| Inguinal canal | |
|---|---|
 Front of abdomen, showing surface markings for arteries and inguinal canal. (Inguinal canal is tube at lower left.) | |
 Thescrotum. On the left side (image right side), the cavity of thetunica vaginalis has been opened; on the right side (image left side), only the layers superficial to thecremaster have been removed. (Right inguinal canal visible at upper left.) | |
| Details | |
| Identifiers | |
| Latin | canalis inguinalis |
| MeSH | D007264 |
| TA98 | A04.5.01.026 |
| TA2 | 2381 |
| FMA | 19928 |
| Anatomical terminology | |
Theinguinal canal is a passage in theanteriorabdominal wall on each side of the body (one on each side of themidline), which in males, convey thespermatic cords and in females, theround ligament of the uterus. The inguinal canals are larger and more prominent in males.
The inguinal canals are situated just above the medial half of theinguinal ligament. The canals are approximately 4 to 6 cm long,[1] angled anteroinferiorly and medially. In males, its diameter is normally 2 cm (±1 cm in standard deviation) at the deep inguinal ring.[2][notes 1]
A first-order approximation is to visualize each canal as a cylinder.[3]
To help define the boundaries, these canals are often further approximated as boxes with six sides. Not including the two rings, the remaining four sides are usually called the "anterior wall", "inferior wall ("floor")", "superior wall ("roof")", and "posterior wall".[4] These consist of the following:
| superior wall (roof): Medial crus of aponeurosis of external oblique Musculoaponeurotic arches of internal oblique and transverse abdominal Transversalis fascia conjoint tendon | ||
| anterior wall: aponeurosis ofexternal oblique fleshy part of internal oblique (lateral third of canal only)[5] superficial inguinal ring (medial third of canal only)[6] | (inguinal canal) | posterior wall: transversalis fascia conjoint tendon (Inguinal falx, reflected part of inguinal ligament, medial third of canal only)[6] deep inguinal ring (lateral third of canal only)[6] |
| inferior wall (floor): inguinal ligament lacunar ligament (medial third of canal only)[6] iliopubic tract (lateral third of canal only)[5] |
Thedeep inguinal ring (internal or deep abdominal ring,abdominal inguinal ring,internal inguinal ring,annulus abdominalis) is the entrance to the inguinal canal.
The surface marking of the deep inguinal ring is classically described as half an inch above the midpoint of the inguinal ligament.[7]
However, the surface anatomy of the point is disputed. In a recent study,[8] it was found to be in a region between the mid-inguinal point (situated midway between theanterior superior iliac spine and thepubic symphysis) and the midpoint of theinguinal ligament (i.e. midway between theanterior superior iliac spine and thepubic tubercle). Traditionally, either one of these two sites was claimed as its location. However, this claim is based upon the study's dissection of 52 cadavers, and may not reflect the livein vivo anatomy.
Some sources state that it is at the layer of thetransversalis fascia.[9]
The deep inguinal ring is an opening in thetransversalis fascia.[10] It is of an oval form, the long axis of the oval being vertical; it varies in size in different subjects, and is much larger in the male than in the female. It is bounded, above and laterally, by the arched lower margin of the transversalis fascia; below and medially, by theinferior epigastric vessels. It transmits thespermatic cord in the male and theround ligament of the uterus in the female.
From its circumference, a thin funnel-shaped membrane, theinfundibuliform fascia, is continued around the cord and testis, enclosing them in a distinct covering.
Thesuperficial inguinal ring (subcutaneous inguinal ring orexternal inguinal ring) is an anatomical structure in the anterior wall of the mammalianabdomen. It is a triangular opening that forms the exit of the inguinal canal, which houses theilioinguinal nerve, the genital branch of thegenitofemoral nerve, and thespermatic cord (in men) or theround ligament (in women). At the other end of the canal, thedeep inguinal ring forms the entrance.[11]
It is found within theaponeurosis of the external oblique, immediately above thepubic crest, 1 centimeter above and superolateral to thepubic tubercle. It has the following boundaries—medial crura by pubic crest, lateral crura by pubic tubercle and inferiorly by inguinal ligament.[9]
The structures which pass through the canals differ between males and females:
The classic description of the contents of the spermatic cords in the male are:
3 arteries: artery to vas deferens (or ductus deferens),testicular artery,cremasteric artery;
3 fascial layers:external spermatic,cremasteric, andinternal spermatic fascia;
3 other structures:pampiniform plexus,vas deferens (ductus deferens), testicular lymphatics;
3 nerves: genital branch of thegenitofemoral nerve (L1/2), sympathetic and visceral afferent fibres,ilioinguinal nerve (N.B. outside spermatic cord but travels next to it)
Note that theilioinguinal nerve passes through thesuperficial ring to descend into thescrotum, but does not formally run through the canal.
During development, eachtesticle descends from the starting point on theposterior abdominal wall (para-aortically) from thelabioscrotal swellings near the kidneys, down theabdomen, and through the inguinal canals to reach thescrotum. This way, each testicle descends through the abdominal wall into the scrotumbehind[clarification needed] theprocessus vaginalis (which later obliterates).
Abdominal contents (potentially including intestine) can be abnormally displaced from the abdominal cavity. Where these contents exit through the inguinal canal, having passed through thedeep inguinal ring, the condition is known as anindirect or oblique inguinal hernia. This can also cause infertility. This condition is far more common in males than in females, owing to the inguinal canal's small size in females.
A hernia that exits the abdominal cavity directly through the deep layers of the abdominal wall, thereby bypassing the inguinal canal, is known as adirect inguinal hernia.
In males with strong presentation of thecremasteric reflex, the testes can—duringsupine sexual activity or manual manipulation—partially or fully retract into the inguinal canal for a short period of time. In juveniles and adults with inguinal injury, retraction can be prolonged and potentially lead to overheating-related infertility.[13]
The superficial ring ispalpable[14] under normal conditions. It becomes dilated in a condition calledathletic pubalgia. Abdominal contents may protrude through the ring ininguinal hernia.
Thus lymphatic spread from a testicular tumour is to the para-aortic nodes first, and not the inguinal nodes.
The inguinal canals can be penetrated for sexual stimulation. This practice is calledmuffing.
| International | |
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| Other | |
