INGUINAL REGION
I. DESCENT OF GONADS
A. Gonads develop originally at midlumbar levels
1. in extraperitoneal C T
2. covered anteriorly (ventrally) by parietal peritoneum
3. inferior fold of peritoneum contains fibrous C T
B. Evagination of coelom develops in inguinal region pushing all layers of abdominal wall outward
1. scrotal/labial swelling - outpocketing of abdominal wall lined with peritoneum
2. processus vaginalis - the actual peritoneal protrusion
C. Descent of testis
1. Inferior C T ligament from testicle fuses with C T in extraperitoneal layer of the scrotum - complete ligament is called gubernaculum testis
2. Superior C T ligament contains vessels and nerves to testis
3. Testis is drawn down into the scrotum by differential body growth - appears to be pulled into scrotum
4. Opening of process vaginalis narrows to just a ring
5. 12 weeks on pelvis, 28 weeks at deep ring, 3 days to traverse the canal, 32 weeks in scrotum
6. By 8th month of fetal life, testes should be in scrotum
7. Scrotal ligament is the C T left between testis and scrotal wall
8. Process vaginalis closes - forms closed tunica vaginalis testis
9. Cryptorchism - undescended testis
10. Blood vessels, ducts and nerves follow the descent of the testis
a. called spermatic cord
b. as the abdominal wall grows, these structures appear to pass through the wall to scrotum
c. inguinal canal - passage through the abdominal wall
D. Descent of the ovary
1. Gubernaculum develops as in males
a. becomes attached to developing uterus along midlength
b. proximal portion becomes ovarian ligament
i. attaches ovary to uterus
ii. ovary only descends as low as uterus
c. distal portion becomes round ligament of uterus
i. connects uterus to the C T of labia majora
ii. follows same path as spermatic cord
2. Processus vaginalis closes off earlier in female, tunica vaginalis obliterates
II. LAYERS OF ABDOMINAL WALL IN INGUINAL REGION
NOTE: all references to spermatic cord are equivalent to round ligament in female in terms of gross relationships and layers
A. External oblique
1. Inguinal ligament (Poupart’s) - free lower border of the aponeurosis of the external oblique between anterior superior iliac spine and pubic tubercle
2. Lacunar ligament - turned under medial continuation of inguinal ligament that attaches to the pectineal line
3. Pectineal ligament (Cooper’s) - dense ligament that runs along pectineal line posterior and lateral to the lacunar ligament
4. Deep inguinal ring-site of outpocketing of the transversalis f.; lateral to inferior epigastric a.
5. Superficial inguinal ring - a triangular opening in the aponeurosis of the external oblique just superior and lateral to the pubic tubercle
a. lateral crus - lateral border of opening-attaches to pubic tubercle
b. medial crus - medial border-attaches to pubic crest
c. intercrural fibers - C T fibers crossing opening
6. External spermatic fascia
a. continuation of plane of external oblique
b. covers spermatic cord and forms part of scrotal wall
B. Internal oblique
1. Has some origin from lateral 2/3 of inguinal ligament
2. Lower fibers arch over spermatic cord to their insertion
3. Lower fibers insert in superior border of pubis and pectineal line
a. conjoint tendon (falx inguinalis) - common insertion of internal oblique and transversus into pubis and along pectineal line
4. Cremasteric muscle and fascia - extension of internal oblique over spermatic cord and into scrotum
a. innervation - genitofemoral n (L1-2).
b. action - raises testicle within scrotum
C. Transversus abdominus
1. Has some lower origin from lateral 1/3 of inguinal ligament
2. Lower fibers arch over spermatic cord to insert via conjoint tendon
3. No direct extension into scrotum
4. Interfoveolar muscle (ligament)
a. few fibers of transversus plane which descend vertically behind the spermatic cord
b. often undefinable
D. Transversalis fascia
1. Forms continuous covering on inside of the opening below the arch of the internal oblique and transversus
2. Internal spermatic fascia - extension of plane over spermatic fascia and into scrotum
a. Deep inguinal ring - evagination of the transversalis fascia just superior to the inguinal ligament, lateral to the inferior epigastric artery and medial to the most medial origin of the transversus
b. Femoral sheath - similar evagination around femoral vessels
E. Peritoneum
1. Forms continuous covering over the inside of the inguinal region
2. Persistent process vaginalis may occur - would enter deep inguinal ring
III. INGUINAL CANAL
A. Definition - oblique passageway between the deep inguinal ring and the superficial inguinal ring, containing spermatic cord/round ligament
B. Borders of the inguinal canal
1. Posterior
a. laterally - transversalis fascia
b. medially - conjoint tendon
2. Anterior
a. laterally - internal oblique arising from inguinal ligament
b. medially - external oblique
3. Roof
a. formed by arching fibers of the internal oblique and transversus as they run from an anterolateral to posteromedial relationship to the canal
4. Floor
a. laterally - formed by the inguinal ligament
b. medially - formed by part of the lacunar ligament
5. Open at each end
C. Contents of the inguinal canal
1. Ductus (vas) Deferens-sperm from epididymis to ejaculatory duct
2. Testicular Artery-from aorta
3. Artery of Vas Deferens-from inf. vesical a.
4. Cremaster a.-from inferior epigastric a.
5. Pampiniform venous plexus-drain to testicular vv.
6. Sympathetic fibers-vasomotor
7. Parasympathetic fibers-to vas deferens
8. Genital Br. of Genitofemoral n.-supplies cremasteric m.
9. Lymphatics-to lumbar nodes
D. Inferior epigastric artery - serves as a landmark within inguinal region
1. Br. of external iliac a. as it passes posterior to inguinal ligament
2. Passes just medial to deep inguinal ring
3. Runs in extraperitoneal fat to arcuate line of the rectus sheath where it enters the sheath
E. Iliopubic Tract-deep crural arch-transversalis f. internal to inguinal lig.-demarcates the deep ring-laproscopic landmark
IV. SCROTUM/LABIA
A. Scrotum - cutaneous pouch of bilateral origin
1. Layers
a. Skin - pigmented more heavily than rest of body
b. Dartos fascia (Tunica Dartos) = hypodermis
i. one layer
ii. contains smooth muscle-attaches to skin
iii. contains no fat
iv. continuous with Scarpa's f. and Colle's f
2. Raphe - exterior line of C T fusion in midline of embryonic bavioscrotal swelings
3. Septum - internal extension of raphe dividing scrotum
B. Labia majora - develops similar to scrotum except for fusion
1. Layers
a. skin
b. hypodermis - no Dartos layer but contains encapsulated fat
2. Round ligament ends in hypodermis
C. Nerve supply –(see diagram of lumbosacral plexus above)
1. Anterior scrotal/labial nn. = terminals of ilioinguinal n. (L1)
2. Posterior scrotal/labial nn. = terminals of pudendal n.(S2-4)
3. Genitofemoral n.=L1-2
D. Blood supply
1. Superficial external pudendal br. of femoral a.=anterior scrotal aa.
2. Deep external pudendal br. of femoral a.
E. Lymphatics - rich plexus drains to superficial inguinal nodes
F. Testicular coverings
1. The scrotum develops as an outpocketing of the abdominal wall and is thus lined by the same layers
2. Since testis descends from lumbar regions into the scrotum, it is covered by all layers lining the scrotum and abdomen
3. Layers covering the testicle
a. Tunica vaginalis - remnant of peritoneum
i. visceral and parietal layers
ii. visceral layer covers only anterior testis
iii. posterior testis is still in "extraperitoneal layer"
iv. sinus of epididymis - invagination of peritoneum between testis and epididymis
b. Internal spermatic fascia - from transversalis fascia
c. Cremasteric muscle - striated muscle cover developed from internal oblique
d. External spermatic fascia - from external oblique
e. Tunica Dartos - subcutaneous - some smooth muscle
G. Layers in labia majora - most tend to disappear
H. Testis - discussed with perineum and pelvis
V. INGUINAL HERNIAS
A. Inguinal triangle (Hesselbach’s triangle) - area on the inside of the abdominal wall. Bounded by:
1. Inguinal ligament-inferiorly
2. Inferior epigastric artery-superolaterally
3. Rectus abdominus-medial
B. Hernia - abnormal protrusion through a "wall", most involve internal organs (often gut tube)
C. Indirect inguinal hernia
1. Intestinal loop and accompanying peritoneal sac pass through deep inguinal ring, inguinal canal and superficial ring into the scrotum
2. Leaves abdominal cavity lateral to inferior epigastric artery
3. Congenital indirect inguinal hernia - due to failure of processus vaginalis to close
4. most common
5. commonly enters scrotum
6.Acquired indirect inguinal hernia - not inside old processes vaginalis
D. Direct Acquired inguinal hernia
1. Intestinal loop and accompanying peritoneal sac pass through inguinal triangle, then to superficial ring. Not enter scrotum.
2. Leaves abdominal cavity medial to inferior epigastric artery
3. Predisposition caused by conjoint tendon with only limited insertion
4. Hernial sac is covered by transversalis f.
5. Protrudes through Hesselbach's Triangle
VI. FEMORAL REGION AND HERNIAS
A. Femoral sheath - an extension of transversalis fascia into the thigh, along femoral vessels, ends blindly
B. Femoral canal - medial, unfilled portion of sheath
C. Femoral ring - opening into femoral canal. Bounded by;
1. Inguinal ligament - separates femoral ring from inguinal canal
2. Femoral vein
3. Lacunar ligament
VII. INSIDE OF LOWER ABDOMINAL WALL
A. Folds - raised areas of parietal peritoneum produced by underlying structures
1. Median umbilical fold - from tip of bladder to umbilicus
a. produced by median umbilical ligament - remnant of urachus (reduced allantoic stalk)
2. Medial umbilical folds - from side of bladder to umbilicus
a. produced by medial umbilical ligament - remnant of occluded umbilical aa.
3. Lateral umbilical folds
a. cover inferior epigastric vessels
B. Fossae - between folds-potential site of hernia
1. Supravesical fossa - between median and medial umbilical folds-peritoneum reflects from wall onto bladder
2. Medial inguinal fossa - between medial and lateral folds
3. Lateral inguinal fossa - lateral to lateral fold-site of indirect hernias