The root of the penis

Penis

The penis is a biological feature of male animals including both vertebrates and invertebrates...

is triradiate in form, consisting of the diverging crura

Crus of penis

For their anterior three-fourths the corpora cavernosa penis lie in intimate apposition with one another, but behind they diverge in the form of two tapering processes, known as the crura, which are firmly connected to the ischial rami....

, one on either side, and the median urethral bulb.

Each crus is covered by the Ischiocavernosus, while the bulb is surrounded by the Bulbospongiosus

Bulbospongiosus muscle

Bulbospongiosus is one of the superficial muscles of the perineum. It has a slightly different origin, insertion and function in males and females. In males, it covers the bulb of the penis...

.

The root of the penis lies in the perineum

Perineum

In human anatomy, the perineum is a region of the body including the perineal body and surrounding structures...

 between the inferior fascia of the urogenital diaphragm

Urogenital diaphragm

Older texts have asserted the existence of an urogenital diaphragm, also called the triangular ligament, which was described as a layer of the pelvis that separates the deep perineal sac from the upper pelvis, lying between the inferior fascia of the urogenital diaphragm and superior fascia of the...

 and the fascia of Colles

Fascia of Colles

The deep layer of superficial fascia is thin, aponeurotic in structure, and of considerable strength, serving to bind down the muscles of the root of the penis.It separates the skin from the superficial perineal pouch.-Relations:...

.

In addition to being attached to the fasciæ and the pubic rami

Inferior pubic ramus

The inferior pubic ramus is a part of the pelvis and is thin and flat. It passes laterally and downward from the medial end of the superior ramus; it becomes narrower as it descends and joins with the inferior ramus of the ischium below the obturator foramen....

, it is bound to the front of the pubic symphysis

Pubic symphysis

The pubic symphysis or symphysis pubis is the midline cartilaginous joint uniting the superior rami of the left and right pubic bones. It is located anterior to the urinary bladder and superior to the external genitalia; for females it is above the vulva and for males it is above the penis...

 by the fundiform and suspensory ligaments.

• The fundiform ligament
  Fundiform ligament
  The fundiform ligament is a specialization, thickening, of the superficial fascia extending from the linea alba of the lower abdominal wall....
  
   springs from the front of the sheath of the Rectus abdominis and the linea alba; it splits into two fasciculi which encircle the root of the penis.

• The upper fibers of the suspensory ligament pass downward from the lower end of the linea alba, and the lower fibers from the pubic symphysis
  Pubic symphysis
  The pubic symphysis or symphysis pubis is the midline cartilaginous joint uniting the superior rami of the left and right pubic bones. It is located anterior to the urinary bladder and superior to the external genitalia; for females it is above the vulva and for males it is above the penis...
  
  ; together they form a strong fibrous band, which extends to the upper surface of the root, where it blends with the fascial sheath of the organ.