae: The cervical vertebrae consist of two transverse foramina.

Thoracic Vertebrae: The thoracic vertebrae do not contain other foramina.

Laminae

Cervical Vertebrae: The upper surface of the lamina of the cervical vertebrae is narrow and thin. The lower surface of it is large and triangular.

Thoracic Vertebrae: The lamina of the thoracic vertebrae is thick, broad, and imbricated.

Spinous Processes

Cervical Vertebrae: The spinous process of the cervical vertebrae is slender and bifid (C2-C6).

Thoracic Vertebrae: The spinous process of the thoracic vertebrae is long, fairly thick and most inferiorly-projected.

Transverse Processes

Cervical Vertebrae: The transverse processes of the cervical vertebrae are small.

Thoracic Vertebrae: The transverse processes of the thoracic vertebrae are large and blunt.

Direction of the Superior Articulate Facets

Cervical Vertebrae: The superior articulate facet of the cervical vertebrae is posterosuperior.

Thoracic Vertebrae: The superior articular facet of the thoracic vertebrae is posterolateral.

Direction of the Inferior Articulate Facets

Cervical Vertebrae: The inferior articulate facet of the cervical vertebrae is anteroinferior.

Thoracic Vertebrae: The inferior articulate facet of the thoracic vertebrae is anteromedial.

Size of the Intervertebral Disk

Cervical Vertebrae: The intervertebral disk is thick relative to the size of the vertebral bodies.

Thoracic Vertebrae: The intervertebral disk is thin relative to the size of the vertebral bodies.

Conclusion

Cervical and thoracic vertebrae are two types of vertebrae of the upper vertebral column. The cervical vertebrae occur in the neck region while the thoracic vertebrae occur in the thoracic region of the body. The main function of both cervical and thoracic vertebrae is to protect the spinal cord. The main difference between cervical and thoracic vertebrae is their location and role.  

Reference:

1. “Cervical Vertebrae – Anatomy Pictures and Information.” Innerbody, Available here.
2. “The Thoracic Spine.” TeachMeAnatomy, 22 Dec. 2017,  Available here.

Image Courtesy:

1. “Cervical vertebrae animation small” By Anatomography – en:Anatomography (CC BY-SA 2.1 jp) via Commons Wikimedia
2. “Gray84” By Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body (See “Book” section below)Bartleby.com: Gray’s Anatomy, Plate 84, Public Domain) via Commons Wikimedia
3. “Gray82” By Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body, Bartleby.com: Gray’s Anatomy, Plate 82 (Public Domain) via Commons Wikimedia
4. “Gray90” By Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body, Bartleby.com: Gray’s Anatomy, Plate 90 (Public Domain) via Commons Wikimedia
5. “Thoracic vertebrae back4” By Anatomography – en:Anatomography  (CC BY-SA 2.1 jp) via Commons Wikimedia
6. “Gray85” By Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body, Bartleby.com: Gray’s Anatomy, Plate 85 (Public Domain)  via Commons Wikimedia