Show Me The Unseeable:
Internal Structures of the Penis
How do we create an accurate illustration of a subject without directly being able to observe it?
The main goal of this project was to illustrate a structurally accurate anatomical subject with a cutaway to reveal an aspect of its internal structure. The subject must look alive with real world lighting cues that suggests its form, volume, and texture.
I chose a subject that would be helpful to my peers and myself to use when studying anatomy – something that could not be found in the textbooks we currently use. The anatomy of the penis, especially the spatial relationship of its internal contents, was difficult to understand for many students. I noticed that many anatomy atlases and textbooks only contained images of the penis with a coronal or sagittal cross-section and so I wanted to create an illustration that combined the two viewpoints.
This project was completed as part of BMC's Visual Representation of Medical Knowledge.
Client: Prof. Michael Corrin
Content Advisor: Dr. Anne Agur
Media: ZBrush, Cinema 4D, Adobe Photoshop and Illustrator
Format: Print, figure in an anatomy textbook
Audience: Medical students
Date: December 2019
Rough sketches completed during the research stage.
Originally I also wanted to show the relationship of the bulb and crus of the penis with its overlaying muscles (ischiocavernosus and bulbospongiosus) to the rest of the penis. Ultimately, this idea was shelved as it was too complicated to fit into one illustration and I decided to focus on communicating only the internal layers of the penis.
Various textbook illustrations and photos were used as reference. I spoke to my content advisor, Dr. Anne Agur, about using cadaveric specimens as reference however she advised against using cross-sections as it would be too difficult to distinguish tissues from each other. I did review cadaveric specimens for overall form of the penis.
From the website Anatomography, I used human body polygon data that was extracted from MRI images as the basis for my maquette (data version: 2016107i4; Object set: 20161017). OBJs used were the corpus cavernosum, corpus spongiosum, deep artery, dorsal vessels, glans of penis, and urethra.
These OBJs were brought into ZBrush and the “Nickz_HumanMaleAverage” tool preset was altered to “fit” the penis skin (using the move tool) over the OBJs from Anatomography. Then, I created cross-sections through the various layers of the penis using the Boolean operation. Lighting and rendering of the maquette was completed in Cinema 4D.
Modelling in ZBrush
Lighting and rendering in Cinema 4D
The final sketch was created in Adobe Photoshop based off of the maquette. With this final sketch, I received confirmation from my content expert, Dr. Anne Agur, about the anatomical accuracy of the illustration. Some minor fixes I made were making sure that the veins looked more collapsed compared to the stiffer arteries and that there would be limited fat.
I brought the final sketch into Adobe Illustrator to create all the main shapes before putting it into Adobe Photoshop for the tonal rendering.
Tonal rendering was completed in Adobe Photoshop.
I worked in low-key lighting for the tonal rendering stage as I found it helped me to paint in more detail. I adjusted the levels after I was done to create a high-key lit painting for the colouring stage.
Colour rendering was completed in Adobe Photoshop.
After receiving feedback from my peers and teachers, a few revisions were made. Some of these revisions included fixing the shape of the scrotum (shortening it and adding more wrinkles) and filling in the space near the glans of the penis where it is cross-sectioned.
1. Acland’s Video Atlas of Human Anatomy. “Penis: distal part.” Aclandanatomy.com. https://aclandanatomy.com/MultimediaPlayer.aspx?multimediaid=10528669 (accessed December 5, 2019). 2. Agur, A., and Arthur F. Dalley. 2017. Grant’s Atlas of Anatomy, 14th ed. Philadelphia: Lippincott Williams & Wilkins. Fig. 5.56: Cross Sections of Penis. 3. BodyParts3D/Anatamography “Penis.” lifesciencedb.jp. https://lifesciencedb.jp/bp3d/ (accessed November 15, 2019). 4. Grant, J.C. Boileau. 1962. Grant’s Atlas of Anatomy, 5th ed. Baltimore: Lippincott Williams & Wilkins. Fig. 198-201: Penis. 5. Sobotta, J. 1988. Sobotta Atlas of Human Anatomy, 11th ed. Baltimore-Munich: Urban & Schwarzenberg. Fig. 337-344: Male Reproductive Organs. 6. Van De-Graaff, K., David A. Morton, and John L. Crawley. 2007. A Photographic Atlas for the Anatomy & Physiology Laboratory, 6th ed. Colorado: Morton Publishing Company. Fig. 17.17: Penis. 7. Washington State University. “Lab 12: Urogenital ; Proximal Penis.” wsu.edu. https://undergraduate.vetmed.wsu.edu/courses/vph-308/gross/lab-12-gross-urogenital/male-reproductive/penis-cross-sections (accessed December 5, 2019). 8. Yokochi, C., Johannes W. Rohen, and Eva L. Weinreb. 1989. Photographic Anatomy of the Human Body, 3rd ed. New York: Igaku-Shoin. Fig. 7.9-7.14: Male Reproductive Organs