Clitoral anatomy was shown most clearly in the axial plane. The sagittal and coronal planes provided further details and they were complementary. Ultimately all components of the clitoris, crura, corpora, bulbs, glans and its neurovascular bundle could be clearly identified on MRI after the combination of the 3 planes was used. Each plane provided a different representation of the structure.
shows a typical axial proton density scan without fat saturation. The clitoris is ventral to the urethra and vagina. Its body projects into the fat of the mons pubis. It is composed of 5 components, namely the paired corpora united in the midline and separated only by a fibrous septum, the bilateral (vestibular) bulbs and the single glans. The glans is a more caudal structure and, therefore, it was seen in more caudal sections (). The corpora diverge and follow the pubic rami on each side, where they are called the crura. The clitoris is distinct from the urethra and vagina. In the target-like appearance of the urethra is particularly distinct with the urethral wall having a darker gray color than the surrounding clitoris. The bulbs flank the urethra and vagina laterally. This axial section lies directly caudal to the symphysis pubis. The fat in this sequence is the whitest structure, followed by the cavernous tissue of the clitoris, the urethral lumen, the vaginal wall, the urethral wall and finally muscle in decreasing order of intensity. Dorsally the clitoris, urethra and vagina are related to the ischiorectal fat and in the midline they are related to the anal canal. The body of the clitoris is an angled structure that projects inferiorly into the mons pubis fat with its most caudal part continuous with the glans clitoris. shows an axial section 1.0 cm caudal to the section. Because of the shape of the clitoris, the glans is typically seen in a more caudal axial section than the rest of the clitoris. In this woman the glans is seen in 2 sections (). In the more caudal sections the urethra and vagina are not distinct and the caudal limit of the bulbs is just visible lateral to the urethra. The glans is the most distinct clitoral structure in these sections. In some women the urethral meatus was also distinct in the most caudal section.
Fig. 1 A, clitoris and its components, including bulbs, crura and corpora, are well demonstrated in axial plane. These structures lie ventral and lateral to urethra and vagina as cluster or complex. MRI specifications for this scan were FSE, TR:4000, TE:15/Ef, (more ...)
The cavernous or erectile tissue was highlighted using a fat saturation technique. In this type of scan the fat appeared black and the cavernous structures of the clitoris were bright white (). The urethral wall and vagina were also highlighted with this technique, although to a lesser extent than cavernous tissue. Other surrounding tissues, muscle and bone appeared as dark structures, increasing the contrast with the centrally placed cavernous structures. In axial section the clitoris formed a triangular complex with the urethra and vagina, namely the clitorourethrovaginal complex.
Fig. 2 Using fat saturation highlighted cavernous tissue of clitoris surrounding urethra and vagina, while other structures appeared gray or black. Triangular clitorourethrovaginal complex was clearly seen using this sequence. MRI specifications were FSEIR, (more ...)
In the structures best seen are the vessels of the neurovascular bundles arising from the pelvic side wall, where the terminal component of the pudendal neurovascular bundle bifurcates into perineal and clitoral divisions to supply the clitorourethrovaginal complex. The perineal division is also best seen in , while the clitoral division, which ascends along the inferior pubic ramus adjacent to the crura, is best seen in . The neurovascular bundle is cranial to the clitoral body. The autonomic cavernous neurovascular supply to the clitoris is not visible on these MRI studies. The large clitoral neurovascular bundles on either side ascend along the ischiopubic ramus to the under surface of the pubic symphysis in the midline, from which they run along the cephalad surface of the clitoral body toward the glans. These bundles, which were easily seen using dissection techniques, were not large enough to be visible consistently on MRI, although fat saturation is known to highlight the vascular structures.
Fig. 3 A, this axial section cephalad to image shown in and reveals divisions of pudendal neurovascular bundle (clitoral and perineal neurovascular bundles) supplying complex. Vascular structures of bundle and cavernous tissue are highlighted (more ...)
Sagittal scans demonstrated the angled clitoral body and glans projecting into the mons on the under surface of the symphysis pubis (). The bulbs and crura were also visible in more lateral sections, although not well displayed. Coronal sections revealed the 2 corpora forming the body and ending as the glans clitoris (). The body was seen attached to the under surface of the symphysis pubis. The labia minora and majora were well seen in this coronal section. The glans is visible extending more dorsal toward the anus because of its tendency to curve dorsal and caudal.
This midline sagittal section highlights almost boomerang-like appearance of clitoral body, crura and glans. MRI specifications were FSE, TR:4000, TE:15/Ef, EC:1/1 16kHz, FOV: 20x20, 4.0thk/1.0sp, 30/04:16, 256x256/2 NEX, FCf/NP.
Fig. 5 Coronal section reveals paired clitoral corpora comprising clitoral body, located caudal to pubic symphysis. Caudal limit of body is glans. Relationship between glans and labia is seen. MRI specifications were FSE, TR:4000, TE:15/Ef, EC:1/1 16kHz, FOV:16x16, (more ...)
Bulbar anatomy is best displayed in axial views and it was seen to a limited extent in sagittal and coronal views in all women. The bulbs met ventral to the urethra. Dissection studies have shown that they are not continuous across the midline.4
They descend on either side of the urethra and flank the lateral aspect of the distal vaginal wall bilaterally.4
The bulbs have a more consistent relationship with the clitoris and urethra than with the vestibule. Thus, in this study the bulbs are named the bulbs of the clitoris according to their consistent relationship to the clitoris.