The Alimentary System

山东大学医学院 解剖教研室李振华

Composition

Digestive tube 消化管• Mouth 口腔

• Pharynx 咽• Esophagus 食管• Stomach 胃

• Small intestine 小肠

• Large intestine 大肠

Duodenum 十二指肠Jejunum 空肠

Ileum 回肠

Digestive glands 消化腺

Superior digestive tube 上消化道

Inferior digestive tube 下消化道

• Major salivary glands 大唾液腺• Liver 肝• Pancreas 胰

Function: ingestion, digestion, absorption, egesting

Mouth Pharynx

Esophagus

Stomach

Duodenum

JejunumIleum

Large intestine

Liver

Pancreas

Major salivary glands

The Oral Cavity 口腔

Consists of two parts Oral vestibule 口腔前庭 : between che

eks and lip and teeth Oral cavity proper 固有口腔 : within arc

h of teeth

Boundaries Anterior and lateral: gum and teeth Posterior: isthmus of fauces Roof: palate Floor: tongue, muscles and mucous

membraneOral vestibule leads, by the space behin

d the molar teeth, into the oral cavity proper

Palate 腭Two parts Hard palate: anterior 2/3, forme

d by the maxilla and palatine bone

Soft palate: posterior 1/3 Velum palatinum 腭帆 Uvula 腭垂 Palatoglossal arch 腭舌弓 Palatopharyngeal arch 腭咽弓

Isthmus of fauces 咽峡 formed by posterior border of velum palatinum, both side of palatoglossal arches, and root of tongue.

Teeth 牙

General features Two sets:

Deciduous 乳牙 Permanent 恒牙

Classification: Incisors 切牙 Canine 尖牙 Premolars 前磨牙 Molars 磨牙

Deciduous teeth: are 20 in number Ten teeth in each mandibular and maxillary arch Central incisor 中切牙 , lateral incisor 侧切牙 , canine 尖牙 , first mo

lar 第一磨牙 and second molar 第二磨牙 in each quadrant

Upper jaw total 20Ⅰ Ⅱ Ⅲ Ⅳ Ⅴ

Lower jaw in. in. can. mol. mol.

Eruption: stars at about 6 mouth of age and continues to beginning of 3rd year

Shedding: occurs between 6th and 12th years with replacement by permanent teeth

Permanent teeth (adult): are 32 in number Sixteen in each mandibular and maxillary arch Two incisors, one canine, two premolars, and three mol

ars in each quadrant

Upper jaw 1 2 3 4 5 6 7 8 total 32

Lower jaw First permanent molar － appears at about 6 years Third molars (wisdom teeth) － many erupt at any time

after 12 years of age or not at all (impaction).

General description Each tooth consists of 3 par

ts: Crown 牙冠 Neck 牙颈 Root 牙根

Dental cavity 牙腔－ contains connective tissue, blood vessels and nerves, and is continuous with the periodontal tissue through the root canal and apical foramen.

Calcified tissues 牙组织 Dentine 牙质－ is a yellowish whit

e tissue, that forms the bulk of tooth.

Enamel 釉质－ is a head, brittle white tissue that covers the crown of the tooth

Cement 牙骨质－ is an unusual form of bone that covers the root of the tooth

Periodontal tissue 牙周组织 Periodontal membrane 牙周膜 Alveolar bone 牙槽骨 Gum 牙龈

Tongue 舌－ muscular organTwo parts: divided two parts by v-s

haped terminal sulcus 界沟 Body of tongue 舌体－ ant 2/3 ，

apex of tongue 舌尖－ free rounded tip

Root of tongue 舌根－ post 1/3 At the apex of terminal sulcus is a s

mall median pit, the foramen cecum of tongue 舌盲孔

Lingual mucous membrane Papillae of tongue 舌乳头

Filiform papillae 丝状乳头 fungiform papillae 菌状乳头 foliate papillae 叶状乳头 contain taste buds vallate papillae 轮廓乳头

Lingual tonsil 舌扁桃体 － masses of submucosal lymph

oid tissue on the root of tongue

Inferior surface of tongue

Frenulum of tongue 舌系带－ a midline fold of mucous membrane connecting tongue to floor of mouth

Sublingual caruncle 舌下阜－ small elevation

Sublingual fold 舌下襞

Muscles of tongue 舌肌 Intrinsic muscles of tongue

Involved in changing shape of tongue

Include longitudinal, transverse and vertical muscles of tongue

Extrinsic muscles of tongue Genioglossus 颏舌肌

Arises from mental spine of mandible and inserts into either side of midline of tongue

Action: acting together draw tongue forward and downward (depresses and protrudes tongue ); acting along making apex of tongue to opposite side

Hyoglossus 舌骨舌肌 Tyloglossus 茎突舌肌 Involved in determining shape and

position of tongue

Major salivary glands

Parotid gland 腮腺 Superficial part: triangular in shap

e, lies below and in front of the external acoustic meatus, and partially covers the masseter.

Deep part: lies deep to medial pterygoid .

Parotid duct: arises front anterior border of gland, runs over the masseter a finger’s breadth below the zygomatic arch to pierce the buccinator and opens into the mouth cavity, opposite the upper second molar tooth

Submandibular gland 下颌下腺 Position: lies in submandibular tri

angle, between anterior and posterior bellies of digastric

Duct opens on to sublingual caruncle

Sublingual gland 舌下腺 position: situated beneath the mu

cous membrane of the floor of mouth

Ducts Major sublingual duct － opens

onto the sublingual caruncle Minor sublingual ducts － open

onto the sublingual fold

The Pharyny 咽

General features A –fibromuscular tube, par

t of digestive and respiratory systens

Extends from base of skull to the inferior border of cricoid cartilage (lower border of C6 leavel)

Three segments

Nasopharynx 鼻咽 － posterior to nasal cavities

Extends from the base of skull to level of soft palate, below

Features Pharyngeal opening of audito

ry tube 咽鼓管咽口 Tubal torus Pharyngeal recess 咽隐窝 Tubal tonsil 咽鼓管扁桃体 Pharyngeal tonsil 咽扁桃体

Oropharynx 口咽 － posterior to oral cavity

Lies below soft palate, extends to upper border of epiglottis

Oropharynx 口咽 Features

Median glossoepiglottic fold 舌会厌正中襞

Epiglottic vallecula 会厌谷 Palatine tonsil 腭扁桃体－ lies

within tonsillar fossa

Lymphatic ring － consists of pharyngeal tonsil, tubal tonsil, and lingual tonsil, forming a circular band of lumphoid tissue at oropharyngeal isthmus

Laryngopharynx 喉咽－ posterior to larynx Extends from upper border of epiglottis to the level of lower bor

der of C6 Piriform recess 梨状隐窝－ a deep depression on each side of a

perture of larynx, common side for lodgement of foreign bodies (for example, fish bones)

The Esophagus 食管General features －

a muscular tuber about 25cm long, connecting the pharynx at level of C6 vertebra, passes through the diaphragm at level of T10 vertebra and after 1~2 cm enters the stomach

Division: Cervical part Thoracic part Abdominal part

Three constrictions At its beginning, 15cm fro

m incisors, lies at level of C6, is the narrowest part of the esophagus

Where it is crossed by left main bronchus, 25cm from incisors, lies at level of intervertebral disc between T4 and T5.

Where it passes through the esophageal hiatus of diaphragm, 40cm from incisors, at level of T10

The Stomach 胃Shape

Two surface: anterior and posterior Two curvatures

Lesser curvature 胃小弯 : short, concave and directed to the right and upward, near its lower part is angular incisure 角切迹

Greater curvature 胃大弯 : long, convex and directed to the left and downward, at the junction of left margin of esophagus and greater curvature is cardiac incisure 贲门切迹

Two openings Cardia 贲门 Pylorus 幽门

Four parts Cardiac part 贲门部 Fundus of stomach 胃底 Body of stomach 胃体 Pyloric part 幽门部

Pyloric antrum 幽门窦 Pyloric canal 幽门管

Cardiac part 贲门部

Fundus of stomach 胃底

Body of stomach 胃体

Pyloric antrum 幽门窦Pyloric canal 幽门管

Pyloric part 幽门部

Structure of stomach wall － consists of four usual layers

Mucous membrane Submucous ( loose areolar tissue c

onnecting the mucous and muscular layer)

Muscular layer contains: The most superficial longitudinal frb

res Inner circular fibres

Sphincter of pylorus 幽门括约肌 Pyloric valve 幽门瓣

Innermost oblique fibres Serous (visceral peritoneum)

Position

－ Mainly parts is situated in the left hypochondriac region, small in the epigastric region; the cardia is situated to the left of T11, the pylorus lies to the right of L1

The Small Intestine 小肠 About 5-7m long, Divided into

Duodenum Jejunum Ilium

Duodenum

Jejunum Ilium

DuodenumFour parts Superior part 上部

Duodenal cap 十二指肠球 Superior duodednal flexur

e 十二指肠上曲 Descending part 降部

Longitudinal fold of duodenum 十二指肠纵襞

Major duodenal papilla 十二指肠大乳头

Minor duodenal papilla 十二指肠小乳头

Inferior duodenal flexure 十二指肠下曲

Horizontal part 水平部 Ascending part 升部

duodenojejunal flexure 十二指肠空肠曲

Suspensory muscle of duodenum 十二指肠悬肌 (ligament of Treitz), a surgical landmark, descends from the right crus of diaphragm to duodenal termination.

Jejunum and ileumCharacteristic Jejunum Ileum

Position Upper 2/5 Lower 3/5

Diameter Greater Less

Wall Thicker Thin

Circular folds Larger, numerous and large villi

Fewer ， smaller and less abundant villi

Vascularity Greater Less

Vasa recta Long Short

Colour Deeper red Paler pink

Lymphatic follicles Solitary Aggregated

Fat in mesentery Less More

Jejunum and ileum

Meckel’s diverticulum Persistence of proximal portion of yolk sac(vitelline d

uct, omphalomesenteric duct) Common malformation of digestive tract (2 － 4%)

－ more prevalent in males About 2 － 5cm long and located 30 － 100cm from i

leocecal valve Usually asymptomatic but:

May become inflamed (mimicking appendcitis) or bleed May be attached to umbilicus by a fibrous cord (distal end o

f yolk stalk) and cause intestinal obstruction by compressing adjacent intestinal loops

Large Intestine

Approximately 1.5m long, Five parts:

Cecum 盲肠 Vermiform appendix 阑尾 Colon 结肠 Rectum 直肠 Canal 肛管

Large Intestine 大肠Features Colic bands 结肠带 Haustra of colon 结肠袋 Epiploic appendices 肠脂垂

Cecum 盲肠

Blind sac, first part of large intestine, with largest diameter and thinnest wall

Lies in right iliac fossa The ilium enters the cecum

obliquely, and partially invaginates into it, forming the ileocecal valve － consists of two folds, probably delays flow of ileal contents into large intestine

Vermiform appendix 阑尾 Blind worm-like tube, 6 －

8cm long, about 0.5cm in diameter

Opens into posteromedial aspect of cecum ， about 2 cm below ileoceal orifice 　

The base at the appendix lies at the point of convergence of three colic bands (used as a guide to find the appendix during operation)

Surface marking of the base is at the so-called McBurney’s point which is at junction of lateral and middle thirds of line joining right anterior superior iliac spine and umbilicus

Tip variable in position Preileal － 28% Pelvic － 26% Retrocecal － 24% Retroileal － 8% Subcecal － 6%

Mesentery of vermiform appendix 阑尾系膜

Triangular mesentery － extends from terminal part of ileum to appendix

Appendicular a. runs in free margin of the meseoappendix then along wall of appendix

Colon 结肠 Ascending colon 升结肠

right colic flexure 结肠右曲 Transverse colon 横结肠

left colic flexure Descending colon 降结肠

descends almost vertically from left colic flexure to sigmoid colon at left iliac crest.

Sigmoid colon 乙状结肠－ extends from descending colon to rectum at level of S3.

Rectum 直肠Position: within pelvic cavity, ext

ends from S3 to pelvic diaphragm.

Curves Sagittal plane

Sacral flexure 直肠骶曲 convex backward

Perineal flexure 直肠会阴曲 convex forward.

Coronal plane Upper and lower part － convex t

o the right. Middle part － convex to the left.

Lower part of rectum dilated, to from ampulla of rectum 直肠壶腹

Three transverse folds of rectum 直肠横襞

Anal canal 肛管 Anal columns 肛柱－ 6-11 in numb

er, Anal valves 肛瓣 Anal sinuses 肛窦 Anorectal line 肛直肠线 Dentate line 尺状线

Above line, of endodermal origin Below line, of ectodermal origin

Anal pecten 肛梳 White line 白线 (Hilton’s line) Anus 肛门 Anal sphincters 肛门括约肌

Sphincter ani internus 肛门内括约肌 Sphincter ani externus 肛门外括约肌

The Liver 肝

Shape Two surfaces

Diaphragmatic surface 膈面 Convex and smooth Divided into right and left lob

es by falciform lig. of liver 镰状韧带

Visceral surface 脏面

Visceral surface －has a H-shaped fissures and grooves

Left limb of H Anteriorly: fissure for liga

mentum teres hepatis 肝圆韧带裂

Posteriorly: fissure for ligamentum venosum 静脉韧带裂

Right limb of H Anteriorly: fossa for gallbla

dder 胆囊窝 Posteriorly: sulcus for ven

a cava 下腔静脉沟

Cross-bar of H is the porta hepatic 肝门 : traversed by right and left hepatic ducts, left and right branches of proper hepatic artery and hepatic portal vein, nerves and lymphatic vessels. These structures which are surrounded by connective tissue called hepatic pedicle 肝蒂

Four lobes: left, right, quadrate and caudate lobes

Inferior border –thin and sharp

Notch for ligamentum teres hepatis 肝圆韧带切迹

Nothch for gallbladder 胆囊切迹

Position: Most of liver lies in the right hypochondriac region and epigastric region, less part extending into the left hypochondriac region

Surface projection Upper border: on the right midclavicul

ar line it extends the level of 5th rib Lower border: Normally, the right lobe

extends just beneath the costal margin, it doesn’t down beyond the costal margin; on the anterior median line its lower border crosses a point about 3~5cm below the xiphoid process. In children, the liver being larger in proportion to the body than in the adult stage, it extends below the costal arch within in 2cm.

The segments of the liver The segmentation of the liver, bases upon the principal divisio

ns of the proper hepatic artery and accompanying hepatic ducts and hepatic portal vein － Glisson system.

The hepatic veins, however do not follow the same pattern and vary: their main tributaries tend to run rather intersegmental.

Extrahepatic Biliary Apparatus

Consists of Gallbladder 胆囊 Left and right hepatic d

ucts 肝左、右管 Common hepatic duct

肝总管 Common bile duct 胆

总管

Gallbladder 胆囊Position :lies in fossa for gallbladder

on visceral surface of liverFour parts Fundus of gallbladder 胆囊底 Surface projection: at the junction

of right midclavicular line and right costal arch

Body of gallbladder 胆囊体 Neck of gallbladder 胆囊颈 Cystic duct 胆囊管Function: stores and concentrate

bile

Biliary duct system Right and left hepatic

ducts unite outside of liver to form the common hepatic duct

Cystic duct joins common hepatic duct to form common bile duct

Common bile duct and pancreatic duct run obliquely through the wall of the descending part of duodenum where the two ducts usually unite to form the hepatopancreatic ampulla 肝胰壶腹 (ampulla of Vater), which rounded by sphincter of hepatopancreatic ampulla 肝胰壶腹括约肌 (sphincter of Oddi), each has an independent sphincteric mechanism for regulating flow, and opens at the major duodenal papilla

Divisions and relations of common bile duct

Supraduodenal segment Descends along the right marg

in of hepatoduodenal lig. To the right of proper hepatic a. Anterior to hepatic portal v.Retroduodenal segment Behind the superior part of duo

denum Anterior to the vena cava To the right of the hepatic port

al v.

Pancreatic segment Lies in a groove between po

sterior surface of head of pancreas and duodenum

Intraduodenal segment Enters the wall of descendin

g part of duodenum obliquely where jions the pancreatic duct to form the hepatopancreatic ampulla

opens at the major duodenal papilla

Bile is secreted by the liver cells

Common hepatic duct

when the fat enters the small intestine, the gallbladder contracts, the sphincter of hepatopancreatic ampulla relax

Common bile duct

Major duodenal papilla

Biliary ductuli Right and left hepatic ducts

Cystic duct Gallbladder (store, concentrate)

Triangle of Calot Boundaries: the common hepatic duct on the left, the cystic du

ct on the right, the liver, superiorily Content: cystic artery

The Pancreas 胰Shape and Position A soft yellowish lobulat

ed gland Lies behind the periton

eum on the posterior abdominal wall, roughly at the level of of L1~L2

Three parts Head

Flattened and located in C-shaped curvatune of duodenum

Uncinate process Neck － constricted par

t Body Tail － runs in base of li

enorenal ligament to reach hilum of spleen

Pancreatic duct Main Pancreatic duct

Begins at tail and throughout gland

Joins common bile duct before entering descending part of duodenum at major duodenal papilla

Accessory pancreatic duct Opens 2cm above main

duct at lesser duodenal papilla

Divisions and relations of pancreasHead of pancreas Located in C-shapes curvature

of doudenum Anteriorly

Transverse mesocolon Posteriorly

Inferior vena cava Right renal vessels Common bile duct

Neck of pancreas Anteriorly － pylorus Posteriorly － commencement pf

hepatic portal v. (formed by union of splenic and superior mesenteric veins

Body of pancreas Anteriorly

Separated from stomach by omental bursa

Posteriorly Abdominal aorta Left suprarenal gland Left kidney Left renal vessels Spleen vein

Superiorly Celiac trunk Celiac plexus Splenic a.

Tail of pancreeas Runs in spleicorenal liga

ment to reach hilum of spleen

Accompanies with splenic vessels

Function The pancreas is both an exocrine and an

endocrine gland. The exocrine portion of the gland produces a secretion that contains enzymes that are capable of hydrolyzing proteins, fats, and carbohydrates. The endocrine portion of the gland, the pancreatic islet, produces the hormones insulin and glucagons that play a key role in carbohydrate metabolism.