Gut Book 3: Supracolic Compartment: Esophagus, Stomach, Spleen, Liver, Pancreas Flashcards
Supracolic compartment definition
peritonealized area between the thoracoabdominal diaphragm and the transverse colon and its associated mesocolon
Supracolic compartment contents
Contains the distal esophagus, stomach, spleen, liver, gall bladder, and part one of the duodenum
Discuss the transverse mesocolon’s categorization
Since the transverse mesocolon straddles the pancreas, it is retroperitoneal and not in either the supra or infracolic compartment.
Subdivision of the supracolic compartment
by the lesser omentum, thereby forming the omental bursa.
Esophagus origin
begins at the cricoid cartilage opposite CV6
Esophagus muscular composition
outer longitudinal, inner circular smooth muscle
Clinical Correlation: Zenker’s diverticulum
The upper 1/3 (approx) of the esophagus is composed of striated muscle continuous with the inferior constrictor and innervated by the recurrent laryngeal nn. Weakness sometimes occurs in the area of the posterior pharyngo-esophageal junction. Because fibers of the inferior portion of the inferior constrictor (cricopharyngeus/ upper esophageal sphincter) diverge, a small area is left where the mucosa and adventitia can be directly opposed without intervening muscle fiber. An out-pocketing of these two opposed layers can occur, referred to as a Zenker’s diverticulum, which gathers food, fills the retrovisceral/ retroesophageal space and impedes swallowing.
Esophagus: course
neck: slightly to the left of the midline upper thorax (TV4): midline middle thorax (TV8): crosses to the left (anterior to aorta) lower thorax (TV10): left of the midline to penetrate the diaphragm
Esophagus: sites of potential constriction
1- at the junction of the pharynx and esophagus, cricopharyngeus m. (upper esophageal sphincter)
2- aortic arch
3- left primary bronchus
4- esophageal hiatus
Where does the esophagus pierce the diaphragm?
level of the 10th thoracic vertebra.
Esophagus attached to the margins of the esophageal hiatus via…
the phrenico-esophageal ligament (dorsal mesentery). It attaches to the esophagus both superior and inferior to the hiatus, allowing independent movement of the esophagus and diaphragm during breathing.
2 common types of hiatal (esophageal) herniation
sliding and paraesophageal
sliding hiatal herniation
due to elongation of the mesenteric attachments of the esophagus to the diaphragm a portion of the lesser curvature and fundus “slide” through the esophageal hiatus into the thoracic cavity; the gastro-esophageal junction (cardia) will be located superior to the diaphragm; associated with “heartburn.”
paraesophageal hiatal herniation
protrusion of the fundus of the stomach through a defect in the diaphragm next to the esophagus; the gastro-esophageal junction (cardia) remains INFERIOR to the diaphragm– this is more dangerous than the sliding one as the fundus may strangulate.
Abdominal course of esophagus
approximately 2.5 cm in length
only peritonealized portion (mesoesophagus)
joins cardiac portion of stomach at approximately the level of the 11th thoracic vertebra
Gastro-esophageal junction (borders)
Right border– continuous with the lesser curvature of the stomach
left border- separated from the fundus of the stomach by the cardiac notch
Esophageal mucosa
demonstrates an epithelial transitional zone (stratified squamous to simple columnar, aka, “Z” line)
Lower esophageal sphincter
Although not anatomic, a functional physiologic sphincter exists at the esophageal cardiac junction (L.E.S.- lower esophageal sphincter) which appears to be important in regulating the entrance of food into the stomach and in preventing esophageal reflux.
Arterial supply to the esophagus
- cervical portion: inferior thyroid a.
- thoracic portion: branches from the bronchial aa. & from the aorta directly
- abdominal portion: esophageal branch of the left gastric a.
Venous drainage of the esophagus
- esophageal submucosal veins are drained by venae comitantes of the arterial supply.
- These veins drain to systemic (brachiocephalic and azygos vv.), and viscera venous systems (portal vein)
Esophageal varices
Reversal of venous drainage due to circulatory blockage within the liver causes distension of the esophageal submucosal veins, resulting in the formation of esophageal varices which over time can rupture causing death.
GERD (Gastroesophageal reflux disease)
produces “heartburn” (pyrosis)- referred pain is to the substernal region, made worse by sliding hiatal hernia.
Stomach- function and shape
First organ of digestion; mixes food with digestive juices
Typically J-shaped, however, shape varies with stature and content
Stomach: fastening
Fastened securely to the diaphragm superiorly (TV11) via the gastrophrenic ligament; inferiorly to the posterior body wall via its continuity with the retroperitoneal portion of the duodenum (LV1-LV2)
Mobility of stomach
Since the remainder of the stomach is only loosely secured by the omenta (greater and lesser), it is highly mobile, so much so, that when sufficiently filled may extend into the major pelvis.
Stomach: external structure: curvatures
Greater: convex lateral border
lesser: concave medial border
Stomach: external structure: notches
- Cardiac: notch between junction of esophagus and fundus
2. angular incisure: sharp angulation of lesser curvature at the junction of body and pyloric portion
Stomach: external structure: regions
Cardia- indefinite area around esophageal entrance
Fundus- portion more superior than cardia
Body- area between fundus and pyloric antrum
Pyloric portion:
pyloric antrum- expanded portion proximal to pyloric canal
pyloric canal
pylorus: thickened muscular portion forming sphincter between stomach and duodenum, located to the right of the midline at LV1-LV2
Congenital Hypertrophic Pyloric Stenosis
1-4/1000 live births; 4:1 male/ female- grossly increased muscle layer (mainly circular) at the pylorus which does not open enough to pass stomach contents. It is palpable in the right upper quadrant just to the right of the midline and is usually identified in the first 3-6 weeks of life after episodes of progressive vomiting; can be surgically dilated.
Stomach: muscular wall
- outer longitudinal
- inner circular: greatly thickened segment of which forms the PYLORIC SPHINCTER
- innermost oblique: modified circular fibers often forming an incomplete layer
Stomach: internal: mucosa
- When the muscular layers are contracted the mucosa displays longitudinally oriented folds called RUGAE (Magenstrassen- stomach streets)
- Located predominantly along the lesser curvature; forms GASTRIC CANAL (temporarily visible during swallowing)
Stomach relations/ contact areas: anterior
a. anterior abdominal wall
b. diaphragm
c. left lobe of the liver
Stomach relations/ contact areas: superior
diaphragm
Stomach relations/ contact areas: posteriorly and inferiorly
referred to as the STOMACH BED- area related to the stomach that directly cradles it, including retroperitoneal structures behind the posterior wall of the omental bursa.
a. left hemidiaphragm
b. spleen
c. body and tail of pancreas
d. Superior pole of left kidney
e. left suprarenal gland
f. splenic artery
g. transverse colon & transverse mesocolon
h. left colic flexure
gastric/ peptic ulcer
Erosion of the posterior wall of the stomach due to gastric/ peptic ulcer can erode into ANY of the above structures. Erosion of the splenic a. as it courses through the substance of the pancreas can result in severe hemorrhage, pancreatitis, and peritonitis.
Spleen: function
largest single mass of lymphatic tissue in the body.
a. reservoir of red and white cells
b. removes old RBCs and waste products
c. Elaborates lymphocytes (immune surveillance & response)
Spleen as emergency resource (clinical note)
The spleen can expel its reservoir of blood in time of need, i.e. decreased volume or increased demand, through contraction of smooth muscle located in the capsule.
Spleen: location
the left upper quadrant within the dorsal mesentery suspended between the greater curvature of the stomach (gastrosplenic ligament) and the diaphragm (phrenicolienal ligament) at ribs 9, 10, 11. Also, the spleen rests on the phrenicocolic ligament (sustentaculum lienis: shelf for the spleen).
spleen palpation and splenomegaly (clinical note)
The spleen normally does not extend inferior to the costal margin and therefor is not palpable through the abdominal wall– needs to be at least 3X normal size to palpate.
Spleen: size and shape
Normal weight range 100-250 gm
Wedge shaped or tetrahedral, shape depending on:
- distribution of vessels within
- fullness of surrounding organs, i.e. stomach, transverse colon