GA Flashcards
what is the anterior portion of the abdominal wall made up of?
aponeuroses and muscles
layers of the anterior and antero-lateral abdominal walls:
skin, superficial fascia, deep fascia/epimysium, muscles, fascia transversalis, extraperitoneal fat, peritoneum
roles of the abdominal wall:
- protects viscera of the abdomen
- flexes and laterally rotates the spine
- depresses the ribs
- increases intra-abdominal P by contracting muscles
- assists in forced expiration, coughing, sneezing, peeing, pooping
tension lines
direction of collagen fibers on the skin which result in a practically invisible scar if an incision is made in the direction in which they run
4 abdomen shapes and what could cause it:
shapes: flat, rounded, scaphoid, protrubent
causes: feces, fetus, food, flatus, fluid, fat
superficial fascia
divided into two layers separated by the neurovascular bundle: Camper’s fatty layer (superficial fatty layer) and Scarpa’s membranous layer (superficial vessels) which becomes continuous with the fascia of the back and thorax
deep fascia/epimysium
thin connective tissue sheath that covers individual abdominal muscles anteriorly and posteriorly
muscles of the abdomen
3 lateral: external oblique (most superficial), internal oblique (perpendicular to external) and transversus abdominis
2 medial: rectus abdominis and pyramidalis (strengthens linea alba but may not be present or paired in some people)
fascia transversalis
thin layer of fascia lining transversus abdominis muscle continuous with another layer lining the diaphragm and iliacus muscle
rectus sheath
formed from aponeuroses of the three anter-lateral muscles to encapsulate the rectus abdominis muscles
*internal oblique aponeurosis will split and half follows the external oblique muscle anteriorly and the other half follows the tranversus aponeurosis posteriorly (wraps n the rectus muscle)
extraperitoneal fat
thin layer of CT with fat that lies between fascia transversalis and peritoneum
peritoneum
large serous membrane containing a single layer of epithelial cells lying on a layer of loose CT serving to minimize friction, resist infection and store fat
*parietal when lining the abdominal wall and then reflexed to become visceral when surrounding organs–> peritoneal fluid exists in the peritoneal cavity formed between the parietal and visceral peritoneum
foramen epiplocium/of Winslow
the way by which the greater and lesser sac communicate with one another
intraperitoneal vs. retroperitoneal organs
intraperitoneal: surrounded by peritoneal cavity (ex: liver, spleen)
retroperitoneal: only one part is dressed (ex: kidneys)
greater omentum vs. lesser omentum
greater: hangs from transverse colon and has 4 layers of peritoneum (2 anterior and 2 posterior)–> usually perforated (from the dorsal mesentery)
lesser: from the inferior part of the liver to other organs and consists of the hepatogastric ligament (liver to stomach) and the hepatoduodenal (porta hepatis to duodenum containing portal triad) ligament (from the ventral mesentery)
what connects the liver to the diaphragm?
visceral ligaments made of double layers of peritoneum and the lesser omentum:
1 falciform
2 coronary
2 triangular
what makes up the portal triad?
bile duct, hepatic vein and hepatic artery
mesentery
folds of peritoneum connecting intestines to posterior abdominal wall and contains vessels and nerves
(if organ presents it, it will be intraperitoneal)
9 regions of the abdomen
left to right:
R hypochondriac, epigastric, L hypochondriac
R lumbar, umbilical, L lumbar
R iliac, hypogastrin, L iliac
what exists in each quadrant?
upper right: liver, gallbladder, stomach antrum, duodenum, right kidney, right adrenal (suprarenal), pancreas (head), colon (hepatic flexure), IVC
upper left: abdominal esophagus, stomach fundus, spleen, left kidney, left adrenal, abdominal aorta, pancreas (body, tail), part of jejunum, colon (spenic flexure)
lower right: ileum, ascending colon, cecum, appendix, right ureter
lower left: part of jejunum, part of ileum, descending colon, sigmoid colon, left ureter
where does the esophagus pierce the diaphragm and then where does it enter the stomach?
pierces diaphragm at: esophageal hiatus
enters stomach at: cardia
what determines sites of organ formation?
interactions between the endoderm and visceral mesoderm
divisions of the primitive gut tube
foregut (head to liver), midgut (liver to right 2/3 and left 1/3 of transverse colon) and hindgut (left 1/3 of transverse colon to cloacal membrane)
development of the esophagus and clinical significance
development: develops from the foregut then at 4 weeks, lung buds evaginate and the tracheoesophageal septum separates the foregut into the primordium of the respiratory tract from the esophagus
clinical significance: defects leads to esophageal atresia or tracheoesophageal fistula preventing normal swallowing leading to excess fluid in the amniotic sac (polyhydramnios)
development and rotation of the stomach
5th week- stomach rotates 90 degrees to the right around the craniocaudal axis–> dorsal aspect grows more rapidly forming greater curvature and ventral portion becomes lesser curvature
further growth- stomach rotates around its anteroposterior axis so caudal/pyloric end moves to right and cephalic/cardiac end moves to left ballooning out and forming the omental bursa (space behind stomach)
development of duodenum and clinical significance
development: retroperitoneal and forms a C-shaped loop that rotates right whose lumen is obliterated by proliferation of cells from walls but is soon recanalized
clinical significance: duodenal stenosis or atresia if canalization is incomplete (leads to polyhydramnios)
what causes the mesoduodenum to fuse with the peritoneum?
the duodenum and head of the pancreas pressing against the dorsal body wall
development of liver and gallbladder; clinical significance
development:
LIVER (week 3)- hepatic diverticulum grows from ventral side of duodenum and proliferation will result in penetration of the septum transversum and narrowing of connection to duodenum forming the bile duct
GALLBLADDER- cystic diverticulum from ventral side of duodenum and formation of cystic duct
clinical significance: liver= major hematopoietic organ in embryo, accessory hepatic ducts and duplication of the embryo is common, hepatic ducts recanalize if not: extrahepatic biliary atresia, and defects in duct formation in liver: intrahepatic biliary duct atresia
development of the pancreas and clinical significance
development: forms from two buds that fuse when duodenum rotates forming uncinate process and main pancreatic duct and later the pancreatic islets of Langerhans
clinical significance: two parts of ventral bud can migrate in different directions causing the duodenum to be surrounded by pancreatic tissue–> annular pancreas (could obstruct/constrict duodenum so needs to be bypassed)
development of the spleen
mesoderm derived and develops within the dorsal mesentery located on the left after the stomach rotates and is connected to the kidney by lienorenal ligament
Meckel’s diverticulum
2 inch long remnant of the vitelline duct (remaining open as a fistula or forming a cyst) projecting from distal ileum that can become inflamed, can bleed or can obstruct
herniations
umbilical hernia: protrusion of bowel through umbilical ring that usually closes spontaneously
omphalocele: herniation of the bowel through umbilical ring covered by a thin membrane that could rupture (often patients have other issues)
gastroschisis: bowel protrudes lateral to umbilical ring into amniotic cavity with no covering and can be damaged by amniotic fluid exposure
development of the hindgut and clinical significance
development: results in distal 1/3 of transverse colon and beyond forming anorectal canal and urogenital sinus
clinical significance: rectourethral or rectovaginal fistulas, imperforate anus or anal stenosis and congenital megacolon/Hirschprung (absence of parasympathetic ganglia)
development of the midgut and *clinical significance
development: midgut communicates with yolk sac via vitelline duct and elongation of gut leads to primary intestinal loop and then physiological umbilical herniation occurs
* 90 degree rotation outside of the body occurs and then after return to the abdominal cavity, a 180 degree rotation occurs and the cecal bud and appendix form
clinical significance: asymmetry of midgut from errors in 180 degree rotation (non-rotation, reversed rotation, mixed rotations) causing twisting–> volvulus which will obstruct or compromise blood supply
Ligament of Treitz
suspends the duodeno-jejunal flexure from the diaphragm
what shape is the duodenum in and what are its 4 parts?
shape: horseshoe-shaped curve known as the C-loop in which the head of the pancreas lies in it
parts: superior, descending, transverse and ascending in which the last three are retroperitoneal
jejunum vs. ileum
jejunum: more and thicker folds/plicae circulares
ileum: more arcades and vessels
which part of the colon is intraperitoneal?
the sigmoid colon which is located in the pelvis
what forms the appendix?
the joining of the 3 taeniae coli (longitundinal bands) which runs through the entirety of the colon
pancreas
glandular mass whose head rests in the “C” shape of the duodenum and its tail touches the spleen
parts: unciate, head, neck, body, tail
unpaired anterior visceral branches
celiac artery/trunk (foregut), superior mesenteric artery (midgut), inferior mesenteric artery (hindgut)
paired lateral visceral branches
right and left: middle adrenal (kidneys), renal, gonadal (testes or ovaries)
branches of celiac trunk
- left gastric artery: esophageal branches and runs along lesser curvature of stomach anastomosing with right gastric artery (from proper hepatic artery)
- splenic/lineal artery: largest and travels posterior to stomach giving branches to the pancreas and spleen and left gastroepiploic artery (which anastomoses with right gastroepiploic artery from the gastroduodenal artery along greater curvature)
- common hepatic artery: branches into proper hepatic and gastro-duodenal arteries
branches of superior mesenteric artery (SMA)
(R side:) inferior pancreaticoduodenal artery (anterior and posterior), middle coli artery (right and left), right colic artery (descending and ascending), ileocolic artery (superior and inferior)
(L side:) jejunal and ileal arteries
*anastomoses with secondary branches of each other
branches of inferior mesenteric artery (IMA)
left colic artery (ascending, descending), sigmoid arteries (superior, inferior), superior rectal artery
marginal artery of drummond
forms from anastomoses and is a continuous vessel within the inner margin of the large bowel and gives rise to the vasa recta
what elevates the hyoid bone?
CN X, longitudinal pharyngeal muscle
which nerves are responsible for the gag reflex?
afferent- IX
efferent- X
top, bottom, anterior aspects of pharynx
top- occipital bone
bottom- inferior border of the cricoid cartilage at level C6
anterior- no wall since posterior to and continuous with the nasal cavity, mouth and larynx
purpose of pharyngeal constrictor muscles
to direct food to the esophagus (pushes it down)
3 divisions of the pharynx
- nasopharynx: respiratory; above soft palate and lateral walls contain Eustachian tube openings near torus tubarius, salpingopharyngeal fold, pharyngeal recess and pharyngeal tonsils (posterior and superior to Eustachian tubes)
- oropharynx: digestive; below soft palate and anterior to C2 and C3 with palatoglossal and palatopharyngeal arches (which enclose respective muscles) and tonsillar bed in between
- laryngopharynx: anterior to C3-C6, communicates with larynx through laryngeal inlet which has piriform recesses on either side
what are the pharyngeal tonsils called when they are inflamed?
adenoids
tonsillar bed
- between palatoglossal and palatopharyngeal arches
- vessels and nerves reside deep in its mucosa (ascending pharyngeal artery, facial artery, external palatine vein, glossopharyngeal nerve)
what happens if tonsillectomy causes damage to vessels or nerve within tonsillar bed
- damage to vessels (ascending pharyngeal artery, facial artery, external palatine vein)–> extensive bleeding
- damage to nerve (glossopharyngeal)–> loss of taste
palatine tonsils
accumulations of lymphoid tissue that sit in tonsillar beds and protect the body from entry of extraneous materials via the mucosa
piriform recesses
- depressions on either side of the laryngeal inlet formed by invaginations of the larynx into the anterior wall of the laryngopharynx
- recesses are separated from the laryngeal inlet by the aryepiglottic folds
- lateral walls of the piriform recess are formed by the thyrohyoid membrane and the thyroid cartilage
- foreign bodies can become lodged here injuring the internal and recurrent/inferior laryngeal nerves
muscles of the pharynx
- external layer: 3 pairs (superior, middle and inferior constrictors) with circumferentially oriented fibers fusing at midline at median pharyngeal raphe forming 3 muscular bands; helps propel bolus
- innervation fro pharyngeal plexus (sensory- IX, motor- X)
-internal layer: 3 longitudinally oriented muscles–> stylopharyngeus, salpingopharingeus and palatopharyngeus which elevate the pharynx and larynx during phonation and swallowing
soft palate
separates the nasopharynx from the oropharynx and is moveable (attached to hard palate) and composed of 5 muscles (levator veli palatine, tensor veli palatine, palatoglossus, palatopharyngeus and musculus uvulae) which insert into palatine aponeurosis that forms the substance of the soft palate
innervation of the pharynx
- motor: CN X supplies all muscles except stylopharyngeus muscle (CN IX) and tensor veli palatine (CN V3)
- external and recurrent branches of vagus also supply inferior pharyngeal constrictor muscle
- sensory: CN IX to all three pharynx regions
- general sensory- to pharynx, tonsils, soft palate and posterior 1/3 of tongue
- special sensory- to posterior 1/3 of tongue
tympanic plexus and lesser petrosal nerve
branch of CN IX that has sensory afferent fibers from mucosa of the tympanic cavity, Eustachian tube and mastoid air cells
*lesser petrosal nerve–> continuation of tympanic plexus with preganglionic parasympathetic fibers that synapse in otic ganglion and postganglionic parasympathetic fibers which are secretomotor to the parotid gland
deglutition
main purpose of the pharynx (swallowing) that has voluntary and involuntary components involving muscles of tongue, soft palate, pharynx and larynx
*3 stages
1st stage of deglutition
oral preparatory phase and oral transfer phase
- voluntary cortical control
- base of tongue and soft palate close oral cavity posteriorly to prevent food from spilling into the open larynx
- contraction of palatoglossus and palatopharyngeal muscles lower the soft palate
- suprahyoid muscles elevate and fix the hyoid bone- stabilizes the larynx
2nd stage of deglutition
pharyngeal phase
- involuntary rapid movement to the esophagus
- swallow/pharyngeal reflex
- *pharynx changes from being an air channel to a food channel
- soft palate closes nasopharynx
- airway sealed by glottis
- suprahyoid muscles and longitudinal pharyngeal muscles pull the larynx and hyoid bone up and forward so inlet is brought under tongue to open passageway for food
3rd stage of deglutition
esophageal phase
- involuntary
- inferior pharyngeal constrictor muscles relax allowing food to enter the esophagus
- infrahyoid muscles control the descent of the larynx and stabilize the hyoid bone
input to parotid, submandibular and sublingual glands
parotid gland- parasympathetic input by way of lesser petrosal nerve and otic ganglion
submandibular and sublingual glands- parasympathetic input by way of chorda tympani and submandibular ganglion
recurrent laryngeal nerve importance and what happens if damaged
function: adducts the vocal cords during bolus passage and allows necessary glottis closure during cough reflex
damage causes: ipsilateral vocal cord paralysis, trouble swallowing liquids and poor/weak cough reflex
hypoglossal nerve deficits (CN XII)
affects food bolus manipulation within the oral cavity interfering with bolus delivery to the oropharynx
adenoids
enlargement of pharyngeal tonsils impeding passage of air from the nose and can block Eustachian tube opening (impairs hearing/promotes infection)
dysphagia
difficulty swallowing
