Cow urinary bladder anatomy refers to describing its location, parts, and ligaments. It is a thick-walled, muscular sac that serves as a reservoir for urine that comes from the cow’s kidneys, delivered through the ureters.
Here, I will describe the detailed anatomy of the cow’s urinary bladder with hand-drawn diagrams and real pictures.
Quick answer: Cow bladder anatomy describes its variable location, three different parts, and two ligaments.
Thus, I will help you understand why the cow’s bladder location varies. However, I will also describe the different parts and ligaments so you can identify them in real samples.
Where is the urinary bladder located in a cow?
Figure 1 shows the hand-drawn presentation on the variable location of the cow’s urinary bladder. It shows the bladder remains in two body cavities (especially the pelvic and abdominal) under two different conditions.
Here, the location or position of the cow’s bladder differs according to the amount of its contents (urine). However, the shape and size of the urinary bladder also depend upon the amount of urine it contains.
Thus, the location of the cow’s urinary bladder is –
- In an empty condition: The cow’s bladder remains completely contracted. It lies on the floor of the pelvic cavity, formed by the ischium and pubis of the cow’s pelvic bones.
- In a moderately full condition: It is also located on the pelvic floor but extends a variable distance into the floor of the abdominal cavity.
Shape of the cow’s bladder: In the empty and contracted condition, the cow’s bladder becomes a dense piriform mass. It is about the size of the fist. However, it becomes oval in shape in the distended condition.
Again, you will feel the difference in the thickness of the wall of the cow’s bladder. It is thick-walled when empty, whereas it becomes thin when distended.
Capacity of the cow’s bladder: Capacity ranges from 2.8 to 3.8 liters (varies with the age and physiology of the cow).
Cow urinary bladder anatomy
Figure 2 highlights an overview of the anatomy of the cow’s urinary bladder. This figure is made with a combination of diagrams and real pictures of the cow’s bladder.
Thus, according to the figure, you might mention the following features when describing the cow’s bladder anatomy –
- Location of the cow/cattle’s bladder
- Parts of the cow’s urinary bladder
- Attachments or ligaments of the urinary bladder
As I have already described the location, let’s start with the parts of the urinary bladder. You might mention all the features in your examination paper that I have highlighted in the figures.
Parts of the cattle’s urinary bladder
Figure 3 shows the three parts of the cow/cattle urinary bladder. It shows the cranial apex (vertex), middle body, and caudal neck of the urinary bladder.
Apex of the urinary bladder
Figure 4 highlights the cranial rounded blind extremity of the cow’s urinary bladder. This is the apex or vertex of the urinary bladder.
At the middle of the apex or vertex of the cow’s urinary bladder, there is a mass of cicatricial tissue. It is the vestige of the urachus, which forms the communication between the fetal bladder and the allantois.
However, if the urachus remains patent, a urinary fistula may develop. Thus, the urine can pass to the placenta.
Body of the cow’s bladder
Figure 5 highlights the middle part of the cow’s bladder, called the body. It is rounded and somewhat flattened dorsoventrally except when distended.
The body of the cow/cattle/ruminant’s bladder has two surfaces: dorsal and ventral. However, these two surfaces are convex when the bladder is full.
Again, the dorsal surface is more strongly convex than the ventral surface. This occurs especially at the caudal part of the cow’s urinary bladder.
However, just caudal to this area, the ureters from the corresponding kidneys enter the bladder.
Neck of the cattle/cow’s bladder
Figure 6 presents the caudal part of the cow’s urinary bladder. It is a narrow tubular portion called the neck of the cow’s urinary bladder.
The wall of the neck of the bladder is comparatively thick. However, this part of the bladder continues with the cow’s urethra (shown in the figure).
Topographic relations of the cow’s urinary bladder
When describing the anatomy of the bladder of a cow, you might mention its topographic relations with other organs. Figure 7 provides an overview of the topographic relationship of the cow’s bladder to the surrounding organs and structures.
However, this topographic relationship varies with bladder fullness. I suggest you mention the relations of organs or structures to the dorsal and ventral surfaces of the cow’s bladder.
Ventral surface: Here, the ventral surface of the bladder relates to the ventral wall of the pelvis. Again, it extends forward on the ventral wall of the abdomen as the bladder fills.
Here, the ventral wall of the abdomen is formed by the cow’s straight abdominal muscles. Again, the aponeurotic parts of the oblique and transverse abdominal muscles also contribute.
Dorsal surface: Here, the dorsal surface of the cow’s bladder remains in contact with the body of the uterus.
You will find variable relations of the vertex, or apex, of the cow’s bladder when full. It reaches the rumen compartment of the cow’s stomach and the small intestine. However, it also relates to different parts of the cow’s colon.
How is the cow’s bladder fixed in its position?
The cow’s bladder is fixed in position by three peritoneal folds. These peritoneal folds are called the ligaments of the cow’s urinary bladder.
Here, in Figure 8, I tried to show the position of the ligaments of the cattle’s urinary bladder. However, this is a hand-drawn presentation of the three ligaments of the urinary bladder.
Ligaments of the cow/cattle’s bladder
Thus, according to the figure, there are the following ligaments in the cow’s bladder –
- Middle/ventral ligament of the bladder
- Lateral ligaments of the bladder, and
- Round ligament of the bladder
Middle ligament: Here, the middle ligament is the median ventral triangular fold of the peritoneum. However, this ligament extends from the ventral surface of the bladder to the floor of the cow’s pelvis and abdomen. Its posterior part contains elastic and muscular fibers.
Lateral ligaments: These are the right and left transverse ligaments of the cow’s bladder. However, they extend from the lateral aspect of the bladder to the lateral aspect of the cow’s pelvis.
Round ligaments: The right and left lateral ligaments are membrane-like. However, each contains a rounded, firm cord-like structure on its free margin known as the round ligament.
Here, the round ligaments are the remnant of the large foetal artery. However, they have a larger lumen compared to the older cow.
The caudal part of the cow’s bladder lacks peritoneal covering. Thus, this part of the bladder is known as the retroperitoneal part.
However, the caudal part of the bladder is attached to the surrounding parts by huge fat and dense connective tissue.
The caudal, or posterior, part of the cow’s bladder has a definite, fixed position. However, the cranial or anterior part of the bladder is movable.
Structures of the cow’s urinary bladder
Figure 9 presents an overview of the structures of the cow’s urinary bladder. It shows that the bladder wall consists of a distinct outer serous layer, a middle muscular layer, and an inner mucous layer.
Serous coat: However, the cranial part of the bladder only has the serous coat on its dorsal and ventral surfaces. Again, you will also find slight variation in the serous coat on these surfaces.
Muscular coat: The muscular coat consists of involuntary muscles, which are pale and not clearly divided into two layers. However, the muscles have a flexiform arrangement.
Here, the longitudinal muscle fibers occur on the dorsal and ventral surfaces. However, the lateral muscles become oblique and decussate with each other.
Mucous coat: The bladder’s mucous membrane is pale and thin. However, it is loosely attached to the elastic submucosa and muscular coat.
The mucous coat is modified over the triangular area on the bladder’s caudodorsal aspect. This triangular area is termed the trigonum vesicae of the cow’s bladder, where the mucous membrane is firmly attached without any folds.
Vessels and nerves of the bladder
Arteries: The arteries of the cow’s bladder derive chiefly from the internal pudendal. However, branches also come from the obturator and umbilical arteries.
Veins and lymphatics: Veins terminate chiefly in the internal pudendal vein and form a plexus caudally. Again, the lymph vessels form a plexus on both surfaces of the muscular coat.
Nerves: The nerves of the cow’s bladder derive from the pelvic plexus. However, the sympathetic and ventral branches of the third and fourth sacral spinal nerves form this plexus.
FAQ’s on the cow’s bladder
A distinctly circular arrangement of involuntary muscle is found at the neck of the cow’s bladder. These circular muscle fibers form the sphincter vesicae of the cow’s bladder.
The trigonum vesicae has two cranial angles that present openings of the two ureters. However, the caudal angle of this surface presents the opening for the cow’s urethra. This orifice is termed the internal urethral orifice of the bladder.
The cow’s bladder differs from those of other animals, such as the horse and dog, in size and shape. However, the location is relatively variable compared to other animals.
In the horse, the bladder is short but wider than the cow’s. However, it does not extend up to the abdominal cavity, even when distended.
Again, the dog’s urinary bladder is abdominal when distended and is completely covered by the peritoneum. However, the urinary bladder of the sheep and goat differs little from that of the cow.
Conclusion
So, the cow urinary bladder anatomy includes its location in two different conditions along with other features. It describes the anatomical features of the three parts (apex, body, and neck) of the bladder.
However, the fixation of the cow’s urinary bladder is also important for its anatomical description. Again, the wall of the cow’s bladder consists of three layers, and the muscular layer has some of the most peculiar muscle arrangements.
References
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