Hernia anatomy Flashcards
1
Q
External oblique
A
- arises mainly above and sweeps downwards and forwards
- arises from 5-12th ribs just lateral to their anterior extremities
- lower 4 slips interdigitate w costal fibres of lat dorsi and upper 4 w digitations of serratus anterior
- insertion
- most of it is aponeurotic
- free posterior border: from 12th rib to its insertion into the anterior half of the outer lip of the iliac crest
- forms anterior boundary of lumbar spaces
- free horizontal upper border of aponeurosis from 5th rib to xiphisternum
- aponeurotic below a line between ASIS to umbilicus & medial to a vertical line drawn from tip of 9th costal cartilage
- lower border (betwen ASIS and PT) forms inguinal ligament
- edge is rolled inwards to form a gutter; lateral part of this gives origin to part of int oblique and transversus abdominis muscles
- superficial ring = an oblique, triangular gap in the aponeurosis just above and lateral to PT
2
Q
Internal oblique
A
- arises mainly behind and below; sweeps upwards and forwards
- origin: thoracolumbar fascia, anterior 2/3 iliac crest, lateral 2/3 inguinal ligament
- from lumbar fascias, muscle fibres run upwards along costal margin, to which they are attached, becoming aponeurotic at tip of 9th costal cartilage
- below costal margin, aponeurosis splits around rectus muscle; posterior layer ends at arcuate ligament where aponeuroses pass in front
- muscle fibres that arise from ing ligament are continued into an aponeurosis that is attached to crest of pubic bone and more laterally to pectineal line; this aponeurosis is fused w similar arrangement of transversus aponeurosis to form conjoint tendon
- so has a free lower border which arches over spermatic cord; laterally margin consists of muscle fibres in front of cord; medially tendinous fibres behind cord
3
Q
Transversus abdominis
A
- arises from 12th rib, inner aspects of lower six (7th-12th) costal cartilages where it interdigitates with diaphragm, anterior 2/3 iliac crest, lateral 1/3 inguinal ligament & from thoracolumbar fascia
- majority of its fibres end as the posterior layer of the rectus sheath and linea alba but above the level of the umbilicus the muscle often extends behind the rectus before forming the sheath
- at arcuate line passes in front of rectus
- inserts xiphoid process to pubis
- lower fibres of aponeurosis curve downwards & medially w those of int oblique as conjoint tendon
4
Q
Transversalis fascia
A
- the layer of fibrofatty tissue which lies between the inner surface of the transversus muscle and the peritoneum
- lines all inner side of abdominal muscles
- posteirorly fuses w fascia behind psoas muscle (thoracolumbar fascia)
- 2 inferior thickenings
- iliopubic tract
- sling through which spermatic cord enters canal (forms superior & inferior crura of deep ring)
5
Q
Rectus abdominis
A
- arises by 2 heads:
- medial from in front of pubic symphysis
- lateral from upper border of pubic crest
- inserts onto front of 5th-7th costal cartilages
- lower parts of the 2 muscles are narrower & lie edge to edge
- upper parts are broader and separated from each other by linea alba
- 3 tendinous insertions typically - at umbo, xiphi and one between these; sometimes 1 or 2 incomplete intersections are sometimes found below the umbilicus
- tendinous insertions blend with anterior layer of rectus sheath and occupy only the superficial part of the rectus; don’t penetrate to posterior surface of muscle
- between the 2 recti all aponeuroses that form rectus sheath fuse to form linea alba
- umbilicus = a defect in linea alba through which fetal umbilical vessels pass
- innervation: ventral rami of lower 6 or 7 intercostal (thoracic spinal) nerves which enter lateral and posterior aspect of muscle
6
Q
Rectus sheath
A
- aponeurosis of int oblique splits into ant & post layers to enclose rectus muscle
- ext oblique aponeurosis fuses w anterior layer to form ant layer of sheath
- transversus abdominis fuses w posterior layer to form posterior layer of sheath
- from halfway between umbo & pubic symphysis all 3 aponeuroses pass in front of muscle
- posterior layer of sheath has free lower margin concave downwards, arcuate line
- superiorly, posterior layer of sheath is attached to costal margin (7th, 8th, 9th costal cartilages)
- above costal margin the ant layer of the sheath consists only of ext oblique aponeurosis
- splitting of int oblique aponeurosis along lateral border of rectus muscle forms a relatively shallow groove, the semilunar line
- curves up from pubic tubercle to costal margin at tip of 9th costal cartilage in transpyloric plane
- contents
- rectus and pyramidalis muscles
- ends of lower 6 thoracic nerves & their accompanying posterior intercostal vessels, and the superior and inferior epigastric vessels
- intercostal nerves (T7-11) pass from their intercostal spaces into the abdominal wall between IO and transversus muscles, and run around in this neurovasc plane to enter the sheath by piercing the posterior layer of the int oblique aponeurosis
- then proceed behind rectus muscle to about its midline, where they pierce the muscle, supply it and pass through anterior layer of sheath to become ant cutaneous nerves
- in sheath, T7 runs upwards just below costal margin, T8 transversely & the others obliquely downwards
- before they reach the sheath the nerves give off their lateral cutaneous branches, which pierce int and ext oblique to reach skin
- lowest thoracic nerve = T12 or subcostal
- superior epigastric artery = a terminal branch of int thoracic, enters sheath by passing between sternal & highest costal fibres of diaphragm
- supplies rectus muscle and anastomoses within it with:
- inferior epigastric artery which leaves ext iliac at inguinal ligament, passes upwards behind conjoint tendon, slips over arcuate line & enters sheath
- veins accompany these arteries, draining to int thoracic and ext iliac veins, respectively
7
Q
Pyramidalis muscle
A
- arises from body of pubis and symphysis between rectus abdominis and its sheath
- converges w its fellow into linea alba 4cm or so above its origin
- supplied by ventral ramus of subcostal nerve (T12)
8
Q
Innervation of the abdominal wall
A
- rectus muscle and ext oblique: lower 6 (T7-T12) intercostal and subcostal nerves
- come from main nerves and enter muscle wall laterally
- these nerves run alongside intercostal and lumbar arteries in plane between int oblique and transversus abdominis muscles
- penetrate linea semilunaris at lateral border of rectus muscle (important to prseerve these nerves during dissection of lateral abdominal wall to avoid deneravation of rectus complex)
- T12 = subcostal nerve
- internal oblique and transversus: same nerves but addition of iliohypogastric and ilioinguinal nerves (L1) and are innervated by the VENTRAL RAMI of these nerves
- thus nerve supply enters muscle more anteriorly than nerve supply to ext oblique which is supplied from main trunks of nerves
- lowest fibres of int oblique and transversus that continue medially as conjoint tendon receive the L1 innervation, which thus helps to maintain integrity of inguinal canal
- pyramidalis is supplied by ventral ramus of subcostal nerve (T12)
9
Q
Peritoneal folds of anterior abdominal wall
A
- falciform ligament with ligamentum teres in its inferior border (obliterated left umbilical vein)
- runs slightly to right of midline & attached to a notch on inf surface of liver
- median umbilical ligament inconsistently present - obliterated urachus
- medial umbilical ligaments = obliterated umbilical artery which is terminal branch of ant division of int iliac artery
- lateral umbilical folds = formed by inf epigastric vessels; unlike other umbilical ligaments doesn’t pursue a path towards umbilicus, rather a few cm laterally
10
Q
Inguinal canal
A
- Overview
- oblique intermuscular slit ~4cm long lying above medial half of ing ligament
- commences at deep ing ring, ends at superficial ing ring and transmits the spermatic cord and ilioinguinal nerve in male and round ligament of uterus and ilioinguinal nerve in female
- just above inguinal ligament
- Boundaries (MALT for roof, anterior, floor, posterior)
- area between deep and superficial inguinal rings
- superficial ring = triangular aperture in ext oblique aponeurosis, lies ~2cm above pubic tubercle (usu won’t admit tip of little finger)
- deep ring = U-shaped condensation of transversalis fascia, lies 1.25cm above and slightly medial to midpoint of ing ligament (midway between PS and ASIS)
- inf crus = iliopubic tract
- superior crus = transversus abdominis aponeurotic arch
- lateral border connected to transversus abdominis; forms shutter mechanism to limit development of indirect hernia
- roof/superior wall
- arching fibres of int oblique & transversus abdominis muscle
- anterior wall
- aponeurosis of ext oblique
- int oblique/conjoined muscle for lateral 1/3
- floor/inferior wall
- incurved edge of ext oblique/inguinal ligament
- iliopubic tracct and lacunar ligament further medially
- posterior wall
- transversalis fascia
- medially conjoint tendon (aponeurosis of transversus and int oblique)
- laterally the transversalis fascia in posterior wall is strengthened by interfoveolar ligament - tendinous/sometimes muscular fibres derived from transversus abdominis muscle which arch down from lower border of transversus around vas to ing ligament & constitute functional medial edge of deep ring (vas or round ligament enter ing canal by hooking round interfoveolar ligament)
- area between deep and superficial inguinal rings
- Contents
- spermatic cord (male)
- 3 coverings
- ext spermatic fascia (from ext oblique)
- cremasteric muscle and fascia (from int oblique)
- internal spermatic fascia (from transversalis fascia)
- contents
- 3 arteries: testicular (from aorta), cremasteric (from inf epigastric), deferential (from inf or sup vesical)
- 3 nerves: genital branch of genitofemoral nerve, cremasteric, sympathetic nerve fibres
- 4 other things: ductus deferens, pampiniform plexus, lymphatic vessels (essentially those from testis draining to para-aortic nodes but including some from the coverings which drain to ext iliac nodes), processus vaginalis (obliterated remains of peritoneal connection w tunica vaginalis of testis; when patent, forms sac of indirect ing hernia)
- NB ductus deferens travels medially or posteirorly in cord behind obliterated processus vaginalis & blood vessels
- 3 coverings
- spermatic cord (male)
- Round ligament + obliterated processus vaginalis + lymphatics from uterus (females
- Ilioinguinal nerve (both)
11
Q
Femoral sheath
A
- formed from fascia which is adherent to iliac vessels as they exit under ing ligament & become femoral vessels
- posterior part
- pectineal ligament & below it the pectineus fascia
- bc of obliquity of iliopsoas muscle mass the fascia covering this muscle forms part of posterior wall also but is mainly a lateral relation
- anterior part
- arises from iliopubic tract part of transversalis fascia
- as this curves medially to the pectin it also bounds the medial part of opening into femoral sheath
- arises from iliopubic tract part of transversalis fascia
- sheath descends with the vessels becoming progressively narrower & eventually ends 4cm below ing ligament by fusing w adventitia of vessels
- divided into 3 compartments by AP running septa
- lateral compartment: contains femoral arery
- middle compartment: femoral vein
- medial compartment: femoral canal
- femoral nerve in iliac fossa lies in gutter between psoas & iliacus, behind iliac fascia; lateral to femoral sheath the transversalis fascia & iliac fascia fuse w inguinal ligament, and femoral nerve thus enters thigh outside femoral sheath
12
Q
Femoral canal and femoral ring
A
- femoral canal contains only fat, lymphatics and a lymph node (Cloquet’s node - in females drains directly from clitoris and in male from glans penis)
- function = supposedly to allow expansion of femoral vein
- only 1-2cm long before its walls fuse
- widest at its abdominal end, where its opening, the femoral ring has 4 boundaries
- femoral ring = entrance to femoral canal; bounded by tissues of femoral sheath
- anteriorly = iliopubic tract from transversalis fascia & beyond it lacunar ligament
- medially = lacunar ligament
- posteriorly = pectineal/Cooper’s ligament
- laterally = femoral vein
- NB when femoral ring expanded, as in femoral hernia, the more unyielding structures form its boundaries, ie ing ligament in front & lacunar lig medially
- when a femoral hernia occurs, it is initially deep to fascia lata so may be difficult to feel
- as it enlarges, tends to protrude through weakest area in region = region of saphenous vein penetrating to deep vein - the fossa ovalis
- however, deep layer of superficial fascia descending from abdomen inserts into the distal margin of this fossa
- thus as a sac enlarges this fascial attachment tends to prevent downwards extension of the sac so it bulges upwards
- therefore large femoral hernias can give appearance of being above ing ligament
13
Q
Femoral triangle
A
- boundaries
- lateral: medial border of sartorius
- medial: medial border of adductor longus
- base: inguinal ligament
- apex: subsartorial canal/adductor hiatus (SFA & vein along w saphenous nerve ext femoral triangle at its apex & enter subsartorial canal/adductor hiatus)
- floor: gutter-shaped, formed from medial to lateral by
- adductor longus, adductor brevis, pectineus, iliopsoas
- roof: fascia lata
- pierced by GSV entering to join femoral vein, via the thin cribriform fascia covering the fossa ovalis
- contents
- medial to lateral at inguinal ligament
- femoral canal
- CFV
- CFA - branches into SFA & PFA within triangle; PFA travels deep to adductor longus
- smaller branches of CFA just inf to ligament are: SEA, SCIA, SEP, DEP
- femoral nerve & lateral femoral cutaneous nerve
- femoral nerve divides into ant & post division within triangle
- nodes throughout
- superficial draining LNs lie subinguinally & along GSV (drain to deep nodes)
- deep nodes lie within femoral canal (incl node of Cloquet) & between femoral vessels (drain to pelvis along obturator & int iliac vessels)
- medial to lateral at inguinal ligament
14
Q
Myopectineal orifice
A
- all hernias of groin originate from this single zone of weakness, which is covered only by transversalis fascia and peritoneum
- contents
- bissected by inguinal ligament
- ing canal superiorly
- femoral canal inferiorly
- borders
- inferior: superior pubic ramus and pectineal (Coopers) ligament)
- medial: rectus abdominis muscle and conjoint tendon
- superior: conjoint tendon (fusion of int oblique and transversalis fascia)
- lateral: iliopsoas muscle and lateral border of femoral sheath
15
Q
Inguinal ligament vs iliopubic tract
A
- inguinal ligament not seen in lap repair bc it is an anteiror lamina structure
- ing ligament = inf edge of ext oblique aponeurosis, extending from ASIS to PT, turning posteriorly to form the ‘shelving edge’
- medial fibres fan out & insert along pectin & pectineal ligament
- iliopubic tract = aponeurotic band formed by transversus abdominis aponeurosis and transversus fascia
- located posterior and parallel to ing ligament
- extends from PT medially & passes over femoral vessels to insert on ASIS/iliopectineal arch laterally
- is a posterior lamina structure
- curves around femoral vessels & femoral canal to blend with pectineal/Cooper’s ligament
