The axis of an ox is the second cervical vertebra that shows unique and modified osteological features. You will find the cranial dens and undivided transverse process in the structure of the axis bone of the oxes.
Here, I will share the essential osteological facts of the bovine axis bone with the labeled diagram. After completing this article, you will identify and differentiate the ox axis bone from other animals.
Quick overview of the ox axis: this is the second cervical vertebra bone of the ox neck. It possesses body, arch, and three processes like the other cervical vertebrae, but slightly modified in their confirmatory.
So to get the anatomy of the bovine axis vertebra and identify all its osteological features, let’s continue this article.
What is the axis of the ox?
Quick answer: axis is the modified second cervical vertebra in the vertebral column of an ox. The cranial extremity of the axis body shows exceptional dens, which attach to the fovea dentis of the previous bone (atlas).
“This bone is called axis because the skull and the atlas rotate partially around it.”
If you see the vertebrae from the axial skeleton of an ox, you will find 7 cervical vertebrae in this series. Among these 7 cervical vertebrae, the first two – atlas and axis are highly modified in their structure.
The third, fourth, and fifth cervical vertebra shows the typical features in their bodies, arches, and processes. Again, the sixth and seventh (6th and 7th) cervical vertebrae of the ox show few unique features from other cervical vertebral bones.
Here, I will only focus on the osteological features of axis bone. But, it will be better if you have a basic knowledge of the different features of a typical vertebra.
For that, you may go through the below-mentioned article, where I have already described the typical features of the body, arch, and processes of the vertebra –
This article might help you understand why the ox axis vertebra is anatomically different from the other vertebrae of this series.
Ox axis bone identification
Here, I will show the important and unique osteological features of the ox axis bone with the diagram. Let’s try to identify the below-mentioned facts from the body, arch, and processes of the cow’s axis bone –
- #1. Body, arches, and three processes,
- #2. Dens or odontoid process on the cranial part of the body,
- #3. Convex articular surface on the ventral part of the dens,
- #4. Cranial notches on the pedicles of both aspects,
- #5. Intervertebral foramen behind the pedicle’s notches,
- #6. A caudal articular process with its surfaces,
- #7. Single, small, and undivided transverse processes of the axis bone,
- #8. The large and strong spinous process of the axis bone, and
- #9. The caudal concave articular surface on the axis body,
You will not find any cranial articular process in the structure of the bovine axis bone. All the above-mentioned osteological features from the ox axis vertebra are identified in the provided labeled diagrams.
Unique features of the ox axis vertebra
The axis bone is different than other cervical bones of the neck for the following reasons (key features) –
- Presence of unique dens or odontoid processes,
- Have intervertebral foramen just behind the cranial notches on the pedicle,
- There is no cranial articular process in the axis vertebra,
- Have a small undivided transverse process (but typically, the transverse process of the cervical vertebrae is divided into two parts),
- Possess small transverse foramen compared to other cervical vertebrae, and
- The spinous process of the axis is larger and strong compared to other cervical bones,
I hope you can understand the main differences between the anatomical facts between the axis and the rest of the cervical bones.
Axis of ox anatomy
To describe the axis of ox anatomy, you might cover the following –
- #1. Osteological features of the axis body,
- #2. Features of the arches (pedicle and lamina), and
- #3. Osteological features of the three distinct processes of the axis bone,
Let’s start with the description of the axis body with the diagram.
Body of the cattle axis bone
The body of the cattle axis bone is cylindrical and long but not like the third, fourth, or fifth cervical vertebrae. You know there are two extremities in the body of any vertebrae – cranial and caudal.
The cranial extremity of the axis vertebra shows exceptional osteological features compare to other cervical bones. You will see the short and wide outward projection of the cranial extremity of the axis bone.
There is a ventral spine in the structure of the axis body. This ventral spine is sharp and extends caudally.
What is the odontoid process of the axis of the ox?
The odontoid process is the short and wide outward bony projection of the axis bone on the cranial extremity of the body. It articulates with the fovea dentis or dens of ox atlas bone (first cervical vertebra).
Again, you will see a bony articular convex plate in the ventral part of the odontoid process of the axis bone. This bony articular plate articulates with the ventral arch of the atlas bone.
You may know the details of anatomical facts of ox atlas bone from the below-mentioned article of anatomy learner –
You will not find such unique osteological features in the body of any other cervical vertebrae of the ox. Again, this structure (odontoid process) differs in their conformity in various animals.
At the end of this article, you will find this variation in the structure of the odontoid process of different animals (see Tables 1 and 2).
Arch of the bovine axis bone
You will not find the typical features of the arch (pedicle and lamina) on the structure of the axis vertebra. But, still, you may identify the pedicle and lamina from the arch of the bovine axis vertebra.
The pedicle of the bovine axis vertebra possesses the notches on its cranial and caudal ends. You will find the larger notch on the pedicle on its cranial aspect.
You will find the intervertebral foramen on both sides of the arch just behind the notches. This is another exceptional osteological feature in the second cervical vertebra of an ox.
The lamina of the axis bone is also more exceptional than the typical vertebra. They fuse in the midline of the bone and form the thick spinous process dorsally.
Processes of ox second cervical vertebra
You will find the three distinguishable processes in the structure of the second cervical vertebra of an ox. But, these three processes of the second cervical vertebra are more highly modified than these of the other cervical vertebrae.
The ox second cervical vertebra possesses the followings processes –
- #1. Articular process (only caudal articular process),
- #2. Spinous process (thick and strong), and
- #3. Transverse process (undivided),
Here, you will only see the caudal pairs of articular processes in the structure of ox second cervical vertebra. But, the cranial pair of articular processes are absent in the axis bone.
The caudal pair of articular processes are located at the ventral aspect of the spinous process. They are typical, well-developed, and directed backward.
The unique transverse processes on both sides of the axis vertebra are small. They are undivided and possess small foramen transversarium.
“Undivided transverse process of the axis is another unique osteological feature compared to other cervical vertebrae of the cows.”
The direction of the transverse process of the ox second cervical vertebra is backward.
Finally, the spinous process of the axis vertebra is large and strong. The upper part of the spinous process is rough and inclines forward.
The height and thickness of the spinous process increase caudally.
But, you will find the exceptional osteological feature in the spinous process of horse axis vertebra compared to the cows.
How to differentiate the axis of the horse from the ox?
Quick answer: the appearance of the odontoid process and the spinous process might help you differentiate the horse’s axis from the ox. The odontoid process of the horse axis bone is narrow but longer than the oxes.
Again, the spinous process of the horse axis vertebra is rougher and thickens caudally. The caudal part of the spinous process continues to the caudal articular process by two ridges.
Let’s find the other differentiating points between the horse and cows axis vertebrae from Table 1 –
|Features||Horse Axis||Ox Axis|
|Spinous process||Divided into two parts|
|Transverse foramen||Larger||Smaller compared to a horse|
I hope you will identify and differentiate the horse axis vertebra from the cow.
What are the differences between dog and cow axis vertebrae?
The body of the dog’s axis bone is less developed than the oxes. Again, the odontoid process of the dog axis bone shows unique features to these of horses and cows.
You will find the pointed and rod-shaped unique odontoid process in the structure of the dog axis vertebra. Again, the spinous process of the dog axis vertebra is thin and large compared to the cows.
You will not find the intervertebral foramen behind the cranial notch of the pedicle. The foramen transversarium is smaller in the dog axis vertebra.
Let’s see all these differentiating osteological features between the dog and cows axis vertebrae from Table 2 –
|Features||Dog Axis||Ox Axis|
|Odontoid process||Long rod shape|
|Wide and short|
|Spinous process||Thin and long||Thick and strong|
|Intervertebral foramen||Absent||Present behind notch|
Axis vertebra of ox labeled diagram
Now, you will again see the various osteological features from the axis vertebra of an ox with the labeled diagram. Here, I tried to show you the features of the axis with different views (lateral, cranial, and caudal).
The labeled diagram of the bovine axis vertebra shows the odontoid process, and ventral articular surface. Again, the single strong spinous process, caudal pair of articular process, and undivided transverse process are also identified in the labeled diagram.
Let’s find more labeled diagrams on the bovine or cattle axis and other vertebrae from social media of anatomy learners.
So, the axis of an ox shows some unique osteological features, like the atlas. The short and wide odontoid process and the undivided single transverse process are two of the important osteological features of the bovine axis vertebra.
Again, the cranially directed single and strong spinous and caudal articular processes of the axis differ from those of the horse and dog. Now, you may differentiate the ox axis vertebra from other species at your anatomy learning laboratory.