Veterinary Anatomy Guide » Cow patella bone

The cow patella is a large sesamoid type of bone in its skeleton. In this guide, I will discuss the detail osteological features of a cow patella bone with diagrams.

Quick answer: the cow patella is a large sesamoid bone applied against the trochlea of the femur that presents 2 surfaces, 2 borders, a base, and an apex.

I will show the key identifying features of the cow’s patella bone with diagrams. Thus, you may easily identify it from the anatomy laboratory samples.

Here, I will also discuss the variation of the patella bones in different species, especially the horse, dog, pig, and others, compared to the cows.

Table of Contents

Cow patella bone

Among different types of bones in the cow skeleton, the patella is considered the largest sesamoid. Actually, the cow’s proximal and distal sesamoids/ navicular bones are the small, seed-like bones that develop within the tendons.

But the cow patella is larger than those of the proximal and distal sesamoids. However, this bone also has all the properties of a typical sesamoid bone.

Figure 1 shows the cow’s larger sesamoid (patella) and proximal and distal sesamoid bones from its hindlimb.

Proximal and distal sesamoid bones in the cow’s hindlimb

Location and shape of the cow patella

The cow patella bone is located in front of the trochlea of the femur bone. It is an irregularly triangular bone that forms the stifle joint with the femur proximally and the tibia distally.

Here, Figure 2 shows the location of the cow’s patella between the thigh and leg segments of the hindlimb bones. It also shows the irregular triangular shape of the cow’s patella.

Cow patella bone anatomy – description

The cow’s patella presents two surfaces, two borders, a base, and an apex for description –

Surfaces: cranial (rough and convex), and caudal (smooth and concave).
Borders: lateral (convex) and medial (concave).
Base: faces upward (actually, it is the dorsal border of the patella).
Apex: narrow and pointed (actually, it is the ventral angle of the patella).

Here, Figure 3 shows the surfaces, borders, base, and apex of the cow’s patella bone.

Surfaces, borders, base, and apex of the cow patella bone

Now, I will discuss the osteological features of the surfaces, borders, base, and apex of the cow’s patella separately.

Surfaces of the cow’s patella

How will you differentiate the cranial surface of the cow’s patella from the caudal surface? Well, let’s get back to the osteological features of the distal extremity of the cow femur bone.

Here, Figure 4 shows the cranial part of the distal extremity of the femur bone, which presents a trochlea. The trochlea has a concave area with two ridges that host the patella bone.

The trochlea of a cow femur shows middle concave areas with two ridges

Thus, the surface that articulates with the trochlea of the femur must have the reverse osteological features. That means, this surface must have the middle vertical ridge with lateral and medial concave areas.

So, the surface that articulates with the trochlea is the caudal surface.

Now, let’s list the features from the caudal and cranial surfaces of the cow’s patella bone.

Caudal surface of the cow patella

Another name: the caudal surface is also known as the articular surface.
Shape and size: it is small and triangular in outline.
Vertical ridge: it is rounded and divides the caudal surface into two, lateral and medial concave areas.
Medial concave area: this area is larger and not very well adapted to the medial ridge of the trochlea.

These lateral and medial concave areas are applied against the lateral and medial ridges of the trochlea of the cow’s femur. Thus, they create a pulley-like arrangement for the upward and downward sliding of the cow’s patella bone.

Cranial surface of the cow’s patella

Another name: the cranial surface of the cow’s patella is also known as the free surface.
Appearance: It is convex and rough for the attachment of the muscles and ligaments.

The extensor of the cow’s leg passes over this cranial surface, which provides leverage for these muscles. You will also find the attachment of the patellar’s three straight ligaments on the cranial surface.

Here, Figure 5 shows the caudal and cranial surfaces of the cow’s patella. It also shows the attachment of the patellar straight ligament on the cranial surface of the cow’s patella.

Borders of the cow patella bone

Some authors identified three borders (Ghosh, 2000), whereas some authors identified two distinct borders (Getty, 1970) in the cow patella bone. The borders of the cow’s patella are –

Lateral border: convex.
Medial border: concave.
Dorsal border: it is known as the base of the cow’s patella bone.

Here, the lateral and medial borders converge distally and form the apex. However, they also converge proximally with the base or dorsal border on medial and lateral aspects.

Thus, when the lateral border meet base on the lateral aspect, it forms a lateral prominence/angle. Again, the medial border meet to base on the medial aspect and forms a medial prominence/ angle.

Here, the lateral angle is less prominent, whereas the medial angle is larger in the cow’s patella. Figure 6 shows the borders and angles of the cow patella.

The larger medial angle gives attachment to the fibro-cartilage of the cow’s patella. Moreover, this fibro-cartilage of the cow’s patella increases the articular surface.

Base and apex of the cow’s patella

The base of the cow’s patella faces upward and backward. It is wide and convex transversely, concave from before backward.

The apex of the cow’s patella forms a blunt and point structure that directs downward.

Comparison of the patella among the cow, horse, and dog

Table 1 shows the comparative osteological features of the patella bones in cow, horse, and dog –

Features	Cow patella	Horse patella	Dog patella
Shape	Irregular triangular	Irregular quadrilateralWider and longer	Somewhat elongated Long and narrow
Cranial surface	Rough and convex	Quadrilateral and convex	More convex than cow
Caudal surface	Has vertical ridges and two concave areas	Same to cow, but the ridge is more rounded	Concave along length and convex across the width
Angles	Medial angle larger	Not prominent	Practically absent

So, the shape and the features of the cranial surface are the key differentiating points of the cow’s patella from the horse’s and the dog’s.

Compare cow vs horse patella bones

Sometimes it is very difficult to compare the cow and horse patella bones for students. I may help you to differentiate the patella between a cow and a horse in an easy way.

First, let’s see the appearance of the patella bones between the cow and horse from Figure 7. It clearly shows that the cow’s patella is almost triangular in shape. Whereas the horse’s patella is not triangular, it is wider and longer than that of the cow’s patella.

Comparative anatomy of the patella between cows and horses

Again, the cranial surface of the horse patella resembles to the irregular quadrilateral and convex. The cranial surface of a cow’s patella resembles an irregular, slightly elongated triangular shape.

The caudal surface of both the cow and horse patella shows almost similar osteological features. Only the vertical ridge is wider and more rounded in the caudal surface of the horse patella.

The lateral and medial angles in the cow’s patella bone are prominent. Again, the medial angle is larger and can be considered as the unique identification feature for cow’s patella. In contrast, the lateral and medial angles in the horse’s patella bone are not prominent.

Again, you may also compare the features of the apex of the patella between the cow and the horse. You will find the little blunt apex in the horse’s patella, whereas the cow’s patella shows a pointed apex.

How to identify the right and left patella of a cow?

Well, it is very easy to identify the right and left patella of a cow. You may follow the below-mentioned identification strategies for the right or left patella of a cow –

First, try to identify the cranial and caudal surfaces according to their unique identifying features.
Second, make sure the wide base faces the dorsal aspect, and the pointed apex faces downward.
Third, try to identify the convex lateral and concave medial borders.
Fourth, make sure the larger medial angle faces medially.

Now, let’s hold the patella according to its normal position with right/left hand.

Why is this the right patella bone of a cow?

Figure 8 shows the right patella bone of a cow.

It is the cow’s right patella for the followings –

It presents a convex cranial and a concave caudal surface with a middle vertical ridge.
This bone presents a wider base upward and a pointed apex downward.
It also presents a larger medial angle on the medial aspect.

Now, let us hold this patella bone with the right hand, the large medial angle will face the medial aspect. Thus, this is the right patella of the cow.

What is a patella bone?

The patella is the larger sesamoid bone in an animal’s stifle joint. It articulates with the trochlea of the femur bone on its distal cranial aspect.
Its cranial surface is for the attachment of the muscles, ligaments, and tendons.

Does a cow have a patella?

Yes, a cow has a patella bone, which is located on the cranial distal part of the femur on its trochlea. It hosts the patellar ligament and forms the stifle joint. In the stifle joint, it works as a pulley and changes the direction of ligaments.

How is the cow’s patella different from the dog’s?

The cow’s patella is different from the dog’s in different ways. Here, the dog’s patella is comparatively longer and narrower than that of the cow’s patella.
Again, the cranial surface of the dog’s patella is more convex than that of the cow’s. However, the caudal articular surface of the dog’s patella is concave along its length and convex across the width.

What is a cow’s leg called?

A cow’s leg is made up of tibia and fibula bones. They are articulated with the distal part of the femur above and the tarsals below.

Conclusion

So, the cow patella bone is the large triangular sesamoid that is placed in front of the trochlea of the femur bone. It presents 2 surfaces, 2 borders, a base, and an apex, which contain unique osteological features.

The caudal surface of the cow’s patella articulates with the trochlea to form the stifle joint. Again, the convex cranial surface hosts the patellar straight ligaments and other tendons.

References

Shivaprakash and Usturge., Observations on upward fixation of patella in cattle and buffaloes: Review of 350 cases. Buffalo Bull. 2004;23:58-63.
Hazewinkel et al., Chapter 17 – Locomotor system, Med his. & Physical Exam. in Companion Animals, 2nd ed., W.B. Saunders, 2009, Pages 135-159, ISBN 9780702029684.
Supriya et al., Anatomy of the femorotibial joint of stilfe of buffalo calves. Buffalo Bulletin, 2016; Vol.35 No.4
Nichols and Anderson., Determination of the normal arthroscopic anatomy of the femoropatellar and cranial femorotibial joints of cattle. The Canadian Veterinary Journal, 2014; 55(3):232-239.
Ghosh, R. K. : Primary veterinary anatomy, 2nd Edn.Current Books International, Kolkata.
Getty, R,. S and G’s The anatomy of the domestic animals, 5th Edn. W. B. Saynders and Co. Philadelphia (USA).
Rowen D. Frandson, W. Lee Wilke, and A. Dee: Anatomy and physiology of farm animals, 4th edn.Wiley-Blackwell, USA

Written by

Sonnet Poddar

I am Sonnet Poddar (Veterinarian; Faculty member of Veterinary Anatomy), founder of VeterinaryAnatomyGuide.com. Over the last 9 years, my efforts have focused on veterinary anatomy teaching to undergraduate and Master’s students. Currently, I am running more than 7 educational websites and offer my students unique learning resources.