Anatomy of the Digestive System Organ System Cluster Prepared by: Maria Michaela Valenzuela, PTRP

Reference Seeley, R., Stephens, T., and Tate, P., Anatomy & Physiology. 8th ed. McGraw Hill Company Inc., (2008) Snell, R., Clinical Anatomy by Regions. 8th ed. Lippincott Williams & Wilkins (2008)

Regional Division of the Abdomen Used to facilitate location of the various organs of the abdominal cavity.

Abdominal quadrants: 4 – note umbilicus is used as reference Abdominal regions:9 – note lines used: *upper horizontal - transpyloric plane (L1) *lower horizontal – intertubercular plane (L5) *vertical – pass midpoint between ASIS & symph pubis

Organs of the Digestive System Alimentary tract: main passage of food Mouth Pharynx Esophagus Stomach Intestines Accessory Organs Teeth Tongue Salivary Glands Liver Pancreas

Histology of the Alimentary Canal Mucosa Innermost Stratified squamous, simple columnar cells Absorption Submucosa Connective tissue Secretory function Meissner’s plexus of nerve cells

Histology of the Alimentary Canal Muscularis Inner layer of circular smooth muscle Outer layer of longitudinal smooth muscle Myenteric Plexus of nerve cells Motility function Serosa Outermost Visceral peritoneum

Alimentary Tract: Mouth Anteriorly: teeth Posteriorly: fauces (throat) Laterally: cheeks Superiorly: palate Inferiorly: muscular floor

Alimentary Tract: Mouth Divisions Anterior vestibule Posterior oral cavity proper

Accessory Organ: Tongue Muscular structure occupying floor of the oral cavity Attached to the floor by frenulum Intrinsic & extrinsic muscles

Vestibule, hard palate, soft palate, uvula, palatine tonsils, tongue, lingual frenulum

Accessory Organ: Teeth 32, distributed over dental arches 1 central incisor 1 lateral incisor 1 canine 2 pre molars 3 molars

Accessory Organs: Salivary Glands Parotid Anterior to the ear Sublingual Lie below mucous membrane of the oral cavity floor Submandibular Inferior border of the posterior half of the mandible

Alimentary Tract: Pharynx Nasopharynx Oropharynx Laryngopharynx Stratified squamous epthelium  Transmit food

Alimentary Tract: Esophagus Extends between the pharynx & stomach 25 cm long Mediastinum, posterior to trachea, anterior to vertebrae Sphincters UES LES

Alimentary Tract: Stomach Divisions Fundus Body Pyloric Greater & Lesser Curvature Sphincters Cardiac

Fundus, body, pylorus, LES (cardiac sphicnter), , lesser curvature, greater curvature, pyloric sphicnter

Alimentary Tract: Stomach Serosa – visceral peritoneum Muscularis Longitudinal Circular Oblique Mucosal layer with rugae

Alimentary Tract: Small Intestine 6 m long Where greatest amount of digestion & absorption take place Divisions Duodenum Jejunum Illeum

Alimentary Tract: Small Intestine Duodenum Short superior part Duodenal papilla (minor & major) for entry of common bile duct Mucosa & submucosa thrown into folds plica circulares Microvilli

Alimentary Tract: Small Intestine Jejunum & Illeum Smaller in diameter Jejunum: Major site of absorption (with duodenum) Submucosal Lymphatic nodules: Peyer’s patches Ileocecal junction with ileocecal valve

Accessory Organ: Liver Largest organ 1.36 kg ® upper quadrant against the inferior surface of diaphragm Lobes (L) & ® Caudate quadrate

Accessory Organ: Gall Bladder Sac-like structure on inferior surface of liver 8cm long, 4cm wide 3 tunics

Accessory Organ: Pancreas Endocrine & Exocrine functions 2 types of cells Acini Islet Parts Head projecting on the duodenum Body projecting towards the spleen tail

Alimentary Tract: Large Intestine From ileocecal junction to anus Divisions Cecum Colon Rectum Anal canal

Alimentary Tract: Large Intestine Cecum Proximal Attachment of appendix Colon Ascending colon & ® colic flexure Transverse colon & left colic flexure Descending colon

Alimentary Tract: Large Intestine Colon 3 bands of Longitudinal muscle: teniae coli Outpouching called haustra Fatty tags: appendices epiploicae Rectum & Anus Muscular tube lined with Simple columnar epithelium Internal & External Anal Spincter

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