Anatomy of digestive system

Expalined in depth about Anatomy the digestive system by Dr.Shamili Balaji.

1. Digestive systemDigestive system

2. Digestive systemDigestive system
Elements of digestive systemElements of digestive system
1. Alimentary Canal1. Alimentary Canal
It is a tube that extends from the lips to the anus. It is a tube that extends from the lips to the anus.
This canal consists of following consecutive This canal consists of following consecutive
segments;segments;
Mouth, Pharynx, Esophagus, Stomach, Small Mouth, Pharynx, Esophagus, Stomach, Small
intestine, and Large intestineintestine, and Large intestine
2. Accessory Organs2. Accessory Organs
Tongue, Teeth, Salivary Glands, Liver, Spleen and Tongue, Teeth, Salivary Glands, Liver, Spleen and
PancreasPancreas
Other relevant structuresOther relevant structures
Abdominal Cavity and Peritoneum Abdominal Cavity and Peritoneum

3. Alimentary canalAlimentary canal

4. MouthMouth
The first part of alimentary canal and is used The first part of alimentary canal and is used
for holding, grinding, and mixing food with for holding, grinding, and mixing food with
saliva.saliva.
PARTS PARTS
The mouth consists of two parts:-The mouth consists of two parts:-
1. Vestibule1. Vestibule
2. Oral Cavity proper2. Oral Cavity proper

5. Lips and cheekLips and cheek
LipsLips
Two musculo-membranous folds which Two musculo-membranous folds which
surround the orifice of the mouth. surround the orifice of the mouth.
The lips are densely innervated by sensory The lips are densely innervated by sensory
fibers.fibers.
CheeksCheeks
The cheeks form the sides of the mouth.The cheeks form the sides of the mouth.

6. Hard palateHard palate
It is formed by the incisive, maxilla and palatine It is formed by the incisive, maxilla and palatine
bones.bones.
It is bounded in front and on sides by dental It is bounded in front and on sides by dental
arches and is continuous with soft palate behind.arches and is continuous with soft palate behind.
It consists of:-It consists of:-
Median Line/RapheMedian Line/Raphe
Palatine RidgesPalatine Ridges
Incisive PapillaeIncisive Papillae

7. Soft palate and tonsilsSoft palate and tonsils
Soft PalateSoft Palate
It is a musculo-membranous structure which It is a musculo-membranous structure which
separates the cavity of the mouth from that of separates the cavity of the mouth from that of
pharynx.pharynx.
TonsilsTonsils
The tonsils are bean shaped structures which are The tonsils are bean shaped structures which are
aggregation of lymphatic nodules residing in the aggregation of lymphatic nodules residing in the
tonsilar sinus. tonsilar sinus.

8. TongueTongue
TongueTongue
The tongue consists of a mass of muscle covered by The tongue consists of a mass of muscle covered by
mucous membrane. mucous membrane.
LocationLocation
The tongue is situated on the floor of the mouth, The tongue is situated on the floor of the mouth,
between the rami of the mandible.between the rami of the mandible.
PartsParts
The tongue is divided into three parts.The tongue is divided into three parts.
1. Root: 1. Root: It is attached to the hyoid bone, soft palate and It is attached to the hyoid bone, soft palate and
pharynx.pharynx.
2. Body: 2. Body: It constitutes the main mass of the tongue.It constitutes the main mass of the tongue.
3. Apex: 3. Apex: It is free, pointed end of the tongue.It is free, pointed end of the tongue.

9. TongueTongue
Types of Papilla:Types of Papilla: These are of four kinds These are of four kinds
i. Filliform = thread-like i. Filliform = thread-like
ii. Fungiform = mushroom like ii. Fungiform = mushroom like
iii. Lenticular = round-shapediii. Lenticular = round-shaped
iv. Vallate = cup-shapediv. Vallate = cup-shaped
Gross features of Tongue: Gross features of Tongue:
1.1.Dorsum LinguaeDorsum Linguae
2.2.Frenulum LinguaeFrenulum Linguae
3.3.Transverse GrooveTransverse Groove
4.4.Glosso- epiglottic FoldGlosso- epiglottic Fold

10. TeethTeeth
LocationLocation
The teeth are implanted in the alveoli of the bones The teeth are implanted in the alveoli of the bones
of the jaws. Teeth are arranged in two dental of the jaws. Teeth are arranged in two dental
arcadesarcades
PartsParts
A tooth constitutes three parts;A tooth constitutes three parts;
i) Crowni) Crown
ii) Rootii) Root
iii) Neckiii) Neck

11. TeethTeeth
Types of teethTypes of teeth
The teeth are of four types: The teeth are of four types:
IncisorIncisor
CanineCanine
PremolarPremolar
Molar Molar
CompositionComposition
Teeth are composed of four types of tissues; (from within to Teeth are composed of four types of tissues; (from within to
outward)outward)
i) Pulpi) Pulp
ii) Dentineii) Dentine
iii) Enameliii) Enamel
iv) Cementumiv) Cementum

12. Salivary GlandsSalivary Glands
1. Chief Salivary Glands1. Chief Salivary Glands
i) Parotid glandi) Parotid gland
ii) Mandibular gland ii) Mandibular gland
iii) Sublingual glandiii) Sublingual gland
2. Minor Salivary Gland2. Minor Salivary Gland
i) Labial gland i) Labial gland
ii) Buccal glandii) Buccal gland
iii) Lingual glandiii) Lingual gland
iv) Palatine glandiv) Palatine gland

13. Salivary GlandsSalivary Glands
Type of Salivary glands on the basis of nature of Type of Salivary glands on the basis of nature of
secretionssecretions
1.1.Serous glandsSerous glands secrete a watery fluid. Eg secrete a watery fluid. Eg Parotid Parotid
glandgland
2.2.Mucous glands Mucous glands secrete mucus. Egsecrete mucus. Eg Minor salivary Minor salivary
glandgland
3.3.Mixed gland Mixed gland produces both mucous and serous produces both mucous and serous
fluids. Egfluids. Eg Mandibular and Sublingual glands Mandibular and Sublingual glands

14. PharynxPharynx
It is a musculo-membranous sac which forms common It is a musculo-membranous sac which forms common
passage for both the respiratory and digestive systems.passage for both the respiratory and digestive systems.
Division Division
The pharynx is divided into three parts;The pharynx is divided into three parts;
1. Oropharynx1. Oropharynx
2. Nasopharynx2. Nasopharynx
3. Laryngopharynx3. Laryngopharynx
OpeningsOpenings
The cavity of the pharynx presents seven openings for The cavity of the pharynx presents seven openings for
Oral cavity, Nasal cavity, Eustachian tubesOral cavity, Nasal cavity, Eustachian tubes, , Larynx Larynx and and
EsophagusEsophagus..

15. EsophagusEsophagus
It is a collapsible, musculo-membranous tube extends from the It is a collapsible, musculo-membranous tube extends from the
pharynx to the stomach. pharynx to the stomach.
Course Course
From Pharynx From Pharynx  dorsal to the trachea dorsal to the trachea  Thoracic inlet Thoracic inlet 
Thoracic cavity Thoracic cavity  enters Diaphragm at the esophageal hiatus enters Diaphragm at the esophageal hiatus 
Within the abdominal cavity, the esophagus joins the stomach.Within the abdominal cavity, the esophagus joins the stomach.
Division Division
The esophagus consists of two parts:-The esophagus consists of two parts:-
i) Cervical Parti) Cervical Part
ii) Thoracic partii) Thoracic part
Blood and nerve supplyBlood and nerve supply
Blood supply - Esophageal artery from thoracic aorta Blood supply - Esophageal artery from thoracic aorta
Nerve supply – Vagus nerve.Nerve supply – Vagus nerve.

16. StomachStomach
It is a muscular bag forming the widest and most It is a muscular bag forming the widest and most
distensible part of the digestive tube. distensible part of the digestive tube.
It intervenes between the esophagus and the small It intervenes between the esophagus and the small
intestine.intestine.
The stomach is formed of four parts:
• Cardia
• Fundus
• Body
• Pylorus

18. Small intestineSmall intestine
The small intestine is the tube which connects the stomach with The small intestine is the tube which connects the stomach with
the large intestine.the large intestine.
Division Division
i) Fixed part:i) Fixed part: Duodenum. Duodenum.
ii) Mesenteric Part: Jii) Mesenteric Part: Jejunum and Ileum. ejunum and Ileum.
1.1.DuodenumDuodenum
The duodenum is the shortest, widest, first part of the small The duodenum is the shortest, widest, first part of the small
intestine, begins at the pylorus. It forms S-shaped curve.intestine, begins at the pylorus. It forms S-shaped curve.
OpeningOpening
The bile duct and pancreatic duct joins together and opens at The bile duct and pancreatic duct joins together and opens at
the same point in the duodenum. the same point in the duodenum.

19. Small intestineSmall intestine
2.2.JejunumJejunum
It is the longest part of the small intestine. The It is the longest part of the small intestine. The
jejunum is defined by the marked increase jejunum is defined by the marked increase
in the length of the supporting mesentery. in the length of the supporting mesentery.
3.3.IleumIleum
The ileum is the short and last part of the small The ileum is the short and last part of the small
intestine that joins the large intestine. It is intestine that joins the large intestine. It is
distinguished from the jejunum by a fold of distinguished from the jejunum by a fold of
mesentery between it and the cecum. mesentery between it and the cecum.

20. Large intestineLarge intestine
The large intestine extends from the ileum to the anus.The large intestine extends from the ileum to the anus.
PARTS PARTS
The large intestine is divided into 4 parts;The large intestine is divided into 4 parts;
CaecumCaecum
The caecum is a blind sac between the small intestine and colon.The caecum is a blind sac between the small intestine and colon.
i) Basei) Base
ii) Bodyii) Body
iii) Apexiii) Apex
ColonColon
The colon consists of :-The colon consists of :-
Ascending colon and Descending colonAscending colon and Descending colon
RectumRectum
Terminal part of the alimentary canal, extends from the pelvic inlet to the anus.Terminal part of the alimentary canal, extends from the pelvic inlet to the anus.
Anal CanalAnal Canal
The lower part of the large intestineThe lower part of the large intestine

21. Accessary organsAccessary organs

22. LiverLiver
It is the largest gland of the body, constituting about 1-2 % of It is the largest gland of the body, constituting about 1-2 % of
total adult body weight. It secretes bile and performs various total adult body weight. It secretes bile and performs various
other metabolic functions. other metabolic functions.
LocationLocation
The liver is located in right side, in contact with the diaphragm.The liver is located in right side, in contact with the diaphragm.
DescriptionDescription
The liver presents two surfaces; The liver presents two surfaces;
(i) Parietal Surface(i) Parietal Surface
It is attached with the diaphragm and with last 2-3 rib.It is attached with the diaphragm and with last 2-3 rib.
(ii) Visceral Surface(ii) Visceral Surface
It is related to the stomach, pancreas and esophagus. It is related to the stomach, pancreas and esophagus.
Gall BladderGall Bladder
It is pear-shaped sac that lies partially in contact with the visceral It is pear-shaped sac that lies partially in contact with the visceral
surface of the liver.surface of the liver.
It is regarded as the reservoir for the bile.It is regarded as the reservoir for the bile.

23. LiverLiver
Ligaments of liverLigaments of liver
The attachment of the liver is governed by six chief ligaments;The attachment of the liver is governed by six chief ligaments;
1. Coronary Ligament1. Coronary Ligament
2. Falciform Ligament2. Falciform Ligament
3. Hepatorenal Ligament3. Hepatorenal Ligament
4. Round Ligament4. Round Ligament
5. Right Lateral Ligament5. Right Lateral Ligament
6. Left Lateral Ligament6. Left Lateral Ligament
Blood SupplyBlood Supply
The liver receives two blood supplies. The liver receives two blood supplies.
1. The Hepatic artery, a branch of ceoliac artery supplies the 1. The Hepatic artery, a branch of ceoliac artery supplies the
liver. liver.
2. The Portal vein carries blood to the liver, while all the venous 2. The Portal vein carries blood to the liver, while all the venous
blood is pour down into the posterior vena cava via hepatic veins.blood is pour down into the posterior vena cava via hepatic veins.

24. SpleenSpleen
It is a lymphatic organ which acts as a filter for blood and plays It is a lymphatic organ which acts as a filter for blood and plays
an important role in the immune responses of the body.an important role in the immune responses of the body.
DescriptionDescription
Two endsTwo ends
i) Dorsal end i) Dorsal end
ii) Ventral endii) Ventral end
Two SurfacesTwo Surfaces
i) Parietal surface (related to diaphragm) i) Parietal surface (related to diaphragm)
ii) Visceral surface (attached to the stomach)ii) Visceral surface (attached to the stomach)
Two BordersTwo Borders
i) Anterior borderi) Anterior border
ii) Posterior borderii) Posterior border

25. SpleenSpleen
LocationLocation
It lies on the stomach just behind the diaphragmIt lies on the stomach just behind the diaphragm
LigamentsLigaments
There are two ligaments that attach the spleen with other viscera.There are two ligaments that attach the spleen with other viscera.
1. Gastro-splenic ligament1. Gastro-splenic ligament
2. Suspensory Ligament 2. Suspensory Ligament
Blood supplyBlood supply
The splenic artery-a branch of the celiac artery. The splenic artery-a branch of the celiac artery.
The splenic vein carries blood to the portal vein.The splenic vein carries blood to the portal vein.

26. PancreasPancreas
The pancreas is a gland that is partly exocrine and partly endocrine.The pancreas is a gland that is partly exocrine and partly endocrine.
It is soft, reddish brown and elongated organ. The exocrine part secretes the It is soft, reddish brown and elongated organ. The exocrine part secretes the
digestive pancreatic juice and the endocrine part secretes hormones, e.g. digestive pancreatic juice and the endocrine part secretes hormones, e.g.
insulin.insulin.
LocationLocation
It lies entirely to the right of the median plane with the visceral surface of the It lies entirely to the right of the median plane with the visceral surface of the
liver and attached with the duodenum.liver and attached with the duodenum.
Lobes of pancreasLobes of pancreas
There are two lobes of the pancreas;There are two lobes of the pancreas;
i) A large Right Lobei) A large Right Lobe
ii) A small Left Lobe.ii) A small Left Lobe.
Blood supplyBlood supply
Pancreatic arteries, from the branches of the celiac & anterior mesenteric Pancreatic arteries, from the branches of the celiac & anterior mesenteric
arteries. arteries.
The pancreatic veins carry blood to the portal vein.The pancreatic veins carry blood to the portal vein.

27. Abdominal cavityAbdominal cavity
The abdominal cavity is the largest of the body cavities. The abdominal cavity is the largest of the body cavities.
It encloses the peritoneal cavity between its parietal and It encloses the peritoneal cavity between its parietal and
visceral layers. visceral layers.
It is separated from the thoracic cavity by It is separated from the thoracic cavity by DiaphragmDiaphragm..
It is continuous behind with It is continuous behind with PelvicPelvic cavitycavity..
It consists of :-It consists of :-
FlankFlank
Paralumbar fossaParalumbar fossa

28. PeritoneumPeritoneum
It is a large thin serous membrane which lines the It is a large thin serous membrane which lines the
abdominal cavity and pelvic cavity. It is in the form of a abdominal cavity and pelvic cavity. It is in the form of a
closed sac which is in-vaginated by a number of viscera.closed sac which is in-vaginated by a number of viscera.
Peritoneal cavityPeritoneal cavity
It is formed by the lining of the peritoneum. It is formed by the lining of the peritoneum.
Layers of peritoneum Layers of peritoneum
As a result, the peritoneum is divided into:As a result, the peritoneum is divided into:
(i) An outer parietal layer(i) An outer parietal layer
(ii) An inner visceral layer(ii) An inner visceral layer
(iii) Folds of peritoneum (iii) Folds of peritoneum

29. PeritoneumPeritoneum
1.1.Parietal PeritoneumParietal Peritoneum
It lines the inner surface of the abdominal and pelvic walls It lines the inner surface of the abdominal and pelvic walls
and the lower surface of the diaphragm. and the lower surface of the diaphragm.
2.2.Visceral peritoneumVisceral peritoneum
It lines the outer surface of the visceraIt lines the outer surface of the viscera
3.3.Folds of PeritoneumFolds of Peritoneum
Many organs within the abdomen are suspended by folds of Many organs within the abdomen are suspended by folds of
peritoneum.peritoneum.
Peritoneal folds are :-Peritoneal folds are :-
(i) Omentum:(i) Omentum: Types of omenta areTypes of omenta are
i)i)Greater OmentumGreater Omentum
ii)ii)Lesser OmentumLesser Omentum
iii)iii)Gastro-splenic OmentumGastro-splenic Omentum
(ii) Mesentary: (ii) Mesentary: Types of mesentary areTypes of mesentary are
1.1.Mesentary of small intestestineMesentary of small intestestine
2.2.Mesentary of large intestestineMesentary of large intestestine
(iii) Ligaments(iii) Ligaments

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