The cow scapula is a flat and rough triangular bone that forms the shoulder segment of the forelimb. In this guide, you will learn the osteological features of a cow scapula bone with real figures and labeled diagrams.
Quick answer: the cow scapula is a flat, triangular bone of the forelimb that possesses two surfaces, three borders, and three angles.
I will help you to identify the osteological features from the different surfaces, borders, and angles of the scapula bone. Finally, I will also show you the key differences of the scapula bone among different species, like horse, dog, and pig, compared to the cows.
Cow scapula bone
The cow scapula is the forelimb’s bone that is located at the cranial / anterior part of the lateral wall of the thorax. As this is the first flat type of bone that I am going to discuss from the cow skeleton, first, you might know what you should learn, and what you should describe under it.
For a flat bone like a cow’s scapula, you might describe the followings –
- Location of the bone: cranial part of the lateral wall of the thorax.
- Direction of the bone: obliquely downward and forward (extends from the third or fourth thoracic spine to the distal extremity of the first rib).
- Surfaces of the bone: possess 2 surfaces – lateral and medial.
- Borders of the bone: having 3 borders – anterior, posterior, and superior / dorsal / vertebral.
- Angles of the bone: possess 3 angles – anterior, posterior, and inferior / ventral / glenoid.
[In every individual bone of the cow’s skeleton, you might follow this learning approach with little changes. For example, while reading the osteological features of a long bone, you might describe its location, direction, features from different surfaces, and borders.]
Here, Figure 1 shows the location, direction, surfaces, borders, and angles of the cow’s scapula bone.
How are the surfaces, borders, and angles formed in the cow’s scapula bone?
It is very important to understand the surfaces, borders, and angles of the flat bone, like the scapula, even from the long bone, like the humerus. Let’s try to understand the surfaces, borders, and angles of the flat triangular scapular bone.
Here, Figure 2 shows lateral and medial surfaces, 3 different borders, and 3 angles from the cow’s scapula bone.
In this bone, the outer or uppermost smooth layer is the surface. In other bones, this surface may be rough or curved.
The cow’s scapular bone shows a lateral surface (outside) and a medial surface (inside / towards the thorax).
These two surfaces of this bone meet at different aspects and form corresponding borders. As this is a triangular bone, these lateral and medial surfaces meet anterior, posterior, and also dorsal / proximal aspects.
Thus, when these two surfaces of this bone meet anterior aspect, they form the anterior border. In a similar way, these surfaces meet posterior and dorsal aspects and form the posterior and dorsal borders, respectively.
Two individual borders meet to form the angle of the flat bone. Here, the anterior and dorsal borders meet the anterior aspect and form the anterior angle of this flat bone.
Again, the dorsal and posterior borders meet the posterior aspect to form the posterior angle. Finally, the anterior and posterior borders meet the ventral aspect to form the ventral angle.
Here, Figure 3 shows the formation of the different borders and angles of the cow’s scapula bone.
Now, you may easily describe the features of the different surfaces, borders, and angles of this bone.
Cow scapula bone identification
Let’s see what osteological features you might identify from the different surfaces, borders, and angles of the cow scapula bone. Here, I am going to list the features from this bone, but you might also follow the details information that I have provided later.
Identifying features from the lateral and medial surfaces of the scapula
From the lateral surface of the scapula bone:
- Spine of the scapula bone,
- Tubercle of the spine,
- Acromion process of the scapula,
- Supraspinous and infraspinous fossa,
- Neck of the scapula,
From the medial surface of the scapula bone:
- Subscapular fossa,
- Fascis serrata (area for insertion of serratus muscles),
Features from the borders and angles of the scapula
From the borders of the scapula bone:
- Anterior, posterior, and dorsal borders,
- Dorsal scapular cartilage,
From the angles of the scapula bone:
- Anterior, posterior, and ventral / glenoid angles,
- Glenoid cavity with glenoid notch,
- Supraglenoid tubercle / tuber scapulae,
- Coracoid process (medial to tuber scapulae),
All the above-mentioned osteological features from the scapular bone are shown in Figure 4.
Cow scapula anatomy
The cow scapula bone is curved slightly and slopes outward for adaptation with the thoracic wall. For description purposes, it possesses two surfaces, three borders, and three angles.
Lateral surfaces of the cow’s scapula bone
This surface of the scapula bone is also known as the external surface or dorsum. The most unique feature on the lateral surface is the presence of a spine.
This spine extends from the vertebral / dorsal border to the ventral neck. Again, the spine of the scapula divides the lateral surfaces into upper supraspinous and lower infraspinous fossa.
Here, in the cow’s scapula, the supraspinous fossa is smaller compared to the infraspinous fossa. The supraspinous fossa is smooth and hosts the supraspinatus muscle.
Again, the infraspinous fossa is wide and smooth at its upper part. It becomes narrow at the lower part and possesses several rough lines. These rough lines are designed for the muscles attachment with this fossa tightly.
Near the neck, this infraspinous fossa also contains the nutrient foramen and a vascular groove.
The free edge of the spine of the scapula bone is thick and rough. In the middle of the spine, you will find a tubercle, which is known as the tuber of the spine. Within this tuber, the trapezius muscle is attached.
Again, the distal end of the spine becomes a pointed projection, which is known as the acromion process. This process of the spine is projected downward and slightly forward.
The deltoid muscle of the cow arises from the acromion process of the scapula. Here, Figure 5 shows all the osteological features of the lateral surface of the cow’s scapular bone.
Medial surface of the scapula bone
The medial surface is also known as the costal surface of the scapula bone. It is a little hollow along its length with the subscapular fossa.
The subscapular fossa is more deep in the horse scapular bone then these of the cows. This fossa hosts the subscapular muscles.
At the proximal part of this surface, there are two separated rough triangular areas. These are the cranial and caudal facies serrata that accommodate the seratus cervicis and serratus thoracis muscles, respectively.
At the distal extremity of this surface, there are also several vascular grooves. Here, Figure 6 shows the key osteological features from the medial or costal surface of the cow’s scapular bone.
Borders of the cow scapula bone
The borders of the cow scapula bone do not possess any unique features. But, while comparing this bone with other species, you might have considered different borders.
Here, the anterior / cervical border is convex and thin above, and concave and smooth below.
Again, the posterior border is slightly concave in the cow. It is thick and rough at its proximal third, thin in the middle, and thicken at the distal end.
Finally, the superior / vertebral border of the cow’s scapula is pitted by an impression. On this border, you will find the scapular cartilage, which fits on the impressions.
Here, Figure 7 shows the different borders of the cow’s scapular bone.
Scapular cartilage
The scapular cartilage of the cow’s scapula is the unossified part. Within the depression and elevation of the dorsal border of the scapula, the lower part of the cartilage fits.
This cartilage is thick on its lower part, whereas it is thin towards the free ends. The free end of this cartilage is convex and lies alongside the upper part of the vertebral spine.
Cranially, it continues with the line of the scapula and caudally forms a rounded projection. Again, the lower part of the scapular cartilage undergoes more or less ossification.
Angles of the scapula bone
The anterior angle of the scapula bone is also known as the cervical angle. This angle is formed by the junction between the anterior and dorsal borders.
This angle lies opposite the second thoracic spine. Again, the anterior angle is relatively thin, and it is about a right angle.
The caudal or posterior angle is thick and rough in the cow. This angle is formed by the junction between the dorsal and posterior borders posteriorly. Its position can be determined by the surface approach in living animals.
Features of the distal angle of the cow scapula
Another name of distal angle is the inferior or articular angle. This articular angle joins with the body of the bone by the neck of the scapula.
It is an enlarged angle that contains the glenoid cavity. Thus, this angle is also known as the glenoid angle and articulates with the head of the humerus bone.
The glenoid cavity is oval in outline in the cow and possesses a cut or notch on its lateral margin. This is the glenoid notch of the scapula bone.
Again, in the posterior-lateral part of the notch, there is a small tubercle. On this tubercle, the tendon of the teres major muscle is attached.
Here, Figure 8 shows the different osteological features from the distal angle of the cow’s scapula bone.
At the cranial / anterior aspect of the glenoid cavity, there is a large rough prominence. This large rough prominence is the tuber scapulae / supra glenoid tubercle / bicipital tuberosity of the scapula. The tendon of the biceps brachii muscle originates from the tuber scapulae.
At the medial / costal aspect of the supraglenoid tubercle, there is a small projection which is known as the coracoid process. The coracobrachialis muscle arises from the coracoid process of the scapula.
How to identify the right / left scapula bone in the cows?
Well, this is very important to identify the right / left scapula bone from different animals. If you have the basic osteological features of the scapula bone and skeleton, then it is very easy to identify the right / left bone.
Suppose you want to identify the right scapula bone from the cow’s skeleton. You might consider the followings –
First, identify the lateral and medial surfaces of the scapula bone. The lateral surface of the bone possesses the scapular spine.
Second, the spine divides the lateral surface into a dorsal small portion (supraspinous fossa) and a ventral larger portion (infraspinous fossa).
Third, the glenoid cavity is directed ventrally, where the scapular cartilage will remain dorsal direction.
Fourth, now hold the scapula bone with the right / left hand according to the direction (as found in the skeleton in normal standing condition) and verify the followings –
- The spine is placed on the lateral aspect,
- The supraspinous fossa faces the superior aspect,
- Glenoid cavity faces the ventral/ distal aspect,
If it meets the above-mentioned features while holding the bone in the right / left hand, then it will be the bone of the right / left side.
Why is this scapula bone the right one?
Figure 9 shows the right scapula of the cow’s forelimb. Let’s explain why this scapula bone is the right one.
If you hold this bone with your left hand according to the direction of this bone (as found in the forelimb), then you will see the followings –
- Spine: faces medially
Thus, this is not the bone on the left side.
Now, hold the scapula bone with the right hand according to the direction. You might also make sure that the glenoid angle faces the distal aspect and the scapular cartilage faces the proximal aspect.
Now, the results are followings –
- Spine: faces the lateral aspect,
- Supraspinous fossa: faces the superior aspect,
- Glenoid cavity: faces ventral / distal aspect,
Thus, this is the scapula bone of the right side / cow’s right forelimb.
[Thus, to identify the right / left scapula bone, you might consider some of the landmarks from its surfaces / borders / angles according to your own choice. You might also consider the direction of the specific bone that you identify from the skeleton. These identification strategies will be followed for the identification of every single bone from the animal’s skeleton with little modification.]
Comparative anatomy of animal scapula bones
The basic structural plan of the scapula bone in different animals like cows, horses, dogs, and pigs is almost similar. Thus, how will you differentiate a cow scapula from a horse, dog, and pig scapula?
Well, that is very simple to differentiate the cow’s scapular bone from the horse, dog, and pig scapular bones. Here, I will point-out only the key differentiating osteological features of the scapula bones from different species.
Horse scapula bone anatomy
The horse scapula bone is more triangular than that of cows. Here, the subscapular fossa of the horse scapula is more deep.
The lateral surface of the horse scapula also possesses the spine, but does not reach upto the neck. This spine is located further backward and doesn’t possess the acromion process like the cows.
The glenoid fossa is deep, and the notch is also larger than that of cows. Here, the supraglenoid tubercle of the horse scapula is larger. Again, the coracoid process is also developed in the horse scapula bone compared to that of cows.
Here, Figure 10 shows the comparative anatomy of the scapula bones between the horses and cows.
Dog scapula bone
The scapula bone of a dog shows remarkable differences compared to that of cows. Here, the spine of the dog scapula divides the lateral surface into almost equal halves.
The acromion process is present in the dog scapula that extends up to the level of the glenoid cavity. Here, the glenoid cavity is moderately deep and possesses a blunt supra glenoid tubercle. Again, the coracoid process of the dog scapula is ill-developed.
The unique feature of the dog scapula bone is found in its anterior / cranial border. Both the anterior and dorsal borders are convex, and thus the anterior angle is practically absent.
Here, Figure 11 shows the main identifying features of the dog scapula bone.
Pig scapula bone anatomy
The pig scapula is also roughly triangular in outline. Here, the spine of the pig scapula bone is wider and further directed backward.
The spine of the pig scapula divides the lateral surface into almost two equal halves. The glenoid cavity is moderately deep, and the glenoid notch is absent in the pig scapula bone.
Here, Figure 12 shows the comparative anatomy of the scapula bone between the pigs and cows.
Which species is ideal to learn the scapula bone?
As a first-year veterinary student, you might follow the cow to learn the osteological features of the scapula bone. This is because the cow’s scapula bone ideally possesses all the osteological features.
Secondly, you may also follow the horse scapula bone. But, I would like to suggest that you learn the osteological features of the cow scapula bone first, then compare it with other species.
Conclusion
So, the cow scapula is the flat, rough triangular bone located at the cranio-lateral aspect of the thorax. The direction of the scapula bone is oblique (downward and forward).
As the scapula is a triangular flat bone, it possesses two surfaces, three borders, and three angles. The spine, acromion process, glenoid cavity, and supraglenoid tubercles are the key osteological features of the cow scapula bone.
References
- Ghosh, R. K. : Primary veterinary anatomy, 2nd Edn.Current Books International, Kolkata.
- Hermanson et al., Miller and Evan’s Anatomy of the dog, 5th Edn. Elsevier.
- Mcleod, W. N.: Bovine anatomy, 2nd Edn. Burgess publishing co. Minneapolis.
- Rowen D. Frandson, W. Lee Wilke, and A. Dee: Anatomy and physiology of farm animals, 4th edn.Wiley-Blackwell, USA.
- Rohlan et al., Gross and morphometrical examination of scapula bone of Bluebull (Boselaphus tragocamelus), International Journal of Veterinary Sciences and Animal Husbandry 2024; SP-9(1): 37-40.
- Getty, R,. Sission and Grossman’s The anatomy of the domestic animals, 5th Edn. W. B. Saynders and Co. Philadelphia (USA).
- Nickel, R. Schummer, A. and Seiferle, E.: The anatomy of domestic animals, 1st Edn. Verlag Paul Parey, Berlin.
- Bharti and Singh, Gross and Morphometrical Studies on Scapula of Blue bull (Boselephus tragocamelus), Int. J. Pure App. Biosci. 5 (3): 623-627 (2017)
- Dyce, K. M., W. O. Sack and CSG Wensing : Text Book of Veterinary Anatomy, Lea & Febiger. Philadelphia
