Anatomy clinical correlates: Inguinal region

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Introduction0:00–0:28

The inguinal region located near the groin is found in the lower part of the anterior abdominal wall. And it contains several important structures that enter and leave the abdomen.
Understanding the anatomy of the inguinal region is important for understanding common clinical conditions such as hernias and many others.
Speaking of which hernias occur when an organ or tissue protrudes through the wall of the muscle or tissue that normally contains it.

Hernias0:28–4:04

The majority of hernias occur in the abdominal cavity or the inguinal region through which subcutaneous fat, abdominal omental fat or even abdominal viscera can protrude in order for a hernia to happen.
There is typically a weak point along the abdominal wall such as a weak linea alba. Previous surgical interventions that weaken the abdominal wall muscles or pregnancy.
First, let's look at anterior abdominal wall, hernias. They can be divided into four categories.
Epigastric, umbilical or periumbilical spigelian and incisional hernias. Epigastric hernias are caused by a weakened linea alba and are basically defects in the abdominal midline between the umbilicus and the xiphoid process.
Then there are umbilical or paraumbilical hernias which are hernias through the umbilical ring or around the umbilicus. These are often found in Children because the umbilical ring is weak at birth but can also be acquired in adults and frequently affect pregnant or obese individuals.
Spigelian hernias are found along the semilunar lines which are skin folds from the inferior coastal margin of the ninth coastal cartilage to the pubic tubercles and overlie the tendinous insertions of the rectus abdominis muscle as abdominal tissue can protrude through these areas of tendinous insertions.
Finally, an incisional hernia can develop at the site of a prior surgical incision as the muscle and fascia is typically weakened, for example, over the surgical site of an appendectomy.
Hernias can be classified as reducible, which means that they can be easily pushed back in the abdomen with position changes or a manual pressure or irreducible, which can't be pushed back.
Irreducible. Hernias can become either incarcerated or strangulated.
Incarcerated. Hernias are when the hernia contents are trapped and cannot be reduced leading to swelling and edema of the herniated contents with severe swelling, obstruction of blood flow to the herniated contents can occur.
And this leads to ischemia and necrosis, resulting in strangulation, incarceration and strangulation can affect any protruding structure with a blood supply such as the omentum and bowel.
Risk factors for developing a hernia include genetic defects, increased intraabdominal pressure, aging, obesity and pregnancy symptoms and signs of a hernia may include pain, discomfort and a lump or bulge in the affected area which may be exacerbated by increasing intraabdominal pressure such as coughing or laughing, strangulated hernias can present with severe pain, nausea, vomiting as well as tenderness and overlying erythematous skin changes.
Now, a similar concept to abdominal hernias is rectus abdominis diastasis or divarication of the recti. This is when there's a separation between the rectus muscles due to conditions that weaken and stretch the linea alba.

Rectus abdominis diastasis4:04–5:13

This condition can also be congenital or acquired and risk factors include obesity, pregnancy, connective tissue disorders or prior abdominal surgery.
This particular type of hernia is not what we call a true hernia because technically the midline fascial layer of the abdominal wall is intact.
This means that strangulation doesn't occur. Individuals affected by rectus abdominis diastasis present with a midline abdominal ridge that becomes more obvious when increasing the abdominal pressure and can disappear when the abdominal muscles are relaxed.
Diagnosis is based on physical examination and an abdominal ultrasound can be done to completely rule out a hernia time for a quick quiz.

Quiz5:13–5:23

What are the four main types of anterior abdominal wall hernias? Now, let's look at femoral and inguinal hernias.

Femoral hernias5:23–6:35

Femoral hernias occur when the hernia sac slips through the femoral ring into the femoral canal below the inguinal ligament, medial to the femoral vein and lateral to the pubic tubercle and lacunar ligament.
One important risk factor for femoral hernias is advanced age as the femoral ring can widen with age. Femoral hernias also tend to be more common in biologically female individuals compared to biological males, but don't get confused as inguinal hernias are a more common type of hernia in both biological males and biological females.
Now, as the space in the femoral canal is limited, femoral hernias can often become irreducible and incarcerated. And subsequently, it can cause bowel obstruction if there is bowel located in the hernia sac.
In time, this type of hernia can become strangulated and cause bowel ischemia and necrosis. On the other hand, there are two types of inguinal hernias, direct and indirect inguinal hernias, both occurring above the inguinal ligament.

Inguinal hernias6:35–9:03

When compared with femoral hernias, direct inguinal hernias occur when there is weakness of the transversalis fascia. In this case, the hernia sac pushes through the weak portion of the transversalis fascia above the inguinal ligament.
Here, it protrudes into an area called Hesselbach triangle, which is bounded laterally by the inferior epigastric vessels medially by the lateral wall of the rectus abdominis and inferiorly by the inguinal ligament.
You should note direct hernias do not pass through the deep inguinal ring and may only protrude through the superficial ring.
Therefore, they have no direct route into the scrotum. Indirect hernias occur when the hernia sac emerges lateral to the inferior epigastric arteries, which is in contrast to direct inguinal hernias and protrude through the deep inguinal ring into the inguinal canal with the potential to extend distally into the scrotum.
Indirect hernias are typically caused by a failure of the processus vaginalis to close in biologic males or the deep inguinal ring to close in biologic females remember that the processus vaginalis is an embryonic structure that precedes the descent of the testes through the inguinal canal.
Normally, after the testes have descended into the scrotum, this structure closes up but in some cases, it can remain open and allow for communication between the abdomen and the scrotum.
Inguinal hernias are the most common type of hernia in both biologically male and female individuals. And they occur much more frequently in males.
Direct inguinal hernias are more common in older individuals where indirect ones are more common in infants compared to femoral hernias.
Indirect inguinal hernias are less likely to become strangulated with direct inguinal hernias. The least likely to become strangulated signs and symptoms of both femoral and inguinal hernias are a palpable bulge often exacerbated by increased intraabdominal pressure, pain and discomfort.

Clinical presentation9:03–9:42

If an indirect hernia extends into the scrotum, then it can present as a larger palpable mass in the inguinal canal and scrotal sac.
If a hernia becomes incarcerated and strangulated, for example, during a femoral hernia, this can lead to overlying erythematous skin changes as well as nausea, vomiting, clinical obstruction and extreme pain.

Diagnosis9:42–11:07

Ok. Now, let's take a more practical approach on how to distinguish these different types of hernias based on clinical exam and anatomical landmarks on clinical examination, femoral hernias are typically palpated, lateral and inferior to the pubic tubercle.
Both direct and indirect inguinal hernias occur above the inguinal ligament, direct inguinal hernias push through the Hesselbach triangle medial to the inferior epigastric artery and may protrude into the superficial inguinal ring.
So, clinically, they can be palpated, superficial or medial to the pubic tubercle. Finally, indirect inguinal hernias protrude lateral to the inferior epigastric artery into the deep inguinal canal located at the midpoint of the inguinal ligament and may extend through the inguinal canal and into the scrotum.
Therefore, they may be clinically palpated with deep palpation using the tip of the finger anywhere along the inguinal canal, medial to the pubic tubercle where they exit the superficial ring or along the spermatic cord and into the scrotum.
However, keep in mind, you still may be unable to identify which type of hernia is occurring based on the clinical exam alone.
Ok. Hernias can be resolved surgically with a procedure called herniography.

Hernia repair11:07–12:43

But sometimes complications arise during hernia surgery. Sometimes an artery called the aberrant or accessory obturator artery can be injured.
Typically, the obturator artery branches from the internal iliac artery. However, in up to 20% of people, there can be an additional branch coming from either the inferior epigastric artery or external iliac artery that either replaces the obturator artery or joins it.
And this is called an aberrant or accessory obturator artery. This artery runs in close proximity to the femoral ring and courses along the superior pubic remi.
So, during hernia repair, it can become injured or stapled when this occurs, the artery retracts making it very difficult to locate and ligate leading to uncontrolled bleeding.
This artery has been referred to as corona mortis, which means crown of death as injury to it can be fatal. On the other hand, during inguinal hernia repair, more common complications include damage to the ilioinguinal, iliohypogastric or genitofemoral nerves which can lead to chronic residual neuralgia and postoperative constrictive scar tissue in the surgical area.
Hey, look, it's quiz o'clock where are direct and indirect hernias located in relation to the inferior epigastric artery.

Quiz12:43–12:54

Ok. Now, let's switch gears and look at the testes specifically at cryptorchidism, which is the most common birth defect in biological males.

Cryptorchidism12:54–14:28

Cryptorchidism is the abnormal or partial descent of either one or both testes into the scrotum before birth. Now, the testes developed during the first trimester in the abdominal cavity where in the third trimester of pregnancy, they start to descend into the scrotum via the inguinal canal.
In some biologic males, descent of the testes doesn't occur properly and they can be found anywhere along the inguinal canal while some may even be atrophied or absent.
Risk factors for crypt organism include prematurity, low birth weight, specifically under 2.5 kg and small for gestational age, cryptorchid testes, palpated in the inguinal canal, usually descend by the age of six months.
So the child must be closely monitored during this time. If the testes don't descend by then a surgical procedure called orchiopexy can be done to bring them into the scrotum and this should be done before the age of one complications of cryptorchidism include infertility, malignancy and testicular torsion.
Next up, let's discuss varicoceles and hydroceles. A varicocele is a dilatation of the pampiniform plexus in either testicle which is a network of small veins within the spermatic cord.

Varicoceles14:28–16:50

It occurs in up to 20% of men, typically between the ages of 15 and 25. It is typically more common in the left pampiniform plexus for two reasons.
First, unlike the right gonadal vein, which drains directly into the IVC, the left gonadal vein is longer and drains into the left renal vein at a more perpendicular angle.
Second, the left renal vein may potentially be under higher pressure than the right due to compression between the aorta and superior mesenteric artery as it courses between these two structures resulting in a nutcracker effect.
This further increases the intra vascular pressure in the left gonadal vein and dilation of the pampiniform plexus. So typically a varicocele occurs either bilaterally or in the left pampiniform plexus.
In rare cases, an isolated right sided varicocele occurs which would raise suspicion for thrombosis or nearby malignant compression, affecting the right gonadal vein.
For example, compression from a right renal cell carcinoma. Varicoceles can be asymptomatic but can also present with scrotal pain and a soft scrotal mass which looks and feels like a bag of worms on palpation, not a comforting visual, we know on examination, a varicocele decreases in a supine position and increases withstanding or valsalva maneuvers and doesn't transilluminate when shining a light into the scrotum.
Diagnosis is confirmed by an ultrasound that shows pampiniform plexus dilation and retrograde venous flow. Complications of a varicocele include infertility due to increased temperature and testicular atrophy.
On the other hand, a hydrocele is when there's peritoneal fluid that collects within the tunica vaginalis of the scrotum and is often congenital.

Hydroceles16:50–18:05

Remember, the process is vaginalis. Well, when it fails to close, that doesn't only increase the risk of inguinal hernias but also allows for peritoneal fluid to flow into the tunica vaginalis.
A hydrocele can also be acquired at any age. Typically following infection trauma or a tumor.
Individuals present with a soft fluctuant nontender fullness in the hemiscrotum. Unlike varicoceles, hydroceles transilluminate when shining a light into the scrotum which has a red glow indicating serous fluid in the scrotum.
Hydroceles can be precipitated by inflammatory conditions such as epididymitis and testicular torsion. And complications include transformation into a hematocele, which is a collection of blood in the hemiscrotum as well as calcification and testicular atrophy.

Testicular torsion18:05–21:05

Finally, there's testicular torsion which is just as painful as it sounds. It's one of the most common causes of acute scrotal pain in infants and postpubertal boys and is most common in adolescents.
It often happens due to insufficient fixation of the testis to the tunica vaginalis. This leads to hypermobility and twisting of the testis and the spermatic cord typically affecting the pampiniform plexus first, reducing venous outflow where the arterial blood flow is initially preserved and decreased.
However, with prolonged compression, the arterial supply eventually becomes completely occluded. Leading to hemorrhagic infarction and necrosis.
Testicular torsion can happen spontaneously or after trauma or vigorous physical activity. Individuals present with a swollen erythematous tender scrotum along with acute onset scrotal pain, lower abdominal pain, nausea and vomiting.
Furthermore, individuals may have an asymmetrical high riding testicle on the affected side due to shortening of the spermatic cord.
Also, elevation of the testicle doesn't relieve the scrotal pain, which is called a negative pre sign. Additionally, there may be an absent cremasteric reflex, meaning that the cremaster muscle doesn't contract when lightly stroking the superior and inner part of the thigh.
Normally, stimulation of the motor fibers of the genitofemoral nerve causes contraction of the cremasteric muscle. And as a consequence, contraction of the scrotal sac.
The cremasteric reflex is important in trying to differentiate testicular torsion from other conditions that cause scrotal pain such as epididymitis or inflammation of the epididymis orchitis, which can be caused by mumps and Fournier gangrene, which is a necrotizing fasciitis of the genital area.
And perineum diagnosis of testicular torsion is based on physical examination, but a Doppler ultrasound is required to detect reduced blood flow or twisting of the spermatic cord.
Testicular torsion is a surgical emergency. An urgent urological consultation and surgical detorsion is required.
In addition to fixing both testicles to the scrotal septum to prevent further torsion if surgery is unavailable, manual detorsion of the testicle can be attempted.
Delaying both manual and surgical maneuvers can cause testicular non viability within 12 hours. In which case, surgical removal of the affected testicle or an orchiectomy is needed.
Last quiz. What is a varicocele?

Quiz21:05–21:21

And on what side does it most commonly occur? What's a hydrocele?
All right. As a quick recap hernias in the anterior abdominal wall can be divided into epigastric umbilical spigelian and incisional hernias, reducible hernias can be easily pushed back into the abdomen.

Review21:21–24:18

While irreducible hernias can't irreducible hernias can eventually become incarcerated or strangulated where the hernia contents lose their blood supply and become ischemic and necrotic rectus abdominis diastasis is when there's a separation between the medial sides of the rectus muscles due to a weakened and stretched linea alba femoral hernias occur when the hernia sac protrudes through the femoral ring into the femoral canal.
They occur more commonly in older biological females and have a higher likelihood of becoming strangulated due to the tight space of the femoral ring.
Inguinal hernias are the most common type of hernia in both biological males and females. And they can be direct or indirect, direct hernias are caused by weakness of the transversalis fascia where the hernia sac protrudes into the Hesselbach triangle, medial to the inferior epigastric artery and can push into the superficial inguinal ring but not into the scrotum.
Indirect hernias can be caused by a patent processus vaginalis and occur lateral to the inferior epigastric artery and protrude through the deep inguinal ring into the inguinal canal and may extend into the scrotum.
Cryptorchidism is the abnormal or partial descent of the testes prior to birth complications include infertility, malignancy and testicular torsion.
A varicocele is a dilatation of the pampiniform plexus. More often it occurs on the left side and doesn't transilluminate on examination.
It has a characteristic bag of worms finding on visual inspection and palpation. A hydrocele is an accumulation of peritoneal fluid around the testes in the tunica vaginalis of the scrotum and does transilluminate on examination.
Testicular torsion is the twisting of the testes and the spermatic cord resulting in severe pain, nausea, vomiting and may result in testicular ischemia and necrosis due to restricted blood supply.
It is a surgical emergency and requires manual or surgical detortion immediately.
Anatomy clinical correlates: Inguinal region Video | Osmosis