Interval 3 Flashcards
Foregut
-ends at the entrance of bile duct in second part of duodenum
Spleen
not gut tube derivative, mesoderm derivative
- receives blood flow from celiac artery
- filters RBC and is lymphatic
Teres ligament
- round ligament of the liver
- remnant of fetal circulation
Greater omentum
dorsal mesentery remnant
extends from greater curvature of the stomach
parts of the stomach
- fundus
- body
- antrum
- pyloric canal
lesser omentum
ventral mesentery remnant
CONTAINS:
- hepatpduodenal ligament
- bile duct
- proper hepatic artery
- portal vein
*epiploic foramen: inferior edge of the ventral mesentery
If you block the splenic artery, what else becomes blocked?
-stomach
Pancreas development
- in ventral (head) and dorsal (rest) mesentery
- enveloped by foregut and midgut duodenum (the head shares its blood supply with these areas)
N/B/T: blood supply from the splenic artery
transverse plane
separates the mediastinum between T4 and T5
-heart lies below the transverse plane
heart growth
- into the pericardium from posterior aspect
- has two serous pericardium layers: parietal and visceral (epicardium)
- parietal pericardium has an outer fibrous layer (because there is no wall to cling to, this is nonserous)
- heart is in the middle mediastinum
pericardial space
-potential space
How many vessels must be cut to remove the heart?
-8
inferior vena cava (right atrium)
superior vena cava (right atrium)
4 pulmonary veins (left atrium)
pulmonary trunk (right ventricle)
ascending aorta (left ventricle)
myocardium
formed by cardiac muscle
most prominent in the ventricles
Chorda tendineae
hold leaflets of valves
Right and left border of the heart
RIGHT: 3rd-6th intercostal cartilages, finger breadth from sternum
LEFT: midclavicular line in the 5th intercostal cartilage to 2nd
INFERIOR: xiphoid left to right
SUPERIOR: 2nd left intercostal space to 3rd on right
*1/3 of heart is to the right of median plane
Right border structures
-right atrium, SVC, IVC
Left border structures
-left ventricle and left auricle
Inferior border structures
-right ventricle
Superior border structures
-left and right atria, ascending aorta, pulmonary trunk, SVC
Where are the visceral and parietal pericardium continuous?
- pulmonary veins
- SVC
- IVC
- great arteries
- everywhere else the heart is free within the cavity
- serous fluid allows frictionless beating
Innervation of parietal layers of the pericardium
-sensory branches of the phrenic nerves
transverse pericardial sinus
-between ascending aorta and PT and SVC
oblique sinus
-inferior to the pulmonary veins and left of the IVC
Coronary arteries
- supply arterial blood to the heart
- arise from the right/left aortic sinuses
Right coronary artery
- long
- courses in the coronary sulcus
- supplies the right atrium and right ventricle
- nodal branches supply SA and AV nodes
- marginal branch supplies right ventricle
- typically gives rise to posterior interventricular artery
posterior interventricular artery
- from the right coronary artery
- courses in the posterior interventricular sulcus
- supplies right/left ventricle and posterior part of interventricular septum
Left coronary artery
-short artery that originates from left aortic sinus into the anterior interventricular artery and circumflex artery
anterior interventricular artery
- LAD
- courses in the anterior interventricular sulcus
- supplies right and left ventricles and 2/3 of the interventricular septum (AV bundle)
Circumflex artery
- LCX
- courses in the coronary sulcus
- supplies the left atrium and left ventricle
- marginal branch arises from here and supplies the left ventricle
Right atrium
smooth-walled: sinus venarum
-SVC, IVC, ostium of coronary sinus, and openings of anterior cardiac veins
rough-walled: pectinate muscles
*poorly oxygenated blood
crista terminalis
separates the sinus venarum from the pectinate muscles
contains the fossa ovals (in the interatrial septum)
-remnant of the foramen ovale (shunts blood from lungs)
Right atrioventricular orifice
opens into the right ventricle
closed by the 3 leaflet of the tricuspid valve
right ventricle
rough walled part-trabeculae carneae
smooth walled part - conus arteriosus (infundibulum) which leads to the PT (separated by the semilunar valve)
3 papillary muscles (anterior, posterior, septal)
separated by interventricular septum (membranous and muscular)
Chorda tendineae
attach to papillary musches and to leaflets of the tricuspid valve
left atrium
smooth-walled part
rough-walled part: auricle, contains pectinate muscles
contains the left atrioventricular orifice which opens into the left ventricle (closed by 2 leaflets of the mitral valve)
left ventricle
muscular wall: trabecilae carneae (twice as thick as the wall of the right ventricle)
smooth walled: aortic vestibule - leads to ascending aorta
-2 papillary muscles (anterior/posterior) with chordae tendineae attach to edges of mitral valve
semilunar valve
at the junction between vestibule and ascending aorta
3 cusps: right, left, posterior
-aortic sinus distal to each
Papillary muscles in ventricles during contraction
contract and keep the cusps of tricuspid and mitral valves rom opening
-valves close due to increased pressure
Cardiac conduction
-wave of depolarization
SA Node
in the sinus venarum of right atrium
pacemaker (depolarizes faster than others)
wave spreads to both atria which contract
AV Node
in the interatrial septum
stimulated by depolarized atria
delays depolarization from passing to the ventricles so atria can fully contract
AV Bundle of HIs
arises from cells of AV node, passes into interventricular septum
-right/left branches
causes each of the papillary muscles in the ventricles to contract (keeps AV valves shut when ventricles contract)
Purkinje Fibers
spread a wave of depolarization to cardiac muscle cells in the right and left ventricles
Great cardiac vein
courses with the LAD and drains into the coronary sinus (right atrium)
Complete AV block
-atria and ventricles become dissociated and beat independently
Heart innervation
-autonomic (parasympathetic and sympathetic)
Cardiac plexus
- both autonomic fiber types that reach the heart pass through plexus
1) superficial cardiac plexus: inferior to the arch of the aorta
2) deep cardiac plexus: anterior to bifurcation of trachea
Types of autonomic fibers in cardiac plexus
1) preganglionic parasympathetic axons from vagus nerves CN X
2) postganglionic parasympathetic axons
3) postganglionic sympathetic axons from cervical and upper thoracic splanchnic nerves
Sensory fibers in the cardiac plexus
- innervate baroreceptors/chemoreceptors in the heart, course with vagus nerve and enter CNS
- use sympathetic nerves to carry pain to CNS
- angina pain could therefore be referred to T1-T5 dermatomes
What does sympathetic innervation do in the heart
- accelerates heart rate
- increases the force of cardiac contraction (by increasing rate of depolarization of cells in SA/AV)
What does parasympathetic innervation do in the heart
- slows heart rate
- decreased the force of cardiac contraction
- promotes vasoconstriction of coronary arteries
First heart sound (S1 lupp)
- made by the closing of the mitral and tricuspid valve
- systole
Second heart sound (S2 dubb)
- closing of the aortic and pulmonic valves
- beginning of diastole
- valves close by the backflow of blood
Celiac Artery
-branches from the abdominal aorta at T12
3 branches:
1) splenic artery
2) common hepatic artery
3) left gastric artery
Splenic artery supplies
1) spleen
2) neck, body, tail of pancreas
3) left side of the greater curvature of the stomach (left epiploic artery)
4) fundus of the stomach
Left gastric artery supplies
- lesser curvature of the stomach
- abdominal part of the esophagus
- ulcers in the stomach can erode it
common hepatic artery splits into:
- proper hepatic: part of lesser curvature, branches to left/right hepatic which supply liver
- gastroduodenal: supplies duodenum, superior head of pancreas, right side of greater curvature (right epiploic artery)
- subject to erosion by penetrating ulcer of the posterior wall of the first part of the duodenum
Liver
- functions as both exocrine and endocrine gland
- suspended by remnants of the ventral mesentery: falciform ligament, coronary ligaments, lesser omentum
Anatomic lobes of the liver
-left, right, quadrate, and caudate
Functional lobes of the liver
- left and right (equal size)
- both with own blood supply, venous/biliary drainage
left: quadrate lobe and part of caudate
right: part of caudate
Liver blood supply
- 70% from portal vein (poorly oxygenated)
- 30% from proper hepatic (well oxygenated)
Proper hepatic artery splits into
-left and right
Portal triad
-hepatic ducts, portal vein, and proper hepatic artery enter/exit and porta hepatis and form the triad
common hepatic ducts
- right and left, drain liver
- join to form the common hepatic duct which joins the cystic duct to form bile duct which joins with the pancreatic duct to form the hepatopancreatic ampulla
gallbladder function
- store and concentrate bile produced/secreted by liver
- blood supply: cystic artery
parts of the lesser omentum:
-hepatoduodenal and hepatogastric ligaments
epiploic foramen:
- communication of omental bursa with great cavity
- bounded by hepatoduodenal ligament
hepatoduodenal ligament contains:
- hepatic portal vein
- proper hepatic artery
- bile duct
gastrocolic ligament
part of the greater omentum which extends from the greater curvature to the transverse colon
pancreas head blood supply
-pancreaticoduodenal branches of the gastroduodenal (celiac)
AND
superior mesenteric arteries
Foregut innervation
- parasympathetic and sympathetic axons
- visceral sensory fibers
Parasympathetic innervation in the foregut:
-vagus nerves and neurons in terminal ganglia
Sympathetic innervation in the foregut:
- preganglionic sympathetic axons in lower thoracic splanchnic nerves (T5-T9)
- neurons in the celiac ganglia
Visceral pain in foregut:
- fibers course back to the spinal cord in greater splanchnic nerves
- pain is referred to T5-9 dermatomes
- sensations other than pain carried to CNS via vagus nerve
Midgut intestinal blood supply:
- superior mesenteric artery
- starts at L1
Branches of superior mesenteric arteries
- anterior/posterior inferior pancreaticduodenal branches: supply duodenum and head/uncinate of pancreas
- intestinal branches: supply the ileum
- ileocolic, right, and middle colic: supply midpart of colon
- ileocolic: distal ileum, appendix, cecum, proximal part of ascending colon
- right colic: ascending colon
- middle colic: 2/3 of transverse colon
ligament of Treitz
fibromuscular band that supports the duodenojejunal flexure
Jejunum
thicker walls, larger diameter, more prominent circulares, and greater vascularity than ileum
Ileocecal junction
where ileum ends
colon is continuous with the ileum here
Colon characteristics:
- larger diameter than intestine
- taeniae coli: 3 smooth muscle bands
- Haustrations
- omental appendices: fat suspended by coli
Vermiform appendix
- supplied by the appendicular artery, branches from ileocolic
- inflammation due to stool or hyperplasia (childern) stimulates visceral pain fibers which course back in the lower splanchnic nerves and cause colicky pain referred to umbilical
- McBurney’s point: base of appendix
Midgut innervation:
parasympathetic and sympathetic axons
visceral sensory fibers
Parasympathetic innervation in the midgut:
-preganglionic parasympathetic axons in vagus nerves/neurons in terminal ganglia
Sympathetic innervation in the midgut:
- preganglionic axons in the lower thoracic splanchnic nerves from T5-12
- neurons in the celiac and superior mesenteric ganglia
Visceral pain fibers in the midgut:
- course back to the spinal cord and lower thoracic splanchnic nerves
- referred pain from small intestine: t5-10 dermatomes
- referred pain from cecum, appendix, ascending colon and transverse: T10-12
Arterial supply to the hindgut:
- branches of the inferior mesenteric artery (L3):
- left colic artery: descending colon/transverse
- sigmoid arteries: sigmoid
- superior rectal artery: rectum and canal to the pectinate line
SIgmoid colon
also teniae coli, haustrations, and omental appendages
sigmoid rectal junction marks end of these
Hindgut innervation
parasympathetic and sympathetic axons
visceral sensory fibers
Parasympathetic innervation of the hindgut:
preganglionic parasym axons in splanchnic nerves S2-4 and terminal ganglia
Sympathetic innervation of hindgut
preganglionic sym axons from splanchnic nerves T11-L2
neurons in the inferior mesenteric ganglia
referred pain in hindgut
-T11-L2 dermatomes
hepatic portal vein:
-receives poorly oxygenated blood from gastrointestinal structures
superior mesenteric vein
-drains the midgut and unites with the splenic vein (drains foregut)
inferior mesenteric vein
-drains the hindgut, empties into the splenic veins
Stomach drainage
left and right gastric veins
empty into the portal vein
Hepatic veins
NOT portal
drain blood from the heptic sinusoids
empty into inferior VC
Sympathetic, postganglionic splanchnic nerves:
presynaptic fibers enter paravertebral ganglia via white rami
synapse in upper thoracic and lower cervival ganglia
*do not reenter spinal cord, do not form gray ramus
** go direction to the thoracic viscera above the diaphragm
Sympathetic, preganglionic splanchnic nerves:
greater, lesser, and least thoracic
-enter via white rami but do not synapse with paravertebral
run through sympathetic chain without synapsing
- they are myelinated, preganglionic fibers
- ultimately try to find prevertebral ganglia in the abdomen/pelvis where they synapse
Parasympathetic, preganglionic splanchnics
S2-4, exit with these spinal nerves and go straight to destination
- synapse at those intrinsic ganglia and postganglionic fibers
- includes the vagus nerve
NOTE: NO SUCH THING AS PARASYMPATHETIC POSTGANGLIONIC SPLANCHNICS
ascending aorta
left ventricle
descending aorta
to the left of the midline, goes down the body
transverse mesocolon
connects transverse colon to the posterior wall of abdomen
peritoneum
sigmoid mesocolon
peritoneal fold that connect sigmoid to the pelvic wall
