Gut Book 1: Abdominal Wall & Inguinal Region Flashcards
Abdominopelvic cavity
extends from the thoracoabdominal diaphragm above to the pelvic diaphragm below
Abdominal wall
bones, fascia and muscles which enclose the cylinder-like abdominal cavity and serve to mobilize the abdomen during trunk rotation and compression of contents during defecation and parturition while at the same time protect the abdominal contents.
Abdominal wall components (osseous, fascial and muscular)
Osseous: ribs 7-12, lumbar vertebrae 1-5, pelvis
Fascia: anterior- rectus sheath. Posterior- thoracolumbar fascia
Muscular: external and internal abdominal obliques, transversus abdominis, rectus abdominis, pyramidalis, quadratus lumborum, psoas major and minor
Superficial landmarks of the abdominal wall and inguinal region
xiphoid process (TV 10) costal margin linea alba umbilicus (LV 3-4 interspace) linea transversae (tendinous intersections) linea semilunaris pubic symphysis pubic tubercle inguinal ligament anterior superior iliac spine (ASIS) crest of ilium
Superficial fascia of abdomen
Fatty layer (camper's) Membranous layer (Scarpa's)-- best differentiated below the level of the navel, it has definite attachments to the iliac crest, fascia lata below the inguinal ligament, pubic tubercle, pubic symphysis, perineal boundaries of the urogenital triangle
Clinical correlation of the abdominal scrotal opening
formed by the weak attachment of the membranous layer to the pubic bone between the tubercle and symphysis, represents a potential path for extravasated fluid in the scrotum to ascend into the abdominal wall. However, due to the previously mentioned attachments, fluid remains in the flanks but does not progress into the lower limbs.
Specializations of the membranous layer (scarpa’s) of the superfiscial fascia
Fundiform ligament
Tunica dartos scroti
Fundiform ligament
robust development of membranous connective tissue which extends from the lower linea alba and passes lateral to the penis to end in the scrotal septum; provides support for the scrotum and testes
Tunica dartos scroti
continuation of the fatty and membranous layers of superficial fascia into the scrotum as a single layer containing areolar tissue and SMOOTH MUSCLE, responsible for wrinkling of the scrotal skin
Muscles of the abdominal wall, organized into 3 groups
Anterior: rectus abdominis, pyramidalis
Anterolateral: external and internal obliques, transversus abdominis
Posterior: psoas major and minor, quadratus lumborum
clinical correlation: surgery and the fiber directions of abdominal wall musculature
The fiber direction of the anterolateral and anterior abdominal wall musculature is arranged so that successive layers assume a noncongruent orientation, viz., vertical, horizontal and oblique directions. During surgery this arrangement is preserved by splitting muscles parallel to their fiber direction on a per layer basis. Muscular fibers are never cut perpendicular to their fiber direction because they will scar, not only across the muscle fibers, but successive layers will adhere to one another impairing normal movements, making them painful. Whenever possible, abdominal incisions are placed on the mid-line (linea alba) where only fascial/ tendinous tissue will be incised.
External abdominal oblique (O, I, A, N)
O: Outer surface of lower eight ribs interdigitating with serratus anterior and latissimus dorsi muscles.
I: Anterior 1/2 of the iliac crest (vertical fibers from last two ribs); remaining fibers descend obliquely downward toward the midline and via the external abdominal oblique aponeurosis attach to the linea alba from xiphoid process to pubic symphysis.
A: Both sides acting cause flexion of the vertebral column and pelvis as well as abdominal compression in defecation, parturition and forced expiration; one side acting causes lateral flexion of the trunk with rotation to the OPPOSITE side.
N: intercostal nerves 7-11, subcostal n., iliohypogastric n.
external abdominal oblique aponeurosis
= the modified tendon of insertion of the external oblique muscle. It forms the inguinal ligament, the outermost layer of the rectus sheath and with its opposite counterpart participates in forming the linea alba.
Internal abdominal oblique (O, I, A, N)
O: posterior layer of thoracolumbar fascia, anterior 2/3 of iliac crest, lateral 2/3 of inguinal ligament
I: inferior borders of the lower four or five ribs, linea alba from xiphoid to pubic symphysis via the internal oblique aponeurosis
A: both sides acting cause flexion of the vertebral column and pelvis as well as abdominal compression in defecation, parturition and forced expiration; one side acting causes lateral flexion of the trunk with rotation to the SAME side.
N: intercostal nerves 8-11, subcostal n., iliohypogastric n., ilioinguinal n.
Specializations of the internal abdominal oblique
Cremaster muscle- muscular layer of the spermatic cord derived from the internal abdominal oblique
conjoint tendon (falx inguinalis)- the combined fascias of the IAO and transversus abdominis
Transversus abdominis (O, I, A, N)
O: undersurface of the lower six ribs (interdigitated with the muscular slips of the diaphragm), thoracolumbar fascia, anterior 3/4 of iliac crest, lateral portion of inguinal ligament
I: linea alba from xiphoid to symphysis pubis via transversus abdominis aponeurosis
A: contraction causes compression of the abdomen and its contents
N: intercostal nerves 8-11, subcostal n., iliohypogastric n., ilioinguinal n.
Rectus abdominis (O, I, A, N)
O: anterior surface of the pubis
I: cartilages of the 5th, 6th and 7th ribs; fibers may attach to the lateral anterior surface of the xiphoid process
A: flexes the vertebral column and pelvis, assists in compression of the abdomen
N: intercostal nerves 7-11, subcostal n.
Tendinous Intersections
The rectus abdominis muscle is broader and thinner above, narrow and thicker below. Its course is interrupted at 3 of 4 levels by superficial tendinous intersections (forms 6&8 packs). These intersections are fused to the anterior rectus sheath.
Pyramidalis (O, I, A, N)
O: anterior surface of pubis ventral to the rectus abdominis
I: linea alba a short distance above its origin
A: tenses the linea alba
N: subcostal n.
Rectus sheath: composition
composed of the combined aponeurosis of the external oblique, internal oblique, and transversus abdominis muscles
Linea semilunaris
of rectus sheath: marks the transition of the muscular portions of the three anterolateral abdominal wall muscles to aponeurosis. The three layers are fused along this line and denote the beginning of the rectus sheath.
Splitting of rectus sheath
Upper 3/4 of the sheath is divided into anterior and posterior laminae due to splitting of the internal oblique aponeurosis around the rectus abdominis muscle.
Anterior rectus sheath
The anterior sheath is composed of the fused aponeuroses of the external and internal oblique muscles, while the posterior sheath is composed of the fused aponeuroses of the internal oblique and transversus abdominis muscles.
linea alba
The fascias of the three anterolateral abdominal muscles, after enveloping the rectus abdominis, meet their counterparts from the opposite side at the midline thereby forming the linea alba.
extent of the posterior rectus sheath
approximately midway between the umbilicus and the pubic symphysis the posterior sheath is lacking since all three aponeurotic layers now fuse and pass anterior to the rectus abdominis.
Arcuate line
The point at which the posterior rectus sheath ends. It can be viewed either by looking at the abdominal wall from inside the abdominal cavity or by elevating the rectus abdominis anteriorly.
Order of layers of the abdominal wall (superficial to deep) at approximate level of the umbilicus just off the midline
- skin
- superficial fascia (fatty layer, membranous layer)
- anterior rectus sheath
- rectus abdominis muscle
- posterior rectus sheath
- transversalis fascia
- extraperitoneal connective tissue
- peritoneum
three connective tissue layers internal to the posterior rectus sheath, from superficial to deep
transversalis fascia, extra-peritoneal connective tissue (= subserous fascia), parietal peritoneum
fold or ligament
when peritoneum overlays a structure embedded in the extraperitoneal connective tissue it is referred to as a fold or ligament. Depressions between these peritoneal folds are referred to as FOSSAE.
Umbilical folds
median umbilical fold- formed by the median umbilical ligament, the remnant of the urachus (allantois)
medial umbilical folds- formed by the medial umbilical ligaments (obliterated umbilical arteries)
lateral umbilical folds- formed by the inferior epigastric vessels.
Inguinal fossae
supravesical fossa- fossae above the bladder between the median and medial umbilical folds
medial inguinal fossa- fossa between the medial and lateral umbilical folds (site of direct inguinal HERNIAS)
Lateral inguinal fossa- fossa lateral to the lateral umbilical fold (site of INdirect inguinal HERNIAS)
Vascular beds of anterior and lateral abdominal wall
The arterial suply to the anterior and lateral abdominal wall forms 2 separate vascular beds:
a- a superficial vascular bed coursing in the subcutaneous connective tissue layer originating above from PERFORATING branches of deeper vessels found within the muscular layer and below from branches of the FEMORAL artery
b- a deep vascular bed coursing within the muscular layer originating above from the SUBCLAVIAN artery, in mid-abdomen from the AORTA, and below from the EXTERNAL ILIAC ARTERY.
Superficial (subcutaneous) circulation of superior abdomen (above the umbilicus)
accomplished by perforating branches of arteries located in the muscular layer: 1- superior epigastric aa 2- musculophrenic aa 3- intercostal aa 4- subcostal aa 5- lumbar aa
Superficial (subcutaneous) circulation of inferior abdomen (below umbilicus)
accomplished by branches of the femoral artery. These branches, after traversing the saphenous opening of the groin, course within the membranous layer of the subcutaneous connective tissue to their respective destinations.
1- superficial epigastric a (umbilical region)
2- superficial circumflex iliac a. (iliac region
3- superficial external pudendal a. (suprapubic, pubic and genital regions)
Deep (muscular) circulation is accomplished by which arteries?
Musculophrenic a. Superior epigastric a. Posterior intercostal arteries (10&11) and the subcostal a. Lumbar aa. Inferior epigastric a. Deep circumflex iliac a.
Musculophrenic artery
- one of the terminal branches of the internal thoracic a.
- courses deep to the costal cartilages of ribs 7-11
- provides anterior intercostal aa 7-11
- passes into the anterolateral abdominal wall between the internal oblique and transversus abdominis muscles
- anastomoses with 10th & 11th posterior intercostal & subcostal aa. and ascending branch of the deep circumflex iliac a. and lumbar aa.
Superior epigastric a.
- one of the terminal branches of the internal thoracic a.
- pierces the posterior rectus sheath
- courses between the sheath and the rectus abdominis muscle
- ansastomoses with the inferior epigastric a. near the umbilicus
Posterior intercostal aa (10 & 11) and the subcostal a.
- direct paired branches of the aorta above and below the diaphragm, respectively
- pass laterally and forward between the transversus abdominis and internal oblique muscles
- anastomose within the muscle layer with branches of the musculophrenic, superior epigastric, lumbar and deep circumflex iliac arteries
lumbar arteries
- abdominal counterpart of thoracic intercostal arteries
- four paired branches arise from the abdominal aorta at the upper level of the first four lumbar vertebrae
- pass laterally for a short distance to provide branches mainly to the posterior and posterolateral abdominal wall musculature
inferior epigastric a.
- arises from the external iliac a. prior to its passing beneath the inguinal ligament.
- passing medial to the deep inguinal ring, it angles toward the umbilicus within in the extraperitoneal connective tissue layer raising the lateral umbilical fold
- ascending the anterior abdominal wall internally, it enters the posterior rectus sheath where it will anastomose with the superior epigastric a. above the level of the umbilicus
- near its origin it provides branches to the spermatic cord, round ligament of the uterus, and dorsum of the pubis; along its course it anastomoses with branches of the lower six posterior intercostal aa. close to the lateral border of the posterior rectus sheath.
deep circumflex iliac a.
- arises from the external iliac a. distal and lateral to the origin of the inferior epigastric a.
- courses lateralward toward the ASIS to perforate the transversus abdominis muscle to run between it and the internal oblique along the iliac crest
- provides an ascending branch which anastomoses with the last two posterior intercostal, subcostal, musculophrenic and lumbar aa.
- the direct continuation of the deep circumflex iliac a. anastomoses with the iliolumbar a.
Venous drainage of abdomen– cutaneous and subcutaneous regions
accomplished by venae comitantes of the arteries which supply this region, such that tributaries drain:
- superiorly to the AXILLARY vein
- inferiorly to the GREATER SAPHENOUS vein
venous drainage of musculature of the abdominal wall
also accomplished by venae comitantes of the arterial supply, such that tributaries drain:
- superiorly to the SUBCLAVIAN vein
- laterally and posteriorly to the SVC and IVC
- inferiorly to the EXTERNAL ILIAC vein
Tributaries to the axillary vein (superficial drainage)
thoracoacromial v, lateral thoracic v.
Tributaries to the greater saphenous vein (superficial drainage)
superficial epigastric v., superficial circumflex iliac v., superficial external pudendal v.
Important example of anastomotic channels above and below the umbilicus
Although the venous drainage of the superficial abdominal wall is accomplished by venae comitantes of the arterial supply, the drainage pattern consists of highly anastomotic channels above and below the umbilicus. An important example of this anastomosis occurs between superficial veins of the thorax and abdomen in the form of thoraco-epigastric veins, veins which connect lateral thoracic veins above with superficial epigastric veins below.
Tributaries to the subclavian vein (muscular wall drainage)
superior epigastric v.
musculophrenic v.
Tributaries to the external iliac vein (muscular wall drainage)
inferior epigastric v.
deep circumflex iliac v.
Tributaries to the IVC (muscular wall drainage)
lumbar vv.
tributaries to the SVC via the azygous system (muscular wall drainage)
Posterior intercostal vv. 10 & 11
subcostal v.
Cutaneous lymphatics
an anastamosing plexus of lymphatics exits in the subcutaneous connective tissue of the thorax, abdomen, perineum and genitalia, and drains by the following scheme:
- above the transumbilical plane, lymph drains toward the thorax (parasternal nodes) and axilla (lateral pectoral nodes)
- below the transumbilical plane, lymphatic channels following subcutaneous blood vessels drain to superficial inguinal lymph nodes
Superficial inguinal lymph nodes
represented by as many as 20 lymph nodes arranged in a “T” shaped mass located just inferior to the inguinal ligament. Generally, they receive drainage from the lower abdomen, perineum and genitalia, and lower limb.
Lymphatics of the muscular wall
Lymphatic drainage of the muscular abdominal wall parallels its major vascular supply and therefore follows this scheme:
- along the path of the inferior epigastric vessels to EXTERNAL ILIAC NODES
- along the path of the deep circumflex iliac vessels to EXTERNAL ILIAC NODES
- along the path of lumbar vessels to LUMBAR NODES (nodes along the lumbar portion of the aorta and IVC)
- along the path of the superior epigastric vessels to PARASTERNAL NODES (nodes along the path of internal thoracic vessels on the internal surface of the sternum.
Comparing subcutaneous lymphatic drainage of the abdominal wall with the lymphatic drainage of the muscular abdominal wall
Subcutaneous lymphatics generally drain to lymph nodes located SUPERFICIALLY in the subcutaneous tissue of the thigh and thorax (axilla) while the lymphatics of the muscular abdominal wall and testes drain to nodes located INTERNALLY in the abdominopelvic cavity and thorax.
Dermatomes of the abdomen
represented by cutaneous branches of ventral rami of spinal nerves T7-T11 (referred to as thoracoabdominal intercostal nn.)
Innervation to the muscles of the abdominal wall is accomplished by…
ventral rami of spinal nerves T7-L4. Branches of ventral rami T7-T11 and T12 originate as intercostal and subcostal nerves, respectively. Branches of ventral rami L1-L4 originate within the LUMBAR PLEXUS.
Thoracoabdominal intercostal nn. (T7-T11)
Pass from intercostal spaces to course between the transversus abdominis and the internal oblique muscles.
As they pass medially they are directed inferiorward such that:
- the 7th thoracoabdominal intercostal nn. terminate in the region just inferior to the xiphoid process
- the 10th thoracoabdominal intercostal nn. terminate in the region of the umbilicus
- they provide lateral cutaneous branches, muscular branches to ALL anterolateral and anterior abdominal muscles (except pyramidalis) and terminate as anterior cutaneous nerves.
What nerves pierce the transversus abdominis muscle at its posteromedial most extent and run forward between this muscle and the internal oblique for varying distances?
Subcostal n. (T12)
Iliohypogastric n.
Ilioinguinal n.
Subcostal n. (T12)
has a course and distribution similar to the thoracoabdominal intercostal nn., however, its lateral cutaneous branch distributes to the upper gluteal area. Muscularly, it provides innervation to the EAO, IAO, TA and the SOLE innervation to the pyramidalis muscle.
Iliohypogastric n.
(L1; 50% T12-L1)
- Pierces the internal oblique muscle medial and superior to the ASIS and runs inferiorly and medially between the internal and external oblique muscles.
- Provides a lateral branch to the gluteal area, innervates the EAO, IAO, TA and communicates with the ilioinguinal nerve and terminates as anterior cutaneous branches to the SUPRAPUBIC REGION.
Ilioinguinal n.
(L1)
- Pierces the internal oblique near the deep inguinal ring
- Parallels the course of the iliohypogastric n. on a slightly inferior plane
- Courses through the inguinal canal where it runs on the surface of the spermatic cord and follows it through the superficial inguinal ring.
- Provides muscular branches to the IAO and TA
- Provides cutaneous branches to the upper medial thigh and terminates as the ANTERIOR SCROTAL/ LABIAL BRANCH supplying cutaneous innervation to the root of the penis and scrotum in the male and to the mons pubis and labia majora in the female.
Inguinal ligament
inferior rolled-under border of the external abdominal oblique aponeurosis extending from the ASIS to the pubic tubercle. It forms a “shelving border” which attaches to the fascia lata of the thigh and, with the iliopubic tract of transversalis fascia, participates in forming the floor of the inguinal canal. Together the inguinal ligament and iliopubic tract form a “flexor retinaculum” which spans the subinguinal space containing the iliopsoas, pectineus, and the femoral sheath and its contents.
parts of the inguinal ligament
superficial inguinal ring
lateral (inferior) crus
medial (superior) crus
intercrural fibers
superficial inguinal ring
medial opening of the inguinal canal through the inguinal ligament. It passes the spermatic cord of the male, the round ligament of the uterus of the female. Triangular in shape, its apex is directed laterally toward the ASIS, while its base is located at the pubic crest. Superior and inferior margins are referred to as crura.
Lateral (inferior) crus of the inguinal ligament
formed by the thick portion of the inguinal ligament which attaches to the pubic tubercle
Medial (superior) crus of the inguinal ligament
formed by the portion of the inguinal ligament which attaches to the pubic symphysis. It is thinner than its lateral counterpart.
Intercrural fibers
reinforcing fibers located perpendicular to the crura lateral to the superficial inguinal ring.
Lacunar ligament
medial rolled-under portion of the inguinal ligament which, after being crossed by the spermatic cord, attaches to the pectineal line lateral to the pubic tubercle. When viewed laterally it presents a crescentic free border, hence the name “lacunar” ligament.
pectineal ligament
the continuation of the lacunar ligament laterally along the pectineal line of the superior ramus of the pubic bone. Important as an anchoring point for sutures during inguinal hernia repair.
Reflected inguinal ligament
fibers continued from the pubic tubercle medially and superiorly toward the linea alba which intersect with the contralateral external oblique aponeurosis.
external spermatic fascia
outermost fascial layer of the spermatic cord derived from the external abdominal oblique aponeurotic layer.
conjoined tendon
the most medial and inferior common fused aponeuroses of the internal abdominal oblique and transversus abdominis muscles. The fibers of these two muscles arch from the inguinal lligament where they originate to the pubis where they terminate immediately deep to the superficial inguinal ring. The fusion of these two layers helps strengthen a potentially weak area of the anterior abdominal wall.
Inguinal Canal Boundaries
floor: inguinal ligament and iliopubic tract of transversalis fascia
Anterior wall: external oblique aponeurosis with lowest fibers of internal oblique
Roof: arching fibers of the internal oblique and transversus abdominis which originate from the inguinal ligament and attach medially to the superior pubic ramus
Posterior wall: transversalis fascia laterally; conjoined tendon medially
The internal oblique’s special relationship to the inguinal canal
The lowest fibers of the internal oblique muscle arise from the inguinal ligament lateral and anterior of the deep inguinal ring. They arch over the canal and insert with the fibers of the transversus abdominis as the conjoined tendon posterior to the superficial ring. The internal oblique therefore participates in forming a portion of the anterior wall, roof, and a portion of the posterior wall of the inguinal canal.
Entrance to the inguinal canal
via the superficial inguinal ring
Contents of the inguinal canal
Male: spermatic cord, ilioinguinal n., genital branch of the genitofemoral n.
Female: round ligament of the uterus, artery and vein of the round ligament, ilioinguinal n.
Testes embryonic development
testes develop from coelomic epithelial cells which develop in the extraperitoneal connective tissue layer of the posterior abdominal wall at the upper lumbar level in an area known as the urogenital ridge.
Descent of the testes
As a testis is formed it bulges into the future abdominal cavity raising the peritoneum as it grows.
At its superior and inferior poles, the testis has attached to it peritoneal folds. The superior fold contains the future testicular vessels, nerves and lymphatics. The inferior fold will eventually form the gubernaculum testis.
At the distal site of attachment of the gubernaculum testis, the anterior abdominal wall will evaginate (pouch outward). The peritoneal contribution (innermost layer) of this evagination is called the processus vaginalis. As the processus vaginalis pushes into the scrotal swelling (future scrotum) it carries with it contributions of the muscular and fascial abdominal layers it traverses.
Due to differential growth rates of the embryo, the testis is drawn by its scrotal attachment, the gubernaculum, into the scrotum. As the testis traverses the inguinal canal following the path of the processus vaginalis, the layers of the abominal wall are also applied to it as well as to its trailing future spermatic cord.
After the testis has fully descended, the processus vaginalis is applied to the testis forming an incomplete serous sac, the tunica vaginalis testis.
More proximally, the processus vaginalis atrophies and becomes a fibrous cord thereby closing the deep inguinal ring leaving only a dimple marking its former existence in the anterior abdominal wall.
gubernaculum testis
a fibrous connective tissue cord which attaches the inferior pole of the testis to the site of the future deep inguinal ring on the anterior inferior abdominal wall.
Clinical note: processus vaginalis relationship to indirect inguinal hernia
it is thought that the processus vaginalis is open in 50% of infants until one month after birth; this may lead to weakness of the anterior abdominal wall in the inguinal region contributing to indirect inguinal hernia.
Cryptorchidism
undescended or incompletely descended testes.
Spermatic cord coverings
- External spermatic fascia - from external abdominal oblique; applied as cord penetrates the superficial inguinal ring
- Cremaster muscle and associated fascia- from internal abdominal oblique; applied midway through the inguinal canal
- Internal spermatic fascia- from transversalis fascia, covers entire extent of cord
Tunica vaginalis testis- peritoneum via processus vaginalis testis
Tunica albuginea- outermost connective tissue capsule of testis
Contents of the spermatic cord
1-5 embedded in extraperitoneal connective tissue and surrounded by internal spermatic fascia. 6 courses between the cremaster and the internal spermatic fascia.
1- ductus deferens- efferent duct from epididymis
2- testicular artery- branches directly from the abdominal aorta (TV2)
3- deferential artery and vein- branch of the umbilical a. from internal iliac a.
4.- pampiniform plexus of veins - will form testicular vein; on the right will drain to the IVC, on the left will drain to the left renal vein
5- lymphatics draining testis- drain to lumbar nodes
6- genitofemoral nerve (genital branch L1-L2)- innervation of cremaster muscle
Autonomic nerve fibers to the testes course…
on the surface of the testicular artery and ductus deferens
Abdominal wall hernias (general concept)
are protrusions of ANY portion of the abdominal contents beyond the confines of the abdominal cavity.
Types of adominal wall hernias
epigastric, umbilical, spigelian, incisional, inguinal
Epigastric hernias
a- occur along the linea alba between the xiphoid process and umbilicus
b- can be due to gaps of CT fibers between the linea alba and rectus sheath, stresses of obesity and aging, consequence of surgical intervention
Umbilical hernias
occur through umbilical ring
most common in neonates
due to weakness at site from incomplete closure of umbilical cord ligation and increased intra-abdominal pressure
associated with low birth weight
Spigelian hernias
occur along the semilunar lines
associated with obesity and in ages over 40 years
Incisional hernias
occur at site of previously healed surgical scar
Direct inguinal hernia: definition
protrusion of abdominal contents through the posterior wall of the inguinal canal MEDIAL to the inferior epigastric vessels
Direct inguinal hernia: rationale
transversalis fascia located between the inferior epigastric vessels and the conjoined tendon is termed “weak” fascia due to the occurrence of hernias in this area.
Inguinal triangle
= Hesselbach's triangle boundaries: lateral and superior: inferior epigastric vessels medial: lateral border rectus abdominis base: inguinal ligament
Direct inguinal hernia: course
herniated material first passes through the weak fascia of the posterior wall of the inguinal canal (located directly behind the superficial inguinal ring, lateral to the conjoined tendon, and medial to the inferior epigastric vessels), crosses the canal but does not traverse its lenth, and passes out through the superficial inguinal ring. Direct inguinal hernias very seldom extend into the scrotum.
Direct inguinal hernia: occurrence
15-25% of inguinal hernias
majority occur bilaterally; rare in women
medial to inferior epigastric vessels
through “weak fascia’ of Hesselbach’s triangle
bulge in anterior wall does NOT extend into scrotum or labium
Indirect inguinal hernia: definition
Protrusion of abdominal contents through the deep inguinal ring LATERAL to the inferior epigastric vessels.
Indirect inguinal hernia: rationale
weakness at the deep inguinal ring is due to:
- passage of the spermatic cord/ round ligament of uterus
- failure of the processus vaginalis to completely close
indirect inguinal hernia: course
herniated material passes through the deep inguinal ring, traverses the entire length of the inguinal canal, protrudes through the superficial inguinal ring and extends into the scrotum or labia majora.
Indirect inguinal hernia: occurrence
75-85% of inguinal hernias usually occur on the right; 20x greater in males lateral to inferior epigastric vessels follow path of inguinal canal extends into scrotum or labium
Determining the origin (direct or indirect) of herniated material which has protruded through the superficial inguinal ring…
by the covering of the hernia sac. Both direct and indirect hernias can possess a hernia sac which is covered by the fascial layers which cover the spermatic cord. However, the hernia sac of a direct inguinal hernia should have only a covering of peritoneum and transversalis fascia, while an INDIRECT hernia can be covered first with the constituents of the spermatic cord, i.e. ductus deferens, testicular a., pampiniform plexus, etc., then all of the fascial coverings located in the cord.
Natural protection against inguinal hernias is afforded by the…
internal abdominal oblique and transversus abdominis muscles as they form MUSCULO-APONEUROTIC ARCADES which clamp down or otherwise cause the area of the posterior wall of the inguinal canal to become narrower during standing, straining or coughing. Therefore, surgeons performing appendectomies are careful to NOT cut the iliohypogastric nerve which provides innervation to these muscles in the inguinal region.
