Transcript The Alimentary System

The Alimentary System
SHANDONG UNIVERSITY
Liu Zhiyu
The abdominal regions
——Nine regions
R. hypochondriac
region
Epigastric region
L. hypochondriac region
R. lateral regions
L. lateral regions
R. inguinal region
Umbilical region
L. inguinal region
Pubic region
The abdominal regions
——Four quadrants


Left and right upper
quadrants
Left and right lower
quadrants
Composition
Alimentary canal


Mouth
Pharynx
 Esophagus
 Stomach

Small intestine
Superior alimentary canal
Duodenum
Jejunum
Ileum

Inferior alimentary canal
Large intestine
Alimentary glands



Major salivary glands
Liver
Pancreas
Function: ingestion, digestion, absorption, egesting
Major salivary glands
Mouth
Pharynx
Esophagus
Liver
Duodenum
Ileum
Stomach
Pancreas
Large intestine
Jejunum
Alimentary canal
The Oral Cavity
The Oral Cavity


Consists of two parts

Oral vestibule : between

cheeks and lip and teeth
Oral cavity proper : within
arch of teeth
Boundaries

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
Anterior and lateral: gum and
teeth
Posterior: isthmus of fauces
Roof: palate
Floor: tongue, muscles and
mucous membrane
Oral vestibule leads, by the
space behind the molar teeth,
into the oral cavity proper
Palate

Two parts

Hard palate : anterior 2/3，
formed by the maxilla and palatine
bone Soft palate : posterior 1/3
Velum palatinum
 Uvula
 Palatoglossal arch
 Palatopharyngeal arch
Isthmus of fauces formed
by uvula, free border of velum
palatinum, both side of
palatoglossal arches, and root
of tongue.
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
Teeth
Teeth
General features


Two sets:
 Deciduous
 Permanent
Classification:
 Incisors
 Canine
 Premolars
 Molars
Deciduous teeth


20 in number, ten teeth in each mandibular and maxillary arch
Deciduous central incisor , deciduous lateral incisor , deciduous
canine , first deciduous molar ，second deciduous molar in each
quadrant
Upper jaw
Lower jaw


Ⅰ
in.
Ⅱ
Ⅲ
Ⅳ
Ⅴ
total 20
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
Ⅱ
Ⅳ
Deciduous teeth
Deciduous central incisor
Deciduous lateral incisor
Deciduous canine
First deciduous molar
Second deciduous molar
Permanent teeth (adult)


32 in number，sixteen in each mandibular and maxillary arch
Two incisors, one canine, two premolars, and three molars 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).
3
7
Permanent teeth
3rd molar
2nd molar
1st molar
2nd premolar
1st premolar
Canine
Lateral incisor
Central incisor
Teeth
Part and structure of the teeth

Each tooth consists of 3 parts:
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Crown
Neck
Root
Dental cavity
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Pulp chamber
Root canal transmits the nerves and
vessels to and from the dental cavity
through the apical foramen
Teeth

Calcified tissues

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
Dentine － is a yellowish
white tissue, that forms the
bulk of tooth.
Enamel －is a hard, brittle
white tissue that covers the
crown of the tooth
Cement －is an unusual form
of bone that covers the root of
the tooth
Dental pulp formed
connective tissue, blood
vessels and nerves.
Teeth 牙

Periodontal tissue

Periodontal membrane
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Alveolar bone
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Gum
Teeth
Tongue
Two parts: divided two parts by vshaped terminal sulcus
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Body of tongue －anterior 2/3
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
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Apex of tongue －free rounded
tip
At the apex of terminal sulcus is
a small median pit, the
foramen cecum of tongue
Root of tongue － posterior 1/3
Tongue
Lingual mucous membrane


Papillae of tongue

Filiform papillae

Fungiform papillae
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Foliate papillae

Vallate papillae
Lingual tonsil
－masses of submucosal
lymphoid tissue on the root of
tongue
contain taste
buds
Inferior surface of tongue
Frenulum of tongue
－a midline fold of mucous
membrane connecting tongue to
floor of mouth
Sublingual caruncle
－small elevation
Sublingual fold
Muscles of tongue
Intrinsic muscles of tongue


Involved in changing shape of
tongue
Include longitudinal, transverse
and vertical muscles of tongue
Tongue

Extrinsic muscles of tongue
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
Genioglossus
 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
Tyloglossus
Involved in determining shape
and position of tongue
Major salivary glands
Parotid gland
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
Superficial part: triangular in shape,
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
Major salivary glands
Submandibular
gland
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Position: lies in
submandibular
triangle, between
anterior and posterior
bellies of digastric
Duct opens on to
sublingual caruncle
Major salivary glands
Sublingual gland


Position: situated
beneath the mucous
membrane of the floor
of mouth
Ducts
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
Major sublingual duct－
opens onto the
sublingual caruncle
Minor sublingual ducts－
open onto the sublingual
fold
The Pharynx
General features


A –fibromuscular tube, part of
digestive and respiratory
systems
Extends from base of skull to
the inferior border of cricoid
cartilage (lower border of C6
level)
Three segments
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Nasopharynx
Oropharynx
Laryngopharynx
The Pharynx
Nasopharynx —posterior to nasal
cavities

Extends from the base of skull to
level of soft palate, below

Features

Pharyngeal opening of auditory tube

Tubal torus

Pharyngeal recess

Tubal tonsil

Pharyngeal tonsil
The Pharynx
Oropharynx －posterior
to oral cavity
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Lies below soft palate,
extends to upper border
of epiglottis
Features
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Median glossoepiglottic
fold
Epiglottic vallecula
Palatine tonsil
－lies within tonsillar
fossa
The Pharynx
Laryngopharynx －
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
posterior to larynx
Extends from upper
border of epiglottis to the
level of lower border of
C6
Piriform recess －a
deep depression on
each side of aperture of
larynx, common side for
lodgement of foreign
bodies (for example, fish
bones)
The Pharynx
Lymphatic ring

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Consists of

Pharyngeal tonsil

tubal tonsil

Palatine tonsil

lingual tonsil
Forming a circular band of
lymphoid tissue at
oropharyngeal isthmus
The Esophagus 食管
★Three constrictions
1. Where it beginning, 15cm from
incisors, lies at level of C6, is the
narrowest part of the esophagus
2. Where it is crossed by left
principal bronchus, 25cm from
incisors, lies at level of intervertebral
disc between T4 and T5.
3. Where it passes through the
esophageal hiatus of diaphragm,
40cm from incisors, at level of T10
The Esophagus

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
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Division
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Cervical part
Thoracic part
Abdominal part
The Stomach
Shape
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Two surface: anterior and posterior
Two curvatures
 Lesser curvature : short, concave
and directed to the right and upward,
near its lower part is angular incisure
Greater curvature : long, convex and
directed to the left and downward, at
the junction of left margin of
esophagus and greater curvature is
cardiac incisure
Two openings
 Cardia
 Pylorus
The Stomach

Four parts
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Cardiac part
Fundus of stomach
Body of stomach
Pyloric part
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Pyloric antrum
Pyloric canal
Fundus of stomach
Cardiac part
Body of stomach
Pyloric canal
Pyloric antrum
Pyloric part
The Stomach
Structure of stomach wall

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－consists of four usual layers
Mucous membrane
Submucous ( loose areolar tissue
connecting the mucous and
muscular layer)
Muscular layer contains:
 The most superficial longitudinal
fibers
 Inner circular fibres
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
Innermost oblique fibres
Serous (visceral peritoneum)


Sphincter of pylorus
Pyloric valve
The Stomach
Location



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
Variations in position of stomach
The Small Intestine
Duodenum
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
About 5-7m long
Division:
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
Duodenum
Jejunum
Ileum
Jejunum
Ileum
Duodenum
Four parts
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Superior part
 Duodenal cap
 Superior duodednal
flexure
Descending part
 Inferior duodenal
flexure
Horizontal part
Ascending part
 Duodenojejunal flexure
Duodenum
Descending part
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Longitudinal fold of
duodenum
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Major duodenal papilla
the common opening of the
common bile duct and
pancreatic duct, 75cm from
incisors
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Minor duodenal papilla
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Contrast radiographic
appearance of the duodenum
showing a distended
duodenal cap and the
remainder of the duodenum
up to the duodenojejunal
flexure
Duodenum

Suspensory muscle of duodenum
(ligament of Treitz), a surgical landmark,
descends from the right crus of diaphragm to
duodenal termination.
Jejunum and ileum
Characteristic
Jejunum
Ileum
Position
Upper 2/5, upper left
Lower 3/5, lower right
part of abdominal cavity part of abdominal cavity
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
Color
Deeper red
Paler pink
Lymphatic follicles
Solitary
Aggregated
Fat in mesentery
Less
More
Jejunum and ileum
Jejunum and ileum
Meckel’s diverticulum
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
Persistence of proximal portion of
yolk sac (vitelline duct,
omphalomesenteric duct)
Common malformation of
digestive tract (2－4%) － more
prevalent in males
About 2－5cm long and located
30－100cm from ileocecal valve
Usually asymptomatic but:


May become inflamed (mimicking
appendcitis) or bleed
May be attached to umbilicus by a
fibrous cord (distal end of yolk stalk)
and cause intestinal obstruction by
compressing adjacent intestinal loops
Large Intestine
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
Approximately 1.5m
long,
Five parts:





Cecum
Vermiform appendix
Colon
Rectum
Canal
Large Intestine
Features



Colic bands
Haustra of colon
Epiploic appendices
Cecum

Position: lies in right iliac
fossa

Shape:
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
Blind sac, first part of large
intestine, with largest diameter
and thinnest wall
The ileum 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
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

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 of the appendix lies at
the point of convergence of three
colic bands (used as a guide to
find the appendix during
operation)
Vermiform appendix

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
Vermiform appendix






Tip variable in position
Preileal －7%
Pelvic－41%
Retrocecal －29%
Retroileal－4%
Subcecal－17%
Vermiform appendix
Mesoappendix


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


Transverse colon 横结肠


right colic flexure 结肠右曲
left colic flexure 结肠左曲
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

Position: within pelvic cavity,
extends from S3 to pelvic
diaphragm.

Curves

Sagittal plane



Coronal plane



Sacral flexure : convex backward
Perineal flexure : convex forward.
Upper and lower part－convex to the
right.
Middle part－convex to the left.
Lower part of rectum dilated, to
from ampulla of rectum

Three transverse folds of rectum
Anal canal
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Anal columns : 6 － 11 in number
Anal valves
Anal sinuses
Anorectal line
Dentate line
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
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Above line, of endodermal origin
Below line, of ectodermal origin
Anal pecten
White line (Hilton’s line)
Anus
Anal sphincters


Sphincter ani internus
Sphincter ani externus