Anatomy, Abdomen and Pelvis, Penis Dorsal Nerve


Article Author:
David Weech


Article Editor:
John Ashurst


Editors In Chief:
Yvonne Carter
Jason Wallen


Managing Editors:
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Frank Smeeks
Kristina Soman-Faulkner
Benjamin Eovaldi
Radia Jamil
Sobhan Daneshfar
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Hajira Basit
Phillip Hynes


Updated:
2/6/2019 10:21:58 AM

Introduction

Several branches of the pudendal nerve innervate the penis, including the dorsal nerve of the penis. The pudendal nerve carries axons responsible for sensation and motor responses for defecation, micturition, and procreation.[1] It relays information from the external genitalia as well as the skin around the anus and perineum. It also carries motor axons to various pelvic muscles as well as the external urethral sphincter, the external anal sphincter, and bulbospongiosus muscle.[2] Inside the pudendal canal, the pudendal nerve divides into several branches. It first gives off the inferior rectal nerve followed by the perineal nerve and finally the dorsal nerve of the penis. After branching off of the pudendal nerve, the dorsal nerve of the penis runs along the inferior ischial ramus; then it is joined by the deep dorsal vein at the base of the penis.[1] The dorsal nerve of the penis then courses between the inferior and superior fascial layers of the urogenital diaphragm. As the dorsal nerve of the penis continues, it gives off branches that innervate the corpus cavernosum of the penis. In addition to the efferent fibers of the dorsal nerve of the penis, this nerve includes afferent fibers that innervate the penile skin, including the glans penis. These afferents propagate sensory signals to the central nervous system that are critical to achieve an erection and sexual function.[3]

Structure and Function

The dominant function of the dorsal nerve of the penis is somatosensory, with a direct connection to sexual function and micturition as its afferent transmit signals to the central nervous system.[4] The dorsal nerve of the penis has branching fibers that course laterally and transect the corpus spongiosum to the sinusoidal erectile tissue containing the urethra. The fibers of the dorsal nerve of the penis penetrate the corpus spongiosum to innervate the urethral lumen as afferents. These fibers receive input and relay the information during micturition and ejaculation. Semen is primarily expelled from the bulbous urethra via contraction of the bulbospongiosus muscle.[5] However, this muscle is not innervated by the dorsal nerve of the penis but by a sister branch of the pudendal nerve. Electrophysiological studies have documented that stimulation of the penis's dorsal nerve causes a reflex contraction of the bulbospongiosus muscle. During ejaculation, the penis dorsal nerve fibers provide urethral sensation associated with the passage of seminal fluid necessary to sustain bulbospongiosus contractions until the expulsion of seminal fluid is complete.[6] Neural pathways are arranged in reflex arcs that provide the reflex for ejaculation and bulbospongiosus contraction. The sensory axons of the afferent perineal nerve and the dorsal and ventrolateral branches of the dorsal nerve of the penis merge at the pudendal motor neurons in the conus medullaris portion of the central nervous system. The motor portion of the arc branches from the spinal cord as the perineal nerve to terminate in muscle fibers of the bulbospongiosus muscle for contraction of these muscles leading to ejaculation.[5]

Blood Supply and Lymphatics

A neurovascular bundle runs along the dorsal aspect of the penis in a groove between the corpora cavernosa hemispheres. This includes the dorsal nerve of the penis, dorsal penile vein, and dorsal penile artery. These lay beneath the deep fascia, also known as Buck's fascia.

Nerves

The dorsal nerve of the penis is composed of multiple different collections of axons along the dorsal aspect of the erect penis. They traverse the dorsum of the penis deep to Buck's fascia and superior to the cavernous bodies.[7] The initial cluster consists of fibers parallel to the shaft of the penis that moves distally and ends at the glans of the penis. An additional group of fibers branches from the main body towards the lateral aspects of the penis.[8] These branches vary in position and quantity. However, they always branch laterally away from the main body of the penis. The axons do not cross the dorsal midline. The gauge of the nerve bundles varies greatly, but they consistently narrow as branching continues distally.[4] The dorsal nerve bundles continue straight into the glans penis to form midline branches, and ventrolateral branches arise from the lateral bundles. The distal branches of the terminating nerves travel toward the meatus of the urethra.[9] As the dorsal nerve of the penis enters the glans, it immediately branches and displays a more three-dimensional pattern as opposed to a linear convention seen proximally. Each of the main glandular branches continues along the tunical surface, projecting bundles of smaller nerves that extend into the tissue of the glans and outwards toward the surface of the penis.

Physiologic Variants

The number of dorsal bundles most commonly reported are two and three, but variants of up to 8 have been periodically reported. Most of the dorsal nerves run parallel to each other in the dorsal aspect of the penis traveling distally. Communicating branches are commonly viewed in no specific orientation or frequency. These branches usually communicate amongst each other, but ventral nerve communications are noted in cadaver studies infrequently. Most dissection studies comment on the absence of nerves that cross the dorsal midline.

Clinical Significance

A dorsal penile nerve block is often used for, but not limited to, anesthesia before circumcision, ischemic priapism treatment, the release of paraphimosis, cystoscopy, and the repair of penile lacerations.[10][11] Localizing the dorsal nerve involves injecting 1 to 5 mL of 1% or 2% lidocaine superficially at the 2 and 10 o'clock positions to a depth of approximately 5 mm dorsally. Studies have also proven that a ring block provides better anesthesia for circumcisions as well as other procedures[12]. Care should be taken to avoid lidocaine with epinephrine due to the potential for vascular compromise in this as well as other terminating anatomy.

Many advancements have been made in the transplantation of nerves to restore sexual function and sensation[13]. In a two year trial from 2014 to 2016, nearly two dozen patients underwent sural nerve bridging transplantation in an attempt to restore sensation after a dorsal nerve neurotomy. In follow up, approximately half the patients experienced a marked increase in feeling, a quarter had some improvement, and only one patient had no change. Additionally, stimulation of pudendal afferents such as the dorsal penile nerve has been shown to be effective in studies of neurogenic detrusor overactivity. Previous results in laboratory testing revealed prolonged subdual of the peripheral nervous system urination reflex arc after the stimulation of the penis's dorsal nerve via urethral efferents.[2] In individuals with multiple sclerosis or cord injury, dorsal genital nerve stimulation with an electrode stimulator inhibited detrusor contractions and increased bladder volume that provided urinary continence to those that had previously been without it.[14]


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Anatomy, Abdomen and Pelvis, Penis Dorsal Nerve - Questions

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The dorsal nerve of the penis (DNP) is a branch of which nerve?

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When performing a circumcision which nerve is localized to effectively anesthetize the penis?



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What is the analogous nerve of the dorsal nerve of the penis for females?



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What nerve is responsible for sensory of the urethra?



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Anatomy, Abdomen and Pelvis, Penis Dorsal Nerve - References

References

Si S,Wang H,Pu Y,Cen Y,Xiao H, [Efficacy evaluation of sural nerve bridging transplantation for restoration of penis disturbance of sensation after selective dorsal nerve neurotomy]. Zhongguo xiu fu chong jian wai ke za zhi = Zhongguo xiufu chongjian waike zazhi = Chinese journal of reparative and reconstructive surgery. 2017 Jun 1     [PubMed]
Alyaev YG,Akhvlediani ND, [Comparing efficacy of selective penile denervation and circumcision for primary premature ejaculation]. Urologiia (Moscow, Russia : 1999). 2016 Mar     [PubMed]
Manrique OJ,Adabi K,Maldonado AA,Huang TC,Martinez-Jorge J,Brassard P,Galan R,Ciudad P,Sabbagh MD, Cadaver Study of Combined Neurovascular Sensate Flaps to Create Vaginal Erogenous Sensation During Male-to-Female Genital Confirmation Surgery: The Pedicle     [PubMed]
Qiu Y,Hu AM,Liu J,Du GZ, Dorsal penile nerve block for rigid cystoscopy in men: study protocol for a randomized controlled trial. Trials. 2016 Mar 18     [PubMed]
Alwaal A,Breyer BN,Lue TF, Normal male sexual function: emphasis on orgasm and ejaculation. Fertility and sterility. 2015 Nov     [PubMed]
Rembetski BE,Cobine CA,Drumm BT, Laboratory practical to study the differential innervation pathways of urinary tract smooth muscle. Advances in physiology education. 2018 Jun 1     [PubMed]
Nolan MW,Marolf AJ,Ehrhart EJ,Rao S,Kraft SL,Engel S,Yoshikawa H,Golden AE,Wasserman TH,LaRue SM, Pudendal nerve and internal pudendal artery damage may contribute to radiation-induced erectile dysfunction. International journal of radiation oncology, biology, physics. 2015 Mar 15     [PubMed]
Flores S,Herring AA, Ultrasound-guided dorsal penile nerve block for ED paraphimosis reduction. The American journal of emergency medicine. 2015 Jun     [PubMed]
Jung J,Jo HW,Kwon H,Jeong NY, Clinical neuroanatomy and neurotransmitter-mediated regulation of penile erection. International neurourology journal. 2014 Jun     [PubMed]
Chhabra A,McKenna CA,Wadhwa V,Thawait GK,Carrino JA,Lees GP,Dellon AL, 3T magnetic resonance neurography of pudendal nerve with cadaveric dissection correlation. World journal of radiology. 2016 Jul 28     [PubMed]
Gosling JA,Dixon JS,Jen PY, The distribution of noradrenergic nerves in the human lower urinary tract. A review. European urology. 1999     [PubMed]
Giuliano F, Neurophysiology of erection and ejaculation. The journal of sexual medicine. 2011 Oct     [PubMed]
McGee MJ,Swan BD,Danziger ZC,Amundsen CL,Grill WM, Multiple Reflex Pathways Contribute to Bladder Activation by Intraurethral Stimulation in Persons With Spinal Cord Injury. Urology. 2017 Nov     [PubMed]
Yang BB,Xia JD,Hong ZW,Zhang Z,Han YF,Chen Y,Dai YT, No effect of abstinence time on nerve electrophysiological test in premature ejaculation patients. Asian journal of andrology. 2018 Jul-Aug     [PubMed]

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