Anterior Abdominal Wall & Inguinal Canal (Brauer) Flashcards
What are the bony landmarks of the abdomen and pelvis?
- ribs and costal cartilages
- transverse processes
- ilium and iliac crest
- pubic symphysis and rami
- pubic tubercle
- pecten pubis (pecteal line)
- anterior superior/inferior iliac spines
- greater and lesser pelvis (lesser below pelvic inlet)
Name the following abdominal regions:
- RH: right hypochondrium
- RL: right flank (lateral region)
- RI: right inguinal (groin)
- E: epigastric
- U: umbilical
- P: pubic
- LH: left hypochondrium
- LL: left flank (lateral region)
- LI: left iguinal (groin)
Name the following abdominal quadrants:
- RUQ: right upper quadrant
- LUQ: left upper quadrant
- RLQ: right lower quadrant
- LLQ: left lower quadrant
What structures are present in RUQ?
- liver: right lobe
- gallbladder
- stomach: pylorus
- duodenum: parts 1-3
- pancreas: head
- right suprarenal gland (adrenal gland)
- right kidney
- right colic (hepatic) flexure
- ascending colon: superior part
- transverse colon: right half
What structures are present in LUQ?
- liver: left lobe
- spleen
- stomach
- jejunum and proximal ileum
- pancreas: body and tail
- left suprarenal gland (adrenal gland)
- left kidney
- left colic (splenic) flexure
- transverse colon: left half
- descending colon: superior part
What structures are present in the RLQ?
- cecum
- appendix
- most of ileum
- ascending colon: inferior part
- right ovary (female)
- right uterine tube (female)
- right ureter: abdominal part
- right spermatic cord: abdominal part (male)
- uterus (if enlarged, female)
- urinary bladder (if very full)
What structures are present in the LLQ?
- sigmoid colon
- descending colon: inferior part
- left ovary (female)
- left uterine tube (female)
- left ureter: abdominal part
- left spermatic cord: abdominal part (male)
- uterus (if enlarged, female)
- urinary bladder (if very full)
What structures does the transpyloric plane transect?
- gallbladder fundus
- pylorus (opening from the stomach into the duodenum)
- pancreatic neck
- SMA origin (superior mesenteric artery)
- hepatic portal vein
- root of transverse mesocolon
- hila of kidneys
What structures does the subcostal plane transect?
- passes inferior border of 10th costal cartilage
- level of transverse colon
What structures does transtubercle plane transect?
- between iliac tubercles
- level of iliocecal junction
What does the interspinous plane transect?
- between ASIS
- level of appendix and sigmoid colon
What are the boundaries, walls, and lining of the abdominopelvic cavities?
- boundaries of abdomen and pelvis: between thoracic diaphragm and pelvic diaphragm, can extend to 4th intercostal space, abdomen is separated from pelvis by imaginary border of pelvic inlet (greater pelvis above and lesser pelvis below)
- walls: mostly bone, muscle, and CT
- lining: peritoneum
What are the characteristics of the fascia present in the abdomen?
- integument
- Camper’s fascia: fatty layer of superficial fascia
- Scarpa’s fascia: membranous underlying CT layer of superficial fascia
What physiologically differences are created by Scarpa’s fascia connectivity to Colle’s fascia and fascia lata?
- Scarpa’s fascia is continuous w/ Colle’s fascia of the perineum, but is fused w/ fascia lata of lower limb
- this means fluid cannot go from abdominal wall into leg but can flow into or out of superficial perineum
External oblique M.
- origin:
- insertion:
- innervation:
- action:
External oblique M.
runs in downward medial direction, interdigitates w/ serratus anterior M.
- origin: outer surface of lower 7 ribs
- insertion: aponeurosis and linea alba, anterior iliac crest and pubic tubercle (lower portion rolled under to make inguinal ligament that is attached to ASIS and pubic tubercle; makes opening of superficial inguinal ring; some reflected under to make lacunar ligament)
- innervation: ventral rami of T7-12 of intercostal nerves
- action: compresses abdomen and increase intra-abdominal pressure; move trunk and retain posture
Internal oblique M.
- origin:
- insertion:
- innervation:
- action:
Internal oblique M.
runs 90 degrees from external oblique M.
- origin: iliac crest and some of thoracolumbar fascia
- insertion: lower 10-12 ribs, aponeurosis, linea alba and pubic crest, lower part makes part of conjoint tendon (inguinal falx) (some fibers follow spermatic cord to cremasteric M.; aponeurosis part splits to encompass rectus muscle in upper 3/4s, otherwise all go in front in lower 4th)
- innervation: T7-12 and L1
- action: compresses and supports viscera, lateral flexes and rotates
Transversus abdominis M.
- origin:
- insertion:
- innervation:
- action:
Transversus abdominis M.
runs transverso-medially except for some running toward pubic crest (to contribute to conjoint tendon)
- origin: lower 7-12 ribs, thoracolumbar fascia, iliac crest, and some off upper inguinal ligament
- insertion: linea alba and pubic crest
- innervation: T7-L1
- action: compresses and supports viscera
Rectus abdominis M.
- origin:
- insertion:
- innervation:
- action:
Rectus abdominis M.
paired muscle of anterior abdominal wall, wider at top than bottom; tendinous intersections form part of rectus sheath at umbilical, xiphoid, and midway levels
- origin: pubic symphysis and pubic crest
- insertion: xiphoid process and outer surface of 5-7th intercostal cartilages
- innervation: ventral rami of T7-12
- action: flexes and compresses abdomen
(linea semilunaris present at lateral border of rectus abdominis M.; pyramidis M. missing 20% of ppl)
Describe the characteristics of the rectus sheath:
- made of fascia and aponeurosis of muscles encompassing rectus abdominis M. (RA)
- external oblique (EO) aponeurosis is always anterior to sheath
- internal oblique (IO) aponeurosis splits in upper 3/4 but is all anterior in lower 1/4
- transversus abdominis (TA) aponeurosis is posterior except in lower 1/4
- arcuate line: sharp transition where all EO, IO, and TA aponeuroses become anterior to RA M.; below the line RA is in contact only w/ transversalis fascia
What is the innervation to the anterior abdominal wall?
(nerves run between TA and IO Ms.)
- thoraco-abdominal N. (T7-11): continuation of intercostal N.; both motor and sensory
- subcostal N. (T12): runs along inferior 12th rib; both motor and sensory (sensory superior to iliac crest)
- iliohypogastric N. (L1): runs between 2nd and 3rd muscle layers; motor innervation to IO and TA Ms.); sensory to upper inguinal and hypogastric regions
- ilioinguinal N. (L1): motor innervation to lower IO and TA Ms.; sensory to lower inguinal, anterior scrotum/labia, and near middle thigh regions
What is the arterial supply to the anterior abdominal wall?
- continuation of intercostal arteries
- lumbar arteries (off abd aorta)
- superficial epigastric A. (off femoral A.)
- superficial circumflex iliac A. (off femoral A.): runs along inguinal L.
- deep circumflex iliac A. (off external iliac A.): runs deep along inguinal L.
- inferior epigastric A. (off external iliac A.): runs posterior to RA M.; anastomosis w/ superior epigastric A.
- superior epigastric A. (terminal branch off internal thoracic A.)
How is lymph drained from the anterior abdomen?
- superficial vessels superior to umbilicus drain into axillary nodes w/ a few going to parasternal nodes
- superficial vessels below umbilicus drain to superficial inguinal nodes
- deep lymph vessels accompany deep veins of abominal wall (e.g. external and internal iliac veins)
- rolled-under inferior border of external oblique M. aponeurosis
- attached to ASIS and pubic tubercle
inguinal L.
combined aponeurosis of inferior/medial margins of internal oblique and transversus abdominal Ms. inserting onto pubis
conjoint tendon (inguinal falx)
external opening within aponeurosis for spermatic cord or round ligament
superficial inguinal ring
What are the crural fibers and where are they located anatomically?
- medial crus, lateral crus, and intercrural fibers
- refer to photo for location
- ligament between pubic rami and inguinal L.
- anchors inguinal L. to pubis
lacunar ligament
What are the contents and location of the inguinal rings?
- superficial ring: exit for inguinal canal; where spermatic cord or round ligament exit from canal; this ring is really a partial split in the external oblique M. aponeurosis
- deep ring: entrance to inguinal canal and beginning of the invagination of peritoneum into transversalis fascia; superior to inguinal ligament and lateral to inferior epigastric A.; where vas deferens and gonadal vessels/nerves pass in males and round ligament passes in females
What nerves are near the inguinal ligament, canal, and ring?
- iliohypogastric nerve (L1): motor to abdominal muscles (IO and TA); skin above pubis (hypogastric region)
- ilioinguinal nerve (L1): traverses inguinal canal, exits superficial ring lateral to cord; motor to abdominal muscles (IO and TA); skin over upper/medial thigh and skin at root of penis/clitoris and anterior scrotum/labia
- genitofemoral nerve (L1, L2): genital branch; motor to cremasteric muscle; sensory to small part of medial thigh and scrotal/labial fascia
Describe the process of testicular descent:
- gonads first form near T10 axial level and are connected to future scrotal swellings by gubernaculum
- around 7 months, they start descending along w/ out-pocketing of peritoneal cavity, the processus vaginalis, into future scrotum carrying neurovasculature w/ them (future suspensory ligament)
- layers of abdominal wall (transversalis fascia, IO, and EO) are also carried as spermatic cord develops (see photo on other side of FC)
- around 9-12 months, the connection to peritoneum is closed; the tunica vaginalis represents the remaining processus vaginalis around testes
What are the contents of the spermatic cord and how does it develop?
- development: as gonad descends along w/ its blood supply and vas deferens, it carries layers of abdominal wall w/ it forming spermatic cord:
transversalis fascia > internal spermatic fascia
internal oblique > cremasteric muscle
external oblique > external spermatic fascia
- contents: vas deferens (ductus deferens), testicular A., testicular veins (pampiniform plexus), gonadal nerves/lymphatics
*spermatic cord and inguinal rings are site of abdominal wall weakness*
What is persistent processus vaginalis and what can it lead to?
- persistent processus vaginalis: patent connection between tunica vaginalis and abdomen
- can lead to hydrocele (peritoneal fluid accumulation within tunica vaginalis): more common in babies, can be caused by inflammation or injury in scrotum/testis/epididymis in adults, communicating and non-communicating types, detected w/ transillumination
- can also lead to hematocele (accumulation of blood in tunica vaginalis)
How do the ovaries descend?
- around 2 months, ovaries begin descending while gubernaculum is attached to developing uterus
- upper portion of gubernaculum forms ovarian ligament while lower portion forms round ligament of uterus
- around 15 weeks, round ligament of uterus enters deep inguinal ring and exits superficial ring attaching to labial swellings
What are the structures present around and within the female inguinal canal?
- deep and superficial inguinal rings provide entry/exit for neurovasculature and ligaments
- medial/lateral crus
- lacunar/pectineal ligaments
- conjoint tendon (inguinal falx)
- contents: round ligament of uterus, ilioinguinal nerve, genitofemoral nerve (genital branch)
- suggests a scrotal/labia relationship
How is lymph drained from testes and scrotum?
- testes: drain into lumbar and pre-aortic lymph nodes
- scrotum: drains into superficial inguinal nodes and eventually travel into iliac and lumbar lymph nodes
What are the structures present in the internal surface of the anterior abdominal wall?
- inferior epigastric A.: runs anterior to posterior rectus sheath
- median umbilical fold: created by obliterated urachus
- medial umbilical fold: created by obliterated umbilical arteries
- lateral umbilical fold: created by inferior epigastric A.
- deep inguinal ring: exit of testicular vessels and vas deferens (males) and round ligament of uterus (females)
Where is the inguinal (Hasselbach’s) triangle located and what are the clinical implications due to its location?
- located lateral to rectus abdominis, superior to iliopubic tract (floor of inguinal ligament), and inferior to lateral umbilical ligament/fold (inferior epigastric vessels)
- area where direct hernias occur: inferior to conjoint tendon and medial to lateral umbilical ligament
(iliopubic tract: thickened transversalis fascia running posterior to inguinal ligament, reinforces floor of inguinal canal)
Where do direct, indirect, and femoral hernias occur?
- direct: occurs inferomedially to lateral umbilical fold (inferior epigastric vessels) and inferior to conjoint tendon
- indirect hernia: enters deep inguinal ring, peritoneum of hernia located within spermatic cord
- femoral hernia: occurs inferior to inguinal ligament, more common in women, 40% present as emergencies due to incarceration or strangulation
