Composed of 3 cylindrical shafts

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  2 corpora cavernosa : Main erectile bodies

  
  
  
  
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    On dorsal surface of penis

    
    
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    Diverge at root of penis ( crura ) and are invested by ischiocavernosus muscles

    
    
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    Chambers traversed by numerous trabeculae, creating sinusoidal spaces

    
    
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    Multiple fenestrations between corpora, creating multiple anastomotic channels

  
  
  
  
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  1 corpus spongiosum : Contains urethra

  
  
  
  
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    On ventral surface, in groove created by corpora cavernosa

    
    
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    Becomes penile bulb at root and is invested by bulbospongiosus muscle

    
    
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    Forms glans penis distally

    
    
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    Also erectile tissue but of far less importance

  
  

Tunica albuginea forms capsule around each corpora

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  Thinner around spongiosum than cavernosa

All 3 corpora surrounded by deep fascia ( Buck fascia ) and superficial fascia ( Colles fascia )

Main arterial supply from internal pudendal artery

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  Cavernosal artery runs within center of each corpus cavernosum

  
  
  
  
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    Gives off helicine arteries , which fill trabecular spaces

    
    
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    Primary source of blood for erectile tissue

  
  
  
  
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  Paired dorsal penile arteries run between tunica albuginea of corpora cavernosa and Buck fascia

  
  
  
  
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    Supplies glans penis and skin

  
  

Venous drainage of corpora cavernosa

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  Emissary veins in corpora pierce through tunica albuginea → circumflex veins → deep dorsal vein of penis → retropubic venous plexus

  
  
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  Superficial dorsal vein drains skin and glans penis

Neurologically mediated response eliciting smooth muscle relaxation of cavernosal arteries, helicine arteries, and cavernosal sinusoids

Blood flows from helicine arteries into sinusoidal spaces

Sinusoids distend, eventually compressing emissary veins against rigid tunica albuginea

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  Venous compression prevents egress of blood from corpora, which maintains erection

Prostatic urethra: Traverses prostate

Membranous urethra: Short course through urogenital diaphragm (level of external urethral sphincter)

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  Contains bulbourethral glands (Cowper glands)

Bulbous urethra: Below urogenital diaphragm to suspensory ligament of penis at penoscrotal junction

Penile urethra: Pendulous portion, distal to suspensory ligament

Transducer: High-frequency (7.5- to 10.0-MHz) linear transducer

Patient is supine with penis positioned on anterior abdominal wall

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  Use towels for padding, forming “nest” to keep penis in appropriate position

Transducer placed on ventral side of penis

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  Corpus spongiosum easily compressed, so use ample gel and gentle pressure

For erectile dysfunction studies, vasodilating agent is injected into dorsal 2/3 of shaft

Urethra may also be examined by ultrasound

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  Imaging of anterior urethra is optimal with distension

  
  
  
  
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    Gel may be injected retrograde or patient may be asked to void during scan

  
  
  
  
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  Posterior urethra is best imaged by transrectal ultrasound of prostate

Complex and often multifactorial, including vascular, neurogenic, and psychologic factors

Arteriogenic impotence affects inflow

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  Usually internal pudendal and penile arteries

  
  
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  Blockage may be as high as distal aorta (Leriche syndrome)

  
  
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  Cavernosal artery evaluation

  
  
  
  
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    In flaccid state, there is little diastolic flow

    
    
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    At onset of erection, there is dilatation with increase in both systolic and diastolic flow

    
    
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    At maximum erection, venous drainage is blocked

    
    
    
    
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      Waveform changes to high resistance with reversal of diastolic flow

      
      
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      Peak systolic velocity > 30 cm/s

      
      
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      Cavernosal artery diameter increase > 75%

    
    

  
  

Venogenic impotence affects outflow

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  Ineffective venoocclusion with continuous outflow of blood from sinusoids

  
  
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  At peak erection end, diastolic flow is reversed or absent

  
  
  
  
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    End diastolic velocity > 5 cm/s indicative of venous insufficiency

  
  

Penile fractures occur by forceful bending of erect penis, typically during intercourse

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  Results in rupture of corpus cavernosum with tearing of tunica albuginea

  
  
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  Patients often report “snap” followed by immediate pain

  
  
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  Expanding hematoma; if Buck fascia also disrupted, may extend to perineum and scrotum

Need to carefully evaluate tunica albuginea for any areas of disruption

Document location and extent of hematoma

Localized, benign, connective tissue disorder with fibrotic plaque formation on tunica albuginea

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  Causes painful erections with shortening and curvature of penis

Scan tunica albuginea carefully looking for areas of hyperechoic thickening ± calcifications