Anatomy of Thoracic and Abdominal Cavities

The space within the chest containing organs like the lungs, heart, and parts of the esophagus and trachea.

The space within the abdomen, below the diaphragm, holding organs like the stomach, intestines, liver, and spleen.

The space within the pelvis, at the base of the abdomen, containing organs like the rectum, anal canal, and parts of the urinary and reproductive systems.

The dome-shaped muscle separating the thoracic and abdominal cavities. It plays a crucial role in breathing.

A thin, transparent membrane lining the body cavities and covering organs within them.

The layer of serous membrane lining the walls of the body cavities.

The layer of serous membrane covering the organs within the body cavities.

The intermediate layer of serous membrane connecting the parietal and visceral layers; named after the organ it's attached to.

Thick, cornified epithelium of the oral cavity that provides protection for ruminants, allowing them to consume dry and rough food.

A tough, yielding cushion on the roof of the mouth in ruminants that replaces upper incisor teeth.

The roof of the mouth, which consists of a bony part and a membranous part.

A groove that runs along the middle of the hard palate in ruminants.

Transverse ridges on the hard palate that aid in chewing and swallowing.

A small, raised area on the hard palate.

The part of the oral cavity that includes the tongue and lower teeth.

The area at the front of the tongue that connects to the floor of the mouth.

The flexible, muscular organ in the mouth that plays a crucial role in feeding, tasting, and swallowing.

The free tip of the tongue.

The largest part of the tongue.

The back part of the tongue, facing the soft palate.

The top surface of the tongue, opposite the palate.

Small projections on the surface of the tongue that aid in mechanical processing of food.

Small projections on the surface of the tongue that contain taste buds.

Serous membranes are thin, smooth, and moist linings that cover internal organs and line body cavities. They secrete a lubricating fluid called serous fluid.

Serous membranes act as a suspension mechanism, holding organs in place within their cavities.

The serous fluid lubricates the surfaces of serous membranes, reducing friction and allowing organs to move smoothly.

Serous membranes provide a pathway for arteries and nerves to reach and innervate the organs they surround.

The peritoneum is a specific serous membrane that lines the abdominal cavity and covers the abdominal organs.

The parietal peritoneum lines the abdominal wall, while the visceral peritoneum covers the abdominal organs.

The peritoneum forms folds that connect various organs and structures within the abdomen. These folds are called omentum, mesentery, and ligaments.

The greater omentum is a large fold of peritoneum that connects the stomach to the dorsal abdominal wall.

The lesser omentum is a smaller fold of peritoneum that connects the stomach to the ventral abdominal wall.

The mesentery is a fold of peritoneum that connects the intestines to the dorsal abdominal wall.

The mesoduodenum is a specific mesentery that connects the duodenum to the dorsal abdominal wall.

The mesocolon is a mesentery that connects the colon to the dorsal abdominal wall.

The mesorectum is a mesentery that connects the rectum to the dorsal abdominal wall.

Ligaments are folds of peritoneum that connect organs to each other. They help keep organs in the correct position.

The digestive system is a complex group of organs responsible for breaking down food, absorbing nutrients, and eliminating waste.

A thin, cord-like structure extending from the tip to the root of the tongue, providing structural support and helping with movement.

A large, rounded projection on the dorsal surface of the tongue, near its root.

Small, conical projections on the dorsal surface of the tongue, responsible for the rough texture.

Larger, mushroom-shaped projections on the tongue, containing taste buds for perceiving sweetness, saltiness, sourness, and bitterness.

Large, circular projections on the caudal part of the tongue, containing taste buds for perceiving flavors.

A group of muscles that originate and insert within the tongue, responsible for its shape and movement.

A group of muscles that originate outside the tongue and insert into it, controlling its position and movements.

Fan-shaped muscle originating from the mandible and extending to the hyoid bone, responsible for drawing the tongue forward and downward.

Rectangular muscle originating from the hyoid bone and extending into the tongue's root, responsible for drawing the tongue backward.

Slender muscle originating from the stylohyoid bone and extending to the tongue's apex, responsible for shortening the tongue and elevating the apex.

A U-shaped bone located in the neck, supporting the tongue and providing attachment for muscles involved in swallowing and speech.

A group of muscles attached to the hyoid bone, responsible for its movements and indirectly supporting the tongue.

Flat muscle bridging the intermandibular space, supporting the tongue and helping with swallowing.

Long, spindle-shaped muscle in the intermandibular space, drawing the hyoid bone and tongue forward.

A muscle that originates from the manubrium sterni and inserts on the basihyoid bone, pulling the hyoid bone, root of tongue, and larynx caudally.

A thin muscle originating from the subscapular fascia in horses and pigs, and the deep fascia of the neck in ruminants (absent in carnivores). It inserts on the basihyoid bone, drawing the hyoid bone and larynx caudally.

A muscle plate located under the hyoglossus, situated between the keratohyoid and thyrohyoid bones. It originates from the rostral border of the thyrohyoid and inserts on the caudal border of the keratohyoid and stylohyoid. Its action is to move the larynx rostrodorsally.

Small muscles connecting the keratohyoid bones, linked by an indistinct median tendon. They contribute to hyoid bone movement.

A small muscle originating from the paracondylar (jugular) process and inserting on the dorsal end of the stylohyoid bone. It moves the stylohyoid, root of the tongue, and larynx caudoventrally.

The tendon of the stylohyoideus muscle in a horse is perforated (has a hole).

A large salivary gland located near the ear in horses and cattle, with a shape that varies between species.

A large, long, curved salivary gland located caudal and medial to the mandibular angle in most species.

A salivary gland that typically has two distinct parts: polystomatic and monostomatic, located in the region of the mandible.

The function of saliva is to moisten food, aid in bolus formation, lubricate swallowing, and initiate starch digestion through the enzyme ptyalin.

Major salivary glands, such as parotid, mandibular, and sublingual glands, contribute significantly to saliva production.

Minor salivary glands, such as labial, buccal, and lingual glands, provide local moisture and lubrication.

The parotid duct, which carries saliva from the parotid gland, opens into the buccal vestibule.

The mandibular duct, which carries saliva from the mandibular gland, opens into the buccal vestibule.

The sublingual duct, which carries saliva from the sublingual gland, opens into the buccal vestibule.

The mobile, muscular shelf at the back of the mouth that continues the hard palate, separating the nasal and oral passages during swallowing.

Two arches connecting the soft palate to the pharynx and tongue, crucial for guiding food and air.

The space behind the mouth that connects the nasal cavity and oral cavity to the esophagus and larynx, respectively.

The dorsal part of the pharynx, located above the soft palate, connects the nasal cavity to the larynx.

The ventral part of the pharynx, below the soft palate, connects the oral cavity to the larynx.

The caudal part of the pharynx, below the epiglottis, connects the oropharynx to the larynx.

Muscles surrounding the pharynx, responsible for swallowing and preventing food from entering the respiratory tract.

A muscle that originates from the free border of the palatine bone and extends to the caudal border of the soft palate, shortening the soft palate.

A muscle that originates from the temporal bone and inserts into the aponeurosis of the soft palate, raising the soft palate.

A muscle that originates from the temporal bone and inserts into the soft palate, raising the soft palate towards the cranium.

A valve that prevents food from entering the respiratory tract.

The lining of the pharynx, composed of respiratory epithelium in the nasopharynx and stratified squamous epithelium in the other parts.

A specialized tissue found in the roof of the nasopharynx, involved in immune function.

The openings in the lateral wall of the nasopharynx that connect to the middle ear.

The difficulty of breathing through the mouth in horses because the long soft palate blocks the airway.

A pair of openings at the top of the pharynx that connect it to the nasal cavity, allowing for the passage of air during breathing.

Paired openings on the sides of the pharynx that connect to the middle ear. They allow for the equalization of air pressure between the middle ear and the atmosphere, preventing damage to the eardrum.

The opening between the oral cavity and the oropharynx, which allows for the passage of food and air during breathing.

The opening between the oropharynx and the larynx, which allows for the passage of air during breathing.

The opening at the caudal end of the laryngopharynx that connects the oropharynx to the esophagus, allowing for the passage of food to the stomach.

A lymphatic tissue mass located at the root of the tongue, forming part of the immune system.

A lymphatic tissue mass located on the lateral wall of the oropharynx, forming part of the immune system.

A lymphatic tissue mass located on the base of the epiglottis, forming part of the immune system.

A lymphatic tissue mass located at the lateral wall of the auditory tube opening, forming part of the immune system.

A muscle that helps dilate the pharynx during swallowing.

These muscles help constrict the pharynx, moving food down the throat.

A group of muscles that assist in the chewing process.

A muscular tube that connects the pharynx to the stomach, transporting food from the mouth to the stomach during swallowing.

The middle section of the esophagus, located within the chest cavity.

A muscular sac that receives food from the esophagus, stores it, and begins digestion with gastric juices.

The part of the stomach closest to the esophagus.

The muscular ring controlling the opening between the esophagus and stomach, preventing food from going back up.

The part of the stomach closest to the duodenum (small intestine).

The muscular ring controlling the opening between the stomach and duodenum, regulating food passage.

The upper, dome-shaped part of the stomach near the cardia.

The main central region of the stomach, between the fundus and pylorus.

The lower part of the stomach near the pylorus.

A stomach with a single chamber, found in carnivores (like dogs) and horses.

A stomach with multiple chambers, found in ruminants (like cows, sheep, and goats).

The largest compartment of a ruminant stomach, where microbial digestion occurs.

The second compartment of a ruminant stomach, shaped like a honeycomb, where food is further broken down.

The third compartment of a ruminant stomach, containing numerous folds that further grind and absorb water from food.

The fourth compartment of a ruminant stomach, equivalent to the glandular stomach of other animals, where enzymatic digestion takes place.

The first three compartments of a ruminant stomach (rumen, reticulum, and omasum), where microbial digestion predominates.

A groove that extends from the esophagus to the abomasum in young ruminants, allowing milk to bypass the other stomach compartments.

A double mucous fold that controls the closure of the omaso-abomasal opening, regulating the flow of food from the omasum to the abomasum.

A circular process arising from the inner side of the lesser curvature of the abomasum, controlling the pyloric opening.

The first part of the small intestine, connecting the pylorus to the jejunum, and playing a crucial role in further digestion with the help of pancreatic and bile secretions.

The middle part of the small intestine, responsible for the majority of nutrient absorption.

The last part of the small intestine, connecting the jejunum to the large intestine, and responsible for final nutrient absorption before waste is passed on.

The first part of the large intestine, responsible for water absorption and fermentation, connecting the ileum to the colon.

The main part of the large intestine, responsible for water absorption and waste compaction, connecting the cecum to the rectum.

The final part of the large intestine, storing waste before elimination through the anus.

The openings that connect different compartments of the ruminant stomach, controlling the passage of food between them.

The process by which milk is directly transported from the esophagus to the abomasum in newborn ruminants, bypassing other stomach compartments.

The ascending colon in ruminants forms three loops: a proximal loop (S-shaped), a spiral loop (with centripetal and centrifugal turns), and a distal loop.

The proximal loop of the ascending colon in ruminants has an S-shape.

The spiral loop in ruminants consists of centripetal turns (coils) spiraling towards the center, a central flexure, and centrifugal turns spiraling away from the center.

The number of centripetal and centrifugal turns in the spiral loop varies between species. Oxen have two of each, sheep have three, and goats have four.

The distal loop of the ascending colon in ruminants connects the spiral loop to the transverse colon.

The centrifugal turns in small ruminants have a pearl-string appearance due to the segmented contents characteristic of their feces.

The transverse colon is a short part that crosses the midline from right to left, cranial to the cranial mesenteric artery.

The descending colon begins from the transverse colon and extends caudally, connecting to the sigmoid colon and rectum.

The sigmoid colon is a part of the descending colon with a sigmoid shape.

The rectum is the final part of the large intestine, passing caudally and connecting to the anal canal.

The rectal ampulla is a dilation of the rectum before joining the anal canal.

The anal canal connects the rectum to the external environment.

The anorectal line marks the connection of the anal canal with the rectum.

The anocutaneous line marks the connection of the anal canal with the skin.

Anal sacs are small reservoirs in the anal canal of dogs that secrete a foul-smelling substance, important for territorial marking.

A long and wide pouch in horses that takes on a comma-like shape. It's critical for digestion in herbivores.

A structure found in horses that has a venous plexus and is responsible for partially telescoping the ileum into the cecum.

A long and coiled structure in horses that forms two large loops occupying the lower half of the abdominal cavity. It aids in water absorption and fermentation.

A structure that aids in increasing the surface area of the cecum and colon in horses. It makes the cecum and colon look sacculated.

The part of the colon in horses that passes from right to left in front of the cranial mesenteric artery. It's relatively short compared to the ascending colon.

A fold of peritoneum that suspends the jejunum. It's particularly long in dogs and horses, allowing for extensive motility.

In the dog, jejunal loops are large and few in number, lying between the stomach and pelvic inlet. They are covered by the greater omentum.

The horse's jejunum is very long and lies in the left dorsal part of the abdominal cavity, mingling with the descending colon. Its length allows for wide movement and can cause complications.

The ascending colon of the dog forms a simple U-shaped loop. It's divided into three parts: ascending, transverse, and descending.

The part of the colon in dogs that passes caudally on the left side. It's the final part of the colon before it connects to the rectum.

The horse's colon consists of three parts: ascending, transverse, and descending. The ascending colon is the longest and most distinctive due to its large diameter and multiple loops

A structure in the horse's colon that marks the beginning of the upper loop of the ascending colon. It's formed above the sternal flexure.

The largest gland in the body, responsible for numerous functions like bile production, detoxification, and nutrient storage.

The liver's weight decreases with age and increases proportionally with the amount of food stored.

The liver's coloration is influenced by blood content, species, and age.

A depression on the visceral surface of the liver through which the hepatic artery, portal vein, and hepatic ducts pass.

The right lobe of the liver is undivided in horses and ruminants, but divided into lateral and medial parts in dogs.

The left lobe of the liver is divided into lateral and medial parts in horses, undivided in ruminants, and divided in dogs.

The caudate process is undivided in horses, divided into large and small parts in ruminants, and divided in dogs.

The quadrate lobe is fissured in horses, normal in ruminants, and large and tongue-shaped in dogs.

The liver in horses sits in the right half of the abdominal cavity, while in ruminants, it's more centrally located.

Horses lack a gall bladder, while other species have one.

Bile ductules merge to form hepatic ducts, which then combine to form the common hepatic duct. This duct joins with the cystic duct to form the bile duct, which opens into the duodenum.

The gall bladder in ruminants protrudes ventrally beyond the liver's ventral border, while in dogs, it's visible from both surfaces.

The hepatic portal vein contributes to the V-shaped structure of the pancreas, with varying limb lengths in different species.

The pancreas has a chief pancreatic duct that opens with the bile duct into the duodenum, and an accessory pancreatic duct that opens separately.

In horses, the left limb of the pancreas is long due to the large cecum, while the right limb is short.