E2A Flashcards
Anterolateral abdominal wall and inguinal canal
subcostal plane
horizontal plane that connects lowest points of right and left costal margins (10th costal cartilages) and lies at the level of L3
transtubercular plane
horizontal plane connecting tubercles of right and left iliac crests and lies at the level of L5
midclavicular plane
vertical plane that passes through midpoint of clavicle and intersects halfway a line connecting anterior superior iliac spine (ASIS) to pubic tubercle
upper part
above subcostal plane
consists of epigastric region (center) and right and left hypochondriac regions
middle part
between subcostal and transtubercular planes
consists of umbilical region (center) and right and left lateral regions (lumbar regions or flanks)
lower part
below transtubercular plane
consists of pubic/hypogastric region (center) and right and left inguinal (iliac) regions
layers of anterolateral abdominal wall
superficial to deep
- skin
2, superficial fascia - muscles with their deep (investing) fasciae
- transversalis fascia (part of endoabdominal fascia)
- extraperitoneal fascia
- parietal peritoneum
superficial fascia layers
Camper’s fascia
Scarpa’s fascia
Note: after laceration of spongy (penile) urethra, urine and blood pass into superficial perineal space (deep to Colles’ fascia), scrotum, penis and anterior abdominal wall, but not inferiorly into thighs (because of fusion of Scarpa’s fascia with fascia lata)
Camper’s fascia
superficial fatty layer
continuous with superficial fat over rest of body
may be extremely thick
Scarpa’s fascia
deep membranous layer
inferiorly extends into upper thigh and fuses with fascia lata (deep fascia of thigh) about a fingerbreadth below inguinal ligament
continuous with superficial fascia of penis (or clitoris), dartos tunic/fascia (scrotum) and superficial perineal fascia (Colles’ fascia)
muscles of the anterolateral abdominal wall
- 3 broad and thin (flat) muscles on each side: external oblique, internal oblique and transversus abdominis
- on each side of anterior midline there is a long, vertical muscle called rectus abdominis
- there is usually a small muscle anterior to lower part of rectus abdominis called pyramidalis (absent in about 20% of people)
- 3 flat abdominal muscles are muscular (fleshy) posterolaterally and aponeurotic (fibrous) anteromedially
- aponeuroses of 3 flat muscles pass medially and enclose rectus abdominis (and pyramidalis, if present) and form rectus sheath
- in midline of anterior abdominal wall, aponeuroses of 3 right flat muscles join aponeuroses of 3 left flat muscles and forms fibrous band (linea alba) that extends from xiphoid process to pubic symphysis
external oblique origin
outer surface of lower 8 ribs
external oblique insertion
on an anterior view, fibers run inferiorly and medially (similar to external intercostals) -> lower fibers insert into iliac crest -> remaining fibers become continuous with an aponeurosis which inserts into xiphoid process, linea alba and pubic bone
inguinal ligament
Poupart’s
lower border of external oblique aponeurosis that extends from ASIS to pubic tubercle -> it is folded backward on itself forming a trough -> inguinal ligament forms boundary between abdomen and thigh
superficial inguinal ring
opening in external oblique aponeurosis located immediately superior to pubic tubercle -> it is the anterior (superficial) opening of inguinal canal
internal oblique origin
thoracolumbar fascia, iliac crest and lateral ⅔ of inguinal ligament
internal oblique insertion
on an anterior view, upper fibers run superiorly and medially (similar to internal and innermost intercostals) while lower fibers are more horizontal -> upper fibers insert into inferior border of lower 3 or 4 ribs and their costal cartilages -> remaining fibers become continuous with an aponeurosis which inserts into xiphoid process, linea alba and pubic bone
internal oblique
located immediately deep to external oblique
has a lower free border that arches over contents of inguinal canal
transversus abdominis
lies deep to internal oblique
has a lower free border that arches over contents of inguinal canal
lowest tendinous fibers of internal oblique and transversus abdominis join each other to form conjoint tendon (falx inguinalis) -> attaches inferiorly to pubic bone
transversus abdominis origin
deep surface of lower 6 costal cartilages, thoracolumbar fascia, iliac crest and lateral ⅓ of inguinal ligament
transversus abdominis insertion
fibers run horizontally forward -> become continuous with an aponeurosis which inserts into xiphoid process, linea alba and pubic bone
rectus abdominis
- long strap muscle that extends along whole length of anterior abdominal wall -> narrower and thicker below, broader and thinner above -> it is separated from its fellow by linea alba
- divided into segments by 3 transverse fibrous bands (tendinous intersections or inscriptions) -> superior tendinous intersection is just inferior to xiphoid process, inferior one is at the level of umbilicus, middle one is half-way between the other two
- when it contracts, its lateral margin forms a curved ridge (linea semilunaris) that can be palpated and often seen -> extends from tip of 9th costal cartilage to pubic tubercle
rectus abdominis origin
pubic symphysis and pubic crest
rectus abdominis insertion
5th, 6th and 7th costal cartilages and xiphoid process
pyramidalis
small triangular muscle located anterior to lower part of rectus abdominis, within rectus sheath
may be absent on one or both sides
pyramidalis origin
anterior surface of body of pubis
pyramidalis insertion
linea alba
pyramidalis action
tensor of linea alba
rectus sheath
formed by aponeurosis of 3 flat abdominal muscles
rectus sheath contents
- rectus abdominis
- pyramidalis (if present)
- terminal parts of lower 5 (7th to 11th) intercostal nerves and subcostal nerve
- superior and inferior epigastric vessels
upper ¾ of rectus sheath
aponeurosis of internal oblique splits into 2 laminae -> anterior lamina joins aponeurosis of external oblique to form anterior wall of rectus sheath -> posterior lamina joins aponeurosis of transversus abdominis to form posterior wall of rectus sheath
lower ¼ of rectus sheath
3 aponeuroses pass anterior to rectus abdominis muscle to form anterior wall of sheath -> there is no posterior aponeurotic wall -> at this level, rectus abdominis muscle is directly related posteriorly to transversalis fascia
arcuate line
curved line that marks lower end of posterior aponeurotic wall of rectus sheath -> located half-way between umbilicus and pubic symphysis -> inferior to arcuate line, posterior aponeurotic wall of rectus sheath is lacking (aponeurosis of 3 flat abdominal muscles pass anterior to rectus muscle)
posterior wall of rectus sheath
not attached to rectus abdominis muscle -> anterior wall of sheath is firmly attached to tendinous intersections of rectus abdominis muscle
actions of anterolateral abdominal muscles
- their tone plays an important role is supporting and protecting abdominal organs
- oblique muscles are involved in flexion, lateral flexion and rotation of trunk
- rectus abdominis flexes trunk
- transversus abdominis contributes little to trunk movements assists to maintain and increase intra-abdominal pressure
- by contracting simultaneously with diaphragm, with glottis of larynx (space between right and left vocal folds) closed, anterolateral abdominal muscles increase intra-abdominal pressure help with evacuation of contents of abdominal and pelvic hollow organs (micturition, defecation, vomiting, child birth)
- assist in forced expiration (coughing and sneezing) by pulling down ribs and sternum
transversalis fascia
- superficial and deep surfaces of flat abdominal muscles are covered by deep (investing) fascia -> these fascial layers are unremarkable, except for fascia that covers deep surface of transversus abdominis (transversalis fascia), which is better developed
- transversalis fascia is part of continuous layer of fascia (endoabdominal fascia) that lines inner surface of abdominal walls -> name of fascia changes depending on region or muscle it covers (diaphragmatic fascia, transversalis fascia, iliacus fascia, etc.)
exztraperitoneal fascia
layer of loose connective tissue, with a variable amount of fat, located between transversalis fascia and parietal peritoneum
parietal peritoneum
serous membrane that lines inner surface of anterolateral abdominal wall
nerves of anterolateral abdominal wall
- ventral rami of T7 to T11 spinal nerves (7th to 11th intercostal nerves)
- ventral ramus of T12 spinal nerve (subcostal nerve)
- ventral ramus of L1 spinal nerve (iliohypogastric and ilioinguinal nerves)
- run forward between internal oblique and transversus abdominis
- provide sensory innervation to skin and parietal peritoneum of anterolateral abdominal wall and motor innervation to muscles of anterolateral abdominal wall
7th to 11th intercostal and subcostal nerves
pierce posterior wall of rectus sheath
supply rectus abdominis and pyramidalis (subcostal n. only)
terminate by piercing anterior wall of rectus sheath to supply skin of anterior abdominal wall
iliohypogastric and ilioinguinal nerves
do not enter rectus sheath
pierce internal oblique and run between it and external oblique and its aponeurosis
terminal part of iliohypogastric nerve
pierces external oblique aponeurosis above superficial inguinal ring to supply suprapubic skin
terminal part of ilioinguinal nerve
emerges through superficial inguinal ring to supply skin of superomedial thigh and external genitalia
dermatomes of anterolateral abdominal wall
T7: just inferior to tip of xiphoid process
T10: level of umbilicus
L1: level of pubic symphysis
arteries of the anterolateral abdominal wall
superior epigastric
inferior epigastric
deep circumflex iliac
posterior intercostal and subcostal arteries
superficial epigastric and superficial circumflex iliac
branches of musculophrenic
superior epigastric artery
terminal branch of internal thoracic artery
descends posterior to rectus abdominis within rectus sheath
supplies upper central part of anterior abdominal wall
anastomoses with inferior epigastric artery
inferior epigastric artery
originates from distal part of external iliac artery (just above inguinal ligament)
runs superiorly and medially
enters rectus sheath anterior to arcuate line and ascends posterior to rectus abdominis
supplies lower central part of anterior abdominal wall anastomoses with superior epigastric artery
deep circumflex iliac artery
originates from distal part of external iliac artery (just above inguinal ligament)
runs superiorly and laterally toward ASIS and continues along iliac crest
supplies lower lateral part of anterior abdominal wall
lower 2 posterior intercostal and subcostal arteries (branches of descending thoracic aorta) and lumbar arteries (branches of abdominal aorta)
supply lateral part of anterior abdominal wall
superficial epigastric and superficial circumflex iliac arteries (branches of femoral artery)
supply superficial structures of lower part of anterior abdominal wall
branches of musculophrenic artery
contribute to supply abdominal wall, just inferior to costal margin
superficial veins of the anterolateral abdominal wall
form a network that radiates out from umbilicus -> network drains superiorly into axillary vein and inferiorly into femoral vein -> may provide collateral circulation during blockage of either vena cava
deep veins of the anterolateral abdominal wall
- superior epigastric and musculophrenic veins: drains into internal thoracic vein
- inferior epigastric and deep circumflex iliac veins: drain into external iliac vein
- posterior intercostal and subcostal veins: drain into azygos (right) or hemiazygos (left) veins
- lumbar veins: drain into inferior vena cava
superficial lymph vessels
- above level of umbilicus lymph drains upward toward anterior axillary lymph nodes
- below level of umbilicus lymph drains downward toward superficial inguinal lymph nodes
deep lymph vessels
follow arteries and deep veins and drain into internal thoracic (parasternal), external iliac, posterior mediastinal and lumbar (para-aortic) lymph nodes
inguinal canal
- oblique passage, about 4 cm in length, through lower part of anterior abdominal wall
- lies parallel and immediately above medial part of inguinal ligament
inguinal canal contents
male
spermatic cord (formed by structures running between testis and abdominopelvic cavity) and ilioinguinal nerve
inguinal canal contents
female
round ligament of uterus (fibrous cord that extends from uterus to labium majus) and ilioinguinal nerve
inguinal canal openings
deep inguinal ring
superficial inguinal ring
deep inguinal ring
opening in transversalis fascia
located approximately half way between ASIS and pubic tubercle
inferior epigastric vessels pass medial to deep inguinal ring
superficial inguinal ring
opening in aponeurosis of external oblique
located immediately superior to pubic tubercle
inguinal canal walls
- anterior: aponeurosis of external oblique
- posterior: transversalis fascia
- inferior: inguinal ligament
- superior: arching lowest fibers of internal oblique and transversus abdominis
abdominal hernia
- protrusion of abdominal contents beyond normal confines of abdominal wall
- has 3 parts: hernial sac, contents of sac and coverings of sac
- there are various types of abdominal hernias (inguinal, femoral, umbilical, incisional, etc.); approximately 75% of abdominal hernias occur in inguinal region (most common type of abdominal hernia); inguinal hernias occur more often in males than females
abdominal hernia sac
pouch (diverticulum) of parietal peritoneum (has a neck and a body)
abdominal hernia contents
may consist of any structure found within abdominal cavity (piece of omentum, loop of small intestine, etc.)
abdominal hernia coverings
formed from layers of abdominal wall through which hernial sac passes
indirect inguinal hernia
- most common type of inguinal hernia (⅔ to ¾ inguinal hernias are indirect)
- hernial sac leaves abdominal cavity lateral to inferior epigastric vessels, through deep inguinal ring neck of hernial sac is narrow
- results from a persistent processus vaginalis (outpouching of peritoneum that in the fetus is responsible for formation of inguinal canal); considered to be congenital in origin
- more common in children and young adults
direct inguinal hernia
- hernial sac leaves abdominal cavity medial to inferior epigastric vessels
- hernial sac protrudes through an area of relative weakness in posterior wall of inguinal canal -> inguinal (Hesselbach’s) triangle -> neck of hernia sac is wide
- more common in older men with weak abdominal muscles (considered to be acquired in origin)
inguinal triangle
triangle of Hesselbach
bounded by inferior epigastric vessels (laterally), rectus abdominis (medially) and inguinal ligament (inferiorly)