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GIT –Anatomy questions & AnswersSAQ (5 Marks) Describe the tongue under the following headings: (a) Muscles(extrinsic & intrinsic) (b) Nerve supply (sensory & motor) (c) Lymphatic drainage (d) Embryological development a) Muscles of tongue: Intrinsic and extrinsic muscles. In...

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GIT –Anatomy questions & Answers SAQ (5 Marks) 1.

Describe the tongue under the following headings: (a) Muscles(extrinsic & intrinsic) (b) Nerve supply (sensory & motor) (c) Lymphatic drainage (d) Embryological development

a) Muscles of tongue: Intrinsic and extrinsic muscles. Intrinsic muscles - These muscles are confined to the tongue and are not attached to bone.  Consist of: 1. Superior longitudinal 2. Inferior longitudinal 3. Transverse 4. Vertical  Nerve supply: Hypoglossal nerve  Action: Alter the shape of the tongue Extrinsic muscles- These muscles are attached to bones and the soft palate.  Consist of: 1. Genioglossus 2. Hyoglossus 3. Styloglossus 4. Palatoglossus Extrinsic Origin Insertion Action muscle Genioglossus Superior genial spine of Blends with other muscles Protrudes apex of tongue mandible of tongue through mouth Hyoglossus Body and greater cornu of Blends with other muscles Depresses tongue hyoid bone of tongue Styloglossus Styloid process of temporal Blends with other muscles Draws tongue upward and bone of tongue backward Palatoglossus Palatine aponeurosis Side of tongue Pulls roots of tongue upward and backward. b) Nerve supply of tongue: Sensory nerve supply Anterior ⅔ (originates from 1st pharyngeal arch) General sensation: Lingual nerve of the mandibular nerve, except vallate papillae. Special sensation (taste): Chorda tympani nerve of facial except vallate papillae.  Posterior ⅓ (originates from 3rd pharyngeal arch) General & special sensations: Lingual branch of glossopharyngeal nerve including vallate papillae.  Base (epiglottis & root of the tongue): (originates from 4th pharyngeal arch) General & special sensations: Internal laryngeal nerve, branch of vagus, Motor nerve supply Intrinsic muscles: Hypoglossal nerve  Extrinsic muscles: Muscles of tongue develop from occipital somites, so all the muscles are supplied by the hypoglossal nerve, except the palatoglossus which is supplied by the pharyngeal plexus (formed by accessory nerve XI via pharyngeal branch of vagus).

c) Lymphatic drainage:  Apex, frenulum: Submental nodes bilaterally & then deep cervical nodes.  Anterior two third (Body) : Medial part – Inferior deep cervical lymph nodes. Lateral parts – Submandibular lymph nodes.  Posterior one third (Root): Drains into superior deep cervical nodes (jugulodigastric). Although there is very little cross-anastomosis of lymphatics across the midline of the anterior two third of the tongue, there is a rich cross-anastomosis in the posterior one third. This is important in understanding the spread of infection and metastasis of lingual tumours. d) Development:  Anterior two third (oral part) of the tongue: - Three lingual swellings result from the proliferation of mesenchyme in ventromedial part of the first pair of pharyngeal arches. - The lateral lingual swellings rapidly increase in size, merge with each other, and overgrow the median lingual swelling. - The merged lateral lingual swellings form the anterior two thirds (oral part) of the tongue.  Posterior one third (pharyngeal part) & root of the tongue: Formed by two elevations that develop caudal to the foramen cecum: - Copula forms by fusion of the ventromedial parts of the second pair of pharyngeal arches. - Hypopharyngeal eminence develops caudal to the copula from mesenchyme in the ventromedial parts of the third and fourth pairs of arches.  Components: - Pharyngeal arch mesenchyme forms the connective tissue and vasculature of the tongue. - Tongue muscles are derived from myoblasts that migrate from the occipital myotomes. Tongue-Diagrams

2.

Briefly describe the parotid salivary gland under the following headings: (a) External features & parts (b) Relations (c) Structures within (d) Blood supply (e) Nerve supply (f) Histology with labeled diagram

a) External features: 

Capsule - Formed by investing layer of deep cervical fascia.which splits to enclose the parotid gland. Superficial lamina - Thick, adherent to the gland attached above to the zygomatic arch. Deep lamina - Thin and a portion of deep lamina is thickened to form the stylomandibular ligament, separating the parotid gland from the submandibular gland.

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Parotid salivary gland is like a three sided pyramid. Has base & apex. Base is above and apex directed downwards. 4 surfaces: Superior (base),superficial, anteromedial and posteromedial. 3 borders: Anterior,posterior and medial.

Parts:

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b) Relations: Apex : Overlaps posterior belly of digastric muscle. Cervical branch of facial nerve & two divisions of retromandibular veins emerge from the apex. Base: Related to external acoustic meatus, posterior surface of temporomandibular joint , superficial temporal vessels & auriculatemporal nerve. Superficial surface: Largest surface, covered by skin, superficial fascia containing branches of great auricular nerve, pre auricular lymph nodes, parotid fascia. Postero medial surface: Related to mastoid process, sternocleidomastoid & posterior belly of digastric, external carotid artery enters through this surface. c) Structures within parotid gland: From deep to superficial: 1. Arteries: External carotid artery enters the gland.Maxillary artery & superficial temporal arteries leave. 2. Veins: Retromandibular vein is formed within the gland by the union of maxillary & superficial temporal veins. 3. Facial nerve : enters the gland through the posteromedial surface,divides into five terminal branches (temporal,zygomatic, buccal, mandibular, cervical). 4) A few lymph nodes are scattered in the substance of the gland. d) Blood supply: Arterial supplyBranches from external carotid artery,within and near the gland. Venous drainage – Veins drain to the external jugular vein via local tributaries.

e) Nerve supply: Parasympathetic secretomotor nerves: Preganglionic fibres start from inferior salivatory nucleus, pass through glossopharyngeal nerve, lesser petrosal nerve, relay in the otic ganglion which is situated Inferior to foramen ovale. Postganglionic fibres pass through the auriculotemporal nerve and innervates the gland. Sympathetic fibres are vasomotor, derived from the plexus around the external carotid artery. f) Histology with labelled diagram:  

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Parotid gland is covered by connective tissue capsule and forms numerous septa, which subdivide the gland into lobes and lobules. Each lobule consists of mainly serous acini with cells pyramidal in shape, with a broad base resting on the basal lamina and a narrow apical surface facing the lumen. The cells contain large amounts of rER, free ribosomes, a prominent Golgi apparatus, and numerous spherical secretory granules. Serous acinar cells mainly produce digestive enzymes and other proteins. Myoepithelial cells are contractile cells present below the acinar secretory cells,which help to move the secretory products toward the excretory duct. Salivary acinus is continuous with the following duct system: Intercalated duct, which leads from the acinus, striated duct and excretory ducts that empty into the oral cavity.

Parotid gland- diagrams

3.

Describe the submandibular salivary gland under the following headings: (a) Parts (b) Relations (c) Blood supply (d) Nerve supply (e) Histology with labeled diagram

a) Parts: - Larger superficial part - Smaller deep part Both continuous with each other forming a U-shape at the posterior border of mylohyoid muscle. b) Relations: Superficial part: Anterior- Anterior belly of digastric. Posterior- Stylohyoid, posterior belly of digastric, parotid gland Lateral- Crossed by facial vein and cervical branch of facial nerve, submandibular lymph nodes, submandibular fossa of the mandible. Medial- Mylohyoid and hyoglossus muscle, mylohyoid nerve and vessels, lingual nerve. Deep part: Medial- Hyoglossus and styloglossus. Lateral- Mylohyoid. Superior- Lingual nerve and submandibular ganglion. Inferior- Hypoglossal nerve c) Blood supply: Arterial supplyBranches of facial and lingual arteries. Venous drainageFacial and lingual veins. d) Nerve supply: Nucleus- Superior salivatory nucleus. Preganglionic parasympathetic fibers pass in chorda tympani from facial nerve. Ganglion- Submandibular ganglion. Postganglionic parasympathetic fibers of submandibular & sublingual glands- pass along lingual nerve. e) Histology with labeled diagram:  

  

Submandibular gland is covered by connective tissue capsule and forms numerous septa, which subdivide the gland into lobes and lobules. Each lobule is composed of serous and mucous acini.Serous acini with cells pyramidal in shape, with a broad base resting on the basal lamina and a narrow apical surface facing the lumen. The cells contain large amounts of rER, free ribosomes, a prominent Golgi apparatus, and numerous spherical secretory granules. Serous acinar cells mainly produce digestive enzymes and other proteins. Mucous acini are lined by cuboidal cells, flat nuclei toward the bases of the cells., containing glycoprotein mucin which serves the moistening and lubricating functions of the saliva. Some mucous acini are capped with half-moon shaped serous cells called as demilunes of Gianuzzi. Myoepithelial cells are contractile cells present below the acinar secretory cells,which help to move the secretory products toward the excretory duct.

Submandibular salivary gland -Diagrams

4.

Briefly describe the esophagus under the following headings: (a) Extent (b) Relations (c) Blood supply (d) Histology with labeled diagram

a) Extent: Esophagus is divided into: - Cervical part (4 cm) - Extends from cricopharyngeus muscle in the pharynx at the level of cricoid cartilage (C 6) and ends at the lower border of T1. - Thoracic part (20 cm) - Extends from thoracic inlet (T1) and ends at the level of T10 where it pierces the diaphragm. - Abdominal part (1.25 cm)- Ends at the cardiac end of the stomach at the level of T11 where it enters into the stomach and forms a very sharp angle called cardiac angle. b) Relations: Cervical part: Anterior: Trachea, recurrent laryngeal nerve in the trachea-oesophageal groove, thyroid isthmus. Posterior: Prevertebral layer of deep cervical fascia, cervical vertebra, longus colli muscle. Lateral: Lobes of thyroid gland on each side, carotid sheath, thoracic duct on the left side. Thoracic part: Anterior: Trachea, left principal bronchus, left recurrent laryngeal nerve, left vagus nerve, pericardium and left atrium. Posterior: Thoracic vertebra, right vagus nerve, thoracic duct, descending thoracic aorta, right posterior intercostal arteries, azygous vein. Left : Arch of aorta, left subclavian artery, thoracic duct, mediastinal pleura. Right : Mediastinal pleura, terminal part of azygous vein. Abdominal part: Anterior : Anterior vagal trunk, left lobe of liver. Posterior : Posterior vagal trunk, left crus of diaphragm. c) Blood supply: Arterial supply: -Cervical part by inferior thyroid artery. -Thoracic part by esophageal branches of thoracic aorta and bronchial artery. -Abdominal part by left gastric artery and left inferior phrenic branch of abdominal aorta. Venous drainage: - Cervical part by inferior thyroid vein. -Thoracic part by azygous, hemiazygous and accessory hemiazygous veins. -Abdominal part by left gastric vein and azygous vein. d) Histology with labelled diagram:  

Consists of four layers- mucosa, submucosa, muscularis externa and adventitia. Mucosa consists of epithelium,lamina propria and muscularis mucosa.Epithelium is stratified squamous non keratinized. The lamina propria is made up of loose connective tissue contains blood capillaries,nerves and lymphatics.The muscularis mucosa is made up of thin, double layer of smooth muscle.

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Submucosa contains loose connective tissue and oesophageal glands that secrete mucus to help ease the passage of swallowed food.

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Muscularis externa contains skeletal muscle, in the middle, it is a mixture of smooth and skeletal muscle and in lower third it is entirely smooth.

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Adventitia is made up of loose connective tissue.

Oesophagus - diagrams

5

Describe the stomach under the following headings: (a) Parts (b) Relations (c) Blood supply (d) Lymphatic drainage (e) Embryological development (f) Histology with labelled diagram

a) Parts: Stomach has 4 parts: Cardia, fundus, body and pylorus. -Cardia: At the esophago gastric junction (Z line). The passage of food through this area is regulated by the lower esophageal sphincter. -Fundus: Dome-shaped uppermost area of the stomach that lies just under the diaphragm. It ends in line with the cardia. -Body: Largest part which lies between the fundus and pylorus. -Pylorus: Pyloric antrum is a funnel shaped region that leads to the pylorus. Pyloric canal lies next to the duodenum and contains pyloric sphincter. b) Relations: Stomach has 2 surfaces: Anterior superior surface and posterior inferior surface. - Relations of anterior-superior surface:  Left part: Diaphragm separates it from left lung and pleura, pericardium and transversus abdominis and in contact with gastric area of spleen  Right part: Left lobe and quadrate lobe of liver, anterior abdominal wall, transverse colon. - Relations of postero-inferior surface:  Lies on stomach bed.  Structures forming stomach bed are left crus of diaphragm, left kidney, left suprarenal gland, spleen, splenic artery, body of pancreas, transverse mesocolon, left colic flexure. -

Peritoneal relations: 

Covered with peritoneum everywhere except at the bare area.

c) Blood supply: Arterial supply: Derived from branches of celiac artery1. Left gastric artery- Branch of celiac artery, runs along lesser curvature and supplies the lower right part of the stomach. 2. Right gastric artery- Branch of hepatic artery, runs along lesser curvature and supplies the upper right part of the stomach. 3. Right gastroepiploic artery - Branch of gastroduodenal artery of hepatic artery, runs along greater curvature to supply the stomach along the right part of the greater curvature. 4. Left gastroepiploic artery- Branch of splenic artery, runs along greater curvature to supply the stomach along the left part of the greater

curvature. 5. Short gastric arteries- Branches of splenic artery,supply fundus of stomach.

Venous drainage: - Left and right gastric veins drain into portal vein. - Short gastric veins and left gastroepiploic vein drain into splenic vein, which joins the superior mesenteric vein to form the portal vein. - Right gastroepiploic vein drains into the superior mesenteric vein. d) Lymphatic drainage: -Stomach is divided into three drainage zones: Area 1- Superior 2/3 of the stomach. - Drains along the right and left gastric vessels into celiac nodes located around celiac artery on the posterior abdominal wall. Area 2- Right 2/3 of the inferior 1/3 of the stomach. -Drains along the right gastro-epiploic vessels into the subpyloric nodes and then to celiac nodes located around the celiac artery on the posterior abdominal wall. Area 3- Left 1/3 of the inferior 1/3 of the stomach. -Drains along the short gastric vessels and splenic vessels to the suprapancreatic and then to celiac nodes located around the celiac artery on the posterior abdominal wall.

e) Embryological development: Stomach develops from foregut. - The distal part of the foregut dilates and enlarges. The dilation pattern forms the Stomach’s greater curvature. - During development, stomach rotates 90 degree clockwise around its longitudinal axis. This rotation explains that the lesser curvature moves to the right and greater curvature moves to the left. -Due to the rotation around the anteroposterior axis, the long axis become almost transverse. f) Histology with labeled diagram: Fundus & Body- Consists of 4 main layers: Mucosa, submucosa, muscularis externa and serosa. -Mucosa lined by simple columnar epithelium that invaginates into lamina popria, forming deep gastric pits. Lamina propria contains long gastric glands made up of mucous cells, mucous neck cells, chief cells, parietal cells and enteroendocrine cells. -Submucosa composed of connective tissue containing blood vessels and lymp vessels. -Muscularis externa consists of three layers of smooth muscle-outer longitudinal layer, middle circular layer and inner oblique layer. -Serosa is made up of loose connective tissue lined by single layer of flat mesothelial cells. Pylorus-Consists of four main layers: Mucosa, submucosa, muscularis externa and serosa. -Mucosa consists of simple columnar epithelium that invaginate into lamina propria, forming shallow gastric pits. Lamina propria contains short pyloric glands made up of mucous cells.

-Submucosa is composed of connective tissue containing blood vessels and lymph vessels. -Muscularis externa consists of three layers of smooth muscles—outer longitudinal layer, middle circular layer and inner oblique layer. -Serosa is made up of loose connective tissue lined by single layer of flat mesothelial cells.

Stomach –Diagrams

6.

Describe the liver under the following headings: (a) Lobes, peritoneal reflections (b) Relations (c) Porta hepatis (d) Blood supply (e) Histology with labelled diagram

a) Lobes, peritoneal reflections: Lobes- Liver is divided into larger right and smaller left lobe. Right lobe has quadrate and caudate lobes. Peritoneal reflections- Most part of the liver are covered by visceral peritoneum.Liver is attached to anterior abdominal wall by the falciform ligament which ascends from umbilicus.Within its free border lies ligamentum teres.On the surface of the liver the falciform ligament splits in two-Right side forms the upper layer of the coronary ligament -Left side form upper layer of left triangular ligament -Extremity of coronary ligament form the right triangular ligament -Bare area: Area of liver not covered by peritoneum directly comes in contact with diaphragm. Anterior boundary - Anterior coronary ligament. Posterior boundary - Posterior coronary ligament. Right boundary- Inferior vena cava. -Additional folds of peritoneum connect the liver to stomach (hepatogastric ligament), duodenum (hepatoduodenal ligament),Diaphragm (right and left traingulat ligaments & anterior and posterior coronary ligaments) -Lesser omentum connects the stomach & first part of duodenum to the fissure for the ligamentum venosum & margins of porta hepatis.

b) Relations: Anterior - Diaphragm, which separates liver from 6th to 10th ribs and cartilages on right and from 7th and 8th cartilages on left side. Covered by peritoneum except along attachment of falciform ligament Superior - Under dome of diaphragm, which separates it from lungs on right and heart on left Covered by peritoneum except posteriorly, at edge of bare area. Posterior - Fitted against vertebral column and crura of diaphragm. Bare area: large area between coronary ligaments not covered by peritoneum. Boundaries- inferior vena cava, coronary ligaments. Inferior surface or visceral surface is related to- Fundus of stomach and duodenum. - Right colic flexure. - Right kidney and suprarenal gland. - Gall bladder. - Esophagus. - Inferior vena cava.

c) Porta hepatis : - Porta hepatis, or hilum of the liver, is found on the posteroinferior surface and lies between the caudate and quadrate lobes. - Upper part of the free edge of the lesser omentum is attached to its margins. In it lie the right and left hepatic ducts, the right and left branches of the hepatic artery, the portal vein, and sympathetic and parasympathetic nerve fibers. A few hepatic lymph nodes lie here; they drain the liver and gallbladder and send their efferent vessels to the celiac lymph nodes. d) Blood supply: Arterial supplyHepatic artery, a branch of the celiac artery, divides into right and left terminal branches that enter the porta hepatis. Venous drainagePortal vein divides into right and left terminal branches that enter the porta hepatis behind...