Unit 4: Lecture 1 (Part 2: Inguinal Canal, Spermatic Cord, Scrotum, and Testes)

Inguinal canal

What is an oblique passage through the lower anterior abdominal wall, approximately 4 cm long, running parallel and superior to the medial half of the inguinal ligament?

Aponeurosis of the external oblique muscle.

What forms the anterior wall of the inguinal canal?

Transversalis fascia.

What forms the posterior wall of the inguinal wall?

Arching fibers of the internal oblique and transversus abdominis muscles.

What forms the roof of the inguinal wall?

Inguinal ligament (formed by the rolled-under inferior margin of the external oblique aponeurosis).

What forms the floor of the inguinal wall?

Deep (entrance) and superficial (exit) inguinal rings

What are the openings of the inguinal canal?

True

(T/F) The deep inguinal ring (entrance) is lateral to the superficial inguinal ring (exit).

Deep inguinal ring (entrance)

What is located superior to the midpoint of the inguinal ligament, lateral to the inferior epigastric vessels and is formed by an opening in the transversalis fascia?

Superficial inguinal ring (exit)

What is located superior and medial to the pubic tubercle and formed by a gap in the external oblique aponeurosis?

Spermatic cord, including the vas deferens and testicular vessels.

What are the contents of the inguinal canal in males?

Round ligament of the uterus.

What are the contents of the inguinal canal in females?

Ilioinguinal nerve (L1) - sensory to groin and genital region and genital branch of the genitofemoral nerve - motor to cremaster muscle (males) and sensory

to external genitalia.

What are the shared contents of the inguinal canal between both males and females?

(T/F) Because the canal transmits different contents in men and women and has distinct fascial layers at each opening, its weakness predisposes it to direct and indirect inguinal hernias, especially in males.

Camper fascia

What is the superficial fatty layer of the inguinal canal?

Scarpa fascia

What is the deep membranous layer of the inguinal canal?

Camper fascia, scarpa fascia, external oblique aponeurosis, internal oblique and transversus abdominis muscles, transversalis fascia, and parietal peritoneum

What are the fascial layers of the inguinal canal superficial to deep?

Genitofemoral nerve (L1-L2)

What nerve within the inguinal canal emerges from the anterior surface of the psoas major muscle and divides into genital and femoral branches?

Genitofemoral nerve (L1-L2)

What nerve within the inguinal canal arises from the lumbar plexus, specifically the anterior rami of L1 and L2?

Genitofemoral nerve (L1-L2)

What branch of the genitofemoral nerve enters the deep inguinal ring, travels through the inguinal canal, and continues within the spermatic cord in males?

What nerve innervates:

Motor: Innervates the cremaster muscle (in males).

Sensory:

• Males: Skin of the scrotum.

• Females: Skin of the mons pubis and labia majora.

Genitofemoral nerve

Injury to what nerve during retroperitoneal surgery or hernia repair can cause hypoesthesia of the genital region or absent cremasteric reflex?

Genitofemoral nerve (L1-L2)

What nerve is responsive for cremasteric reflex?

Ilioinguinal nerve (L1)

What nerve of the inguinal canal arises from the L1 spinal nerve?

Genitofemoral nerve (L1-L2)

What nerve runs within the spermatic cord?

Ilioinguinal nerve (L1)

What nerve of the inguinal canal:

• Travels through the inguinal canal but not within the spermatic cord.

• Exits the canal via the superficial inguinal ring.

Ilioinguinal nerve (L1)

What nerve innervates:

• Motor: Supplies internal oblique and transversus abdominis (proximal branches).

• Sensory:

• Males: Skin of the root of the penis, upper scrotum, and adjacent medial thigh.

• Females: Skin of the mons pubis, labia majora, and adjacent medial thigh.

Ilioinguinal nerve (L1)

What nerve is frequently injured during inguinal hernia repairs and Cesarean deliveries,

causing sensory changes or chronic groin pain.

Iliohypogastric nerve (L1)

What nerve of the inguinal canal arises from the L1 spinal nerve?

Iliohypogastric nerve (L1)

What nerve of the inguinal canal:

• Courses above the inguinal canal, running between internal oblique and transversus

abdominis.

• Does not enter the inguinal canal or spermatic cord.

Iliohypogastric nerve (L1)

What nerve of the inguinal canal innervates:

• Motor: Internal oblique and transversus abdominis.

• Sensory: Skin of the hypogastric region and lateral gluteal region.

Iliohypogastric nerve (L1)

What nerve is often entrapped in Pfannenstiel incisions, leading to hypesthesia or neuropathic pain in the lower abdomen.

Perotoneal folds

What are raised ridges on the posterior surface of the anterior abdominal wall, formed by parietal peritoneum overlying structures such as ligaments or vessels?

Median umbilical fold

What peritoneal fold covers the median umbilical ligament, a remnant of the embryonic urachus (allantoic duct) and extends from the apex of the urinary bladder to the umbilicus, in the midline?

Medial umbilical folds (paired)

What peritoneal folds cover the medial umbilical ligaments, which are obliterated umbilical arteries from fetal circulation and run lateral to the median fold on each side?

Medial umbilical folds (paired)

What peritoneal fold is important in distinguishing between direct and indirect inguinal hernias—direct hernias occur medial to these folds, while indirect hernias are lateral?

Lateral umbilical folds (paired)

What peritoneal folds cover the inferior epigastric arteries and veins and are lateral to the medial umbilical folds?

(T/F) The position of the inferior epigastric vessels is key to identifying the deep inguinal ring, which lies just lateral to these folds—a crucial point for distinguishing types of hernias in surgery and imaging.

Inguinal hernias

What type of hernias are most frequent within the abdominal cavity?

Supravesical fossa

What is located between the median and medial umbilical folds and overlies the superior portion of the bladder?

Medial inguinal fossa (Hesselbach's triangle)

What is located between the medial and lateral umbilical folds and is the site of direct inguinal hernias?

Indirect hernias

What is the most common type of inguinal hernias?

Inguinal hernia

What is is defined as a protrusion of peritoneum and/or abdominal contents

(commonly omentum or small intestine) through an abnormal or enlarged opening in the anterior abdominal wall, specifically within the inguinal region?

True

(T/F) Inguinal hernias are classified based on their relationship to the inferior epigastric vessels and how they course through the inguinal canal.

Indirect inguinal hernia (congenital type)

What type of inguinal hernias occur lateral to the inferior epigastric artery and vein?

Indirect hernias

What hernias are more likely to present with a palpable scrotal mass and can be reducible or incarcerated? Ultrasound and CT can delineate the hernia sac and relationship to surrounding structures.

Direct inguinal hernia (acquired type)

What type of hernias typically occurs in older adults, particularly those with weakened abdominal musculature or chronic increased intra-abdominal pressure (e.g., chronic cough, constipation, heavy lifting)?

Direct inguinal hernia (acquired type)

What type of herniation occurs medial to the inferior epigastric vessels, through an area of weakness in the posterior wall of the inguinal canal, specifically Hesselbach's triangle?

What type of hernias only traverse the medial third of the inguinal canal and rarely enter the scrotum.

Direct inguinal hernia (acquired type)

What type of hernias may be identified as a bulge near the pubic tubercle that enlarges with increased intra-abdominal pressure (e.g., Valsalva)?

Inguinal canal

What develops in coordination with the descent of the gonads, a key developmental

process process? This descent involves the formation and remodeling of connective tissue

structures, outpouchings of the peritoneum, and the eventual formation of permanent anatomical features in both males and females.

Gubernaculum

What is a fibrous cord of connective tissue attaching the inferior pole of the gonad to

the anterolateral abdominal wall (eventual scrotum or labia).

Gonads

What begins to develop on the posterior abdominal wall, inferior to the kidneys, during early embryogenesis?

Processus vaginalis

What is an evagination of the peritoneum that precedes the descending gonad through the abdominal wall layers?

3rd month

At what point of male development do testes migrate from their initial position to the pelvic region?

7th month

At what point of male development do testes approach the deep inguinal ring and shortly thereafter pass through the inguinal canal?

8th month

At what point of male development do testes enter the scrotum, following the path created by the processus vaginalis?

Scrotal ligament

What does the gubernaculum become postnatally, anchoring the testis within the

scrotum?

True

(T/F) Failure of complete descent (cryptorchidism) occurs in approximately 3% of full-term male infants and can increase risk of infertility and testicular cancer if uncorrected.

True

(T/F) The ductus deferens, testicular vessels, nerves, and lymphatics accompany the testis during this descent and remain enclosed in the spermatic cord.

(T/F) The processus vaginalis closes proximally but its distal part persists as the tunica vaginalis (with visceral and parietal layers) surrounding the testis.

True

(T/F) Ovaries also originate on the posterior abdominal wall, but descend to the pelvic brim rather than into the inguinal canal.

Upper portion of gubernaculum

In females, what becomes the ovarian ligament, connecting the ovary to the uterus?

Lower portion of gubernaculum

In females, what becomes the round ligament of the uterus, which passes through the inguinal canal and terminates in the labium majora?

Labium majora

The processus vaginalis may form but typically regresses; when it persists, it may protrude

into the ____ ____.

Tunica vaginalis

What does the processus vaginalis become?

Spermatic cord

What is the cord-like structure composed of several components. That runs from the deep inguinal ring to the testis? It suspends the testis in the scrotum and contains structures essential for testicular function, thermoregulation, and transport of sperm.

External spermatic fascia, cremaster muscle and fascia, and internal spermatic fascia

What are the fascial coverings of the spermatic cord?

External oblique aponeurosis.

What is the external spermatic fascia derived from?

Internal oblique muscle and aponeurosis.

What is the cremaster muscle and fascia derived from?

Transversalis fascia.

What is the internal spermatic fascia derived from?

Genital branch

Injury to the what branch of the genitofemoral nerve during surgical dissection of the spermatic cord can result in loss of the cremasteric reflex, which is a useful neurological diagnostic test?

Ductus (vas) deferens, testicular artery, pampiniform venous plexus, and genital branch of genitofemoral nerve.

What are the contents of the spermatic cord?

Ductus (vas) deferens

What is the thick-walled muscular tube that transports sperm from the epididymis to the ejaculatory duct?

Testicular artery

What is the branch of the abdominal aorta that supplies blood to the testis and epididymis?

Pampiniform venous plexus

What is the branch of the abdominal aorta that supplies blood to the testis and epididymis?

Spermatic cord

Clinical conditions such as varicocele, testicular torsion, and hernia repair complications are anatomically centered around the _____ _____.

Scrotum

What is an outpouching of the anterior abdominal wall, forming a sac that houses the testes, epididymides, and the lower part of the spermatic cords that plays a crucial role in thermoregulation of the testes, which is essential for proper spermatogenesis?

Scrotal raphe and median scrotal septum

What are the external features of the scrotum?

Scrotal raphe

What is the midline external ridge indicating the internal division of the scrotum into two compartments?

Median scrotal septum

What is the internal partition that divides the scrotum into two separate chambers, each containing one testis?

True

(T/F) The scrotum is homolygus.

Skin, dartos fascia/muscle, external spermatic fascia, cremaster fascia/muscle, internal spermatic fascia, parietal layer of tunica vaginalis, visceral layer of tunica vaginalis, and tunica albugenia

What are the layers of the scrotum from superficial to deep?

Skin

What layer of the scrotum and testes is thin and pigmented?

Dartos fascia/muscle

What layer of the scrotum and testes is a smooth muscle layer that is directly adherent to the skin that is responsible for wrinkling of the scrotal skin, aiding in temperature regulation and is homologous to the labia majora in females?

External spermatic fascia

What layer of the scrotum and testes is derived from the external oblique aponeurosis?

Cremasteric fascia/muscle

What layer of the scrotum and testes is derived from the internal oblique; elevates the testis?

internal spermatic fascia

What layer of the scrotum and testes is derived from transversalis fascia?

Parietal layer of tunica vaginalis

What layer of the scrotum and testes is a serous membrane lining the inner wall of the scrotum?

Visceral layer of tunic vaginalis

What layer of the scrotum and testes covers the anterior and lateral parts of the testis and

epididymis?

Tunica albugenia

What layer of the scrotum and testes is a dense fibrous capsule surrounding the testis?

Cremasteric reflex

Damage to the _____ _____ arc, which includes the genital branch of the genitofemoral nerve and the cremaster muscle, may impair testicular elevation—affecting thermoregulation and making testicular torsion harder to detect.

Ilioinguinal nerve (L1) and genital branch of genitofemoral nerve (L1-L2)

What are the anterior scrotal nerves?

Pudendal nerve (S2-S4) and posterior femoral cutaneous nerve (S1-S3)

What are the posterior scrotal nerves?

(T/F) The scrotum contains layers derived from abdominal wall structures, including muscle and fascia.

True

(T/F) Innervation of the scrotum spans both the lumbar and sacral plexuses.

Testes

What are paired male gonads located within the scrotum, primarily responsible for spermproduction and testosterone secretion?

Seminiferous tubules

What are the highly coiled structures responsible for sperm production (spermatogenesis).

Sertoli (nurse) cells

What are the columnar epithelial cells that support spermatogenesis?

Interstitial (Leydig) cells

What cells are located in the spaces between seminiferous tubules and are responsible for producing testosterone, the primary male sex hormone?

Interstitial (Leydig) cells

Dysfunction or loss of what cells cells, as seen in conditions like Klinefelter syndrome, leads to hypogonadism and infertility due to impaired testosterone production?