Greater Omentum: Anatomy and Function

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-09-20

The greater omentum is a double-layered fold of peritoneum that attaches the greater curvature of the stomach to the dorsal abdominal wall and drapes ventrally over the abdominal viscera. It encloses the omental bursa, stores fat, participates in immune surveillance through aggregates of lymphoid tissue called milky spots, and can seal wounds and adhere to inflamed tissue.

Why the Greater Omentum Matters in Veterinary Practice

Surgeons use the greater omentum every week. It is wrapped around intestinal anastomoses, used to reinforce tracheal grafts, and harvested as a pedicle to bring blood supply to poorly vascularized tissue. In dogs, it is thin, fenestrated, and covers the intestines like a lacy apron. In ruminants, it is massive, divided into superficial and deep parts, and plays a dominant role in fat storage and abdominal organization. Understanding its anatomy prevents surgical errors, explains imaging findings, and clarifies why omental disease, though rare, produces dramatic clinical signs.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Anatomy of the Greater Omentum

Basic Structure

The greater omentum is a double-layered peritoneal fold. It originates along the greater curvature of the stomach and the dorsal abdominal wall, then folds back on itself to create four layers in some regions. These layers enclose the omental bursa, a potential space within the abdominal cavity that communicates with the greater peritoneal cavity through the omental (epiploic) foramen. The bursa is subdivided into the omental vestibule, caudal omental recess, and splenic recess [1][2].

The greater omentum is distinct from the lesser omentum, which connects the lesser curvature of the stomach to the liver. The lesser omentum is smaller, less vascular, and not the focus of this article.

Canine Greater Omentum

In dogs, the greater omentum is thin, transparent, and fenestrated. It drapes over the ventral surface of the intestines like a curtain. The fenestrations are natural openings that allow communication between the omental bursa and the greater peritoneal cavity, permitting fluid movement without requiring flow through the omental foramen [1].

The arterial supply to the canine omentum is contained within folds of the superficial omental wall. Doom and colleagues identified consistent arteries that serve as anatomical landmarks for unambiguous communication about the omentum [3]. These vessels provide the vascular pedicle used in omentalization procedures, where the omentum is surgically transposed to another site to deliver blood supply and immune cells.

Feline Greater Omentum

The greater omentum of cats has a lace-like appearance. A scanning electron microscopic study found that the omentum is continuous at birth with no pores, and microvilli are present on the mesothelial cells. Small pores appear sporadically by 3 months of age, and by 6 to 12 months, more and larger pores are present. These pores are formed by the movement of organs such as the stomach, intestines, and diaphragm. Their presence allows ascites to pass between the omental bursa, the greater omentum, and the serosal cavity of the wall without flowing through the omental foramen [4].

Ruminant Greater Omentum

In ruminants, the greater omentum is extensive and divided into superficial and deep parts. The superficial part covers the ventral surface of the rumen, reticulum, omasum, and abomasum. The deep part extends between the abomasum and the intestines. This arrangement creates a large, fat-filled structure that occupies much of the ventral abdomen. The omentum in cattle and sheep serves as a major site of fat storage, which is why it is sometimes called the "abdominal fat depot."

Equine Greater Omentum

The horse has a relatively small greater omentum compared to ruminants. It connects the greater curvature of the stomach to the dorsal abdominal wall and covers the dorsal aspect of the intestines. The equine omentum is not as fenestrated as the canine omentum and does not drape as extensively over the ventral abdomen.

Comparative Anatomy Table

Functions of the Greater Omentum

Fat Storage

The greater omentum contains adipose tissue that serves as an energy reserve. In ruminants, the omentum is a primary site of fat deposition, and its size reflects the animal's nutritional status. In dogs and cats, the omentum stores fat but is not the dominant depot. The adipose tissue also provides cushioning for the abdominal organs.

Immune Surveillance and Milky Spots

The greater omentum contains aggregates of lymphoid tissue called milky spots. These are clusters of macrophages, B lymphocytes, T lymphocytes, and plasma cells embedded in the omental tissue. Milky spots filter peritoneal fluid and respond to pathogens and foreign particles. They are part of the innate and adaptive immune response within the abdominal cavity. The omentum also produces angiogenic factors that promote new blood vessel formation, which supports its role in wound healing and tissue repair [3].

Adhesion and Wound Sealing

When inflammation or injury occurs in the abdominal cavity, the greater omentum migrates toward the affected area. It adheres to the site, seals perforations, and delivers immune cells and growth factors. This "omental patch" mechanism is a natural defense against peritonitis. The omentum can wall off infections, limiting their spread. This adhesive property is also why the omentum is used surgically to reinforce healing tissues.

Omentalization in Surgery

Omentalization is the surgical transposition of the greater omentum to another site to provide vascular supply, immune support, and tissue coverage. In veterinary medicine, this technique is used in several contexts:

• Bone healing: Experimental studies in dogs have shown that free nonvascularized greater omentum grafts enhance bone healing in nonunion models. In one study, osteotomies treated with autogenous greater omentum achieved complete union, while control osteotomies failed to unite [5]. Another study found that omentum combined with adipose-derived stem cells demonstrated superior osteogenic potential in healing radial bone defects [6]. A third study showed that wrapping omentum with periosteum and adipose-derived stem cells promoted bone tissue formation in the abdominal cavity [7].

• Lymphedema treatment: In dogs with experimental obstructive lymphedema, microvascular insertion of a free omental graft reduced the magnitude of lymphedema by 38% after six months [8]. A separate study in dogs compared four methods of omental transplantation for lymphedema relief, though results varied [9].

• Tracheal reconstruction: Two-stage tracheal autotransplantation using the greater omentum was feasible in dogs. Grafts implanted into the omentum first, then transplanted orthotopically, survived well with intact structure and no shrinkage, granulation, or necrosis [10]. Prior implantation of tracheal grafts in the omentum preserved chondrocyte viability and graft structure [11].

• Kidney revascularization: Omentonephropexy, where the greater omentum is fixed to the kidney, promoted new vessel growth in dogs after renal artery ligation [12].

• Bronchial stump regeneration: The greater omentum supported regeneration processes in the bronchial stump when placed in the pleural cavity with a vascular pedicle [13].

• Brain revascularization: Autografting a greater omental fragment to the brain formed functional vasculature between the omentum and the meninx vasculosa within 24 hours in experimental ischemic lesions [14][15].

• Tissue engineering: Decellularized greater omentum from sheep preserved extracellular matrix and retained VEGF content, supporting its use as a scaffold for in vitro oocyte maturation [16].

These applications exploit the omentum's natural properties: rich vascularity, immune cell content, and ability to adhere and promote healing.

How the Greater Omentum Is Examined in Practice

Physical Examination

The greater omentum is not directly palpable on routine abdominal palpation. However, abdominal distension, fluid waves, or a mid-abdominal mass may prompt further imaging. In dogs with omental disease, a large, freely mobile abdominal mass may be detected [17][18].

Diagnostic Imaging

Radiography: Survey abdominal radiographs may show a soft tissue opacity in the mid-abdomen, displacement of intestines, or loss of serosal detail. The omentum itself is not visible unless it is thickened or mineralized.

Ultrasonography: Ultrasound can identify omental masses, fluid accumulation, and changes in echogenicity. The omentum appears as a hyperechoic, striated structure in normal animals. Inflammatory or neoplastic disease may appear as a hypoechoic or mixed-echogenicity mass.

Computed Tomography (CT): CT provides detailed cross-sectional images of the omentum and omental bursa. A retrospective study of seven dogs with confirmed inflammatory or neoplastic disease of the omenta found that all had fluid in the greater peritoneal cavity, and 5 of 7 also had fluid in the omental bursa. Primary suppurative inflammatory disease was present in three dogs, each with a large abscess containing central gas in either the omental vestibule or caudal omental recess. Neoplasia was present in four dogs and either arose from the omentum (hemangiosarcoma, carcinoma) or infiltrated it from an adjacent organ (splenic leiomyosarcoma, gastric adenocarcinoma). Neoplasms created mass-like tumors, infiltrative tumors, or both [2].

Biopsy and Histopathology

Definitive diagnosis of omental disease requires surgical biopsy or resection. Histopathology and immunohistochemistry differentiate inflammatory from neoplastic conditions. For example, a myxosarcoma arising from the greater omentum in a dog was characterized by spindle-shaped to atypical-shaped neoplastic cells with basophilic stroma in the omental adipose tissue. Immunohistochemistry showed the cells were positive for vimentin but negative for cytokeratin, S-100 protein, and alpha-smooth muscle actin [17]. A malignant peripheral nerve sheath tumor arising from the greater omentum in a dog showed spindle-shaped cells in interlacing bundles, with PAS-positive eosinophilic globules and positivity for vimentin, S-100 protein, glial fibrillary acidic protein, myelin basic protein, neuron-specific enolase, and myoglobin [18].

Clinical Relevance, Limitations and Common Mistakes

Omental Torsion and Herniation

Omental torsion is rare but possible. It occurs when the omentum twists around its vascular pedicle, causing ischemia and necrosis. Clinical signs include acute abdominal pain, vomiting, and abdominal distension. Herniation of the omentum through abdominal wall defects or diaphragmatic tears can also occur. Both conditions require surgical intervention.

Omental Neoplasia

Primary omental tumors are uncommon but reported. Examples in dogs include myxosarcoma [17], malignant peripheral nerve sheath tumor [18], alveolar rhabdomyosarcoma [19], hemangiosarcoma, and carcinoma [2]. In humans, extragastrointestinal stromal tumors (EGISTs) can arise from the greater omentum, presenting as large abdominal masses [20]. Omental tumors often remain clinically silent for a long time because the omentum has enough space to grow before becoming symptomatic.

Omental Adhesions

Adhesions form when the omentum adheres to inflamed or injured tissue. While this is a natural healing response, excessive adhesions can cause intestinal obstruction, chronic pain, or infertility. Surgeons must handle the omentum gently during abdominal procedures to minimize adhesion formation.

Common Mistakes Students Make

1. Confusing the greater and lesser omentum. The greater omentum attaches to the greater curvature of the stomach and drapes over the intestines. The lesser omentum connects the lesser curvature to the liver.

1. Assuming the omentum is avascular. The omentum is highly vascular. Its arteries are contained within folds of the superficial omental wall and provide the blood supply for omentalization procedures [3].

1. Overlooking species differences. The canine omentum is thin and fenestrated, while the ruminant omentum is thick and divided into superficial and deep parts. These differences affect surgical approaches and imaging interpretation.

1. Forgetting the omental bursa. The omental bursa is a potential space within the abdominal cavity. Fluid or abscesses can accumulate there, and CT is useful for detecting them [2].

1. Underestimating the omentum's immune role. Milky spots are not just passive fat. They contain active immune cells that respond to peritoneal pathogens.

Quick Review

1. The greater omentum is a double-layered peritoneal fold attaching the stomach to the dorsal abdominal wall.
2. It encloses the omental bursa, which communicates with the peritoneal cavity via the omental foramen.
3. In dogs, it is thin, fenestrated, and covers the intestines ventrally.
4. In ruminants, it is extensive and divided into superficial and deep parts.
5. Functions include fat storage, immune surveillance (milky spots), adhesion, wound sealing, and omentalization in surgery.
6. Omental torsion and herniation are rare but possible.
7. Omentalization is used in bone healing, lymphedema treatment, tracheal reconstruction, and other surgical procedures.

Development of the Greater Omentum and Its Embryologic Logic

Understanding how the greater omentum forms explains why its adult anatomy looks the way it does, and why the omental bursa has the shape it has. The omentum begins as a dorsal mesogastrium, the dorsal mesentery of the primitive stomach. As the stomach rotates during development, the dorsal mesogastrium is carried to the left and elongates dramatically, forming a double-layered sac that hangs into the abdominal cavity. This elongation is why the greater omentum in adult animals is so much larger than the stomach itself and why it drapes so far ventrally.

The rotation of the stomach also determines the orientation of the omental bursa. Because the stomach rotates, the original right side of the dorsal mesogastrium becomes the dorsal wall of the bursa, and the original left side becomes the ventral wall. This embryologic detail matters clinically: it explains why the omental vestibule sits where it does and why the caudal omental recess extends so far caudally in dogs [1][2]. When you are trying to understand a CT image of fluid accumulating in the omental bursa, you are looking at a space whose boundaries were set before the animal was born.

In cats, the developmental timeline of fenestration is unusually well documented. The omentum is continuous at birth, with no pores, and microvilli are present on the mesothelial cells. Small pores appear sporadically by 3 months of age, and by 6 to 12 months, more and larger pores are present. These pores form because of the mechanical movement of organs such as the stomach, intestines, and diaphragm [4]. This is a useful example of anatomy being shaped by function: the omentum is not born fenestrated, it becomes fenestrated through use.

For students, the practical takeaway is that species differences in omental anatomy are not arbitrary. They reflect differences in embryologic folding, organ size, and mechanical forces within the abdomen. A ruminant omentum is massive because the forestomach compartment is massive and because fat storage is a major function. A canine omentum is thin and fenestrated because it needs to drape and move freely over a mobile intestinal tract.

Step by Step: How to Approach the Omentum in a Dissection

Dissection of the greater omentum is one of the best ways to learn peritoneal anatomy, but it is easy to destroy the structure before you understand it. The following sequence is a practical approach for a canine or feline cadaver.

1. Open the abdominal cavity with a ventral midline incision and reflect the abdominal wall. Before you touch anything, identify the thin, transparent sheet draped over the intestines. That is the greater omentum.
2. Note its attachment along the greater curvature of the stomach. Gently lift the omentum and look for the vessels running within its superficial wall. These arteries are consistent landmarks and should be identified before any cutting [3].
3. Trace the omentum caudally. In the dog, you will see that it forms a curtain over the ventral intestines. Look for the fenestrations, the natural openings that allow communication between the omental bursa and the greater peritoneal cavity [1].
4. Lift the caudal edge of the omentum and look underneath. You are now looking into the omental bursa. Identify the omental vestibule and the caudal omental recess [2].
5. Insert a finger or probe through the omental foramen (epiploic foramen) to appreciate its communication with the greater peritoneal cavity. This foramen is the classic landmark that separates the greater and lesser omentum.
6. Reflect the omentum to the left and identify the spleen and the splenic recess of the bursa.
7. In a ruminant specimen, repeat the process but expect a much thicker, fat-laden structure divided into superficial and deep parts. The superficial part covers the ventral surface of the rumen, reticulum, omasum, and abomasum, while the deep part extends between the abomasum and the intestines.

If you lose your orientation during dissection, return to the stomach. The greater curvature is the fixed point from which everything else follows. Students who get lost usually started cutting before identifying the gastric attachment.

Worked Example: Omentalization for a Nonhealing Wound

Omentalization is easier to understand through a worked example than through a definition. Consider a dog with a nonhealing wound or a poorly vascularized surgical site in the abdominal or thoracic region. The surgeon wants to bring a source of blood supply, immune cells, and tissue coverage to that site.

Step 1: Assess the omentum. Confirm that the omentum is healthy, not thickened, and not involved in the primary disease process. An omentum that is already inflamed or neoplastic is not a good donor tissue.

Step 2: Plan the pedicle. The omentum must remain attached to its vascular supply. The arteries within the superficial omental wall provide the vascular pedicle [3]. The surgeon must preserve enough length to reach the target site without tension.

Step 3: Mobilize the omentum. The omentum is gently freed from its attachments while preserving the vascular pedicle. Handling must be atraumatic because excessive manipulation promotes adhesion formation.

Step 4: Transpose the omentum to the target site. The omentum is wrapped around, sutured to, or laid over the target tissue. In intestinal anastomoses, it is wrapped around the repair to reinforce it. In tracheal reconstruction, grafts have been implanted into the omentum first and then transplanted orthotopically, surviving well with intact structure and no shrinkage, granulation, or necrosis [10].

Step 5: Secure the omentum. The omentum is fixed in place with sutures that do not compromise its blood supply. The goal is contact between the omentum and the target tissue, not tight strangulation.

Step 6: Monitor postoperatively. The omentum will adhere to the target site, deliver immune cells and growth factors, and promote new blood vessel formation. This is the same mechanism that seals perforations and walls off infection in natural disease.

The same principles apply across the experimental applications described in the literature: bone healing, lymphedema treatment, kidney revascularization, bronchial stump regeneration, and brain revascularization all rely on the omentum's rich vascularity, immune cell content, and ability to adhere and promote healing [8][6][7][5][12][13][14][15].

Troubleshooting Omental Problems in the Clinic

Omental disease is uncommon, which is exactly why it is easy to miss. The following troubleshooting framework helps organize your thinking when the omentum appears abnormal on imaging or at surgery.

Problem: A mid-abdominal mass of unknown origin. The omentum is a possible source. Primary omental tumors are uncommon but reported, including myxosarcoma, malignant peripheral nerve sheath tumor, alveolar rhabdomyosarcoma, hemangiosarcoma, and carcinoma [17][18][19][2]. Because the omentum has enough space to grow before becoming symptomatic, these tumors often remain clinically silent for a long time. A large, freely mobile abdominal mass may be detected on palpation [17][18].

Problem: Fluid in the omental bursa on CT. In a retrospective study of seven dogs with confirmed inflammatory or neoplastic disease of the omenta, all had fluid in the greater peritoneal cavity, and 5 of 7 also had fluid in the omental bursa [2]. Fluid in the bursa should prompt careful evaluation of the omentum itself, not just the general peritoneal cavity.

Problem: A large abscess with central gas in the omental vestibule or caudal omental recess. Primary suppurative inflammatory disease was present in three dogs in that same study, each with a large abscess containing central gas in either the omental vestibule or caudal omental recess [2]. This is a specific pattern that should raise suspicion for omental suppurative disease.

Problem: Acute abdominal pain with vomiting and distension. Consider omental torsion, which occurs when the omentum twists around its vascular pedicle, causing ischemia and necrosis. Herniation of the omentum through abdominal wall defects or diaphragmatic tears can also occur. Both conditions require surgical intervention.

Problem: Adhesions causing obstruction, chronic pain, or infertility. Adhesions form when the omentum adheres to inflamed or injured tissue. This is a natural healing response, but excessive adhesions are a surgical complication. Gentle handling of the omentum during abdominal procedures minimizes adhesion formation.

Problem: Difficulty distinguishing inflammatory from neoplastic omental disease. Definitive diagnosis requires surgical biopsy or resection, with histopathology and immunohistochemistry. For example, a myxosarcoma arising from the greater omentum in a dog was characterized by spindle-shaped to atypical-shaped neoplastic cells with basophilic stroma in the omental adipose tissue, with cells positive for vimentin but negative for cytokeratin, S-100 protein, and alpha-smooth muscle actin [17]. A malignant peripheral nerve sheath tumor arising from the greater omentum in a dog showed spindle-shaped cells in interlacing bundles, with PAS-positive eosinophilic globules and positivity for vimentin, S-100 protein, glial fibrillary acidic protein, myelin basic protein, neuron-specific enolase, and myoglobin [18]. These immunohistochemical patterns are what separate one omental tumor from another.

Common Misconceptions About the Greater Omentum

Misconception 1: The omentum is a passive fat pad. This is the most persistent misconception. The omentum contains milky spots, which are clusters of macrophages, B lymphocytes, T lymphocytes, and plasma cells embedded in the omental tissue. Milky spots filter peritoneal fluid and respond to pathogens and foreign particles, participating in both innate and adaptive immunity within the abdominal cavity. The omentum also produces angiogenic factors that promote new blood vessel formation [3]. Calling it a fat pad ignores its immune and vascular roles.

Misconception 2: The omentum is avascular, so it can be cut freely. The omentum is highly vascular. Its arteries are contained within folds of the superficial omental wall and provide the blood supply for omentalization procedures [3]. Cutting the omentum without regard for its vascular pedicle destroys the very property that makes it surgically useful.

Misconception 3: All omenta are essentially the same across species. The canine omentum is thin and fenestrated, the feline omentum is lace-like with pores that develop after birth, the ruminant omentum is thick and divided into superficial and deep parts, and the equine omentum is relatively small and covers only the dorsal aspect of the intestines. These differences affect surgical approaches, imaging interpretation, and even the feasibility of omentalization.

Misconception 4: The omental bursa is a closed space. The omental bursa communicates with the greater peritoneal cavity through the omental foramen, and in dogs, the fenestrations in the omentum allow additional communication between the bursa and the greater peritoneal cavity, permitting fluid movement without requiring flow through the omental foramen [1]. In cats, pores that develop after birth allow ascites to pass between the omental bursa, the greater omentum, and the serosal cavity of the wall without flowing through the omental foramen [4].

Misconception 5: Omental disease always presents with obvious signs. Omental tumors often remain clinically silent for a long time because the omentum has enough space to grow before becoming symptomatic. A large, freely mobile abdominal mass may be the first detectable sign [17][18].

Misconception 6: The greater and lesser omentum are interchangeable terms. The greater omentum attaches to the greater curvature of the stomach and drapes over the intestines. The lesser omentum connects the lesser curvature of the stomach to the liver. The lesser omentum is smaller, less vascular, and not the focus of this article.

Practical Applications Beyond Surgery

The greater omentum has applications that extend beyond the operating room, and these are worth knowing because they connect anatomy to research and to clinical reasoning.

In tissue engineering, decellularized greater omentum from sheep preserved extracellular matrix and retained VEGF content, supporting its use as a scaffold for in vitro oocyte maturation [16]. This is a good example of how a structure's natural composition, rich in extracellular matrix and growth factors, can be repurposed as a biological scaffold.

In bone healing research, free nonvascularized greater omentum grafts enhanced bone healing in nonunion models. In one study, osteotomies treated with autogenous greater omentum achieved complete union, while control osteotomies failed to unite [5]. Another study found that omentum combined with adipose-derived stem cells demonstrated superior osteogenic potential in healing radial bone defects [6]. A third study showed that wrapping omentum with periosteum and adipose-derived stem cells promoted bone tissue formation in the abdominal cavity [7]. These studies are experimental, but they illustrate the omentum's capacity to support tissue regeneration.

In lymphedema research, microvascular insertion of a free omental graft reduced the magnitude of lymphedema by 38% after six months in dogs with experimental obstructive lymphedema [8]. A separate study compared four methods of omental transplantation for lymphedema relief, though results varied [9]. The variation in results is itself instructive: the omentum's benefits depend on how it is transplanted and how its vascular supply is managed.

In kidney revascularization, omentonephropexy, where the greater omentum is fixed to the kidney, promoted new vessel growth in dogs after renal artery ligation [12]. In bronchial stump regeneration, the greater omentum supported regeneration processes when placed in the pleural cavity with a vascular pedicle [13]. In brain revascularization, autografting a greater omental fragment to the brain formed functional vasculature between the omentum and the meninx vasculosa within 24 hours in experimental ischemic lesions [14][15].

For the veterinary student, the common thread is that the omentum is a mobile, vascular, immune-active tissue that can be redirected to sites of need. The experimental applications are not yet routine clinical practice, but they explain why the omentum attracts so much research attention.

Reading Omental Imaging: A Structured Approach

When you encounter an abdominal imaging study, the omentum is easy to overlook because it is normally thin and blends with surrounding fat. A structured approach prevents missed findings.

On survey radiography, look for a soft tissue opacity in the mid-abdomen, displacement of intestines, or loss of serosal detail. The omentum itself is not visible unless it is thickened or mineralized.

On ultrasonography, the normal omentum appears as a hyperechoic, striated structure. Inflammatory or neoplastic disease may appear as a hypoechoic or mixed-echogenicity mass. Ultrasound can identify omental masses, fluid accumulation, and changes in echogenicity.

On computed tomography, the omentum and omental bursa are seen in cross section. In the retrospective study of seven dogs with confirmed inflammatory or neoplastic disease of the omenta, all had fluid in the greater peritoneal cavity, and 5 of 7 also had fluid in the omental bursa. Primary suppurative inflammatory disease was present in three dogs, each with a large abscess containing central gas in either the omental vestibule or caudal omental recess. Neoplasia was present in four dogs and either arose from the omentum (hemangiosarcoma, carcinoma) or infiltrated it from an adjacent organ (splenic leiomyosarcoma, gastric adenocarcinoma). Neoplasms created mass-like tumors, infiltrative tumors, or both [2].

The practical lesson is to evaluate the omental bursa deliberately, not incidentally. Fluid in the bursa, a gas-containing abscess in the vestibule or caudal recess, or a mass arising from or infiltrating the omentum are all patterns that should change your differential diagnosis list.

Comparative Notes for the Clinical Student

The comparative table in the main article summarizes the major species differences, but a few clinical implications deserve emphasis.

In dogs, the thin, fenestrated omentum is the reason omentalization is common in this species. The omentum is easy to mobilize, has a consistent vascular pedicle, and drapes extensively over the intestines, making it ideal for wrapping anastomoses and reinforcing repairs [3][1].

In cats, the lace-like omentum with pores that develop after birth means that the omental bursa and the greater peritoneal cavity communicate more freely than in species without fenestrations. This affects how fluid distributes in the abdomen and how you interpret ascites on imaging [4].

In ruminants, the massive, fat-laden omentum divided into superficial and deep parts is a dominant feature of the ventral abdomen. Its size reflects nutritional status, and it plays a major role in abdominal organization. Surgical use of the ruminant omentum is rare, but its size makes it a significant consideration in abdominal surgery and in the interpretation of abdominal fat deposition.

In horses, the relatively small omentum covers only the dorsal aspect of the intestines and is not as fenestrated as the canine omentum. This limits its surgical utility compared with dogs and changes how omental disease would present.

For examination purposes, the key comparison is dog versus ruminant, because these represent the two extremes: thin and fenestrated versus thick and divided. If you can explain why those differences exist and what they mean clinically, you understand the comparative anatomy.

Integrating Anatomy, Function, and Clinical Practice

The greater omentum rewards a integrated approach. Its embryology explains its adult shape. Its shape explains its function. Its function explains its clinical and surgical uses. Its species differences explain why a technique that works in a dog may not translate directly to a ruminant or a horse.

When you study the greater omentum, resist the urge to memorize it as a list of facts. Instead, trace the logic: a double-layered peritoneal fold that encloses the omental bursa, communicates with the peritoneal cavity through the omental foramen and, in some species, through fenestrations, stores fat, houses milky spots for immune surveillance, adheres to inflamed tissue, and can be surgically transposed to deliver blood supply and immune support. Every clinical application, from omentalization for bone healing to CT interpretation of omental abscesses, follows from those basic properties.

That logic is what makes the greater omentum a high yield topic. It connects peritoneal anatomy, comparative species anatomy, immunology, imaging, and surgery in a single structure. Students who understand the omentum well tend to understand the peritoneum well, and that understanding pays off across abdominal medicine and surgery.

Frequently Asked Questions

What is the greater omentum?

The greater omentum is a double-layered fold of peritoneum that attaches the greater curvature of the stomach to the dorsal abdominal wall and drapes over the abdominal organs.

What does the greater omentum do?

It stores fat, supports immune surveillance through milky spots, seals wounds and adhesions, and is used surgically in omentalization procedures.

How does the greater omentum differ between dogs and ruminants?

In dogs, it is thin, fenestrated, and covers the intestines ventrally. In ruminants, it is extensive, fat-laden, and divided into superficial and deep parts.

Can the greater omentum cause disease?

Yes, though rarely. Omental torsion, herniation, and primary tumors such as myxosarcoma or malignant peripheral nerve sheath tumor can occur.

What is omentalization?

Omentalization is the surgical transposition of the greater omentum to another site to provide blood supply, immune support, and tissue coverage.

How is the greater omentum examined?

It is examined by physical examination, radiography, ultrasonography, CT, and biopsy with histopathology.

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3. Morphology of the Canine Omentum Part 1: Arterial Landmarks that Define the Omentum.
4. Scanning electron microscopic study for pore formation of the greater omentum of cats.
5. Autogenous greater omentum, as a free nonvascularized graft, enhances bone healing: an experimental nonunion model.
6. Effects of adipose tissue stem cell concurrent with greater omentum on experimental long-bone healing in dog.
7. Wrapped omentum with periosteum concurrent with adipose derived adult stem cells for bone tissue engineering in dog model.
8. Microsurgical transfer of the greater omentum in the treatment of canine obstructive lymphoedema.
9. Evaluation of the greater omentum in the treatment of experimental lymphedema.
10. Successful tracheal autotransplantation with two-stage approach using the greater omentum.
11. Improvement of tracheal autograft survival with transplantation into the greater omentum.
12. [[Kidney neovascularization by the greater omentum after pretreatment with omental angiogenic factor].](https://pubmed.ncbi.nlm.nih.gov/16018282/)
13. [[Application of greater omentum for regeneration of bronchial stump].](https://pubmed.ncbi.nlm.nih.gov/10584520/)
14. [[Microsurgical revascularization of the brain with an autograft of the greater omentum (experimental research)].](https://pubmed.ncbi.nlm.nih.gov/8209590/)
15. [[The microsurgical revascularization of the brain with an autograft of the greater omentum].](https://pubmed.ncbi.nlm.nih.gov/8268986/)
16. Three-dimensional in vitro maturation of rabbit oocytes enriched with sheep decellularized greater omentum.
17. Huge myxosarcoma arising from the greater omentum in a dog.
18. Primary malignant peripheral nerve sheath tumor with eosinophilic cytoplasmic globules arising from the greater omentum in a dog.
19. Alveolar rhabdomyosarcoma of the greater omentum in a dog.
20. Primary EGIST of the greater omentum - a rare presentation.