The crus of the clitoris, often referred to as the crura, represents the primary internal structure of the clitoris, which is far larger than its visible external portion. These paired structures are essentially the “legs” of the clitoris, extending deep into the pelvis and forming a significant part of the organ’s overall size and shape. While the visible glans is only the tip, the crura account for the majority of the clitoris’s length, which can measure 9 to 11 centimeters in total. The crura are necessary for grasping the full anatomy and function of the clitoris as an integrated system for sexual response and pleasure.
Location and Anchoring Within the Pelvis
The crura diverge backward from the clitoral body, creating an inverted “V” shape that surrounds the urethra and vagina within the pelvic cavity. These extensions are the longest segments of the clitoral structure, running along the sides of the pubic bones. Each crus attaches firmly to the inner surface of the ischiopubic rami, which are parts of the bony framework of the pelvis. This attachment anchors the entire clitoral complex securely within the superficial perineal pouch. This bony connection ensures the organ remains in a fixed position during physical activity and sexual arousal, allowing the internal clitoris to receive indirect stimulation.
The Role of Cavernous Tissue in Engorgement
The crura are composed entirely of corpus cavernosum, a specialized type of erectile tissue homologous to the tissue found in the shaft of the penis. This tissue is a sponge-like network of vascular spaces, or cavernous sinuses, surrounded by trabecular smooth muscle. During sexual arousal, a neurovascular process is initiated to bring about engorgement. The relaxation of the smooth muscle is triggered by the release of neurotransmitters, notably nitric oxide (NO). This relaxation allows a significant increase in arterial blood flow into the vascular spaces, causing the crura to swell and firm up.
The volume of the crura can increase two to three times their resting size during this process. This swelling is a foundational component of clitoral erection and sexual pleasure, as it increases the tension of the internal structure. The crura are also covered by the ischiocavernosus muscles, which contract during arousal and orgasm. This muscle contraction helps compress the veins that drain blood from the clitoris, effectively trapping the blood within the erectile tissue and maintaining the organ’s rigidity.
Integration into the Clitoral System
The crura are fully integrated into the larger, complex bulbo-clitoral organ. They originate posteriorly and merge anteriorly to form the clitoral body, or shaft, which terminates in the highly sensitive glans. This anatomical continuity ensures that stimulation of the external clitoris is physically linked to the engorgement response occurring internally in the crura. The crura lie adjacent to another pair of erectile structures called the bulbs of the vestibule.
While both the crura and the vestibular bulbs contain erectile tissue and swell with blood during arousal, they are anatomically distinct. The bulbs are situated around the vaginal and urethral openings. The swelling of both the crura and the vestibular bulbs causes the surrounding tissue, such as the labia, to increase in size. This combined internal swelling intensifies sensation and creates pressure on the vaginal wall, contributing to the holistic experience of sexual response.