Anatomy
Abdomen
A 21 year old man presents to ED complaining of groin pain. Examination reveals an indirect inguinal hernia. Which of the following nerves is most likely compressed by the herniating structure in the inguinal canal to cause pain:
Answer:
The ilioinguinal nerve runs with the spermatic cord in the inguinal canal to innervate the anterior portion of the scrotum and proximal parts of the genitals, and could become compressed in an indirect inguinal hernia.Inguinal Canal
Anatomy / Abdomen / Inguinal Region
Last Updated: 11th April 2019
The inguinal canal is a slit-like passage that extends in a downwards and medial direction, just above and parallel to the lower half of the inguinal ligament. It begins at the deep inguinal ring and continues for approximately 4 cm, ending at the superficial inguinal ring.
Table: Anatomical Boundaries and Contents of the Inguinal Canal
| Inguinal Canal | Anatomy |
|---|---|
| Position | Between deep and superficial inguinal rings, just above and parallel to lower half of inguinal ligament |
| Anterior wall | Formed by external oblique aponeurosis (reinforced by internal oblique muscle laterally) |
| Posterior wall | Formed by transversalis fascia (reinforced by conjoint tendon medially) |
| Roof | Formed by transversus abdominis and internal oblique muscles |
| Floor | Formed by medial one-half of inguinal ligament (reinforced by lacunar ligament medially) |
| Deep inguinal ring | Opening in transversalis fascia, located just superior to mid-inguinal point (midway between ASIS and pubic symphysis) |
| Superficial inguinal ring | Opening in external oblique aponeurosis, located just superior to pubic tubercle |
| Contents | Genital branch of genitofemoral nerve, spermatic cord, round ligament, ilioinguinal nerve |
![Modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons](https://mrcemsuccess.com/wp-content/uploads/2017/02/Inguinal-canal-2.png)
Inguinal Canal. (Image modified by FRCEM Success. Original by Henry Vandyke Carter [Public domain], via Wikimedia Commons)
Roof, walls and floor
The anterior wall of the inguinal canal is formed along its entire length by the aponeurosis of the external oblique muscle, and reinforced by the internal oblique muscle laterally.
The posterior wall of the inguinal canal is formed along its entire length by the transversalis fascia and reinforced by the conjoint tendon medially.
The roof of the inguinal canal is formed by arching fibres of the transversus abdominis and internal oblique muscles.
The floor of the inguinal canal is formed by the medial one-half of the inguinal ligament, reinforced medially by the lacunar ligament.
Deep inguinal ring
The deep inguinal ring, the opening in the transversalis fascia, is the beginning of the inguinal canal.
The surface marking of the deep inguinal ring is commonly described as being located at either:
- the midpoint of the inguinal ligament (midway between the anterior superior iliac spine and the pubic tubercle)
- the mid‐inguinal point (midway between the anterior superior iliac spine and the pubic symphysis)
It lies just above the inguinal ligament and immediately lateral to the inferior epigastric vessels; the femoral artery can be palpated in the same position but below the inguinal ligament.
Superficial inguinal ring
The superficial inguinal ring is the end of the inguinal canal.
The superficial inguinal ring is located just superior to the pubic tubercle. It is a triangular opening in the aponeurosis of the external oblique, with its apex pointing superolaterally and its base formed by the pubic crest.
Contents
The inguinal canal contains:
- the genital branch of the genitofemoral nerve (within the spermatic cord in men)
- the spermatic cord in men
- the round ligament in women
- the ilioinguinal nerve (passes through part of the canal, exiting the superficial inguinal ring with the other contents)
Report A Problem
Is there something wrong with this question? Let us know and we’ll fix it as soon as possible.
Loading Form...
- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
