From the Guidelines
The interior circle triangle, also known as the circle of Willis, is formed by three anatomic structures: the internal carotid arteries anteriorly, the posterior cerebral arteries posteriorly, and the posterior communicating arteries laterally, which connect the internal carotid arteries with the posterior cerebral arteries. The circle of Willis is a critical structure for cerebral blood supply, and its configuration is highly variable, with a complete circle present in fewer than 50% of individuals 1. The internal carotid arteries, which arise from the common carotid arteries, give rise to the anterior cerebral arteries, which connect with the circle of Willis through the anterior communicating artery. The posterior cerebral arteries, which arise from the vertebrobasilar circulation, connect with the internal carotid arteries through the posterior communicating arteries. Some key points about the anatomy of the circle of Willis include:
- The internal carotid arteries typically bifurcate into the anterior cerebral and middle cerebral arteries
- The anterior cerebral arteries connect with the circle of Willis through the anterior communicating artery
- The posterior communicating arteries connect the internal carotid arteries with the posterior cerebral arteries
- The configuration of the circle of Willis is highly variable, with a complete circle present in fewer than 50% of individuals 1. Understanding the anatomy of the circle of Willis is essential for diagnosing and treating cerebrovascular diseases, such as stroke and aneurysms.
From the Research
Anatomic Structures of the Interior Circle Triangle
The interior circle triangle, also known as the urogenital triangle, is a region in the perineum. The three sides of this triangle are made up of the following anatomic structures:
- The pubic symphysis, which forms the base of the triangle 2
- The ischial tuberosities, which form the lateral sides of the triangle
- The perineal body, which forms the apex of the triangle
Related Conditions
Pelvic organ prolapse, which is the descent of one or more of the anterior vaginal wall, posterior vaginal wall, the uterus (cervix), or the apex of the vagina (vaginal vault or cuff scar after hysterectomy), can affect the anatomic structures of the interior circle triangle 3. Pelvic fractures can also disrupt the pelvic floor and cause stress urinary incontinence (SUI) or pelvic organ prolapse (POP) 4.
Surgical Treatment
Surgical treatment options for pelvic organ prolapse include reconstructive pelvic surgery with or without mesh augmentation and obliterative surgery 3. The use of devices such as the Capio slim suture capturing device can also be effective in treating vaginal vault prolapse 5.
Determinants of Pelvic Organ Prolapse
Determinants of pelvic organ prolapse include low income, vaginal tear, menopausal status, body mass index (both underweight and overweight), and chronic constipation 6.