ABDOMEN

ABDOMEN

cylindrical chambers

boundaries: inferior margin of the thorax superior margin of the pelvis

and lower limb

ABDOMINAL VISCERA

major elements of the GIT system caudal end of the esophagus, stomach, small

and large intestines, liver, pancreas and gallbladder

spleen components of the urinary system

kidney and ureters

suprarenal glands major neurovascular structures

FUNCTION OF ABDOMEN

1. Houses and protects major viscera2. Assist in breathing3. Changes in intra-abdominal pressure

COMPONENT PARTS OF ABDOMEN

A. ABDOMINAL WALL partly made up of bone but mostly of

muscle skeletal elements are:

L1-L5 vertebrae and IV discs Superior expanded parts of the pelvic

bones bony components of the inferior thoracic

wall(costal margin, 12th rib, end of 11th rib, xiphoid process

COMPONENT PARTS OF ABDOMEN

ABDOMINAL WALL Muscular elements are

quadratus lumborum, psoas major, iliacus muscle

Transverse abdominis, internal oblique, exyternal oblique

Rectus abdominis

COMPONENT PARTS OF ABDOMEN

B. ABDOMINAL CAVITY Suspended by mesenteries, from its

posterior to anterior abdominal wall ventral mesentery dorsal mesentery

Lined by peritoneum parietal peritoneum – lines the abdominal wall visceral peritoneum – covers the suspended

organs

COMPONENT PARTS OF ABDOMEN

ABDOMINAL CAVITY1. Intraperitoneal structures

Are the elements of the GI system suspended from the abdominal wall by

mesenteries

2. Retroperitoneal structures Renal system: kidneys and ureters Not suspended from the abdominal wall by

mesenteries Lies b/w parietal peritoneum and abdominal

wall

COMPONENT PARTS OF ABDOMEN

C. INFERIOR THORACIC APERTURE is the superior aperture of the

abdomen and closed by the diaphragm

COMPONENT PARTS OF ABDOMEN

D. DIAPHRAGM separates the abdomen from the thorax anchored by CRUS (muscular extension)

anterolaterally as far as L3 on the RIGHT and L2 on the LEFT

Anchored by arcuate ligament posteriorlya. Medial and lateral arcuate lig. – cross the

muscles of the posterior abdominal wallb. Median arcuate ligament – crosses the aorta

and continous with the CRUS on each side

COMPONENT PARTS OF ABDOMEN

E. PELVIC INLET the circular margin is formed entirely

by bone posteriorly – sacrum Anteriorly – pubic symphisis Laterally – bony rim of the pelvic bone

PRIMITIVE GUT TUBE

A. Foregut Gives rise to the distal end of the

esophagus, the stomach and proximal part of the doudenum

Gives rise to the liver, gallbladder, pancreas and spleen

PRIMITIVE GUT TUBE

B. MIDGUT Gives rise to the distal part of the

doudenum, the jejunum, ileum, ascending colon,proximal 2/3 of the transverse colon and cecum

C. HINDGUT Gives rise to the distal 1/3 of the

transverse colon, descending colon, sigmoid colon and the superior part of the rectum

SKIN AND MUSCLES INNERVATION

MYOTOMEIntercostal Nerves T7-T11 and subcostal

nerve T12 ---supply the skin and muscles of the abdominal wall

T5-T6 --- supply upper parts of the EOML1 --- supply the skin and muscle in the

inguinal and suprapubic regions

SKIN AND MUSCLES INNERVATION

DermatomeT6 --- skin over the infrasternal angleT10---skin around the umbilicusL1 --- skin in the inguinal and suprapubic

regions

ARTERIES OF THE GI SYSTEM

1. Celiac Artery Supplies the foregut

2. Superior mesenteric artery Supplies the midgut

3. Inferior mesenteric artery supplies the hindgut

VEINS OF THE GI SYSTEM

1. Left renal vein drains the kidney, suprarenal gland and

gonad on the same side

2. Left common iliac vein drains the lower limbs, pelvis, perineum

and parts of the abdominal wall

3. Left lumbar veins drain the back and posterior abdominal

wall on the left side

ABDOMINAL WALL

Boundaries:

Superiorly – xiphoid process and costal margin

Inferiorly – upper parts of the pelvic bonePosteriorly – vertebral column

LAYER

Skinsuperficial fascia-fatty layer (Camper’s fascia) superficial fascia-membranous layer (Scarpa’s Fascia) external obliqueinternal obliquetransversus abdominisytransversalis fasciaextraperitoneal fasciaparietal peritoneum

ANTEROLATERAL MUSCLES

3 flat muscles: EOM; IOM; TAM2 vertical muscles: RAM; PyramidalisFunctions:1. Forms firm but flexible wall that keeps the

abdominal viscera within the abdominal cavity2. Protects the viscera from injury3. Helps maintain the position of the viscera in the

erect posture against the action of gravity4. Contraction of these muscles assist in both quiet

and forced expiration, coughing and vomitting5. Increase intra-abdominal pressure during

parturition (childbirth), micturation and defecation

3 FLAT MUSCLES

External Oblique Muscles Most superficial, immediately under the

Scarpa’s fascia From lateral to midline aponeurosis

forms the linea alba-seen from the xiphoid process down to the pubic symphisis

Derives from the aponeurosis of EOM: Inguinal ligament, lacunar ligament and

pectineal (Cooper’s) ligament

3 FLAT MUSCLES

Internal Oblique Muscle Smaller and thinner than EOM Blends with linea alba Muscle fibers passing in a superomedial

directionTransversus abdominis muscle Muscle fibers passing in a horizontal

direction Blends with linea alba

3 VERTICAL MUSCLES

Rectus abdominis muscle Long and flat muscles and extends the

length of the anterior abdominal wallPyramidalis Small, triangular-shaped muscle which

maybe absent Anterior to the rectus abdominis Base on the pubis and apex is attached

to the linea alba

ORGANS

A. Abdominal esophagus

B. StomachCardia-surrounds the

opening of the esophagus into the stomach

Fundus of stomach-area above the level of the cardial orifice

Body of stomach-largest region of the stomach

Pyloric part – antrum and canal; distal end of the stomach

Other features:Greater curvature –point of attachment for the gastrosplenic ligament and the greater omentumLesser curvature – point of attachment for the lesser omentumCardial notch- the superior angle created when the esophagus enters the stomachAngular incisure- bend on the lesser curvature

ORGANS Large Intestine

Parts: Cecum Colon (ascending, transverse, descending & Sigmoid) Rectum AnusFXN:  Its function is to absorb water from the remaining

indigestible food matter, and then to pass useless waste material from the body

Small IntestineParts:duodenumjejunumileumFxn: - where much of the digestion and absorption of food takes place- absorption of nutrients and minerals found in food

ORGANS

Liver largest visceral organ in the body this organ plays a major role in metabolism and has a

number of functions in the body, including glycogen storage, decomposition of red blood cells, plasma protein synthesis,hormone production, and detoxification

surfaces : diaphragmatic surface (anterior, superior, posterior directions visceral surface (inferior direction)

Functions: Formation of Bile Major organ for Fat Metabolism Biotransformation of Drugs

ORGANS

Gall Bladder a pear-shaped sac lying on the

visceral surface of the right lobe of the liver

a small organ that aids mainly in fat digestion and concentrates bile produced by the liver

Parts: Fundus, body and neck Fxn: receives, concentrates and stores bile

from the liver

ORGANS

Pancreas lies mostly posterior to the stomach Parts: head, uncinate process, neck and tail of

pancreas a gland organ in the digestive and endocrine system

of vertebrates is both an endocrine gland producing several

important hormones, including insulin, glucagon, and somatostatin, as well as an exocrine gland, secreting pancreatic juice containing digestive enzymes that assist the absorbtion of nutrients and the digestion in the small intestine. These enzymes help to further break down the carbohydrates, proteins, and lipids in the chyme.

1: Head of pancreas2: Uncinate process of pancreas3: Pancreatic notch4: Body of pancreas5: Anterior surface of pancreas6: Inferior surface of pancreas7: Superior margin of pancreas8: Anterior margin of pancreas9: Inferior margin of pancreas10: Omental tuber11: Tail of pancreas12: Duodenum

ORGANS

Spleen lies against the diaphragm, in the area of

rib IX to rib X Lies in the left upper quadrant of the

abdomen Fxn: It removes old red blood cells and

holds a reserve of blood in case of hemorrhagic shock while also recycling iron

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