Upper Git: Foregut - 2025 PDF

ANATOMY-LEC: LE 4 | TRANS 3 Upper GIT: Foregut MA. JENINA ANGELA ESGUERRA-PACULAN, MD | 01/13/2025 OUTLINE ✔​ Stating how the pyloric sphincter is formed, noting I.​ Oral Region...

ANATOMY-LEC: LE 4 | TRANS 3 Upper GIT: Foregut MA. JENINA ANGELA ESGUERRA-PACULAN, MD | 01/13/2025 OUTLINE ✔​ Stating how the pyloric sphincter is formed, noting I.​ Oral Region III. Stomach possible signs and symptoms in pyloric stenosis. A.​ Oral Cavity A.​ Parts ✔​ Describing the innervation, blood supply, and B.​ Lips, Cheeks, and B.​ Curvatures lymphatic drainage of the stomach. Gingivae C.​ Position of the CLINICAL CORRELATION C.​ Teeth Stomach D.​ Palate D.​ Variations of E.​ Tongue Stomach Shape F.​ Clinical Correlation E.​ Interior Stomach II. Esophagus F.​ Relations of the A.​ Esophageal Stomach Constrictions G.​ Vasculature B.​ Esophageal H.​ Pyloric Sphincter Restrictions I.​ Clinical Correlation C.​ Vasculature IV. Embryology of the GIT D.​ Clinical V. Review Questions Correlation VI. References ​ VII. Appendix Figure 1. Radiograph of an 8-year old boy who swallowed a ₱10 coin [Lecturer’s PPT] SUMMARY OF ABBREVIATIONS AOG Age of Gestation ​ An 8-year-old boy accidentally swallowed a ₱10 coin about 2 hours prior to ER consult ❗️ Must know 📣 Lecturer 📖 Book 📋 Previous Trans ​ Child was brought to the ER 2 hours after the incident so the coin did not block the airway. LEARNING OBJECTIVES ​ Since the patient swallowed the coin, it is probably in the ✔​ Relate the structures of the foregut with your activity esophagus. of eating. I. OVERVIEW OF THE GASTROINTESTINAL SYSTEM ✔​ Hypothesize the structures involved in the different ​ Three main functions pathology in the foregut.Defining the functions of the →​Transport food digestive system. →​Digest food ✔​ Naming, in consecutive order, the component parts of →​Absorb food the digestive tract. →​Maintain health and survival of individual (together with 📣 ✔​ Describing the anatomy of the oral cavity, with respect accessory organs) to its walls and boundaries, communication with the ​ Food comes in through the mouth and goes down to oropharynx, and its subdivisions. the esophagus, stomach, small bowel, to your large colon, ✔​ Describing the general structure of a tooth. and exits through the anal canal ✔​ Stating the approximate time and order of eruption of the two (2) sets of teeth and the total number of each I. ORAL REGION set. ✔​ Describing the gross structure of the tongue, including its innervation (sensory and motor), blood supply, and lymphatic drainage. ✔​ Describing the actions of the extrinsic muscles of the tongue. ✔​ Describing the structure of the soft and hard palate. ✔​ Identifying the openings of the salivary glands. ✔​ Locating the palatine tonsils and describing their innervation, blood supply, and lymphatic drainage. ✔​ Describing the gross anatomy (structure, anatomic relations, blood supply, lymphatic drainage, and innervation) of the esophagus. ✔​ Locating the stomach and giving its anatomical relations. ✔​ Describing the shape and parts of the stomach including some variations. ✔​ Identifying the peritoneal attachments of the stomach. ✔​ Describing the gross structure of the mucosa of the stomach. Figure 2. Overview of the Oral Cavity [Lecturer’s PPT] ✔​ Stating mechanisms that serve sphincteric functions at the cardiac orifice of the stomach. LE 4 TRANS 3 VER 2 TG-A15: J. Cordoba, A. Coronado, J. Cortez*, B. Coteok, TE: P. Conwi, AVPAA: M. Bailey Page 1 of 20 A. Cruz, J. Cruz  A. ORAL CAVITY (MOUTH) ORAL CAVITY PROPER ​ It is the space between the upper and lower dental arches ​ Anything between the upper and lower teeth, except lateral to the teeth between the cheek, it is the oral ​❗️ vestibule Boundaries of the Oral cavity proper →​Lateral and Anterior limitation: teeth and dental arches →​Posterior: Communicates with oropharynx →​Roof: Hard and Soft palate ​ Fully occupied by tongue when mouth is closed SWALLOWING Figure 3. Left Retromolar Region [Lecturer’s PPT] Thin dotted line: Internal oblique ridge; Solid line: External Figure 5. Stages of Swallowing oblique ridge; BM: Buccal mucosa; RP: Retromolar pad; T: Tongue ​ Swallowing occurs in two stages: the oropharyngeal and esophageal stages ​ Two parts ​ At the start of a swallow, a food bolus is pressed against →​Oral vestibule the tongue, at the roof of the mouth, and backwards towards the pharynx ​📣→​Oral cavity proper Slit-like space between the teeth, gingiva and lips and the cheeks Figure 6. Reflex Mechanisms ​ In response to activation of the pharyngeal pressure receptors, the swallowing center in the medulla initiates reflexes that prevent food entry into the respiratory passageway preventing aspiration ​ As the bolus passes through, the uvula contracts, blocking [Lecturer’s PPT] nasal passages from the pharynx Figure 4. Oral Cavity ORAL VESTIBULE ​ Communicates with the exterior through the oral fissure or the opening (mouth) →​Opened at the fourth week of gestation ​ A slit like opening or space between the teeth and the gingiva, and the lips and the cheek ​ Size of the fissure is controlled by the perioral muscles →​Orbicularis oris - sphincter of the oral fissure →​Buccinator, risorius, depressors and elevators of the lips (dilators) Figure 7. Laryngeal Mechanisms ​ The laryngeal muscles then contract, closing the glottis, and the food goes down. ANATOMY Upper GIT: Foregut Page 2 of 20  Figure 11. Labial and Lingual Frenula [Lecturer’s PPT] ​ Labial and Lingual Frenula Figure 8. Peristalsis →​Superior and inferior labial frenula →​Free-edged folds of the mucous membrane in the ​ Upon the closed glottis, to protect the airway. Begins the midline extending from the vestibular gingiva to the esophagus, the esophageal sphincter opens and closes mucosa of the upper and lower lips while the food goes down. The waves like movement is ▪​ Vestibule and the oral cavity proper is the vestibular known as peristalsis gingiva →​Smaller frenula may appear laterally at premolar vestibular regions NEUROVASCULATURE OF THE LIPS Figure 9. Secondary Peristalsis ​ At the distal esophagus, bolus enters the stomach. If the bolus is sticky, the remains are pushed down by secondary peristalsis B. LIPS, CHEEKS, GINGIVAE LIPS AND CHEEKS Figure 12. Superficial Arteries of Face [Moore] ​ The superior and inferior labial arteries anastomose with →​📣 each other at the lips forming an arterial ring If you grasp your lips in between two fingers, you can feel the pulsation of this arterial ring Table 1. Summary of the Neurovasculature of the Lips Lymphatic Arteries Innervation Figure 10. Lips and Cheeks [Lecturer’s PPT] Drainage Superior Superior (Including ​ Lips are mobile musculo-fibrous folds surrounding the labial labial lateral lower mouth branches of branches of lip) ​ Extends: Upper Lip the facial the Submandib →​Laterally and Superiorly: Nasolabial sulci and nares and infra-orbital ular lymph →​Inferiorly: Mentolabial sulcus infra-orbital nerves of nodes ​ Contains arteries CN V2 →​Orbicularis oris Inferior Inferior (Medial ▪​ Controls entry and exit from the mouth and the upper labial labial lower lip) alimentary and respiratory tracts branches of branches of Submental →​Superior and inferior labial muscles, vessels, and Lower Lip the facial the mental lymph nerves and mental nerves of nodes ​ Covered externally by skin, and internally by mucous arteries CN V3 membrane ​ Functions: →​Act as the valves of the oral fissure →​Grasping food, sucking different kinds of liquids, keeping food out of the vestibule, forming speech, and osculation (kissing) ANATOMY Upper GIT: Foregut Page 3 of 20  GINGIVAE (GUMS) NERVE SUPPLY OF THE ORAL CAVITY Figure 14. Nerves supplying the gingiva underlying the alveolar bone and periodontium) [Moore] ​ Superior alveolar nerve (CN V2) →​Alveolar bone and periodontium at the maxillary area ​ Mandibular nerve (CN V3), with numerous branches such as the mental, dental, and buccal branches →​Supplies the gingiva underlying the alveolar bone at the mandibular area ​ Periodontium Figure 13. Oral Vestibule and Gingivae [Moore] →​Surrounds the root of the tooth anchoring it to the tooth sockets ​ Composed of fibrous tissue covered with mucous membrane SENSORY INNERVATION OF GINGIVA, TONGUE, AND ​ Gingiva Proper PALATAL MUCOSA →​Firmly attached to the alveolar process of the maxilla, mandible, and necks of the teeth ▪​ Covers the roots of the teeth →​Normally pink, stippled. and keratinizing →​Superior and Inferior Lingual Gingiva ▪​ Gingiva proper closes or adjacent to the tongue →​Maxillary gingiva ▪​ Gingiva proper adjacent to the lips →​Mandibular (Buccal) Gingiva ▪​ Gingiva proper adjacent to the cheeks PRACTICALS TIPS ​ Identify pointed (red arrow) structure be specific: Superior labial gingiva →​Pinned structure is beside your lips ​ If the mouth is open is its beside the tongue: Lingual gingiva (depends on where, if superior or inferior) Figure 15. Innervation of Mouth and Teeth [Moore] ​ If pin is near the molar at the cheek: Buccal gingiva ​ Innervations in Figure 15 →​Yellow (posterior region): Vagus nerve ​ 📣 Alveolar mucosa is red, shiny, and non-keratinizing and attached to the lips →​Green: Glossopharyngeal nerve →​Pink area in tongue: Lingual nerve →​Blue area on gingiva anterior to incisors: Mental nerve ***See Figure 70. Innervation of the oral mucosa in the appendix ANATOMY Upper GIT: Foregut Page 4 of 20  ​ Children have 20 deciduous teeth →​Supplied by superior labial branches of the infraorbital nerves ▪​ Branches of the maxillary branch of the trigeminal nerve Figure 16. Sensory innervation of the gingiva [Moore] ​ Upper part of oral cavity →​Supplied by superior labial branches of the infraorbital 📣 nerves →​ Superior alveolar nerves ▪​ Branches of the maxillary branch of the trigeminal Figure 18. Baby Teeth Chart [Lecturer’s PPT] nerve Table 2. Deciduous Teeth Chart [Moore 9th Ed.] ​ Lower part of oral cavity Deciduous Eruption Shedding →​Supplied mostly by the inferior labial branches of the Teeth (months) (years) 📣 mental nerves Central Incisor 6-8 6-7 →​ Inferior alveolar nerves Lateral Incisor 8-10 7-8 ▪​ Branches of the mandibular branch of the trigeminal Canine 16-20 10-12 nerve 1st Molar 12-16 9-11 C. TEETH 2nd Molar 20-24 10-12 ​ Incise, reduce, and mix food with saliva during mastication ​ Help sustain themselves in the tooth sockets by assisting ​ ❗ Helps determine the problem and age based on the eruptions and shedding the development and protection of the tissues that support them →​The more you use them, the better the teeth Table 3. Permanent Teeth Chart [Moore] →​A person with dentures, the bones underneath the Permanent Teeth Eruption (years) absent tooth will demineralize Central Incisor 7-8 ​ Participate in articulation Lateral Incisor 8-9 ​ Two kinds: Canine 10-12 →​Deciduous (primary) 1st Premolar 10-11 →​Permanent 2nd Premolar 11-12 ▪​ 32 teeth in adults surrounded by alveolar bones 1st Molar 6-7 ▪​ Alveolar bone proper 2nd Molar 12 −​ Adjacent to cementum and surrounding bone 3rd Molar 13-25 −​ Resorbs along the loss of teeth ​ Keeps the structure of oral cavity TYPES OF TEETH →​Gums regress after tooth extraction or loss DECIDUOUS TEETH Figure 19. Teeth Regions [Moore] [Moore] Figure 17. Deciduous teeth ANATOMY Upper GIT: Foregut Page 5 of 20  ​ Incisors: have cutting edges for tearing ​ Cement ​ Canine: single prominent cones for piercing →​Covers the root ​ Premolars or bicuspids: have two cusps (can be seen ​ Pulp Cavity from the root) →​Contains the connective tissue, blood vessels, and ​ Molars: have three or more cusps for crushing nerves, which pass through the apical foramen (root ​ Eight kinds of permanent teeth (from midline to most foramen) lateral portion): →​During root canal, pulp cavity is emptied of its contents, →​Central incisor removing the connective tissue together with its →​Lateral incisor neurovascular structures →​Canine NEUROVASCULATURE OF THE TEETH →​1st Premolar →​2nd Premolar ​ Superior and inferior labial arteries →​1st Molar →​2nd Molar ▪​📣 →​Branches of the facial artery Lymphatic drainage and alveolar veins have the same name as the arteries →​3rd Molar (wisdom teeth) ​ Erupts at age 18-25 ​ Superior alveolar arteries and veins →​Drains into the submandibular lymph nodes ​ Innervation →​Dental Plexuses ▪​ Branches of superior (CN V2) and inferior (CN V3) alveolar nerves ▪​ Supplies maxillary and mandibular teeth D. PALATE Figure 20. Inferior view of maxillary teeth (left) and superior view of mandibular teeth (right) [Lecturer’s PPT] ​ 📣 Incisors and canines are sometimes referred to as “labial” while premolars and molars are sometimes referred to as “buccal” PARTS OF THE TOOTH Figure 22. Median section of the head and neck [Moore] ​ Forms the arched roof of the mouth and the floor of the nasal cavities ​ Separates the oral cavity from the nasal cavity and the nasopharynx (superior to the palate) ​ Superior/Nasal surface: covered by respiratory mucosa ​ Inferior surface: covered by oral mucosa Figure 21. Longitudinal section of an incisor and molar [Moore & HARD PALATE Lecturer’s PPT] ​ Crown →​Projects from the gingiva →​Biting surface →​Hardest substance in the human body (enamel) →​When root canal procedure is done, this portion is replaced ​ Neck →​Between the crown and root →​Portion surrounded by the gingivae ​ Root →​Fixed in the root socket surrounded by the periodontium or the connective tissues surrounding the roots Figure 23. Inferior view of hard palate [Moore] →​Number of roots varies on the type of tooth: ▪​ Canine: 1 root ​ Concave structure with its space mostly filled by the ▪​ Bicuspids/Premolars: 2 roots tongue at rest ▪​ Tricuspids/Molars: 3 or more roots ​ Anterior 2⁄3 of the palate forming the bony skeleton, ​ Dentine formed by the palatine process of the maxilla and the →​Covered by enamel over the crown horizontal plates of the palatine bones ​ Cleft palate: failure of fusion of the intermaxillary bones ANATOMY Upper GIT: Foregut Page 6 of 20  OPENING OF THE HARD PALATE ​ Palate has a rich blood supply ​ Incisive fossa ​ Greater palatine artery →​Depression at the midline of the bony palate at the back →​Branch of descending palatine artery of the central incisor teeth where the incisive canals ​ Lesser palatine artery open →​Smaller branch of descending palatine artery that enters ​ Incisive canal the palate to the lesser palatine foramen and 📣 →​Where the nasopalatine nerve passes from the nose anastomosis with ascending palatine artery which is a ▪​ You can taste food with just smelling it and you can smell it better if you taste it 📣 ​ branch of your facial artery Veins of the palate are tributaries of the pterygoid venous plexuses ​ Greater palatine foramen →​Located medial to the 3rd molar →​Pierces the lateral border of the bony palate 📣 ​ Sensory nerves are branches of Maxillary nerve ​ Palatine nerves accompanies the arteries of the greater →​Significance: neurovascular provisions of the palate →​Where greater palatine vessels and nerves emerge ❗️ ​ and lesser palatine foramina Except Tensor Veli Palatini: supplied by V3, the rest are V2 from this foramen and run anteriorly to the palate ​ Lesser palatine foramen →​Posterior to the greater palatine foramen 📋 Table 4. Innervation of Palate Nerve Structure →​Pierces the pyramidal process of the palatine bone →​Significance: transmits the lesser palatine vessels and Gingivae, mucus membrane, nerves to the soft palate and adjacent structure Greater palatine nerve glands of most of the hard palate Mucus membrane of the Nasopalatine nerve anterior part of the hard palate Less palatine nerve Soft palate E. TONGUE PARTS OF THE TONGUE Figure 24. Nerves and vessels of palate [Moore] SOFT PALATE ​ Movable structure forming the posterior 1⁄3 of the palate ​ Suspended from the border of the hard palate ​ No bony skeleton ​ The palatine aponeurosis attaches to the free edge of the hard palate ​ Posteroinferiorly, the soft palate has a curve free margin from where hands the muscular uvula ​ Continuous with the walls of the pharynx laterally Figure 26. Parts of the tongue [Moore] ​ It is joined to the tongue and the pharynx by the palatoglossal and palatopharyngeal arches ​ Root ​ Contains a few taste buds at its oral surface →​Attached between the mandible, hyoid and vertical ​ Sometimes uvula would be single but sometimes you will posterior surface of the tongue have uvula that has two bell (meaning palate has some ​ Body delays in closure) 📋 VASCULATURE AND INNERVATION OF PALATE →​2⁄3 of the tongue ​ Apex (tip of the tongue) →​Anterior end of the body that rests on the incisors ​ The body and the tip of the tongue are extremely mobile while the root does not move ​ Allows you to speak as fast as you can Figure 25. Nerves and vessels of palate [Moore] ANATOMY Upper GIT: Foregut Page 7 of 20  SURFACES OF THE TONGUE MUSCLES OF THE TONGUE Figure 29. Muscles of the tongue [Moore] [Moore] Figure 27. Top surface of the tongue ​ There are two opposing forces by the muscles that allows ​ Top of the tongue (Dorsum of tongue) the tongue to stick out at the midline (like genioglossus →​Terminal Sulcus supplied by hypoglossal nerve) ▪​ V shaped groove which divides the tongue to anterior INNERVATION OF TONGUE and posterior surfaces of the tongue →​The angle which points posteriorly is the Foramen Cecum ▪​ A small pit (usually not visible) that is a remnant of the embryonic thyroglossal duct from which the hyoid gland developed →​Can be located because of the lining of papilla called Vallate papilla ​ Midline groove →​Divides the tongue into left and right parts Figure 30. Nerve supply of the tongue [Moore] ​ ❗️All muscles of the tongue EXCEPT the PALATOGLOSSUS receive motor innervation from CN XII ​ Anterior ⅔ →​Touch and Temperature - Lingual nerve (V3) Figure 28. Inferior surface of the tongue [Moore] →​Taste (except for vallate papillae) - chorda tympani nerve(VII) ​ Underside of the tongue / inferior tongue ​ Posterior 1⁄3 →​Movable, no lingual papillae →​Mucosa of the posterior 1/3 and vallate papillae is →​Covered by a transparent mucous membrane supplied by the lingual branch of the Glossopharyngeal ​ Frenulum Nerve (IX) for both general sensation and taste →​Allows anterior part of the tongue to freely move ​ 4 basic taste sensations →​Sweet (Apex), Salty (Lateral Margin), Sour & Bitter (Posterior) →​All other tastes aside from 4 are not actual tastes, they come from olfactory sense ANATOMY Upper GIT: Foregut Page 8 of 20  VASCULATURE OF TONGUE Figure 31. Vasculature of Tongue[Moore] ​ Arteries are derived from lingual artery which arise from external carotid artery →​Dorsal lingual arteries ▪​ Supply root of the tongue Figure 33. Oral Cavity proper [Plenary] →​Deep lingual arteries F. SALIVARY GLANDS ▪​ Supply tip of the tongue →​Arteries separated by lingual septum ▪​ Are always a pair ​ Veins of the tongue →​Dorsal lingual veins that accompanies the lingual arteries LYMPHATIC DRAINAGE OF TONGUE Figure 32. Lymphatic drainage of the tongue [Moore] ​ Superior deep cervical lymph nodes Figure 34. Salivary glands [Moore] →​Drains bilaterally from root of the tongue ​ Inferior deep cervical lymph nodes ​ Submandibular gland →​From medial part of the body of the tongue →​Submandibular/Wharton’s duct ​ Submandibular lymph nodes ​ Sublingual gland →​From right and left parts of the body of the tongue →​Rivinus duct ​ Submental lymph nodes ​ Parotid gland ​📋→​From tip/apex of the tongue All lymph from the tongue drains to the deep cervical nodes and passes via the jugular venous →​Stensen’s duct ​ Functions of Saliva →​Keeps the mucous membrane moist trunk. →​Lubricates food during mastication →​Begins digestion of starches →​Serves as an intrinsic mouthwash →​Plays a significant role in prevention of tooth decay and in the ability to taste ANATOMY Upper GIT: Foregut Page 9 of 20  G. DISEASES OF THE ORAL CAVITY SUPERNUMERARY TEETH CLEFT LIP Figure 38. Supernumerary teeth [Lecturer’s PPT] ​ Existence excessive number of teeth in relation to the normal dental formula ​ Common orthodontic problem ​ Easily be corrected by extraction or braces ​ Associated with other symptoms III. ESOPHAGUS Figure 35. Cleft lip [Lecturer’s PPT] ​ Caused by a failure in development on the 4th-8th week of life, AOG (when the face is developing) ​ Highly correctable with surgery CLEFT PALATE Figure 39. Esophagus [Netter] ​ Muscular tube Figure 36. Cleft palate [Lecturer’s PPT] ​ 25 cm long with 2 cm average diameter ​ Function: conveys food from the pharynx to the stomach ​ Caused by a failure of the intermaxillary suture and ​ 3 constrictions (where potential foreign body may lodge) interpalatine suture to fuse →​Cervical constriction ​ Highly correctable with surgery →​Thoracic/ Broncho-aortic constriction CYANOSIS OF THE LIPS →​Diaphragmatic constriction A. ESOPHAGEAL CONSTRICTIONS ​ Important in reviewing radiographs and evaluation of dysphagia →​Dysphagia: difficulty in swallowing ​ Can be visualized through barium swallow test →​Special type of imaging test that uses barium and xrays to create images of your upper GI tract Figure 37. Cyanosis of the lips [Lecturer’s PPT] ​ May be physiologic →​Lips generally have abundant superficial arteriole supply that constrict during cold →​Purplish cold is caused by deficiency of oxygen ​ May also be pathologic, as in heart conditions Figure 40. Barium swallow [Lecturer’s PPT] ANATOMY Upper GIT: Foregut Page 10 of 20  CERVICAL CONSTRICTION Will food still go down to the stomach if a person is ​ At the upper esophageal pharyngo-esophageal junction sphincter at the ​ 📣 upside-down? Yes, even if there is an inversion, the natural progression of food is from the mouth to the stomach. ​ 15 cm from the incisors ​ Caused by cricopharyngeus muscles ​ Flares distally into a trumpet shape as it enters the cardiac THORACIC / BRONCHO-AORTIC CONSTRICTION orifice of the stomach ​ 2 constrictors ​ Phrenico-esophageal ligament ​ 1st constrictor →​Permits independent movement of the diaphragm and →​22.5 cm from the incisors esophagus during respiration and swallowing →​Caused by the arch of the aorta →​Help keep the independent motion of the esophagus ​ 2nd constrictor and the diaphragm during swallowing and respiration. →​27.5 cm from the incisors ​ Esophagogastric junction/gastroesophageal junction 📣 →​Caused by the left main bronchus →​Right border of the abdominal esophagus DIAPHRAGMATIC CONSTRICTION →​ Gastroesophageal sphincter: lies to the left side of ​ Passes through the esophageal hiatus of the diaphragm the T11 vertebra as it enters the stomach, on the ​ 40 cm from the incisors, at the level of T10 horizontal plane that passes through the xiphoid B. RELATED STRUCTURES TO THE ESOPHAGUS ▪​📣 process At the junction of the esophagus and stomach, with the diaphragm located immediately above →​Z line: jagged line where the mucosa abruptly changes from esophageal to gastric mucosa ​ Esophageal hiatus →​Immediately above the gastroesophageal junction →​Functions as physiologic inferior esophageal sphincter (contracts and relaxes) Figure 41. Esophagus and its relationships [Moore] ​ Follows the curve of the vertebral column as it descends down the neck and the mediastinum ​ It has internal circular and external longitudinal muscle layers →​Proximal 1⁄3 of the external layer - voluntary striated Figure 42. Esophageal body and lower esophageal sphincter [Lecturer’s PPT] muscles →​Distal 1⁄3 of the external layer - smooth muscles ​ General direction of the esophagus is vertical, but it →​Middle 1⁄3 of external layer - both smooth and striated presents as two slight curvatures. ​ General direction: vertical but will have 2 slight curves →​First curvature starts at the midline then it inclines to the through its course left side up to the root of the neck. →​Starts at the midline → inclines to the left side (at the →​Then, it passes to the midline again at the level of the root of the neck level) → passes through the midline 5th thoracic vertebrae. again (at T5 level) → deviates to the left as it passes →​Finally, deviates to the left as it passes down the forward to the esophageal hiatus and diaphragm esophageal hiatus →​Important when accessing the esophagus for drainage in cases of trachea-esophageal fistula (TEF) ▪​ You should drain at the left side of the neck (natural ​📣 curvature) General direction is straight, vertical up, but with deviations to the left ​ Encircled by the esophageal plexus distally →​Formed by the vagal trunks and thoracic sympathetic trunks via the greater splanchnic nerves ​ Food passes rapidly due to the peristaltic action of its musculature ​ It is also aided by gravity ANATOMY Upper GIT: Foregut Page 11 of 20  C. NEUROVASCULATURE OF THE ESOPHAGUS ARTERIAL SUPPLY Figure 47. Vasculature of the Esophagus [Lecturer’s PPT] ​ Cervical esophagus →​Supplied by the inferior thyroid artery ▪​ Each artery gives off ascending and descending Figure 43. Thoracic esophagus and thoracic aorta[Lecturer’s PPT] branches that anastomose with each other and across the midline ​ Thoracic esophagus →​Supplied by the branches of thoracic aorta ▪​ Bronchial arteries ▪​ Esophageal arteries ​ Abdominal esophagus →​Supplied by the ascending branches of: ▪​ Left phrenic arteries ▪​ Left gastric arteries VENOUS DRAINAGE ​ Esophageal veins arise from this plexus and drain in a segmental way similar to the arterial supply ​ Cervical esophagus →​Drains into the inferior thyroid vein ​ Thoracic esophagus Figure 44. Limit of abdominal esophagus[Lecturer’s PPT] →​Drains into the azygos and hemiazygos veins (to the SVC), intercostals, and bronchial veins ​ Abdominal esophagus →​Drains into the left gastric vein (tributary of the portal venous system) ▪​ Portal hypertension or liver disease leads to the dilation of these esophageal veins, causing bleeding INNERVATION ​ Esophageal plexus →​Formed by the vagal trunks and the thoracic sympathetic trunks via the greater splanchnic nerves and periarterial plexuses around the left gastric and inferior phrenic arteries ​ Thoracic esophagus →​Right and left vagus nerves ▪​ Left vagus nerve: travels down anteriorly and laterally Figure 45. Sample esophagogastroduodenoscopy (also ▪​ Right vagus nerve: travels down posteriorly called EGD or upper endoscopy)[Lecturer’s PPT] →​Left recurrent laryngeal nerve ​ Abdominal esophagus ​ 📣 LARP: Left Anterior, Right Posterior →​Left Vagus Nerve travels down Laterally and Anteriorly →​Right Vagus Nerve travels down Laterally and Posteriorly ​ Applicable to stomach due to the development of the gut ANATOMY Upper GIT: Foregut Page 12 of 20  III. STOMACH B. CURVATURES OF THE STOMACH ​ Expanded part of the digestive tract between the ​ Lesser Curvature esophagus and the small intestine →​Shorter concave at right border of the stomach ​ Functions: →​Angular notch/incisure →​Accumulates ingested food ▪​ Most inferior part that lies to the left of the midline →​Food blender →​Reservoir →​Chief function: Enzymatic digestion ▪​ 📣 ▪​ Indicates the junction of the body and pyloric part Signifies the end of the body of the stomach, at the end of the lesser curvature is dimple-like or ​ Larger in diameter than intestine, capable of accumulating fold-like structure →​ 📣 2-3L of food Stomach can accommodate more food with ​ Greater Curvature →​Longer convex at the left border of the stomach →​ 📣 repeated exposure to larger meal Size, shape, and position of the stomach varies with eating habits ​ Chyme →​Gastric juices convert masses of food into a semiliquid mixture called chyme which passes into the duodenum A. PARTS OF THE STOMACH Figure 49. Curvatures of the stomach[Lecturer’s PPT] ​ 📣 Take note of the junction of the abdominal esophagus and the aorta Figure 48. Parts of the stomach [Moore] 1.​Cardia →​Receives terminal portion of the esophagus 2.​Fundus →​Dilated superior part 3.​Body →​Major part of the stomach between the fundus and the pyloric antrum 4.​Pyloric part →​Funnel-shaped region →​Pyloric Antrum →​Funnel-shaped region Figure 50. Curvatures of the stomach[Lecturer’s PPT] 📣 →​Pyloric Sphincter →​Leads to the duodenum ​ Visible are the greater curvature (red line) ant cut →​Aids as a gatekeeper pylorus, showing the start of the small bowel Identify the pinned (red arrow) structure be specific. C. POSITION OF STOMACH SHAPE ​ 📣 Pyloric antrum is the better answer, but pylorus is okay. ​ Pyloric sphincter is not acceptable, unless the area is cut open, and the muscular layer is visible. Figure 51. Common position of stomach in a person of medium build in supine position [Moore] ​ Part of the stomach is within the thoracic cage ANATOMY Upper GIT: Foregut Page 13 of 20  D. VARIATIONS OF STOMACH SHAPE Figure 55. Gastric canal [Lecturer’s PPT] ​ Gastric canal/groove/fold →​Forms temporarily and longitudinally during swallowing along the lesser curvature Figure 52. Variations of stomach shape [Moore] 📣 →​Observed endoscopically →​ Empties the stomach of liquid after a few minutes ​ Muscular pylorus ​ Size, shape, position of stomach varies on your eating habits →​Thickened portion at the most distal part of the stomach →​Wide and fat: More superiorly located →​Leads to the pyloric canal and into the duodenum →​Long and slim: More inferiorly located, almost to the pelvis E. INTERIOR STOMACH Figure 56. Mucosa of the stomach[Lecturer’s PPT] F. RELATIONS OF THE STOMACH Figure 53. Interior stomach (pathologic)[Lecturer’s PPT] ​ Figure 54. Stomach interior view with anterior wall reflected[Lecturer’s PPT] 📣 ​ Gastric folds/Gastric Rugae →​ Stomach walls are mostly smooth before they reach the pylorus Figure 57. Relations of the stomach[Lecturer’s PPT] →​Longitudinal ridges or wrinkles formed when the ​ Stomach is covered by visceral peritoneum except where ▪​ 📣 stomach contracts Longitudinal ridges and rugae are different for this organ system the blood vessels run along its curvatures ​ Two layers of the lesser omentum extending around the →​Found along the pyloric part along the greater curvature stomach and leaves the greater curvature as the greater →​More prominent when stomach is contracted curvature omentum ▪​ Diminishes as the stomach is distended (filled) →​These two layers of the anterior and posterior portion of the stomach joins at the greater omentum, making it four layers ANATOMY Upper GIT: Foregut Page 14 of 20  BRANCHES OF THE CELIAC TRUNK Figure 60. Branches of the celiac trunk[Lecturer’s PPT] ***See Figure 60 in the appendix Figure 58. Stomach bed[Lecturer’s PPT] ​ Borders →​Anterior: Diaphragm, left lobe of the liver, and anterior abdominal wall →​Posterior: Omental bursa and pancreas →​Inferolaterally: Transverse colon along the greater curvature of the stomach and to the left colic flexure ​ Stomach bed →​Posterior aspect on which the stomach rests in the supine position →​Formed by structures of the posterior wall of omental bursa (superior to inferior): ▪​ Left dome of the diaphragm ▪​ Spleen ▪​ Left kidney and suprarenal gland ▪​ Splenic artery Figure 61. Anterior view of the celiac trunk branches[Lecturer’s ▪​ Pancreas PPT] 📣 ▪​ Transverse mesocolon G. VASCULATURE OF THE STOMACH ​ Celiac trunk is 1 cm - 1.5 cm below the diaphragm →​Looks like a fat trunk of a tree with 3 branches: Splenic ARTERIAL SUPPLY artery, Left gastric artery, and Common hepatic artery →​If not visible in the cadaver because of an intact stomach, try blunt dissection through the lesser omentum until the aorta or descending aorta ​ Left gastric artery →​Towards the lesser curvature ​ Splenic artery →​Towards the fundus and the spleen →​Short gastric artery →​Left gastro-omental artery ​ Common hepatic artery →​Towards the liver →​Hepatic artery proper ▪​ Right gastric artery ▪​ Right and left hepatic artery →​Gastroduodenal artery ▪​ Superior pancreaticoduodenal artery ▪​ Right gastro-omental artery Figure 59. Arterial supply of the stomach[Lecturer’s PPT] ​ 💬 →​Supraduodenal artery Foregut is innervated by the branches of the celiac trunk ​ From the celiac trunk of the abdominal aorta ​ Most blood is supplied by anastomosis along the: →​Lesser curvature by the right and left gastric arteries →​Greater curvature by the right and left gastro-omental arteries (gastroepiploic arteries) →​The fundus and the upper body of the stomach are supplied by the short and posterior gastric arteries ANATOMY Upper GIT: Foregut Page 15 of 20  VENOUS DRAINAGE NERVE SUPPLY Table 5. Summary of the nerve supply T6 to T9 segment of the Vagus spinal cord Anterior vagal trunk Greater splanchnic nerve Posterior vagal trunk Left vagus (anterior to the esophagus, to the lesser curvature of stomach) Right vagus (posterior surface of the esophagus, to the lesser curvature of Figure 62. Venous drainage of the stomach[Lecturer’s PPT] stomach) Distribution ​ Gastric veins are parallel to the arteries T6 to T9 segment of the Vagus ​ Right and left gastric veins drain into the hepatic portal spinal cord vein Hepatic and duodenal ​ Short gastric and left gastro-omental vein drains into the branches (Anterior vagal splenic vein trunk) →​Which joins with the superior mesenteric vein to form the hepatic portal vein Anterior and posterior ​ Right gastro-omental vein drains into the superior surfaces of stomach ​📣mesenteric vein which drains to the portal vein Prepyloric vein →​Located at the angular incisure (Posterior vagal trunk) Innervation T6 to T9 segment of the →​Used as a landmark in identifying the pylorus during Vagus spinal cord surgery Parasympathetic Sympathetic ▪​ To drain excessive hydrochloride, speed up gastric emptying H. PYLORIC SPHINCTER ​ Band of smooth muscle that controls the movement Drainage may be memorized for theoretical exams partially digested food and juices from the pylorus to the ​ T/F Right gastro-omental vein will drain to the splenic duodenum vein? ​ Characterized by a high-pressure zone that relaxes with →​False because the Left gastro-omental vein is the antral peristalsis one that drains to the splenic vein, then into the ​ Contracts as a response to endogenous duodenal stimuli superior mesenteric vein, and the portal vein ​ Altered by retrograde movement of duodenal contents ​ The human pylorus is a true physiological sphincter ​ There is a gastro-omental vein that drains to the inferior mesenteric vein? CLINICAL CORRELATION →​None. Left gastro-omental vein drains into the ESOPHAGEAL VARICES splenic vein and Right gastro-omental vein drains into the superior mesenteric vein. LYMPHATIC DRAINAGE Figure 63. Venous drainage of the stomach[Lecturer’s PPT] ​ Gastric lymphatic vessels accompany arteries along the 📣 lesser and greater curvature of the stomach →​ Drains to the nearest lymph nodes ​ Gastric and Gastro-omental lymph nodes →​Drains anterior and posterior surfaces towards the curvatures ​ Celiac lymph nodes →​Efferent vessels course together the large arteries to the Figure 64. Endoscopic photo of ruptured celiac lymph nodes esophageal varices[Lecturer’s PPT] ANATOMY Upper GIT: Foregut Page 16 of 20  ​ Due to the submucosal veins of the inferior esophagus ​ Arises from endoderm gastrulation of the trilaminar draining to both the portal and systemic venous system, embryo, consisting of the ectoderm, endoderm, and they constitute a portal systemic anastomosis mesoderm ​ In portal hypertension, blood is unable to pass through the ​ Extends from the buccopharyngeal membrane to the liver via the hepatic portal vein, causing a reversal of flow cloacal mucosa (mouth to anus) in the esophageal tributary ​ The endodermal germ layer mainly gives rise to the GIT ​ Large volume of blood is caused by the enlarged →​There are still contributions from other germ cell layers submucosal veins because of the failure to drain into the ​ The germ layers cover the ventral surface of the embryo, portal system and forms the roof of the yolk sac GASTRIC ULCER ​ Open lesions on the mucosa of the stomach ​ Peptic ulcers →​Lesions on the mucosa of the pyloric canal; more often found in the duodenum ​💬→​Infection brought about by Helicobacter pylori People prone to experiencing anxiety have a higher rate of developing gastric ulcer →​Cause most infections of the duodenum and the stomach ▪​ Symptoms −​ Burning stomach pain −​ Fullness or bloating −​ Fatty food intolerance −​ Heartburn −​ Nausea Figure 68: Sagittal midline sections of embryos at various stages of development to demonstrate cephalocaudal folding and its effect on position of the endoderm-lined cavity. A. 17 days. B. 22 days. C. 24 days. D. 28 days. Arrows, head and tail folds.[Langman’s Medical Embryology] ​ With the development of the brain vesicles, the embryonic disc begin to bulge into the amniotic cavity Figure 65. Gastric Ulcer[Lecturer’s PPT] ​ Lengthening of the neural tube will cause the embryo to curve into fetal position (C) IV. EMBRYOLOGY →​The head and the tail region folds in more ventrally ​ In (C) the left side shows the coronal part, the head, where GIT there is the oropharyngeal part. While the right side is the caudal end Figure 69: Cross sections through embryos at various stages Figure 66: Parietal layers lined by ectoderm come to meet of development to show the effect of lateral folding on the each other, pulling the amniotic cavity around the endoderm-lined cavity. A. Folding is initiated. B. Transverse embryo.[Lecturer’s PPT] section through the midgut to show the connection between the gut and yolk sac. C. Section just below the midgut to show the closed ventral abdominal wall and gut suspended from the dorsal abdominal wall by its mesentery. Arrows, lateral folds..[Langman’s Medical Embryology] ​ Simultaneously you have two lateral body folds that move ventrally to close the ventral body wall →​As the head and the tail of the two lateral body folds move ventrally, they pull the amnion down towards them →​Resulting in the embryo lying in the amniotic cavity ▪​ The amniotic cavity turns into a fetal position Figure 67: Mesoderm differentiation.[Lecturer’s PPT] ANATOMY Upper GIT: Foregut Page 17 of 20  →​The ventral body wall closes completely except for the upper lip. On the other hand, the lower lips are umbilical region where the connecting stalk and yolk innervated by the inferior labial branches of the sac remains attached mental nerves of CN V3 (Choice D). ▪​ It eventually folds in and closes the body wall 3. A The maxillary gingiva is the gingiva proper →​Inability to close the lateral body folds leads to ventral adjacent to the lips. The superior and inferior wall defects (e.g. umbilical hernia) lingual gingiva closes or adjacent to the tongue, ▪​ May lead to peritoneal fold defects, an example of a while the mandibular (buccal) gingiva is ventral fold adjacent to the cheeks. ​ The cephalocaudal growth and the closure of lateral body 4. C The GIT is mainly formed by the endodermal wall folds, a continuously larger portion of the endoderm is germ layer, with little contributions from the incorporated into the body of the embryo forming the gut ectoderm and mesoderm tube 5. B The stomodeum is the primitive oral cavity, →​The tube is divided into three regions: foregut, midgut which is the only part of the GIT in the foregut and hindgut (Figure 53, C) that is derived from the ectoderm →​The midgut communicates with the yolk sac ▪​ Initially wide, then closes VI. REFERENCES →​In the third week of gestation, the cephalic end, the ​ 2027 Trans foregut, is bounded by an ectodermal and endodermal ​ 2028 Asynchronous Lecture Videos membrane, the oropharyngeal membrane (Figure 53, ​ 2028 Synchronous Session A) →​From the pharynx, the oropharyngeal membrane separates the stomodeum from the part of the foregut that is derived from the endoderm ▪​ Stomodeum is the primitive oral cavity, which is the only part of the GIT in the foregut that is derived from the ectoderm ​ In the fourth week of gestation, the oropharyngeal membrane would rupture →​Forming a connection between the oral cavity and primitive gut →​Produces an entrance for the amniotic fluid →​When the stomodeum ruptures commences the opening of the mouth V. REVIEW QUESTIONS 1.​ T/F The hard and soft palate are the lateral and anterior limitation of the oral cavity proper? a.​ True b.​ False 2.​ What nerves innervate the upper lips? a.​ Superior labial branches of the infra-orbital nerves of CN V3 b.​ Inferior labial branches of the mental nerves of CN V2 c.​ Superior labial branches of the infra-orbital nerves of CN V2 d.​ Inferior labial branches of the mental nerves of CN V3 3.​ The maxillary gingiva is a part of the gingiva proper which is adjacent to what structure? a.​ Lips b.​ Tongue c.​ Cheeks 4.​ The GI tract arises mainly from which germ cell layer? a.​ Mesoderm b.​ Ectoderm c.​ Endoderm 5.​ The stomodeum forms which primitive structure? a.​ Oropharynx b.​ Oral cavity c.​ Oral vestibule ANSWER KEY 1. B The hard and soft palate are considered to be the roof of the oral cavity proper. The lateral and anterior limitation of the oral cavity proper are the teeth and dental arches. 2. C The superior labial branches of the infra-orbital nerves of CN V2 (Choice C) innervate the ANATOMY Upper GIT: Foregut Page 18 of 20  VII. APPENDIX Figure 60. Branches of the celiac trunk Figure 70. Innervation of the oral mucosa [Moore] ANATOMY Upper GIT: Foregut Page 19 of 20  Figure 702. Muscles of the Tongue ANATOMY Upper GIT: Foregut Page 20 of 20