Mouth of a cow

The mouth of a cow is an elongated cavity at the beginning of the alimentary canal of the digestive system. Here, I will describe the anatomy of the different parts/organs of the cow’s mouth cavity with hand-drawing diagrams and real pictures.

Quick answer: The mouth of a cow is the first part of its alimentary canal and comprises two divisions – the vestibule and the mouth cavity proper.

However, the vestibule and the mouth cavity proper are bounded by various organs or structures. Thus, you will know the details of these organs or structures from the mouth cavity in the cows.  

What is the mouth cavity of a cow?

Figure 1 shows the hand-drawing schematic presentation of the cow’s mouth cavity. It also clearly shows the divisions and boundaries of the mouth cavity.

The figure also shows that there are various organs or structures within the cow’s mouth cavity. However, the mouth extends from the lip to the end of the soft palate.

Thus, according to the figure, you may express the cow’s mouth cavity as follows –

• Mouth cavity: The cow’s mouth cavity is an elongated space that consists of the lip, cheek, alveolar arches, gum, and teeth. However, it is bounded dorsally by the palates and ventrally by the body of the mandible, along with the muscles and tongue.

Boundaries of the mouth: Here, the cranial part of the dorsal boundary of the cow’s mouth cavity is bounded by the hard palate. However, the caudal part is bounded by the soft palate (Figure 2).

Again, the lips bound the entrance of the mouth cavity and are termed the rima oris. However, the caudal opening of the mouth cavity into the cow’s pharynx is termed the aditus pharyngis/ isthmus faucium.

Here, Table 1 shows the overview of the boundaries of the cow’s mouth cavity –

Aspects	Boundaries
Dorsally	Bounded by hard and soft palates
Ventrally	Bounded by mandible, muscles, and tongue
Cranially	It is bounded by the lips/rima oris
Caudally	Continue with the pharynx
Laterally	Bounded by the cheek, gum, and teeth

Parts of the cow’s mouth cavity

Figure 3 highlights the divisions of the cow’s mouth cavity. It presents that the mouth cavity is subdivided into two parts by the teeth and the alveolar process of the mandible.

• Vestibule of the mouth: It is the short cranial space of the mouth cavity between the teeth and lip. Thus, the vestibule of the cow’s mouth is bounded externally by the upper and lower lips and cheek, and internally by the gum and teeth.
• Mouth cavity proper: Here, the mouth cavity proper lies deep to the cow’s teeth and is occupied primarily by the tongue. It ends at the narrowing near the base of the tongue, where the digestive tract continues as the pharynx.

Thus, the mouth cavity proper is bounded in front and laterally by the alveolar arches, gums, and teeth.

However, the mucous membrane of the mouth cavity continues with the margin of the lip and the common integument. Again, it continues caudally with the mucous membrane of the pharynx.

So, to describe the cow’s mouth anatomy, you might describe the following organs/structures –

• Lips of the cow (upper and lower)
• Cheeks of the cow (which form the lateral wall)
• The roof of the cow’s mouth (which consists of hard and soft palates), and
• Floor of the mouth cavity (consists of the tongue and teeth),

However, you might also describe the features of the body of the cow’s mandible, highlighting the alveolar sockets for the teeth.

Now, I will describe all the organs/structures mentioned above using hand-drawn diagrams, one by one.

Lips of the cow

Figure 4 shows the upper and lower lips of the cow. These are the musculomembranous folds that form the opening of the cow’s mouth cavity.

Here, the upper and lower lips of the cow meet with each other laterally at the level of the corner of the incisor tooth. These unions are known as the commissures or angles of the cow’s lip.

External surface of the cow’s lip

A thick skin with a variable number of tactile and ordinary fine hairs covers the external surface of the lip. In the middle part of the external surface of the cow’s upper lip and the surface between the nostrils is black and keratinized (Figure 5).

This black, keratinized part of the lip is the muzzle (planum nasolabialis). It remains cool and moist by the fluid secreted by the nasolabial glands.

Here, Figure 5 presents the tactile and ordinary fine hairs of the external surface of the cow’s lip. It also presents the black and keratinized planum nasolabialis/muzzle.

However, the nasolabial glands are located just beneath the skin. The figure also shows that the muzzle is smooth, with irregular grooves where the glands’ ducts open. This small polygonal area (along with the irregular groove) is the superficial indication of the philtrum (Figure 5).

The rest of the surface of the external surface of the upper lip contains long tactile and ordinary fine hairs. However, the external surface of the lower lip presents a rounded prominence in its center. This rounded prominence is the chin of the cow.

Internal surface of the lip

The pigmented mucous membrane lines the internal surface of the cow’s lip. It possesses a variable number of small papillae where the labial glands also open.

There is a fold of mucous membrane that extends from the cow’s upper lip to the gums. It is known as the frenum labii maxillaris. However, in the case of the lower lip and gum, it is known as the frenum labii mandibularis.

The free borders of each upper and lower lip are plain. However, the adjacent part of the internal surface of the lips presents short, blunt papillae. These papillae become larger, sharper, and pointed towards the commissure of the lips.

The orbicularis oris muscle of a cow lies between the external and internal surfaces of the lip. Here, this muscle blends with the facial muscles.

Cheeks of a cow mouth

The cheeks form the lateral wall of the cow’s mouth cavity. Here, the cheek of a cow consists of skin, muscles, glands, and mucous membrane.

Figure 6 shows the continuation of the cheeks with the cow’s lip. It also shows the attachments of the cheeks to the alveolar border of the jaw bones (maxilla and mandible).

Thus, the cheeks are continued externally by the skin and internally by the mucous membrane. However, the layers of muscles, buccal glands, nerves, and vessels lie between the skin and the mucous membrane.

Now, I will discuss the skin, muscles, and buccal glands from the cow’s cheeks.

Skin and muscles

Here, the skin of the face continues over the cow’s cheeks without any modification. However, the skin on the cheeks is thin and elastic.

The cow’s cheeks are formed by different muscles and shown in Table 2 –

Name of the cheek’s muscles	Origin and insertion
Buccinator muscle (chief muscle)	Arises from the alveolar borders of the maxilla and mandibleIt terminates with the orbicularis oris muscle
Levator nasolabialis muscle	Originates from the nasal and frontal bonesTerminates on the nasal cartilage and the premaxilla bone
Levator labii maxilarries muscle
Zygomaticus muscle	Arises from the zygomatic boneIt blends with the orbicularis muscle
Depressor labii mandibularis muscle

Buccal glands on the cheeks

The buccal glands are arranged in three rows in a cow’s cheek –

• Dorsal row: It consists of yellowish glands that are arranged in lobules. They extend from the angle of the lips to the maxillary tuberosity.
• Middle row: The middle row’s buccal glands consist of scattered lobules. They are located on the deep surface of the buccinator muscle.
• Ventral row: It consists of brownish lobules arranged from the angle of the lips to a short distance under the masseter muscle.

Mucous membrane and papillae

The mucous membrane of the cow’s cheeks continues with the gum and soft plate behind. It consists of a large number of cornfield pointed papillae that are directed caudally towards the isthmus faucium.

These papillae are larger at the angle/commissure of the cow’s lip. However, there is a large papilla located on the mucous membrane of the cheek at the level of the upper fifth cheek tooth (Figure 7).

It is papilla salivalis and presents an opening for the sternson’s duct. This duct carries the saliva/secretion from the cow’s parotid salivary gland.

Here, Figure 7 presents the hand-drawing schematic presentation of the papillae and papilla salivalis of the cow.

Roof of the cow’s mouth cavity

Figure 8 shows the roof of the cow’s mouth cavity. It clearly shows two portions of the roof: the anterior/cranial hard palate and the posterior/caudal soft palate.

Here, I will help you to identify the different anatomical features of the roof/palates first. Then, I will describe the hard and soft palates of the cow separately.

Here, the figure shows the following structures from the roof of the cow’s mouth (anterior to posterior) –

• Dental pad (unique in ruminants and only present in the roof/upper jaw),
• Papilla insisive (triangular structure),
• Transverse ridges,
• Longitudinal median raphe (divides transverse ridges into equal halves), and
• The soft palate portion

Hard palate of the cow

Actually, the hard palate forms the roof of the mouth cavity of a cow. It consists of dense connective tissue covered by a mucous membrane.

However, the hard palate attaches to the palatine, maxilla, and premaxilla bones. It is bounded rostrally by the dental pad, on the sides by the alveolar arches of both sides. Finally, it continues caudally with the soft palate of the cow’s mouth.

Figure 9 highlights two important structures from the cow’s hard palate: the dental pad and papilla incisive. However, it also presents other features from the cow’s hard palate.

What is a dental pad in a cow?

Well, it is an area of the upper jaw/premaxilla bone that lacks incisor teeth. Thus, the dental pad is formed by a thick pad of connective tissue on the body of the premaxilla bone.

Here, the cow’s dental pad divides into two halves.

Papilla incisiva: There is a small triangular or diamond-shaped structure at the rostral end of the median raphe. It lies between the dental pads and the first transverse ridge of the hard palate and is called the papilla incisiva.

On either side of the papilla incisiva, there is a fissure that presents a palatine opening for the incisive duct. Here, the nasal opening of the incisive duct lies on the floor of the cow’s nasal cavity.

Transverse ridges and median raphe

Figure 9 also highlights the numerous transverse ridges and one median/central groove. Here, the central/median groove, or raphe, extends the entire length of the cow’s hard palate.

Thus, the median raphe divides the transverse ridges into two halves on both right and left sides. There are about 15 to 19 transverse ridges present in the hard palate.

However, these ridges cover the rostral two-thirds portion of the hard palate. Again, the caudal third of the hard palate is smooth and presents orifices for the ducts of the palatine glands.

Soft palate of the mouth of a cow

Figure 10 highlights the soft palate portion of the cow. It is a musculo-membranous structure that separates the mouth cavity from the esophagus.

Here, the soft palate extends caudally from the hard palate to the epiglottis of the cow’s larynx. The rostral and lateral attachments of the cow’s soft palate are as follows –

• Rostral attachment: Rostrally, it attaches to the caudal border of the horizontal part of the hard palate.
• Lateral attachment: Laterally, it bends with the wall of the pharynx and isthmus faucium.
• Caudal attachment: It is concave and free.

However, the soft palate of a cow presents two surfaces: anterior and pharyngeal. Here, the anterior surface faces ventrally and caudally and is covered by the mucous membrane. Again, the pharyngeal surface faces dorsal and caudal and is also covered with mucous membranes.

Rostral and caudal pillars

Figure 11 shows two pillars of the cow’s soft plate: the rostral and caudal pillars. They are named according to their position and their attachment to the tongue and pharynx.

• Rostral pillar: There is a short, thick fold of mucous membrane that passes laterally and ventrally. However, it extends from the lateral border of the cow’s soft palate to the lateral border of the tongue. It is the rostral pillar/palatoglossal arch of the cow’s soft palate.
• Caudal pillar: The caudal free border of the soft palate continues laterally on each side into the short fold of mucous membrane. They pass to the lower part of the lateral wall of the cow’s pharynx. These folds are referred to as the caudal pillar/palatopharyngeal arch of the cow.

What is tonsilar sinus?

You will find the space between the rostral and caudal pillars on each side. It bears a deep concave sinus called the tonsilar sinus.

However, these sinuses are occupied by a compact mass of lymphoid tissue known as the tonsil. Though the part of the tonsil projects outward, it is not visible in the cow’s mouth cavity.

Floor of the mouth

Figure 12 presents the schematic presentation/diagram of the floor of the cow’s mouth. I made this figure of the floor of the mouth using both hand-drawn diagrams and real photos.

The body of the cow’s mandible and mylohyoideus muscles form the floor of the mouth cavity. However, it is free only in the rostral aspect and is covered by the mucous membrane.

Most of the floor of the cow’s mouth cavity is occupied by the tongue. Mucous of the tongue and the mylohyoid muscle form a narrow groove where the ducts of the sublingual salivary glands open.

• Sublingual caruncle: On either side and behind the third incisor tooth, there is a large leaf-like papilla (Figure 12). It is the sublingual caruncle that is wide, hard, and serrated.

The ducts of the mandibular and a few sublingual glands open jointly or separately on the deep surface of this caruncle.

• Frenum linguae: Just behind the sublingual caruncle, there is a wide median fold of mucous membrane. It passes to the ventral surface of the free part of the cow’s tongue. This fold is known as the frenum linguae of the tongue.

On either side of the frenum linguae, there are linear series of the smaller papillae. Within these papillae, the ducts of the superior sublingual glands open. However, behind the last cheek tooth of the mouth on either side, there is a vertical fold of mucous membrane.

This mucous membrane passes from the cow’s upper jaw to the lower jaw. However, it is the plica pterygomandibularis of the cow’s mouth.

FAQ’s on cow’s mouth anatomy  

Conclusion

So, the mouth of a cow is the beginning part of the alimentary canal and is divided into two main divisions. Here, the vestibule of the cow’s mouth is the space between the lips and the teeth.

Whereas the mouth cavity proper is the largest area, which is bounded dorsally by the palate and ventrally by the floor. However, the alveolar arches, gums, and teeth form the lateral wall of the cow’s mouth cavity proper.

References

• Ghosh, R. K.: Primary veterinary anatomy, 2nd Edn.Current Books International, Kolkata.
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• Hermanson et al., Miller and Evans’ Anatomy of the Dog, 5th Edn. Elsevier.
• Ceferino P. Maala et al., Gross anatomy of the hard palate and palatine in cattle. June 2007Philippine Journal of Veterinary Medicine 44(1):1-7 
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• Madkour, F. A., et al., (2022). Morphometrical investigations on the hard palate of Rahmani sheep. Mic. Res. and Tec., 85(1), 92–105. https://doi.org/10.1002/jemt.23887 

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