Round Ligament

The round ligament of the uterus, also called the ligamentum teres uteri, is a paired fibromuscular cord extending from the uterus toward the anterior abdominal wall and ultimately into the labium majus. Each round ligament begins near the uterine horn, travels laterally within the broad ligament, enters the deep inguinal ring, passes through the inguinal canal, and emerges through the superficial inguinal ring.

The round ligament is an important anatomical connection between the uterus and the anterior abdominal wall. It contributes to maintaining the normal position of the uterus, particularly its anteverted orientation, although it is not the principal mechanical support of the uterus.

Embryologically, the round ligament is derived from the gubernaculum. The ovarian ligament and round ligament of the uterus represent two adult portions of the embryonic gubernaculum separated by their attachment to the developing uterus.

Location

The round ligament extends from the lateral aspect of the uterus to the labium majus. Its course passes through the pelvis, anterior abdominal wall, and inguinal canal.

There is one round ligament on each side of the uterus. The two ligaments extend anterolaterally from the uterine horns toward the corresponding deep inguinal rings.

Structure

The round ligament is a fibromuscular structure containing connective tissue and smooth muscle fibers. These smooth muscle fibers are continuous with the muscular tissue of the uterus.

The ligament also contains small blood vessels, lymphatic vessels, and nerves. Its composition differs substantially from the double-layered peritoneal structure of the broad ligament.

Uterine Attachment

The round ligament begins at the uterine horn, close to the junction between the uterus and uterine tube.

Its attachment is positioned anterior and inferior to the uterine tube. The ovarian ligament attaches nearby but extends posteriorly toward the ovary rather than anteriorly toward the inguinal canal.

Course

From its uterine attachment, the round ligament travels anterolaterally through the pelvis. Its course can be divided into several anatomical portions:

• Uterine origin
• Pelvic portion within the broad ligament
• Passage through the deep inguinal ring
• Course through the inguinal canal
• Exit through the superficial inguinal ring
• Termination within tissues of the labium majus

Pelvic Course

Within the pelvis, the round ligament travels laterally and anteriorly from the uterine horn toward the deep inguinal ring.

During this portion of its course, it lies between the layers of the broad ligament of the uterus. It is generally positioned anterior and inferior to the uterine tube.

Relationship to the Broad Ligament

The round ligament passes between the layers of the broad ligament as it travels from the uterus toward the lateral pelvic wall.

The broad ligament itself is a peritoneal fold rather than a dense supporting ligament. The round ligament is a distinct fibromuscular structure enclosed within or associated with its layers during the pelvic portion of its course.

Deep Inguinal Ring

The round ligament reaches the deep inguinal ring, an opening in the transversalis fascia located lateral to the inferior epigastric vessels.

It enters the inguinal canal through this opening and continues anteriorly through the abdominal wall.

Inguinal Canal

The inguinal canal is an oblique passage through the lower anterior abdominal wall. In females, the round ligament of the uterus is one of its principal contents.

The ligament travels from the deep inguinal ring toward the superficial inguinal ring, accompanied by small vessels, lymphatics, and nerves associated with the canal.

Superficial Inguinal Ring

The round ligament exits the inguinal canal through the superficial inguinal ring, an opening in the aponeurosis of the external oblique muscle.

After leaving the canal, the ligament continues into the connective tissue of the external genital region.

Termination

The round ligament ultimately terminates by blending with connective tissue within the labium majus and adjacent tissues.

Its entire course therefore extends from the uterus through the pelvis and anterior abdominal wall to the external genitalia.

Anatomical Course

Region	Relationship
Uterus	Begins near the uterine horn
Broad ligament	Passes between its layers
Deep inguinal ring	Enters the inguinal canal
Inguinal canal	Traverses the lower anterior abdominal wall
Superficial inguinal ring	Leaves the inguinal canal
Labium majus	Terminates within connective tissues

Relationship to the Uterine Tube

At the uterine horn, the round ligament lies anterior and inferior to the uterine tube. The uterine tube extends laterally within the superior margin of the broad ligament toward the ovary.

This relationship is useful for identifying structures around the uterine horn during pelvic surgery.

Relationship to the Ovarian Ligament

The round ligament and ovarian ligament attach near one another at the uterine horn but extend in opposite directions.

The ovarian ligament extends posterolaterally from the uterus to the medial pole of the ovary, while the round ligament extends anterolaterally toward the deep inguinal ring.

Relationship to the Ovary

The round ligament does not attach directly to the adult ovary. Instead, its developmental relationship to the ovary is explained by their common connection with the embryonic gubernaculum.

The portion of the gubernaculum between the ovary and uterus becomes the ovarian ligament, while the portion extending from the uterus toward the inguinal region becomes the round ligament.

Relationship to the Inferior Epigastric Vessels

The deep inguinal ring lies lateral to the inferior epigastric vessels. Because the round ligament enters the inguinal canal through the deep ring, it passes into the canal lateral to these vessels.

This relationship is important when identifying the deep ring and distinguishing indirect from direct inguinal hernias.

Function

The round ligament contributes to maintaining the normal orientation of the uterus within the pelvis. In particular, its anterior course helps resist excessive posterior displacement of the uterine fundus.

It is commonly described as helping maintain the uterus in an anteverted position.

Anteversion of the Uterus

Anteversion describes the forward inclination of the uterus relative to the vagina. In the usual anatomical position, the long axis of the cervix forms an anteriorly directed angle with the long axis of the vagina.

The round ligaments contribute to this orientation by exerting an anteriorly directed influence on the uterine horns and fundus.

Anteflexion

Anteflexion refers to the forward bending of the body of the uterus relative to the cervix. It is distinct from anteversion, which describes the relationship between the cervix and vagina.

The normal uterine position reflects the combined effects of uterine anatomy, pelvic floor support, fascial supports, intra-abdominal pressure, and associated ligaments.

Role in Uterine Support

The round ligament contributes to uterine positioning but is not the principal support of the uterus.

The major mechanical supports include the pelvic floor, endopelvic fascia, cardinal ligaments, and uterosacral ligaments. The round ligament is more important in maintaining uterine orientation than in preventing uterine descent.

Comparison with Major Uterine Supports

Structure	Primary Role
Round ligament	Helps maintain uterine anteversion
Cardinal ligament	Supports cervix and upper vagina laterally
Uterosacral ligaments	Provide posterior support to cervix and uterus
Pelvic floor	Major muscular support for pelvic organs

Blood Supply

The round ligament receives blood from small vessels accompanying it along its course. These include branches associated with the uterine arterial circulation and the artery of the round ligament, sometimes called the artery of Sampson.

The vascular pattern can vary between individuals.

Artery of the Round Ligament

The artery of the round ligament accompanies the ligament through part of its course and contributes to vascular connections between pelvic and external genital regions.

It is generally a relatively small vessel but may become clinically important during surgery or in pathological conditions involving the round ligament.

Venous Drainage

Small veins accompany the round ligament and communicate with venous networks associated with the uterus, inguinal region, and external genitalia.

These venous pathways may become enlarged during pregnancy because of increased pelvic blood flow and venous pressure.

Lymphatics

Lymphatic vessels from the uterus can accompany the round ligament through the inguinal canal toward the superficial inguinal lymph nodes.

This pathway is clinically important because it provides one route by which lymph from the uterine fundus can reach superficial inguinal nodes.

Lymphatic Drainage of the Uterine Fundus

The uterine fundus has multiple lymphatic drainage pathways. Some lymphatics follow the ovarian vessels toward lumbar lymph nodes, while others travel along the round ligament toward superficial inguinal nodes.

This anatomical arrangement is relevant to patterns of lymphatic spread from uterine disease.

Nerve Supply

Small autonomic and sensory nerve fibers accompany the round ligament and its vessels. The exact distribution is variable and reflects the ligament's continuity with uterine smooth muscle and connective tissues of the inguinal region.

Stretching or tension involving the ligament can produce pain, particularly during pregnancy.

Embryological Origin

The round ligament develops from the gubernaculum, an embryonic fibromuscular structure involved in positioning the developing gonad.

In females, development of the uterus interrupts the gubernaculum, creating two adult ligamentous structures.

Gubernaculum

The embryonic gubernaculum initially extends from the developing gonad toward the future inguinal region.

As the paramesonephric ducts fuse and the uterus develops, the gubernaculum becomes attached to the lateral uterus. This attachment limits further descent of the ovary and divides the gubernaculum into superior and inferior portions.

Ovarian Ligament Development

The portion of the gubernaculum extending between the ovary and uterus becomes the ovarian ligament.

This ligament connects the medial pole of the adult ovary to the uterus near the uterine horn.

Round Ligament Development

The portion of the gubernaculum extending from the uterus toward the inguinal canal becomes the round ligament of the uterus.

It retains the developmental pathway toward the inguinal region and ultimately terminates in tissues of the labium majus.

Relationship to Testicular Gubernaculum

The female round ligament and ovarian ligament are homologous to structures derived from the gubernaculum involved in testicular descent in males.

Differences in gonadal position and reproductive tract development result in different adult anatomical relationships between the sexes.

Processus Vaginalis

During development, an evagination of peritoneum may extend through the inguinal canal alongside the gubernacular pathway. In females, this extension is called the canal of Nuck.

Normally, this peritoneal communication becomes obliterated.

Canal of Nuck

The canal of Nuck is the female developmental counterpart of the processus vaginalis. Persistence of this peritoneal extension can create a potential communication between the peritoneal cavity and inguinal canal.

Failure of obliteration can predispose to indirect inguinal hernia or accumulation of fluid around the round ligament.

Hydrocele of the Canal of Nuck

If a portion of the canal of Nuck remains patent or becomes isolated while retaining fluid, a hydrocele of the canal of Nuck can develop.

It may present as an inguinal or labial swelling and can resemble an inguinal hernia clinically.

Round Ligament Pain in Pregnancy

Round ligament pain is a common pregnancy-associated symptom. As the uterus enlarges, the round ligaments lengthen and experience increased tension.

Pain is commonly described in the lower abdomen or groin and may be triggered by sudden movements, coughing, standing, or changes in position.

Changes During Pregnancy

During pregnancy, the round ligaments undergo substantial elongation and hypertrophy as the uterus enlarges and rises from the pelvis into the abdominal cavity.

Increased blood flow and enlargement of vessels accompanying the ligament can also alter its appearance and clinical behavior.

Round Ligament Varicosities

Round ligament varicosities are dilated veins associated with the round ligament, most commonly occurring during pregnancy.

Because these vessels extend through the inguinal canal, varicosities can produce an inguinal mass that clinically resembles an inguinal hernia.

Indirect Inguinal Hernia

An indirect inguinal hernia enters the inguinal canal through the deep inguinal ring lateral to the inferior epigastric vessels.

In females, a persistent canal of Nuck can provide a pathway through which abdominal or pelvic contents protrude alongside the round ligament.

Round Ligament Endometriosis

Endometriosis can involve the round ligament. Inguinal round ligament endometriosis may present as a painful inguinal mass, sometimes with symptoms varying during the menstrual cycle.

The extrapelvic portion of the round ligament is particularly relevant when evaluating inguinal endometriotic lesions.

Round Ligament Leiomyoma

Smooth muscle within the round ligament can rarely give rise to a leiomyoma. Such tumors may occur within the pelvis or inguinal canal and can resemble other inguinal or pelvic masses.

Their location reflects the fibromuscular composition and extensive course of the ligament.

Round Ligament Cysts

Cystic lesions can develop along the course of the round ligament, particularly within the inguinal canal. Their origins may include developmental remnants and mesothelial or other tissue components.

These lesions can present as groin masses and may require differentiation from hernias, lymph nodes, and vascular abnormalities.

Round Ligament in Pelvic Surgery

The round ligament is an important landmark during gynecological surgery. It is readily identifiable near the uterine horn and may be divided during procedures requiring entry into or mobilization of the broad ligament.

Its location helps orient the surgeon to the anterior and posterior leaves of the broad ligament and nearby reproductive structures.

Round Ligament in Hysterectomy

During many forms of hysterectomy, the round ligament is divided as part of surgical mobilization of the uterus.

Identification of the ligament assists in opening the broad ligament and developing appropriate surgical planes.

Round Ligament in Laparoscopic Anatomy

During laparoscopy, the round ligament can be seen extending from the uterine horn toward the internal aspect of the anterior abdominal wall.

Its course provides a useful orientation landmark when identifying the uterine tube, ovarian ligament, broad ligament, and pelvic sidewall.

Round Ligament versus Ovarian Ligament

Feature	Round Ligament	Ovarian Ligament
Uterine attachment	Near uterine horn	Near uterine horn
Direction	Anterior and lateral	Posterior and lateral
Termination	Labium majus	Medial pole of ovary
Inguinal canal	Passes through it	Does not enter it
Embryological origin	Gubernaculum	Gubernaculum

Round Ligament versus Broad Ligament

Feature	Round Ligament	Broad Ligament
Structure	Fibromuscular cord	Double layer of peritoneum
Origin	Uterine horn	Peritoneal reflection from uterus
Course	Through broad ligament and inguinal canal	Extends from uterus toward pelvic wall
Termination	Labium majus	Continuous with pelvic peritoneum
Primary significance	Helps maintain uterine orientation	Organizes relationships of reproductive structures

Round Ligament versus Cardinal Ligament

Feature	Round Ligament	Cardinal Ligament
Primary role	Maintains uterine orientation	Major support of cervix and upper vagina
Attachment	Uterine horn toward labium majus	Cervix and upper vagina toward lateral pelvic wall
Composition	Fibromuscular tissue	Condensed connective tissue and fascia
Relationship to inguinal canal	Passes through it	No inguinal course

Round Ligament versus Uterosacral Ligament

Feature	Round Ligament	Uterosacral Ligament
Direction	Anterior and lateral	Posterior toward sacrum
Main role	Helps maintain anteversion	Supports cervix and upper vagina posteriorly
Inguinal canal	Traverses it	Does not traverse it

Key Anatomical Relationships

• The round ligament is a paired fibromuscular cord.
• It originates near the uterine horn.
• It lies anterior and inferior to the uterine tube near its uterine attachment.
• It travels between the layers of the broad ligament.
• It enters the deep inguinal ring lateral to the inferior epigastric vessels.
• It traverses the inguinal canal.
• It exits through the superficial inguinal ring.
• It terminates within tissues of the labium majus.
• It is derived embryologically from the gubernaculum.
• It shares its embryological origin with the ovarian ligament.
• It helps maintain the uterus in an anteverted position.
• Some lymphatics from the uterine fundus travel along it toward superficial inguinal lymph nodes.

Clinical Importance

The round ligament is clinically important because its course connects the uterus with the inguinal region. Disorders affecting the ligament can therefore present as pelvic, lower abdominal, groin, or labial abnormalities.

During pregnancy, stretching of the round ligament can produce characteristic lower abdominal or groin discomfort. Dilated veins accompanying the ligament can form round ligament varicosities that resemble an inguinal hernia.

Developmental persistence of the canal of Nuck can predispose to indirect inguinal hernia or hydrocele in females. Endometriosis, cysts, and rare tumors can also occur along the ligament's course.

The round ligament is additionally an important surgical landmark. Its relationship to the uterine horn, broad ligament, uterine tube, ovarian ligament, and anterior pelvic wall helps orient surgeons during hysterectomy and other pelvic procedures.

Functional Importance

The round ligament contributes to maintaining the normal anatomical orientation of the uterus by exerting an anteriorly directed influence on the uterine horns. This assists in maintaining uterine anteversion but does not constitute the uterus's principal mechanical support.

Its anatomy also demonstrates an important developmental relationship between the internal reproductive organs and the inguinal region. Because it derives from the gubernaculum and passes through the inguinal canal, the ligament provides a direct anatomical connection between uterine development, ovarian position, and female inguinal anatomy.

Understanding the round ligament provides a foundation for studying uterine support, uterine position, the broad ligament, ovarian ligament, inguinal canal, female pelvic anatomy, gubernacular development, canal of Nuck, pregnancy-related pelvic pain, inguinal masses, and gynecological surgical anatomy.