Section IV—Digestive and Respiratory Systems

Salivary Glands

The cat has five pairs of salivary gland, two of which— the parotid and mandibular glands—are easily observed (Figure 7.39). They have already been noted in connec­tion with the musculature of the throat.

Note that three veins come together in this region to form the external jugular vein (Figure 7.39). The most dorsal tributary, the maxillary vein, turns dorsally, crosses the anterior part of the mandibular gland, and then passes deep to the parotid gland. Lymph nodes are also present in this region and may be confused with the salivary glands, but lymph nodes are smaller and, as they lack lobules, have a smoother surface. Usually, two are present ventral to the parotid and mandibular glands. Often there seems to be only a single large node that is crossed by the linguofacial vein, but careful dissection will reveal two nodes, with the vein passing between them (Figure 7.39).

Examine the ducts of the parotid and mandibular glands. The parotid duct is the thick, whitish strand crossing over the middle part of the masseter muscle and extending toward the upper lip. Also crossing the masseter are two branches of the facial nerve, the dorsal buccal and ventral buccal branches (Figure 7.39), which are thinner than the duct. One branch lies dorsal and the other ventral to the duct. If you were indelicate in removing the skin, you may have already taken off the duct and nerves.

The mandibular duct emerges from the anteroventral part of the mandibular gland, just dorsal to the lymph node. Dissect carefully in this region. The duct will appear as a whitish strand, thinner than the parotid duct, that passes ventral to a small glandular mass.

Return to the mandibular duct. Dissect the connective tissue binding it by gently pulling the duct taut with forceps and using a needle; a #11 scalpel blade, worked backwards (i.e., the noncutting edge) also works very well. The proximal part of the duct crosses the surface of the digastric muscle as the latter turns dorsally toward the mastoid process of the skull. Continue dis­secting anteriorly to reveal the duct and digastric. Note how the duct crosses the dorsal surface of the digastric and then passes medial to it. At this point, approach the digastric from the ventral surface of the jaw. Reflect and separate it from the mylohyoid. You should easily locate the mandibular duct as it passes deep to the edge of the mylohyoid. Reflect the mylohyoid (which was bisected earlier; see page 178 and Figure 7.38) to see the duct continuing anteromedially. The lingual nerve crosses the duct anteriorly (Figure 7.57). While studying this region, review the hypoglossal nerve (see also Figure

7.38). It is larger than the mandibular duct and runs almost parallel to it, but further posteroventrally.

Oral Cavity and Pharynx

Once the salivary glands and their ducts have been examined, the oral cavity may be opened. To do this, the

FIGURE 7.39 Muscles and other structures of the neck and head of the cat in lateral view.

mandible must be spread apart and the tongue pulled ventrally. Begin by separating the jaws, as follows. Locate the position of the symphysis, which lies between the two middle incisor teeth of the mandible.

When you have passed through the symphysis, use your fingers (but be careful; the cat’s teeth are sharp) to spread the dentaries apart. One of them will probably break. Cut through the musculature and other tissues attaching to the medial surface of each dentary as far back as about the level of the lymph nodes. Then pull the tongue down through the dentaries to give you a clear view into the oral cavity.

In its broad, everyday sense, the mouth includes the structures such as the tongue and the teeth. In a strict sense, however, these structures are part of the oral cavity. The mouth is only the part between the labia (sing., labium). The oral cavity is subdivided into the vestibule, between the lips and teeth, and the oral cavity proper, bounded by the teeth anteriorly and laterally (see Figure 7.40). Posteriorly it extends to just beyond the level of the hard palate. The epithelial covering of the hard palate has roughened transverse ridges, the palatal rugae.

The tongue almost completely fills the oral cavity when the mouth is closed. Pull the tongue dorsally and note the lingual frenulum, a vertical, median flap attaching the tongue to the cavity floor (see Figure 7.40). The surface of the tongue bears various projections or papillae (Figure 7.41). The filiform papillae are most numerous. Interspersed among them are the rounded fungiform papillae. The vallate papillae are set in the posterodorsal surface of the tongue, and the foliate papillae are along the side of the posterior end of the tongue.

The paired palatine tonsils are set partially within ton­sillar fossae.

FIGURE 7.40 Head of the cat in sagittal section.

the hard palate (see Figure 7.40). The bones of the hyoid apparatus that pass to the base of the skull are embed­ded within the palatoglossal arches, as are small muscles that assist in swallowing. Extend the cuts made to open the oral cavity further posteriorly to the level of the palatoglossal arches, but do not cut through the hyoid apparatus. This provides a better view of the oral cavity and pharynx.

The pharynx is the passage common, in part, to both the digestive and respiratory systems. It extends from a line through the posterior edge of the hard palate to a line through the posterior boundary of the larynx. The anterior part of the pharynx is subdivided into dorsal and ventral portions by the soft palate, the fleshy pos­terior continuation of the hard palate. The region dorsal to the soft palate is the exclusively respiratory nasophar­ynx; that ventral to the soft palate the exclusively diges­tive oropharynx (which therefore lies posterior to the oral cavity). Posterior to the soft palate these become continuous and extend posteriorly to the Iaryngophar- ynx, which communicates with the larynx posteroven- trally and with the esophagus posterodorsally (see Figure 7.40). Make a median slit in the soft palate to

FIGURE 7.41 Tongue of the cat with blowups showing detail of the taste buds.

expose the nasopharynx. Anteriorly, it leads to the inter­nal choanae. The opening of the auditory tube (which leads to the middle ear) lies on the dorsolateral wall of the nasopharynx.

The esophagus is the muscular tube of the digestive system that extends from the laryngopharynx to the stomach. The larynx is the chamber at the anterior end of the trachea or windpipe (see Figure 7.38) and is formed from several cartilages. The opening into the larynx is the glottis, which is guarded by the epiglottis, the plough-like, cartilaginous structure at the base of the tongue. The epiglottis, which is supported by an epiglot- tal cartilage, is flipped back to cover the glottis during swallowing, so that food passes posteriorly through the laryngopharynx and into the esophagus. Using a bent probe, reflect the epiglottis forward and slide the probe posteriorly. It will pass through the glottis and enter the trachea. Palpate the trachea to verify this.

Cartilages that contribute to the larynx include the thyroid, cricoid, a pair of arytenoid cartilages, and the epiglottal cartilage just mentioned. Examine them by observing the throat region in ventral view. The thyroid is the largest cartilage. It was noted in connection with the thyrohyoid and sternothyroid muscles (see page 178 and Figures 7.38, 7.40, and Figure 7.57). The thyroid is incomplete dorsally. Anteriorly, it contacts the thyro- hyal of the hyoid apparatus. The epiglottis rests against the anteroventral part of the thyroid. The cricoid lies slightly distal to the thyroid and forms a complete ring, but is narrower ventrally than dorsally. The cricothy­roid muscle extends between these cartilages (see Figure

7.38). Separate the larynx from the surrounding tissue and observe its dorsal surface. The arytenoids (see Figure 7.40) are small cartilages that help complete the larynx dorsally, anterior to the cricoid cartilage.

Make a midventral slit through the larynx and spread it open. Two folds of tissue are present on each side of

FIGURE 7.42 Right pleural cavity of the cat in lateral and slightly ventral view.

the larynx. The vocal cords are the more posterior folds, extending between the arytenoid and thyroid cartilages (see Figure 7.40). The glottis lies between them. The false vocal cords are an accessory pair of folds, extend­ing between the arytenoid and epiglottic cartilages. They are larger, looser and lie anterior to the vocal cords.

The tracheal cartilages are C-shaped, dorsally incom­plete cartilaginous elements that keep the trachea open (see Figures 7.38 and 7.40). The esophagus lies dorsal to the trachea. To examine the rest of the respiratory system, it will be necessary to open the thorax.

The thorax is the region that contains the thoracic cavity, the anterior part of the body cavity or coelom. The thoracic cavity and abdominopelvic cavity (the pos­terior part of the coelom) are separated by a muscular partition, the diaphragm (Figure 7.42). The thoracic cavity is subdivided into three cavities: left and right pleural cavities, each containing a lung, and a median

space, the mediastinum, which contains most of the other structures that lie in or pass into the thorax (such as the heart, esophagus, trachea, and nearly all the vessels and nerves that pass through this region).

Subdivision of the thoracic cavity is due to the presence of thin epithelial membranes that line the inside wall of the cavity and the structures that lie within it. Enclosed body cavities (i.e., those that do not communicate with the exterior environment) such as the thoracic cavity are lined by serous epithelium, a membrane that produces a watery, lubricating secretion to help reduce friction between structures lined by the membrane. The serosa of the thoracic cavity is termed pleura. There are two sheets of pleura, one on the right side and the other on the left. Portions of the pleura are designated based on position. That portion that lines the inside of the cavity is parietal pleura, whereas the portion that envelops the lung is visceral pleura. As noted, these are actually formed by one continuous sheet. The parietal pleura lines the inside of the cavity, but near the sagittal midline it reflects, so that it then passes to cover the lung. Where the right- and left-side pleura meet near the midline, they form a double layer termed the mediastinal septum. The mediastinum is the space or potential space between this double layer. Various structures, as noted above, may occupy this space, but in places the mediastinal septum remains as a double-layered structure.

Open the right side of the thorax first by making a lon­gitudinal cut about 1 cm to the right of the midventral line. Begin posteriorly, at about the midpoint of the xiphihumeralis muscles. This position should be just in front of the diaphragm. You will be cutting through costal cartilages and ribs, as well as musculature, so use a strong pair of scissors. Spread open the thorax and locate the diaphragm. Now cut laterally, following along the anterior surface of the diaphragm. Extend the cut as far dorsally as you can. Spread the thorax further open and nip the dorsal end of each rib, beginning pos­teriorly. This will allow you to push open the right side of the thorax, exposing the right pleural cavity and lung (Figures 7.42-7.44).

Examine the right pleural cavity. It is really only poten­tially a cavity, because it is filled in life by the lung. Its walls are lined by parietal pleura, whereas the lung is covered by visceral pleura (Figure 7.44). The parietal pleura is clearly visible on the inside of the thorax, where it covers the musculature (including the dia­phragm) and ribs. You cut through it in exposing the thorax. In addition, the parietal pleura forms the medial wall of the pleural cavity. Between the medial walls of the right and left pleural cavities lies the mediastinum. The large bulge within it is the heart. Identify the medi­astinal septum, which occurs where the pleurae of the right and left pleural cavities meet at the midline. Lift the sternum to observe the septum, but do not damage it (Figures 7.42 and 7.43).

The right lung consists of anterior, middle, posterior, and accessory lobes. The accessory lobe passes dorsal and then medial to a large vein, the posterior vena cava. This lobe may not be apparent at first because it lies in the caval fold, a pocket-like expansion of the mediasti­nal septum just posterolateral to the heart (Figures 7.42 and 7.43). Dissect the caval fold to expose the accessory lobe and the vena cava (Figure 7.43). The lung is sus­pended in the pleural cavity by the pulmonary ligament, a flat, broad, sheet-like connective tissue. To view it, pull the posterior lobe of the lung ventrally, and examine in lateral view the region dorsal to the lobe (Figure 7.44).

Next, push the lung laterally and look between the lung and mediastinal wall. At about the middle of its medial surface, a fold of pleura will be seen passing from the lung to the mediastinal wall. This fold is part of the pul­monary ligament. Various structures (such as the pul­monary vessels and the bronchus), collectively forming the root of the lung, pass through it.

Examine the mediastinal wall just ventral to the root of the lung. You should discern a thin, whitish strand extending anteroposteriorly. This is the phrenic nerve, which lies in the mediastinum and passes to the diaphragm (Figure 7.43). Using a needle, expose the phrenic nerve and follow it posteriorly as it passes along the ventral surface of the posterior vena cava. Also follow the nerve anteriorly as it passes along the medi­astinum anterior to the heart. Break through into the mediastinum as you do so. Very delicately, clear away fat and connective tissue. The large vessel injected with blue latex is the anterior vena cava. Dorsal to it is the trachea; its cartilaginous elements should be easily recognizable. Note the vagus nerve, running anteroposteriorly along the lateral surface of the trachea. Dorsal and slightly to the left of the trachea is the esophagus (Figure 7.43). Further posteriorly, the esophagus passes through the diaphragm and into the stomach. The trachea passes posteriorly in the mediastinum and bifurcates near the level of the 6th rib into right and left primary bronchii. Postpone their study until the heart has been examined (see Section V). Each bronchus in turn branches into sec­ondary and tertiary bronchii, which further branch into bronchioles that end in the tiny respiratory structures of the lungs, the alveoli. The bronchioles and alveoli, however, cannot be easily dissected and observed grossly.

Open the left pleural cavity by making a longitudinal cut to the left of the midventral line and by repeating the procedures described above for the right plural cavity. This method produces a median flap that leaves the sternum intact. Examine the left lung, and identify the anterior, middle, and posterior lobes (Figure 7.45).

FIGURE 7.43 Deeper dissection of the right pleural cavity of the cat in lateral and slightly ventral view.

The left lung lacks an accessory lobe. Find the left phrenic nerve, just ventral to the root of the lung.

Pericardial Cavity

Cut the median strip ventrally and break through the pleura ventral to the heart so you can lift the sternum (Figure 7.45). Be careful not to injure the internal mammary vessels passing to the inside of the strip. Peel the pleura away from the heart—there may be a con­siderable layer of fat deep to the pleura. Carefully clear the fat to reveal that the heart sits in its own space, the pericardial cavity, which is enclosed by a tough layer of pericardium. Note the great vessels of the heart anteri­orly by cleaning away fat, but do not examine them at this time. Lift the apex of the heart (its posterior end) to better appreciate the extent of the accessory lobe of the right lung. With a pair of scissors, pierce the pari­etal pericardium and cut it longitudinally to expose the surface of the heart, itself covered by visceral peri­cardium (Figure 7.45).

Abdominopelvic Cavity

The abdominopelvic cavity forms the rest of the coelom posterior to the diaphragm and contains most of the

FIGURE 7.44 Deeper dissection of the right pleural cavity, with right lung lifted from dorsal wall, of the cat in lateral and slightly ventral view.

structures of the digestive and urogenital systems. Open the abdominopelvic cavity by making a longitudinal incision, using scissors, about 1 cm to the right of the midventral line. Then cut laterally along the posterior margin of the diaphragm and spread open the muscu­lar walls of the abdomen (Figure 7.46).

The abdominopelvic cavity and its contained structures are lined with serous epithelium termed peritoneum. That portion lining the walls of the cavity is parietal peri­toneum and that covering structures within the cavity is visceral peritoneum. The peritoneum actually represents two separate sheets, each of which encloses separate cav­ities in the embryo. These cavities are the right coelom and left coelom, and the embryonic gut lies between them. Near the midsagittal plane, dorsal and ventral to the embryonic gut, the peritoneum of the right and left coela lie adjacent to each other, forming a sheet-like, double layer (similar to the pleurae of the thoracic cavity) of peritoneum that is termed a mesentery. Other organs, as they arise and enlarge in the embryo, come to occupy a position between the two layers and demarcate separate sections of mesentery. Subsequently in develop­ment, most of the ventral mesentery breaks down, creat­ing a single space from the two originally separate coela. Whereas adults retain only small remnants of the ventral mesentery, nearly all of the dorsal mesentery remains. Mesenteries serve mainly to support structures in the

FIGURE 7.45 Thoracic cavity of the cat in ventral view.

abdominopelvic cavity by anchoring them to the body wall (either directly or by way of other mesenteries) and to provide a channel for the passage of nerves and vessels. Examine an inside wall of the abdominopelvic cavity to observe parietal peritoneum.

Pressed tightly to the posterior surface of the diaphragm is the liver. It is covered by visceral peritoneum. Spread apart the liver and diaphragm. This will pull taut the fal­ciform ligament (an example of ventral mesentery), which passes from the diaphragm to the liver and sepa­rates the liver into left and right halves. In overweight cats the falciform may be hard to distinguish because it is very fatty. The free ventral edge of the falciform ligament may contain a slight expansion, the round ligament. The fibers of the diaphragm converge toward its center and insert on the central tendon, which may be difficult to discern. To see it, separate the liver and diaphragm and observe the posterior surface of the diaphragm. Run a finger along the anterior surface of the diaphragm, toward its center, to the left of the heart. You should be able to make out your finger through the translucent central tendon. The coronary ligament is a very short structure between the diaphragm and liver on either side of the falciform ligament, and binds the liver tightly to the diaphragm and lateral body wall.

As noted above, the falciform ligament separates the liver into right and left halves, each of which is further subdivided (Figures 7.46 and 7.47). The right medial lobe is considerably larger than the left medial lobe. Between these lobes is the small quadrate lobe. It is sep­arated from the right medial lobe by the greenish, sac- like gall bladder. The quadrate and right lateral lobes are connected anterior to the gall bladder, and in some specimens posterior to it as well. The left lateral lobe is larger than the right lateral lobe, which is partly hidden by the right medial. Lift the right lateral lobe to reveal the caudate lobe.

The stomach is the large, light-colored, sac-like organ partially exposed posterior to the left lateral lobe of the liver (Figure 7.46). Dorsal to the edge of this lobe, near the midline, find the esophagus passing through the diaphragm and into the stomach. The stomach’s long, convex surface is the greater curvature; its shorter, concave surface is the lesser curvature. Distally, toward the right, the stomach constricts into the pyloric sphinc­ter, the muscular, valve-like separation between the stomach and the duodenum. Make a slit in the ventral wall of the stomach and note the folds or rugae that line its inner walls. The large dark organ to the left of the stomach is the spleen.

FIGURE 7.46 Abdominopelvic cavity of the cat in ventral view, with diaphragm reflected.

Posterior to the stomach, the abdominal cavity is covered ventrally by the omental bursa, a large, double-layered, fat-laced mesentery that covers the intestines like an apron (Figure 7.46). The bursa is a sac-like structure formed from the greater omentum, which is part of the dorsal mesentery. Its structure will be discussed shortly. The omental bursa extends posteriorly to the urinary bladder, the light-colored, median, sac-like organ lying ventrally. If it is empty, it resembles a collapsed balloon. The mesentery passing from the bladder to the midventral wall, just to the left of the incision made to open the abdominopelvic cavity, is the median ligament (Figure 7.46). The bladder is also supported by lateral ligaments, one on either side, that are often filled by wads of fat.

Return to the anterior part of the abdominal cavity and spread apart the stomach and liver (Figure 7.48). The mesentery extending from the lesser curvature of the stomach and duodenum to the liver is the lesser omentum (another example of ventral mesentery), which is divided into two portions. One part, the hepatogastric ligament, passes from the lesser curvature to the liver. The other, passing from the proximal part of the duodenum to the liver, is the hepatoduode­nal ligament, which appears to head toward the gall bladder. Various structures pass through the lesser omentum, including the common bile duct and the hepatic artery. These will be considered below.

FIGURE 7.47 Diagrammatic illustration of the viscera of the cat in ventral view, with liver reflected to show arrangement of intestines.

FIGURE 7.48 Abdominopelvic cavity of the cat in ventral view, with liver reflected.

The remaining mesenteries associated with the digestive system are mainly part of the dorsal mesentery. Similar subdivisions as were noted for the dogfish may be recog­nized, but they are more complex in the cat. The most conspicuous part is the greater omentum, which, as men­tioned above, forms a double-layered, sac-like omental bursa that is draped over the intestines. The greater omentum consists mainly of two sheets. The ventral sheet attaches to the greater curvature of the stomach and extends posteriorly (Figure 7.46). Near the urinary bladder the sheet curves dorsally and extends back toward the stomach as the dorsal sheet. The greater omentum is delicate and should be handled carefully. Slowly lift its posterior end away from the intestines (you will also lift the spleen) to see the dorsal sheet, which passes dorsal to the stomach (Figure 7.49). Just posterior to the stomach, the dorsal sheet contains glandular mate­rial, the tail of the pancreas, but do not examine it now. The omental bursa is this sac-like part of the greater omentum. Within it is the potential space, normally closed, known as the lesser peritoneal cavity. It commu­nicates with the peritoneal cavity via the epiploic foramen, which will be described shortly. Part of the greater omentum, the gastrosplenic ligament, stretches between the stomach and the spleen (Figure 7.46).

Return to the pyloric sphincter and trace the digestive tract distally without tearing through any mesenteries. Use Figure 7.47 in locating the structures described. The small intestine fills nearly all the abdominal cavity poste-

FIGURE 7.49 Abdominopelvic cavity of the cat in ventral view, with omental bursa and spleen reflected.

rior to the liver and stomach. It is subdivided into three parts. The duodenum is the short distal part, comprising the first loop of the small intestine. The rest of the small intestine is subdivided into the proximal jejunum and distal ileum. The small intestine is tightly coiled and ends toward the right posterior part of the abdominal cavity, where it passes into the large intestine or colon. A very short segment of the colon continues posterior to its union with the small intestine as the blind-ended cecum. The main part of the colon includes the ascending colon, which extends anteriorly on the right side, the transverse colon, which passes from right to the left, and the descending colon, which extends posteriorly on the left side. Note that the duodenum loops dorsal to the colon and that the jejunum and the rest of the small intestine pass ventrally to the rest of the colon. This position is due to rotation of the intestine during embryonic development. The colon continues into the rectum, which lies in the pelvic canal and leads to the anus.

Lift the coils of the small intestine to reveal the descend­ing colon, extending posteriorly, on the left side of the abdominopelvic cavity (Figure 7.50). Pull it gently to see that it is suspended by the mesocolon, which has a broad attachment to the middorsal body wall. The rectum is supported by the mesorectum.

The duodenum extends posteriorly along the right side of the abdominopelvic cavity and then turns anterome- dially. Lift the duodenum to reveal the caudate lobe of the liver. Gently tug the duodenum ventrally and note that it is supported by the mesoduodenum (Figure 7.50), within which is the head of the pancreas. The duode­nocolic ligament, a small, triangular mesentary with a free posterior margin, extends between the mesoduode­num and mesocolon.

Examine the caudate lobe of the liver. The large oval swelling posterior to it is the right kidney. Lift the pos-

FIGURE 7.50 Abdominopelvic cavity of the cat in ventral view, with liver, intestines, and pancreas reflected.

terior end of the caudate lobe. The hepatorenal liga­ment, a small triangular mesentery, extends between the posteromedial end of the caudate lobe and the peri­toneum covering the kidney (Figure 7.50).

The jejuneum and ileum, the distal parts of the small intestine, are supported by the mesentery proper (Figure 7.49). The mesentery has only a restricted attachment to the middorsal body wall, but it fans out to support all but the duodenal portion of the small intestine. Gently spread the coils of the intestine to see the mesen­tery clearly. Note the small mesenteric lymph nodes and the vessels within it.

The gall bladder is a sac used for bile storage. The various ducts associated with the gall bladder and liver are greenish, like the gall bladder itself. The ducts pass to the duodenum through the lesser omentum. To view these structures, carefully dissect the lesser omentum near the caudate lobe of the liver and the gall bladder. Do not injure the vessels that are also present in the lesser omentum. The cystic duct (Figure 7.58) is the duct of the gall bladder. It extends a short distance toward the duodenum before it is joined by usually two hepatic ducts from the liver. The confluence of the cystic and hepatic ducts forms the common bile duct, which con­tinues to the duodenum. Follow the common bile duct to its entrance into the duodenum.

Return to the ventral sheet of the omental bursa and cut across its attachment to the stomach. Examine the dorsal sheet and distinguish the tail of the pancreas (Figure 7.49). Follow the tail toward the right, noting that it is partly tucked behind the stomach and then curves ventrally along the medial side of the duodenum, within the mesoduodenum, as the head of the pancreas.

The pancreas consists of endocrine and exocrine glandu­lar tissue. Of the two, the exocrine portion makes by far the largest part (the endocrine portion consists of small pockets of tissue termed islets of Langerhans, which cannot be distinguished grossly). The pancreas has two ducts that carry its exocrine secretion to the duodenum. The main pancreatic duct passes, together with the bile duct, to the duodenum. Find it in this region and trace it for a short distance into the head of the pancreas by care­fully scraping away pancreatic tissue.

Key Terms: Digestive and Respiratory Systems

abdominopelvic cavity anterior vena cava anus

arytenoid cartilages ascending colon auditory tube bronchus: primary, secondary, tertiary (plur., bronchii) caval fold

cecum

central tendon colon

common bile duct coronary ligament cricoid cartilage cricothyroid muscle cystic duct descending colon diaphragm digastric muscle duodenocolic ligament duodenum epiglottal cartilage epiglottis epiploic foramen esophagus facial nerve falciform ligament false vocal cords filiform papillae foliate papillae fungiform papillae

gall bladder gastrosplenic ligament glottis greater curvature hepatic artery hepatic ducts hepatoduodenal ligament hepatogastric ligament hepatorenal ligament ileum internal choanae intestines jejunum kidney labia (sing., labium)

(lips) laryngopharynx larynx lateral ligaments lesser curvature lesser omentum lesser peritoneal cavity lingual frenulum lingual nerve linguofacial vein

(anterior facial vein) liver: caudate lobe, left lateral lobe, right lateral lobe, right medial lobe, left medial lobe

lung: anterior, middle, posterior, accessory lobes