Experiments on the gross anatomy of the digestive system
Experiments on the gross anatomy of the digestive system
1. Understand the components and gross anatomy of the digestive system.
2. Observe the structure of the oral cavity and learn about the structure and types of teeth, the morphological characteristics of the papillae of the tongue and salivary glands, and the ductal openings.
3. Identify the location and division of the pharynx and the morphological features of the esophagus.
4. Observe the main features of the morphological structure of the stomach, small intestine and large intestine.
5. Observe the main morphological features of the liver and pancreas.
6. Understand the concept of peritoneal cavity, peritoneum, mesentery and omentum.
Operation method
Experiments on the gross anatomy of the digestive system
Materials and Instruments
Head median sagittal specimen Salivary gland dissection specimen Abdominal dissection specimen Tongue Esophagus Stomach Isolated dissection specimens of small and large intestine Liver Pancreas Move I. Oral For more product details, please visit Aladdin Scientific website.
Dissecting forceps Dissecting tray Magnifying glass Tongue depressor Mirror
The following structures were observed and recognized with a median sagittal cross-section specimen of the head, or with a mirror against one's own mouth: the anterior borders of the oral cavity were the upper and lower lips, the posterior borders communicating with the pharynx; the two lateral walls were the cheeks; the upper wall was the palate, which was divided into the anterior hard palate and the posterior soft palate; and the lower wall was the floor of the oral cavity, which was occupied by the tongue. The inner surface of the oral cavity is covered with mucous membrane. The oral cavity can be subdivided into two parts, the oral vestibule and the intrinsic oral cavity, which are bounded by what?
Identify incisors, cuspids, premolars and molars and count the number of each and write the tooth pattern. Each tooth can be divided into three parts: crown, neck and root.
2. lingual position Located at the floor of the mouth. On the dorsal surface of the tongue, a herringbone-shaped groove divides the tongue into the posterior 1/3 of the root, the anterior 2/3 of the body, and the tip of the tongue. In vivo observation, there are many mucosal projections on the dorsal surface of the tongue called lingual papillae. At the tip of the tongue and the back of the tongue body, there are many white filiform papillae. Between the filamentous papillae, there are scattered reddish color and a small number of bacterial papillae. Observed with tongue immersion specimens, also visible in front of the boundary groove there are seven to nine round papillae, called outline papillae, arranged in an inverted "V" shape. In the posterior part of the lateral margins near the tongue, there are fold-like foliate papillae, about 6 to 8 on each side, and the pediatric ones are clearer. The root of the tongue has many bean-shaped mounds, for the tongue tonsils Hugh (lymphatic tissue), the root of the tongue backward connected to the epiglottis.
There is a fold in the middle of the underside of the tongue that is connected to the floor of the mouth, called the tongue tie. On either side of the root of the tongue tie is a pair of rounded projections called the sublingual caruncles (which are the common openings for the ducts of the submaxillary and sublingual glands).
3. Palate In vivo, the hard and soft palates are distinguished. In the center of the free edge of the soft palate there is a rounded downward protrusion called the palatine. The palate is flanked by two pairs of arch-shaped folds: anteriorly, the palatoglossal arch, which continues down to the base of the tongue; and posteriorly, the constricted pharyngeal arch, which migrates to the pharyngeal wall. The crypt between the two arches contains the palatine tonsils. The posterior border of the soft palate, the palatoglossal arches on both sides, and the root of the tongue together form the pharyngeal isthmus, which communicates with the pharynx.
Salivary glands The parotid, submandibular and sublingual glands were observed with anatomical specimens from the head that had exposed the salivary glands. The parotid gland is triangular in shape, below the front of the ear, located subcutaneously, and its duct opens through the buccal muscle into the buccal mucosa directly in front of the maxillary second molar. The submaxillary gland is oval in shape. It is located on the internal surface of the mandible. The sublingual gland is flat and oval in shape and is located on the deep surface of the oral mucosa under the tongue. The submandibular gland and the large duct of the sublingual gland open together in the sublingual caruncle.
Pharynx
Observed with a median sagittal section specimen of the head. The pharynx is located posterior to the nasal cavity, oral cavity, and larynx, and is funnel-shaped, with a slightly flattened anterior-posterior muscular duct. The upper part of the pharynx is connected to the base of the skull, and the lower part of the pharynx continues at the height of the lower edge of the sixth cervical vertebra as the esophagus. The pharynx has almost no anterior wall and communicates with the nasal, oral, and laryngeal cavities through the postnasal aperture, the isthmus of the pharynx, and the laryngeal opening, respectively. The pharynx can be divided into nasopharynx, oropharynx, and laryngopharynx based on its access to these parts.
1. Nasopharynx is the upper part of the pharynx, which is equivalent to the rear of the inferior turbinate on its lateral wall, and there is a pharyngopharyngeal opening on the left and right. This mouth is connected to the tympanic chamber through the Eustachian tube. The posterior wall of the nasopharynx has heaps of more developed lymphoid tissue, called pharyngeal tonsils, in the pharyngeal tube pharyngeal opening around the mucosa also has lymphoid tissue, for the pharyngeal tonsils.
2. Oropharynx is the middle part of the pharynx, behind the isthmus of the pharynx, between the soft palate, the root of the tongue and the upper edge of the epiglottis. There are palatine tonsils on both walls of the oropharynx.
3. Laryngopharynx is the lower part of the pharynx, which is narrower. The laryngopharynx is directly in front of the laryngeal opening.
Esophagus
Observe the morphology, location and segmentation of the esophagus with an esophageal specimen. The esophagus is a muscular tube that runs anterior to the spine and posterior to the trachea. The upper end is connected to the laryngopharynx, and the lower end enters the abdominal cavity through the esophageal hiatus of the septum and continues into the cardia of the stomach. The esophagus can be divided into cervical, thoracic, and abdominal segments, with a total length of 25 cm. There are three stenoses: the first one is at the beginning of the esophagus (flat at the lower edge of the 6th cervical vertebra); the second one is at the intersection of the esophagus and the left bronchus (equivalent to the plane of the angle of the sternum); and the third one is at the esophageal fissure (flat at the body of the 10th thoracic vertebra).
Stomach
The position, division and shape of the stomach were observed with abdominal anatomical specimens and isolated specimens of the stomach. The upper end of the stomach is connected to the abdominal section of the esophagus, and the lower end is connected to the duodenum. Most of the stomach (about 3/4) is located in the left quarter rib area, and a small portion (about 1/4) is located in the supra-abdominal area, and the position, size, and form of the stomach may change with its filling, emptying, and change of body position. It may also vary according to age, sex and body size.
The entrance to the stomach is called the cardia and the exit is called the pylorus. The stomach can be divided into four parts: the part near the cardia is called the cardia; the part of the cardia that expands to the upper left is called the fundus; the middle part of the stomach is called the body of the stomach; and the lower part of the stomach that connects to the duodenum is called the pylorus. The stomach is subdivided into the anterior and posterior walls, the upper and lower rims. The short upper rim is called the lesser curvature of the stomach and the longer lower rim is called the greater curvature of the stomach.
In the dissected specimen of the human stomach, there are many small grooves on the mucosal surface of the stomach intertwined into a mesh, dividing the mucosa into many small cells for the gastric region. Observed with a magnifying glass, there are many small gastric concavities on the surface of each gastric region. The mucosa of the stomach formed several longitudinal folds at the gastric notches, and the other parts were irregular folds. At the pylorus, the mucosa forms an annular pyloric valve due to the well-developed pyloric sphincter.
V. Small intestine
The location, division and mucosal folds of the small intestine were observed with abdominal dissection specimens and dissected specimens from various parts of the small intestine. The small intestine is the longest section of the alimentary canal, with a total length of 5-7m, coiled in the middle and lower part of the abdominal cavity. The small intestine is divided into three parts: duodenum, jejunum and ileum. The jejunum and ileum are fixed to the posterior abdominal wall by the mesentery and have greater mobility.
The length of the eleventh finger intestine is equivalent to my 12 fingers, was horseshoe-shaped, wrapped around the head of the pancreas, divided into the upper part, descending, horizontal and ascending part. The upper part from the flat 12th thoracic vertebrae and the 1st lumbar vertebrae intersect the plane of the pylorus, towards the right posterior, a sharp turn into the descending part; descending part of the body of the 2nd to 3rd lumbar vertebrae immediately to the right, along the medial edge of the right kidney descending, descending part of the left side of the head of the pancreas; horizontal part of the left side across the 3rd lumbar vertebrae in the 3rd lumbar vertebrae on the left side of the continuation in the ascending part; ascending part of the upward to the 2nd lumbar vertebrae to the left side of the front of the bottom of the sharp transfer behavior of the jejunum.
The duodenum was peritoneal only at the pylorus and near the duodenal-jejunal junction; the rest of the duodenum was located in the posterior part of the peritoneum. Observation of the dissected duodenal specimen showed that the mucosa formed many circular folds, and dense fine villi were also visible with magnification. The mucosa of the posterior medial wall of the descending portion had a longitudinal fold, the lower end of which formed a rounded protuberance, the duodenal macropapilla. There is a small hole at the top of the duodenal macropapilla, which is the common opening of the common bile duct and the pancreatic duct. Sometimes a small papilla is also visible above the greater duodenal papilla, which is the opening of the parapancreatic duct.
2. Jejunum and ileum The jejunum and ileum are peritoneal, fixed to the posterior abdominal wall by the peritoneal formation of the mesentery. The edge of the intestinal tube connected to the mesentery is the edge of the mesentery. There is no clear boundary between the jejunum and ileum, and the jejunum and ileum are tortuous and coiled into a number of ileocecal folds. The jejunum accounts for 2/5 of the total length of the small intestine, located in the left lateral abdominal area and umbilical area, with thicker walls, larger diameter, and richer distribution of blood vessels, and is redder in color in vivo; the ileum accounts for 3/5 of the small intestine, located in the umbilical area and right inguinal area, with thin walls, smaller diameter, and fewer blood vessels, and is lighter in color in vivo.
Observation of the dissected jejunum, ileum specimens, visible mucosal surface to form many circular folds, careful observation can be seen on the surface of the villi. Generally, the annular folds of the jejunum are dense and high, and the annular folds of the ileum are sparse and low. The mucosa of the intestinal wall can also be visualized with scattered isolated lymph nodes and long oval shaped aggregated lymph nodes when viewed in the light. Collected lymph nodes are more common in the lower part of the ileum.
Sixth, large intestine
The location, division, morphology and mucosal folds of the large intestine were observed with the anatomical specimen and the dissected specimen of each part of the large intestine. The total length of about 1.5 m, divided into the cecum, colon and rectum three parts. In addition to the appendix and rectum, the external morphology of the large intestine has three characteristics: first, the longitudinal muscle of the intestinal wall is thickened to form three colonic bands parallel to the longitudinal axis of the large intestine; second, the three colonic bands are shorter than the length of the intestinal tube so that the intestinal tube is wrinkled to form a sac-like colonic pouch; third, there is a fat protrusion of varying sizes in the vicinity of the colonic bands, which is called intestinal fat droop.
1. The cecum is located in the right iliac fossa, and is a cecum that protrudes downward. The lower end of the appendix (earthworm), the length of the appendix varies from person to person, generally 7 to 9 cm, most of them have curved. The end of the ileum protrudes into the cecum, and its opening is the ileocecal orifice, and there is a semilunar fold for the ileocecal valve at the upper and lower edges of the orifice.
2. Colon Around the small intestine, shaped like a box, between the cecum and rectum, can be divided into four parts: ascending colon, transverse colon, descending colon and sigmoid colon. The ascending colon is a continuation of the cecum, which rises up to the right lobe of the liver below, and curves to the left to act as the transverse colon. The transverse colon is attached to the posterior abdominal wall by the mesentery. The transverse colon moves leftward to the lower part of the spleen, then turns and moves downward to the descending colon, which moves downward to the left iliac fossa to the sigmoid colon. The sigmoid colon is anchored to the posterior pelvic wall by the mesentery and moves to the rectum at the third sacral vertebra.
The rectum is located in the pelvic cavity, joins the sigmoid colon at its upper end, and passes through the pelvic septum to the anus. Observation of the dissected rectum specimen, can be seen on the mucosa of the lower rectum there are 6 to 10 longitudinal folds, called the anal column. There are half-moon folds connecting the lower end of each column, and these folds are called anal valves. Between the anal valve and the lower end of the neighboring anal column, a small fossa is enclosed for the anal sinus. The anal valve and the lower end of the anal column together form a circular line for the dentate line. Below the line there is a smooth area for the anal comb (hemorrhoidal ring), moving downward into the skin.
VII. Liver and gallbladder
1. Liver Observed with abdominal dissection specimens and specimens of isolated liver. The liver fills most of the entire right quaternary and supra-abdominal regions, with a small portion of its left end reaching the left quaternary region. The liver is wedge-shaped, with a thick and rounded right end and a thin left end; it can be divided into upper and lower surfaces, with anterior, posterior, left and right margins. The upper bulge is in contact with the diaphragm, which is called the diaphragmatic surface; on its surface, it is divided into the left and right lobes by the sickle ligament, with the left lobe being small and thin and the right lobe being large and thick, and the lower part is in contact with the organs, which is called the visceral surface. Observation of the visceral surface of the liver reveals a transverse depression in the center of the porta hepatis, and attention is paid to distinguish the hepatic arteries, hepatic ducts, hepatic portal veins, and nerves entering and exiting therefrom. There is a longitudinal sulcus on each side of the porta hepatis, and the left longitudinal sulcus contains the hepatic round ligament (umbilical vein cord) and the venous ligament (venous conduit). The hepatic round ligament travels within the free edge of the hepatic falciform ligament to the umbilicus. The right longitudinal sulcus contains the gallbladder and the inferior vena cava. The dirty surface of the liver is divided by the above transverse sulcus and the left and right longitudinal sulci into a left lobe on the left side of the left longitudinal sulcus, a right lobe on the right side of the right longitudinal sulcus, a caudate lobe behind the stomata, between the left and right longitudinal sulcus, and a square lobe before the stomata, between the left and right longitudinal sulcus, and a fovea on the right side of the anterior border of the liver, which houses the gallbladder.
Gallbladder The gallbladder is attached to the upper part of the right longitudinal sulcus below the liver in the fossa of the gallbladder, which is connected to the liver by connective tissue and can be easily separated. The gallbladder is pear-shaped and can be divided into the base, body, neck and cystic duct. The cystic duct joins the common hepatic duct to form the common bile duct, which joins the pancreatic duct and opens into the greater duodenal papilla.
Pancreas
Observe the abdominal anatomical specimen (with the transverse colon removed) and the isolated anatomical specimen of the pancreas. The pancreas is posterior to the stomach and lies transversely in the upper part of the posterior wall of the abdominal cavity. The pancreas is soft and dense, shaped like an elongated three-pronged column, and can be divided into three parts: head, body, and tail. The head of the pancreas is encircled in the "C"-shaped groove of the duodenum (left side of the descending duodenum), the body of the pancreas accounts for most of the pancreas, and the tail of the pancreas reaches the splenic hilum. The pancreatic duct joins the common bile duct and opens into the greater papilla of the duodenum; sometimes there is a parapancreatic duct, which opens separately into the lesser papilla of the duodenum.
IX. Peritoneum and peritoneal cavity
Observe with a cadaveric specimen with the abdominal cavity cut open. Peritoneum is a layer of smooth plasma membrane covering the abdominal wall, pelvic wall, abdominal cavity and pelvic organs surface. The peritoneum can be divided into the wall peritoneum and the visceral peritoneum. The wall peritoneum lines the inner surface of the abdominal and pelvic walls; the dirty peritoneum covers the surface of the organs. The narrow space between the wall and the dirty peritoneum is the peritoneal cavity, which contains a small amount of plasma.
In the jejunum, ileum, transverse colon, sigmoid colon and the abdominal wall there is a peritoneal connection between the peritoneum, that is, for the mesentery between the stomach and the transverse colon of the peritoneum is rich in fat, which is downward in the shape of an apron in front of the transverse colon and the small intestine covered with the greater omentum.