7th-the Alimentary System

The Alimentary System Xu Jin Department of Anatomy Chongqing Medical University

Introduction to Splanchnology Splanchnology is dealing with the study of visceral organs

which can be divided into the alimentary, respiratory, urinary and genital systems. The common features of the viscera

Most

organs of the viscera are situated in the thoracic and abdomianl cavities. Almost every system contains two principal constiuents, tubular canal and a series of non-tubular, so-called parenchymatous organs. The wall of the tubular tract, for example (digestive canal ) consists of 4 layers. i. e. mucosa, submucosa, two muscular coats (an outer longitudinal one and inner circular one ) and serosa (adventitia) From the functional point of view, all of the 4 systems are related to metabolism and maintaining the life of species.

The reference line and abdominal regions

Reference line (refer to the textbook)

Nine-area division

The alimentary system Formation

alimentary canal

upper alimentary canal (mouth---duodenum) lower alimentary canal (jejunum---anus)

digestive glands

small ones: such as glands of mucosa; glands of submucosa large ones (salivary glands, liver, pancreas)

The functions of digestive system are as follows:

① To ingest foods; ② To secrete enzymes which modify the sizes of food molecules; ③ To absord the products of the digestive action; ④ To eliminate the unused residues;

The alimentary canal The oral cavity oral lips / cheeks / palate / palatine tonsils / teeth / tongue / salivary glands **isthmus

fauces consists of uvula, the free margin of the palatine velum, the palatoglossal arches and the root of tongue.  teeth (studied by students themselves)  tongue (papillae / frenulum of tongue / sublingual caruncle / sublingual fold)  **muscles of tongue : the relation between the movement of genioglossus and the damage of hypoglossal nerve

salivary glands Name of salivary gland Location of opening Parotid gland

Mucosa of cheek; opposite the crown of 2nd upper molar tooth

Sublingual gland

Sublingual fold

Submandibular gland

Sublingual caruncle

** notice: the location of the openings

The pharynx Divisions nasopharynx oropharynx Laryngopharynx (piriform recess)

Structures of the lateral wall of the nasopharynx pharyngeal opening of auditory tube tubal torus pharyngeal recess

The esophagus cervical part: 6th cervical vertebra to jugular notch of sternum thoracic part: in the thoracic cavity abdominal part: esophageal hiatus to cardiac orifice 3 constricted portions 1st

position distan 15cm at the commencement ce

2nd

25cm

where is crossed by left principal bronchus

3rd

40cm

where it pierces the diaphragm

**Distance : from the incisor tooth

The stomach (gaster) The morphology two openings: cardiac orifice pyloric orifice two surfaces: anteriror surface posterior surface two curvatures: greater curvature lesser curvature

4 divisions    

cardiac part fundus of stomach body of stomach pyloric antrum pyloric part pyloric canal

The small intestine duodenum (4 parts): greater duodenal papilla / hepatopancreatic ampulla jejunum ileum

The large intestine cecum verimiform appendix colon rectum anal canal

Common features of the colon Colic bands / epiploic appendices / haustras of colon

Anal canal *dentate line (pectinate line) *white line (Hilton line)

liver

External features two surfaces: diaphragmatic surface visceral surface four lobes: right one / left one / quadrate lobe / caudate lobe porta hepatis hepatic pedicle

Gallbladder and biliary ducts Division fundus of gallbladder body of gallbladder neck of gallbladder cystic duct

The bile duct

The bile duct right hepatic duct

common hepatic duct

common bile duct

Left Cystic duct

hepatopancreatic ampulla Pancreatic duct

**sphincter of ampulla (oddi’s sphincter)

greater papilla of duodenum

Pancreas (the functions of endocrine and exocrine ) parts

head: uncinate process neck body tail

Summary 1.pharyngeal tonsillar ring palatine tonsils pharyngeal tonsil ---lies in the mucuous membrane of the roof and posterior wall of the nasopharynx tubal tonsils lingual tonsil (on the back of the tongue) however, it does not form a strong defense system against the spread of infection from the oral and nasal cavity to the lower respiratory organs.

2.The clinic significance of junction of alimentary canal (1) isthmus of fauces (2) pyloric valve

prevent the contents of duodenum from returning to stomach

(3).Duodenojejunal flexure It indicates the end of the duodenum and the beginning of the jejunum. Jejunum and ilium of small intestine are called mesenteric small intestine. During abdominal operation, we must check the mesenteric small intestine from the beginning to the end. The landmark of the beginning is suspensory lig. of duodenum. (Treitz’s ligament)

(4). iliocecal valve

The ileocacal valves are one-direction valves, which permit the contents in the small intestine enter the large intestine, but prevent the contents of the large intestine from returning to the small intestine. If the distal part of large intestine is obstructed, with the contents of the small intestine is continuous entering the large intestine, the pressure in the large intestine will be increasing. Finally, the large intestine may be necrosis. Therefore, if the large intestine is obstructed, an emergent operation is needed to be done.

3.The formation of external hepatic ducts (studied by students themselves ) 4.The differences between small intestine and large intestine large intestine has haustra of colon, 3 longitudinal colic bands and epiploic appendices. But some portions of large intestine have not structures mentioned above. Such as appendix, rectum. The place where the 3 bands are converged with each other is the attachments of the root of appendix.

5.The differences between jejunum and ileum

jejunum

ileum

Location

Upper 2/5 of small intestine

Lower 3/5 of small intestine

Tubular wall

Thicker and redder

Thinner

Circular folds Large and thick Lymphatic tissue

Solitary lymphatic follicles

Few and small Aggregated lymphatic follicles