[Anatomy] Abdominal Wall

Front 1

abdominal wall area

Back 1

spans between the xiphoid process/costal margin and the pelvis

Front 2

pelvic bones

Back 2

formed by the fusion of 3 bones: ilium, ischium, pubis

Front 3

landmarks on the ilium related to the abdominal wall

Back 3

iliac crest, anterior superior iliac spine (ASIS)

Front 4

landmarks on the pubis related to the abdominal wall

Back 4

pubic symphysis at midline (where two pubic bones meet), pubic tubercles (prominence lateral to pubic symphysis)

Front 5

umbilicus

Back 5

former site of attachment of umbilical cord, location varies with age and body contours, lies at L4 vertebral level in physically fit person (midway between xiphoid process and pubic symphysis)

Front 6

inguinal ligament

Back 6

spans the distance between the ASIS and pubic tubercle; inferior part of external oblique aponeurosis

Front 7

abdominal planes and quadrants

Back 7

median plane and transumbilical plane form four abdominal quadrants (right upper, left upper, right lower, left lower), transpyloric plane

Front 8

median plane

Back 8

passes vertically through the body midline, from the xyphoid process to the pubic symphysis

Front 9

transumbilical plane

Back 9

passes horizontally through the umbilicus at the L4 vertebral level (corresponding to the level of the iliac crests)

Front 10

transpyloric plane

Back 10

passes through the L1 vertebral level (midway between the manubrium and pubic symphysis)

Front 11

abdominal fascia

Back 11

superficial fascia (camper fascia, scarpa fascia), deep (investing) fascia, transversalis fascia

Front 12

superficial fascia (relative to umbilicus)

Back 12

Inferior to umbilicus, two superficial fascia layers: superficial fatty layer (Camper fascia), Deep membranous layer (Scarpa fascia)

Front 13

scarpa fascia

Back 13

deep membranous layer of superficial fascia, limits the spread of abdominal wall infections inferiorly into the thigh as it is firmly attached to the iliac crest, inguinal ligament, and pubic symphysis

Front 14

deep (investing) fascia

Back 14

surrounds the muscles of the abdominal wall; deep to the superficial fascia and superficial to transversalis fascia

Front 15

functions of abdominal muscles

Back 15

Maintain posture and control movements of the torso; accessory muscles of respiration (forced expiration); Protect abdominal organs; Decrease volume of abdominal cavity, thus increasing intra-abdominal pressure (necessary for defecation, micturition / urination, and parturition / childbirth

Front 16

external oblique and aponeurosis

Back 16

superficial muscle of anterolateral abdominal wall; fier direction: hands in pockets

Front 17

internal oblique and aponeurosis

Back 17

fiber direction: right angle to external oblique

Front 18

transversus abdominus and aponeurosis

Back 18

fiber direction: horizontal; posterior to internal obliques, continuation of innermost intercostals

Front 19

abdominal muscles

Back 19

external obliques, internal obliques, transversus abdominus, rectus abdominus

Front 20

rectus abdominus

Back 20

fiber direction: vertical, lies on either side of the midline; interrupted by tendinous intersections; enclosed by rectus sheath

Front 21

rectus sheath

Back 21

formed by aponeuroses of external and interal obliques and transversus abdominus; linea alba runs verically in midline; arcuate line marks transition in composition of rectus sheath

Front 22

linea alba

Back 22

runs vertically in midline and is formed by fibers of the rectus sheath fusing in the midline

Front 23

arcuate line

Back 23

approximately 1/3 the distance between the umbilicus and pubis, marks a transition in the composition of the rectus sheath

Front 24

superior to arcuate line

Back 24

aponeurosis of internal oblique splits to enclose the rectus abdominis; posterior sheath contains 1/2 aponeurosis of internal oblique, aponeurosis of tranversus abdominus; with transversalis fascia posterior to that

Front 25

inferior to arcuate line

Back 25

all three aponeurotic layers (external, internal, transversalis) pass anterior to the rectus abdominis, leaving only the transversalis fascia posterior to rectus

Front 26

scrotum

Back 26

located posterior to penis; pouch/extension of abdominal wall; superficial layer is skin, deep layer is dartos facia and muscle; contains spermatic cord, testes, and epididymis

Front 27

dartos fascia

Back 27

Contains no fat; continuous with the membranous (Scarpa) layer of superficial fascia of the abdominal wall; due to this connection, infections/fluid from the abdominal wall can collect in the scrotum

Front 28

dartos muscle

Back 28

(smooth muscle fibers); contracts in response to cold, giving the skin of the scrotum a wrinkled appearance and helping reduce heat loss by reducing surface area

Front 29

labia majora

Back 29

homologous to the male scrotum; Also form as an outgrowth of the anterior abdominal wall; Each labium majus is filled with fat, smooth muscle fibers, and contains the round ligament of the uterus

Front 30

skin and muscle innervation of abdominal wall

Back 30

innervated by ventral rami of T7-T11 (continuation of intercostal nerves); T12 (subcostal nerve); L1 (iliohypogastric and ilioinguinal nerves

Front 31

nerves of abdominal wall

Back 31

Emerge from the intercostal spaces and pass anteriorly between internal oblique and transversus abdominis layers; Innervate muscle layers segmentally as they pass through them to reach the skin.

Front 32

dermatomes of abdominal wall

Back 32

o Superior to umbilicus: T7-T9
o At umbilicus: T10
o Inferior to umbilicus: T11-L1

Front 33

injury to single nerve of abdominal wall

Back 33

because nerves innervate muscle layers segmentally, injury would not paralyze an entire muscle, only a segment of it. The paralyzed portion could create a weakened area in the abdominal wall that could allow abdominal contents to protrude or herniate

Front 34

arteries of abdominal wall

Back 34

posterior intercostal arteries, subcostal artery, superior epigastric arteries, inferior epigastric arteries, superficial epigastric arteries

Front 35

posterior intercostal arteries, subcostal artery

Back 35

posterior intercostal arteries are 10th and 11th; descend between internal oblique and transversus abdominis layers

Front 36

superior epigastric arteries

Back 36

Branches of internal thoracic arteries; Located within rectus sheath

Front 37

inferior epigastric arteries

Back 37

Branches of external iliac arteries; Anastomose with superior epigastric arteries within rectus sheath

Front 38

superficial epigastric arteries

Back 38

Branches of femoral artery;
Located in superficial fascia, course vertically towards the umbilicus

Front 39

veins of abdominal wall

Back 39

accompany arteries and share same names; Form extensive venous plexuses with many anastomoses; anastomoses are clinically significant as they provide alternative routes for venous return to the heart when normal venous channels are blocked

Front 40

abdominal wall venous anaStomoses

Back 40

superior and inferior epigastric veins (Caval-caval anastomosis), paraumbilical and superficial epigastric veins (portal-caval anastomosis)

Front 41

caval-caval anastomosis

Back 41

If blood flow through the IVC is blocked, venous blood within the inferior epigastric veins can be shunted to the superior epigastric veins, and from there to the SVC (via numerous tributaries)

Front 42

portal-caval anastomosis

Back 42

If blood flow through the liver is blocked (portal system blockage), venous blood within the paraumbilical veins (part of the portal system) can be shunted to the superficial epigastric veins; the veins radiating from the umbilicus dilate, creating a caput medusae

Front 43

lymphatic drainage of abdominal wall

Back 43

Superior to the umbilicus, lymph drains to the axillary lymph nodes; Inferior to the umbilicus, lymph drains to the superficial inguinal lymph nodes

Front 44

inguinal canal

Back 44

oblique canal (appx 4cm) within the anterior abdominal wall, just superior to inguinal ligament; potential site of weakness in the anterior abdominal wall; however, deep and superficial inguinal rings do not overlap , so increases in intra-abdominal pressure force the walls of the canal to tightly oppose, closing this potential passageway

Front 45

borders of inguinal canal

Back 45

Anterior wall: aponeurosis of external oblique; floor: inguinal ligament, reinforced medially by its extension, the lacunar ligament; posterior wall: Transversalis fascia; roof: internal oblique and transversus abdominis muscles

Front 46

deep inguinal ring

Back 46

Internal "entrance" where structures enter the canal;
located just superior to the midpoint of the inguinal ligament and lateral to inferior epigastric vessels

Front 47

superficial inguinal ring

Back 47

External "exit", where structures leave the canal; Slit-like opening within the external oblique aponeurosis, located superolateral to the pubic tubercle

Front 48

ontogeny of inguinal canal in males

Back 48

Testes initially develop in the posterior abdominal wall. The gubernaculum, a ligamentous cord, attaches the inferior pole of the testis to the developing scrotum. The testes descend and enter the inguinal canal via the deep ring, traverse the canal, exit the superficial ring, and enter the scrotum. As they descend, the testes drag associated vasculature, nerves, lymphatics and the ductus deferens through the canal. These structures form the spermatic cord.

Front 49

fascial coverings of spermatic cord and testis

Back 49

derived from layers of the anterior abdominal wall; External spermatic fascia (from external oblique aponeurosis); Cremaster muscle and fascia (from internal oblique muscle; when muscle contracts, testes are raised); internal spermatic fascia (from transversalis fascia)

Front 50

spermatic cord

Back 50

includes associated vasculature, nerves, lymphatics, and ducts deferens that is dragged through the inguinal canal by the testis

Front 51

ontogeny of inguinal canal in females

Back 51

ovaries develop in the posterior abdominal wall and descend; the gubernaculum connects the ovary and uterus to the developing labium majus. As the ovary never traverses the inguinal canal, the canal is narrower in females compared to males

Front 52

adult derivatives of the gubernaculum in the female

Back 52

Ovarian ligament between ovary and uterus; Round ligament of the uterus between uterus and labium majus

Front 53

contents of the Inguinal Canal

Back 53

Spermatic cord (in male) or round ligament of the uterus (in female); Ilioinguinal nerve (L1); Genital branch of the genitofemoral nerve (L1, L2)

Front 54

ilioinguinal nerve

Back 54

L1; provide sensory innervation to the inguinal region and labia majora/scrotum

Front 55

genital branch of genitofemoral nerve

Back 55

L1, L2; provide sensory innervation to the inguinal region and labia majora/scrotum; provides motor innervation to cremaster muscle in the male

Front 56

inguinal hernias

Back 56

protusion of abdominal viscera through abdominal wall; more frequent in males; indirect (congenital) and direct (acquired)

Front 57

indirect (congenital)inguinal hernia

Back 57

Most common type; Herniating mass enters the deep inguinal ring, lateral to the inferior epigastric vessels, and traverses the inguinal canal. As it traverses the canal, it becomes enclosed in the fascial coverings of the spermatic cord; may exit through the superficial inguinal ring and enter the scrotum (or labium majus)

Front 58

direct (acquired) inguinal hernia

Back 58

Involves area of weakness (inguinal triangle) bounded by the rectus abdominis, inferior epigastric vessels, and inguinal ligament; Herniating mass pushes through peritoneum and transversalis fascia, medial to the inferior epigastric vessels; Enters inguinal canal through its posterior wall; rarely enters the scrotum. If it does, the mass lies lateral to the spermatic cord, not covered by its fascial layers.

Front 59

inguinal triangle

Back 59

area of weakness bounded by rectus adominis, inferior epigastric vessels, and inguinal ligament; associated with direct (acquired) inguinal hernia

Front 60

kidneys

Back 60

primarily retroperitoneal; surrounded by layers of fat and fascia; located at T12-L3 vertebral levels; right kidney sits slightly lower than left kidney; lie in the right or left upper quadrant

Front 61

layers around kidney

Back 61

listed from SF to deep: paranephric (pararenal) fat; renal fascia; perinephric (pararenal) fat

Front 62

features of kidney

Back 62

superior pole, inferior pole, lateral border, medial border, renal hilum, renal capsule, renal cortex, renal medulla, renal papillae, minor/major calyx, renal pelvis

Front 63

renal fascia

Back 63

prolonged inferiorly along ureters; helps prevent the spread of pus/blood, but can act as a conduit for the spread of these fluids to the pelvis

Front 64

superior pole

Back 64

adjacent to suprarenal gland

Front 65

renal capsule and cortex

Back 65

capsule is very thin outer layer of kidney; cortex is deep to capsule

Front 66

renal hilum

Back 66

Vertical cleft on medial border; arteries enter, veins and renal pelvis exit

Front 67

relationships of hilum structures

Back 67

Anterior: renal vein; middle: renal artery; posterior: renal pelvis

Front 68

lateral / medial border of kidney

Back 68

lateral is convex, medial is concave and contains renal hilum

Front 69

renal medulla

Back 69

include renal pyramids and renal columns

Front 70

pathway of urine towards the ureter

Back 70

renal papillae are the apices of the renal pyramids; each minor calyx collects urine from a renal papilla; each major calyx collects urine from 2-3 minor calices; renal pelvis receives urine from the 2-3 major calices and delivers it to the ureter

Front 71

anomalous kidneys

Back 71

pelvic kidney: failure of kidney to ascend during development; horseshoe kidney: right and left kidneys united at inferior poles; ascent stopped by IMA

Front 72

ureters

Back 72

primarily retroperitoneal; fibromuscular tubes extending from renal pelvis to bladder; transport urine via peristaltic contractions

Front 73

suprarenal (adrenal) glands

Back 73

primarily retroperitoneal; located on superomedial aspect of kidneys; enclosed in renal fascia; located in the right or left upper quadrant; right is pyramidal shaped; left is crescent shaped

Front 74

lymphatics of kidneys / suprarenal glands

Back 74

lymph drains to lumbar lymph nodes (along aorta); lumbar nodes drain to chyle cistern > thoracic duct

Front 75

parasympathetic innervation of kidneys

Back 75

preganglionic CB: brain (CN X); preganglionic fibers: vagus nn.; postganglionic cell bodies and fibers: wall of kidney

Front 76

sympathetic innervation of kidneys

Back 76

preganglionic CB: lateral horn of the thoracolumbar spinal cord; preganglionic fibers travel from ventral root > spinal nerve > white ramus communicans > sympathetic trunk > thoracic and lumbar splanchnic nn.; postganglionic CB: renal ganglion; pstganglionic fibers: follow arterial branches to target organ

Front 77

sympathetic innervation of suprarenal glands

Back 77

preganglionic CB: lateral horn of the thoracolumbar spinal cord; preganglionic fibers travel from ventral root > spinal nerve > white ramus communicans > sympathetic trunk > thoracic and lumbar splanchnic nn.; postganglionic CB: secretory cells of suprarenal glands

Front 78

vessels of posterior abdominal wall

Back 78

abdominal aorta (unpaired, paired branches), IVC

Front 79

abdominal aorta (description)

Back 79

begins at aortic hiatus of diaphragm (T12); located to left of midline; bifurcates into common iliac arteries (L4)

Front 80

abdominal aorta unpaired branches

Back 80

unpaired branches to abdominal organs: celiac trunk, SMA, IMA

Front 81

paired branches of abdominal aorta to primarily retroperitoneal organs

Back 81

renal arteries (can have accessory renal arteries from failure of embryonic arteries to degenerate) branch into inferior suprarenal arteries; middle suprarenal arteries; gonadal (testicular or ovarian) arteries

Front 82

paired branches of abdominal aorta to posterior abdominal wall

Back 82

inferior phrenic arteries: supply inferior surface of diaphragm, suprarenal glands (via superior suprarenal arteries); subcostal arteries; lumbar arteries

Front 83

inferior vena cava

Back 83

o Formed by union of common iliac veins at L5 vertebral level
o Located to right of midline
o Exits abdomen through the caval opening (T8) of the diaphragm
o Tributaries of the IVC parallel the paired branches of the aorta

Front 84

exceptions to IVC tributaries parallel to paired branches of aorta

Back 84

• Left gonadal vein drains to left renal vein
• Hepatic veins have no arterial complement

Front 85

posterior abdominal wall muscles

Back 85

iliopsoas (psoas major, ilacus), quadratus lumborum

Front 86

iliopsoas

Back 86

psoas major (origin: anterior aspects of lumbar vertebrae) and iliacus (origin: iliac fossa)fuse to form the iliopsoas, which inserts on the lesser trochanter of the femur

Front 87

quadratus lumborum

Back 87

o Origin: 12th rib and lumbar vertebrae
o Insertion: iliac crest

Front 88

subcostal nerves (T12)

Back 88

o Travel laterally across quadratus lumborum
o Pierce transversus abdominis to enter abdominal wall
o Sensory innervation (T12 dermatome)
o Motor innervation to external & internal obliques, transversus abdominis

Front 89

lumbar plexus

Back 89

Ventral rami of lumbar spinal nerves (L1-L5) form lumbar plexus
• Ilioinguinal & iliohypogastric nerves (L1)
• Genitofemoral nerve (L1, L2)
• Femoral nerve (L2-L4)
• Obturator nerve (L2-L4)

Front 90

sympathetic trunks in diaphragm

Back 90

continues from thorax; located just lateral to lumbar vertebral bodies and anterior surface of sacrum; greater, lesser, least splanchnic nerves pass through diaphragm