The cow jaw bone includes mainly the mandible and maxilla. Here, the mandible forms the lower part, and the maxilla forms the upper part of the cow’s jaw.
This article will discuss the anatomical facts of a cow’s lower jaw with diagrams. But, you will also know little about the upper jaw’s important anatomical features.
Quick overview of cow jaw bones: a cow has two jaws – upper and lower. The upper immovable jaw is formed mainly by the maxilla bone. In contrast, the two halves of the mandible bone form the lower movable jaw.
Finally, I will compare cow and horse lower jaws bone with the labeled diagram. Let’s start learning the anatomy of a cow’s lower jaw (mandible).
Cow jaw bone
Before learning cow jaw bone anatomy, let’s know–how jaws are formed. Well, jaws are formed by the union of two or more bones that form a framework to accommodate teeth and associated structures.
If you notice the mouth cavity of a cow, you will see alveolar sockets with or without teeth on both the upper and lower part. The upper alveolar sockets (with teeth) are hosted in the maxilla bone (on both sides).
You will find 6 alveolar sockets in the maxilla bone (one side). Among these, three are for the molar teeth, and three are for the premolar teeth. There is no alveolar socket for the incisor and canine teeth on the upper part of the cow mouth.
Again, the lower part of the cow mouth also shows alveolar sockets. These alveolar sockets are hosted on the body of the cow’s mandible bone.
You will find 10 alveolar sockets in each half of the cow mandible. Among these ten alveolar sockets of mandibular bone, 3 are for incisor, 1 is for canine, 3 are for premolar, and the rest 3 is for molar teeth.
Thus, there are two important bones in the cow’s jaws – the maxilla and mandible. Now, with an appropriately labeled diagram, you will know the details of these bones, maxilla and mandible bones.
How many jaws does a cow have?
You may easily understand the number of jaws in a cow from the above discussion. Again, the formation of the jaws is easily identifiable from the cow mouth cavity.
Quick answer: cows have 2 jaws – upper jaw and lower jaw. The upper is made of maxilla bone and possesses 6 alveolar sockets. The lower jaw is made of mandible bone and possesses 10 alveolar sockets in each.
Let’s see the summary of the upper and lower jaws of a cow from Table 1 –
|Features||Cow upper jaw||Cow lower jaw|
|Formation||Right and left maxilla bones||Two halves of the mandible|
|Alveolar sockets||12 (6+6)||20 (10+10)|
|Articulation||Articulate together, and|
Articulate with other skull bones
|Two halves of the mandible articulate ventrally|
Form symphysis joint
|Bone features||Possess lateral facial tubercle||Mainly divides into –|
|Papilla on jaw||Have papilla||No papilla|
Do cows have an upper jaw?
Quick answer: yes, cows have an upper jaw. The right and left maxilla bones, along with their associated structures, help to form the upper jaw in a cow.
The upper jaw bones of a cow (maxilla) are shorter but broader and relatively higher than in the horse. It is the largest paired bone in the facial group of a cow skull.
This bone not also forms the upper jaw but also forms the roof of the mouth cavity and the floor of the nose cavity. You will find the articulation of cow maxilla bone with other skull bones like nasal, premaxilla, lacrimal, malar, and palatine.
There are several osteological features found in the maxilla bone of a cow –
- Lateral facial tuberosity or tubercle,
- Several alveolar sockets,
- Osseous lacrimal canal, and
- Several numbers of foramina like infraorbital, sphenopalatine, maxillary, and caudal palatine,
Features of the cow maxilla bone
Here, the tuber maxillare is small, laterally compressed. You ill find the small pointed process on the tuber maxillare in a cow’s maxilla bone.
The palatine process is wider but somewhat shorter than in the horse. Two palatine processes from the maxilla bone (right and left) join together and form the skeleton of the hard palate.
You will see the infraorbital foramen at the lateral surface of the maxilla bone at the level of the first premolar tooth. This infraorbital foramen is the external opening of the infraorbital canal.
The cow maxilla bone encloses the palatine sinus that communicates with the maxillary sinus through the infraorbital canal. Here, the maxillary sinus proper is small and undivided in a cow.
You will see a narrow fissure-like maxillary foramen that is deeply placed at the medial aspect of the lacrimal bulla. But, the maxilla bone of a cow does not take part in forming a palatine canal.
You may also know the anatomical features of other bones from cow skulls from a below-mentioned article of anatomy learner –
Cow lower jaw bone anatomy – mandible
The mandible forms the skeleton of the lower jaw of a cow. The two halves of the mandible bone fuse incompletely at the midline of the body.
This fusion is not complete even in the advanced age of a cow and thus forms the mandibular symphysis. Here, the symphyseal surfaces are extremely rough and are marked by reciprocal projections and cavities.
The cow lower jaw bone anatomy consists of –
- #1. A horizontal body, and
- #2. The verticle ramus,
You will find different osteological features in these bodies and the ramus of a cow mandible bone. Let’s identify different features of the cow mandible bone in the next section of this article.
What does a cow jaw bone look like?
Quick answer: a cow’s jaw resembles a flat triangular bone with a horizontal body and a verticle ramus. They are the symmetric bones in the lower part of the skull and articulate together by mandibular symphysis.
This lower jaw bone (mandible) is considered the largest and most mobile bone of the cow’s skull.
Cow jaw bone identification
Now, you will identify the important osteological features of the lower jaw of a cow. Here, the diagram shows the below-mentioned osteological features from the body and ramus parts of the cow mandible bone –
- #1. Alveolar sockets for incisor, premolar, and molar teeth,
- #2. Rough symphyseal surfaces,
- #3. Body of the cow’s mandible,
- #4. The angle of the cow mandible,
- #5. Groove for passes nerves and vessels on its lateral aspect,
- #6. Groove for a lingual branch of the trigeminal nerve
- #7. Mandibualr foramen on medial aspect,
- #8. Condylar and coronoid processes, and
- #9. The notch between condylar and coronoid processes,
I hope you will easily identify these osteological features from the cow’s lower jaw with the help of provided labeled diagram.
Ramus of cow mandible bone
This is the verticle part of the cow mandible bone and is much smaller than in the horse. The anatomy of the ramus of cow mandible bone shows 2 borders, 2 surfaces, and 2 extremities.
- Borders – cranial and caudal,
- Surfaces – lateral and medial, and
- Extremity – proximal and distal,
Here, the proximal extremity possesses important osteological features –
- #1. Condylar process – this is the caudally projected body projection that articulates with the squamous part of the temporal bone,
- #2. Coronoid process – it is the cranial upward bony projection of the ramus. This process projects upward and inward into the temporal fossa.
- #3. Mandibular notch – this a depression between the condylar process and coronoid process of the cow mandible,
- #4. The neck of mandible – the constricted area below the condylar process is known as the neck of the cow mandible,
The rami of a cow’s mandible diverge more; thus, you will see the wider mandibular space compared to the horses.
Surfaces and borders of ramus of cow mandible
The lateral surface of the ramus of the cow mandible is almost smooth. Unlike the dog mandible, you will not find deep masseteric fossa on the ramus.
The medial surface of the ramus is concave and represents –
- #1. Mandibular foramen – is the opening on the medial aspect of the ramus of the cow mandible that forms the mandibular canal,
- #2. Groove for lingual nerve – just below the mandibular foramen (on the medial aspect),
The ventral border of the ramus is relatively thin below, concave, and wider above. Here, the ventral border of the caudal part of the mandibular body joins with the caudal border of the ramus and forms the angle of the jaw.
You will also find a faint notch at the ventral border of the caudal part of the mandibular body. Within this groove, the cow’s maxillary vessels and parotid duct pass.
Cow jaw bone body with teeth
The body is the horizontal part of the cow jaw bone, which is shorter, wider, and flatter than in the horse. You will find 2 main parts in the body of a cow mandible – anterior (incisival), and posterior (molar) parts.
The incisival part of the mandibular body possesses 2 surfaces – concave lingual and convex labial surface. There are eight rounded and relatively shallow alveoli for the lower incisor teeth. The interalveolar border is long, curved, thin, and sharp in the cow mandible.
You will not find any alveoli for the canine teeth in the lower jaw of the cow mandible. But, the last (fourth alveoli) is considered for the canine teeth.
So, you will not find the true canine teeth in the lower jaw of a cow’s mandible. But, the different author stated that the fourth teeth arrange irregularly and are called the canine teeth.
They are (canine teeth of a cow) less sharp than in horses or dogs.
The narrow part of the incisival segment of a cow mandible shows a depression where you will find the opening of the mental foramen. Again, the posterior part of the mandibular body possesses 2 borders, 2 surfaces, and 2 extremities.
The curviness of the posterior body of a cow’s mandible is more than the horse’s. Again, the angle is more pronounced in the cow mandible compared to the horse.
The ventral border of the posterior body is convex and thick. Again, the dorsal border possesses six alveoli for the lower cheek teeth.
Here, the first socket or alveoli is somewhat small, and they increase in size from before backward. You may find the small groove on the lateral aspect of the posterior body of a cow mandible.
Cow jaw vs horse jaw
The fusion between the two halves of the horse mandible (lower jaw) is complete compared to a cow. You will also find the socket for 2 true canine teeth on the dorsal aspect of the body of the horse mandible.
Here, Table 2 shows the different points for cow jaw from horse jaw (focus on the lower jaw) –
|Features||Cow lower jaw||Horse lower jaw|
|Fusion of two halves||Incomplete||Complete|
|Body||Short, flatter, wider||Long, narrow|
|Alveoli for canine teeth||Absent||Present (true)|
The labeled cow and horse jaw bone diagram shows the lower jaw’s basic differences. You may find more labeled diagrams on cow or horse jaw bones here on social media of anatomy learners.
How big is a cow’s jaw bone?
A medium-sized cow has a lower jaw bone with 35 centimeters long body and 25 centimeters ramus. The height of the body differs from anterior to posterior segments.
The maximum height of the mandibular body ranges from 8 to 15 centimeters. But, the larger cow shows more mandibular body and ramus measurement.
So, the cow’s lower jaw bone possesses the typical osteological feature compared to horses and dogs. Again, the upper jaw is somewhat different in a cow than in a horse.
All the osteological features identified from the major two jaws (upper and lower) bones (maxilla and mandible) might help you to get their basic structure. Now, you should identify the cow’s lower and upper jaw bone features from the actual sample of the bovine skull.