Plastination

Plastination is a technique or process used in anatomy to preserve bodies or body parts, first developed by Gunther von Hagens in 1977.[1] The water and fat are replaced by certain plastics, yielding specimens that can be touched, do not smell or decay, and even retain most properties of the original sample.[2]

Laminitis plastinate hc biovision
A plastinated and sectioned example of a diseased horse's hoof, mounted for teaching purposes.

Process

PlastinationProcess EN
The centerpiece of plastination: "forced impregnation"

Four steps are used in the standard process of plastination: fixation, dehydration, forced impregnation in a vacuum, and hardening.[3] Water and lipid tissues are replaced by curable polymers, which include silicone, epoxy, and polyester-copolymer.[3]

The first step of plastination, fixation,[4] frequently uses a formaldehyde-based solution, and serves two functions. Dissecting the specimen to show specific anatomical elements can be time consuming. Formaldehyde or other preserving solutions help prevent decomposition of the tissues. They may also confer a degree of rigidity. This can be beneficial in maintaining the shape or arrangement of a specimen. A stomach might be inflated or a leg bent at the knee, for example.

After any necessary dissections have taken place, the specimen is placed in a bath of acetone (freezing point −95° C) at −20° to −30° C. The volume of the bath should be 10 times that of the specimen. The acetone is renewed two times over the course of six weeks. The acetone draws out all the water and replaces it inside the cells.[5]

In the third step, the specimen is then placed in a bath of liquid polymer, such as silicone rubber, polyester, or epoxy resin. By creating a vacuum, the acetone is made to boil at a low temperature. As the acetone vaporizes and leaves the cells, it draws the liquid polymer in behind it, leaving a cell filled with liquid plastic.[5]

The plastic must then be cured with gas, heat, or ultraviolet light, to harden it.[4]

A specimen can vary from a full human body to a small piece of an animal organ, and they are known as 'plastinates'. Once plastinated, the specimens and bodies are further manipulated and positioned prior to curing (hardening) of the polymer chains.

Plastinate-forming
Hardening and posing of plastinates

History

In November 1979, Gunther von Hagens applied for a German patent, proposing the idea of preserving animal and vegetable tissues permanently by synthetic resin impregnation.[6] Since then, von Hagens has applied for further US patents regarding work on preserving biological tissues with polymers.[7][8]

With the success of his patents, von Hagens went on to form the Institute for Plastination in Heidelberg, Germany in 1993. The Institute for Plastination, along with von Hagens, made their first showing of plastinated bodies in Japan in 1995, which drew more than three million visitors. The institute maintains three international centres of plastination, in Germany, Kyrgyzstan, and China.[9]

Gunther von Hagens 2
Gunther von Hagens

Related preservation methods

Other methods have been in place for thousands of years to halt the decomposition of the body. Mummification used by the ancient Egyptians is a widely-known method which involves the removal of body fluid and wrapping the body in linens. Prior to mummification, Egyptians would lay the body in a shallow pit in the desert and allow the sun to dehydrate the body.[10]

Formalin, an important solution to body preservation, was introduced in 1896 to help with body preservation. Soon to follow formalin, color-preserving embalming solutions were developed to preserve life-like color and flexibility to aid in the study of the body.[11]

Paraffin impregnation was introduced in 1925, and the embedding of organs in plastic was developed in the 1960s.

Body preservation methods current to the 21st century are cryopreservation, which involves the cooling of the body to very low temperatures to preserve the body tissues, plastination, and embalming.[12]

Other methods used in modern times include the Silicone S 10 Standard Procedure, the Cor-Tech Room temperature procedure, the Epoxy E 12 procedure, and the Polyester P 35 (P 40) procedure.[13] The Silicone S 10 is the procedure most often used in plastination and creates opaque, natural-looking specimen.[14] Dow Corning Corporation's Cor-Tech Room Temperature Procedure is designed to allow plastination of specimen at room temperature to various degrees of flexibility using three combinations of polymer, crosslinker, and catalyst.[15] According to the International Society for Plastination, the Epoxy E 12 procedure is used "for thin, transparent, and firm body and organ slices", while the Polyster P 35 (P 40) preserves "semitransparent and firm brain slices".[13] Samples are prepared for fixation through the first method by deep freezing,[16] while the second method works best following 4–6 weeks of preparation in a formaldehyde mixture.[17]

Uses of plastinated specimens

Plastination is useful in anatomy, serving as models and teaching tools.[18] It is used at more than 40 medical and dental schools throughout the world as an adjunct to anatomical dissection.

Histological section of bovine tongue
Histological section of bovine tongue, epoxy technique

Students enrolled in introductory animal science courses at many universities learn animal science through collections of multispecies large-animal specimens. Plastination allows students to have hands-on experience in this field, without exposure to chemicals such as formalin. For example, plastinated canine gastrointestinal tracts are used to help in the teaching of endoscopic technique and anatomy.[19] The plastinated specimens retain their dilated conformation by a positive pressure air flow during the curing process, which allows them to be used to teach both endoscopic technique and gastrointestinal anatomy.

With the use of plastination as a teaching method of animal science, fewer animals have to be killed for research, as the plastination process allows specimens to be studied for a long time.[20]

TTT sheet plastinates for school teaching and lay instruction provide a thorough impression of the complexity of an animal body in just one specimen.

Scheibenplastinat
TTT sheet plastinate of a fish

North Carolina State University's College of Veterinary Medicine in Raleigh, North Carolina, uses both plastic coating (PC) and plastination (PN) to investigate and compare the difference in the two methods. The PC method was simple and inexpensive, but the PN specimens were more flexible, durable, and life-like than those preserved by the PC method. The use of plastination allowed the use of many body parts such as muscle, nerves, bones, ligaments, and central nervous system to be preserved.[21]

The University of Texas Health Science Center at San Antonio was the first school in the United States to use this technique to prepare gross organ specimens for use in teaching.[22] The New York University College of Dentistry.,[18] Philadelphia College of Osteopathic Medicine,[23] University of Warwick, and University of Northumbria [24] use collections of plastinates as teaching aids. The University of Vienna has its own plastination laboratory.[25]

Ethical concerns

Concern over consent of bodies being used in the plastination process has arisen. Over 20 years ago, von Hagens set up a body donation program in Germany and has signed over 9,000 donors into the plastinate program: 531 have already died. The program has reported an average of one body a day being released to the plastination process. About 90% of the donors registered are German. Although von Hagens says he follows strict consent procedures for whole-body specimens, he maintains, "consent is not important for body parts". Von Hagens' body donations are now being managed by the Institute for Plastination (IfP)[26] established in 1993.[27]

Religious opposition

A number of religious sects prohibit organ donation.[28][29] Ultra-Orthodox Jews oppose post mortem organ donation, and try to pass laws against unclaimed cadavers being used in research.[30] A number of religious organizations, including Catholic[31][32] and Jewish[33] object to the display of plastinated body parts at public exhibitions.

Plastination exhibitions

For the first 20 years, plastination was used to preserve small specimens for medical study. In the early 1990s, the equipment was developed to make plastinating whole body specimens possible, each specimen taking up to 1,500 man-hours to prepare.[34] The first exhibition of whole bodies was displayed by von Hagens in Japan in 1995.

Over the next two years, Von Hagens developed the Körperwelten (Body Worlds) public exhibitions, showing whole bodies plastinated in life-like poses and dissected to show various structures and systems of human anatomy. The earliest exhibitions were presented in the Far East and in Germany, and Gunther von Hagens' exhibitions have subsequently been hosted by museums and venues in more than 50 cities worldwide, attracting more than 29 million visitors..

Gunther von Hagens' Body Worlds exhibitions are the original, precedent-setting public anatomical exhibitions of real human bodies, and the only anatomical exhibits that use donated bodies, willed by donors to the Institute for Plastination for the express purpose of serving the Body Worlds mission to educate the public about health and anatomy. To date, more than 10,000 people have agreed to donate their bodies to Institute for Plastination.[26]

In 2004, Premier Exhibitions began their "Bodies Revealed" exhibition in Blackpool, England, which ran from August through October 2004. In 2005 and 2006, the company opened their "Bodies Revealed" and "Bodies...The Exhibition" in Seoul, Tampa, and New York City. The West Coast exhibition site opened on 22 June 2006 at the Tropicana Resort and Casino Las Vegas. As of June 2009, BODIES... The Exhibition is showing at the Ambassador Theatre (Dublin) in Dublin, Ireland.[35] The exhibition was in Istanbul, Turkey, until the end of March 2011.

Plastination galleries are offered in a few college medical schools, including University of Michigan (said to be the nation's largest such lab)[36] and the Vienna University[37]. Jss Medical College, Mysuru, India.[38] Gunther von Hagens maintains a permanent exhibition of plastinates and plastination at the Plastinarium in Guben, Germany.[39]

See also

References

  1. ^ "The Idea behind plastination". Institute for Plastination. 2006. Retrieved 1 May 2012.
  2. ^ Weiglein, A. H. (2005). "Overview & General Principles of the Plastination Procedures". 8th Interim Conf Plast. Retrieved 27 January 2009.
  3. ^ a b von Hagens, Gunther; Klaus Tiedemann; Wilhelm Kriz (1987). "The current potential of plastination". Anatomy and Embryology. 175 (4): 411–21. doi:10.1007/BF00309677. PMID 3555158.
  4. ^ a b Henry, Robert W.; Larry Janick; Francis Paul Salmos (February 1997). "Specimen preparation for silicone plastination" (PDF). Journal of the International Society for Plastination. 12 (1). ISSN 1090-2171. Retrieved 27 January 2009.
  5. ^ a b Bickley, Harmon C.; Robert S. Conner, Anna N. Walker and R. Lamar Jackson (January 1987). "Preservation of tissue by silicone rubber impregnation" (PDF). Journal of the International Society for Plastination. 1 (1): 30–39. ISSN 1090-2171. Archived (PDF) from the original on 24 June 2015. Retrieved 10 May 2009.
  6. ^ DE patent 2710147, "Präparat aus biologischen verweslichen Objekten und Verfahren zu ihrer Herstellung", issued 14 September 1978
  7. ^ US patent 4205059, "Animal and vegetal tissues permanently preserved by synthetic resin", issued 27 May 1980
  8. ^ US patent 4320157, "Method for preserving large sections of biological tissue with polymers", issued 16 March 1982
  9. ^ "Preservation by Plastination". BIODUR. Retrieved 5 March 2009.
  10. ^ Rymer, Eric. "History of Burial Beliefs in Ancient Egypt". History Link 101. Retrieved 11 May 2009.
  11. ^ "Formaldehyde: Its Development And History Since 1868" (PDF). Museum of Funeral Customs. Archived from the original (PDF) on 6 March 2005. Retrieved 11 May 2009.
  12. ^ US patent 5089288, "Method for Impregnating Tissue Samples in Paraffin", issued 18 February 1992
  13. ^ a b "Other Plastination Methods". International Society for Plastination. 20 October 1998. Archived from the original on 15 May 2009. Retrieved 19 May 2009.
  14. ^ "The Silicone S 10". International Society for Plastination. 2008. Retrieved 19 May 2009.
  15. ^ "The COR-TECH Room Temperature". International Society for Plastination. 2008. Retrieved 19 May 2009.
  16. ^ "The Epoxy E 12". International Society for Plastination. 2008. Retrieved 19 May 2009.
  17. ^ "The Polyester P35/P40". International Society for Plastination. 2008. Retrieved 19 May 2009.
  18. ^ a b "Life, Death, and One Man's Quest to Demystify the Inner Realms of the Human Body". Nexus. Fall 2004. Retrieved 13 February 2009.
  19. ^ Janick, L.; R. C. DeNovo; R. W. Henry (1997). "Plastinated Canine Gastrointestinal Tracts Used to Facilitate Teaching of Endoscopic Technique and Anatomy". Cells Tissues Organs. 158: 48. doi:10.1159/000147910.
  20. ^ "KSUCVM Plastination Laboratory". Vet.ksu.edu. 8 January 2009. Retrieved 18 March 2010.
  21. ^ Holladay SD, Hudson LC (1989). "Use of plastinated brains in teaching neuroanatomy at the North Carolina State University, College of Veterinary Medicine" (PDF). Journal of the International Society for Plastination. 3 (1): 15–17. Retrieved 19 May 2009.
  22. ^ "Pathology Academic Resource Center: UT Health Science Center - Graduate School of Biomedical Science". pathology.uthscsa.edu. Retrieved 22 September 2010.
  23. ^ "Virtual Campus Tour: PCOM Anatomy Lab". PCOM.edu. Retrieved 29 July 2015.
  24. ^ "First University to Acquire von Hagens Plastinations for University Teaching". European-hospital.com. 28 October 2008. Retrieved 18 March 2010.
  25. ^ "Vienna University Plastination Facility". Meduniwien.ac.at. Retrieved 18 March 2010.
  26. ^ a b "Institute". Bodyworlds.com. Retrieved 18 March 2010.
  27. ^ Singh, Debashis; Von Hagens, G (March 2003). "Scientist or showman?". BMJ. 326 (7387): 468. doi:10.1136/bmj.326.7387.468. PMC 1125369. PMID 12609939.
  28. ^ https://emedicine.medscape.com/article/1705993-overview
  29. ^ https://www.independent.co.uk/life-style/health-and-families/features/life-after-death-donating-your-body-for-research-1623676.html
  30. ^ http://www.nydailynews.com/news/politics/exclusive-2-pols-change-unclaimed-cadaver-law-article-1.2165881
  31. ^ KTVI (28 August 2007). "No Body World Exhibit For Catholic Field Trips". Fox Television Stations. Archived from the original on 23 June 2008. Retrieved 17 September 2008.
  32. ^ Archdiocese of Vancouver – Body Worlds Exhibit Archived 13 April 2014 at the Wayback Machine
  33. ^ DEBORAH SUSSMAN SUSSER Associate Editor (9 February 2007). "'Body Worlds' comes to Phoenix – Jewish News of Greater Phoenix". Jewishaz.com. Retrieved 25 February 2010.CS1 maint: Extra text: authors list (link)
  34. ^ Chambless, Ross (19 September 2008). "TheLeonardo Podcast no. 1" (MP3). Retrieved 8 May 2009.
  35. ^ [1]..
  36. ^ "Plastination". Med.umich.edu. Retrieved 18 March 2010.
  37. ^ "Plastination at the Vienna University". Meduniwien.ac.at. Retrieved 18 March 2010.
  38. ^ https://www.jssuni.edu.in/JSSWeb/WebShowFromDB.aspx?MODE=SSMD&PID=10002&CID=4&DID=8&MID=0&SMID=10402. Missing or empty |title= (help)
  39. ^ "The PLASTINARIUM-What is it?". www.plastinarium.de. Gubener Plastinate GmbH. Retrieved 17 August 2018.

Further reading

External links

Adductor brevis muscle

The adductor brevis is a muscle in the thigh situated immediately deep to the pectineus and adductor longus. It belongs to the adductor muscle group. The main function of the adductor brevis is to pull the thigh medially. The adductor brevis and the rest of the adductor muscle group is also used to stabilize left to right movements of the trunk, when standing on both feet, or to balance when standing on a moving surface. The adductor muscle group is used pressing the thighs together to ride a horse, and kicking with the inside of the foot in soccer or swimming. Last, they contribute to flexion of the thigh when running or against resistance (squats, jumping, etc.).

Adductor longus muscle

In the human body, the adductor longus is a skeletal muscle located in the thigh. One of the adductor muscles of the hip, its main function is to adduct the thigh and it is innervated by the obturator nerve. It forms the medial wall of the femoral triangle.

Alar fascia

The alar fascia is a layer of fascia, sometimes described as part of the prevertebral fascia, and sometimes as in front of it.

Cranially, it reaches the skull, and caudally, it reaches the second thoracic vertebra.It is the posterior border of the retropharyngeal space.In 2015, the anatomy of the alar fascia was revisited using dissection in conjunction with E12 plastination. The authors revealed that the alar fascia originated as a well defined midline structure at the level of C1 and does not reach the base of the skull. It is suggested that the area between C1 and the base of the skull is a potential entry into the danger space.

Body Worlds

Body Worlds (German title: Körperwelten) is a traveling exposition of dissected human bodies, animals, and other anatomical structures of the body that have been preserved through the process of plastination. Gunther von Hagens developed the preservation process which "unite[s] subtle anatomy and modern polymer chemistry", in the late 1970s.

A series of Body Worlds anatomical exhibitions has toured many countries worldwide, sometimes raising controversies about the sourcing and display of actual human corpses and body parts. Nevertheless, Von Hagens maintains that all human specimens were obtained with full knowledge and consent of the donors before they died, and his organization keeps extensive documentation of this permission. Von Hagens emphasizes both educational and artistic aspects of his complex and innovative dissections, and offers online teaching guides for educators. He also tries to distinguish his efforts from those of competitors who may have been less thorough in obtaining advance permission from their specimen sources.

Cadaver

A cadaver is a dead human body that is used by medical students, physicians and other scientists to study anatomy, identify disease sites, determine causes of death, and provide tissue to repair a defect in a living human being. Students in medical school study and dissect cadavers as a part of their education. Others who study cadavers include archaeologists and artists.The term cadaver is used in courts of law to refer to a dead body, as well as by recovery teams searching for bodies in natural disasters. The word comes from the Latin word cadere ("to fall"). Related terms include cadaverous (resembling a cadaver) and cadaveric spasm (a muscle spasm causing a dead body to twitch or jerk). A cadaver graft (also called “postmortem graft”) is the grafting of tissue from a dead body onto a living human to repair a defect or disfigurement. Cadavers can be observed for their stages of decomposition, helping to determine how long a body has been dead.Cadavers have been used in art to depict the human body in paintings and drawings more accurately.

Conservation and restoration of human remains

The conservation and restoration of human remains involves the long-term preservation and care of human remains in various forms which exist within museum collections. This category can include bones and soft tissues as well as ashes, hair, and teeth. Given the organic nature of the human body, special steps must be taken to halt the deterioration process and maintain the integrity of the remains in their current state. These types of museum artifacts have great merit as tools for education and scientific research, yet also have unique challenges from a cultural and ethical standpoint. Conservation of human remains within museum collections is most often undertaken by a conservator-restorer or archaeologist. Other specialists related to this area of conservation include osteologists and taxidermists.

Dalian Medical University

Dalian Medical University (Chinese: 大连医科大学; pinyin: Dàlián Yīkē Dàxué) is a university in Dalian, Liaoning, China under the provincial government. It was founded in 1947 in the southern part of Dalian city, China by Mao Zedong.In October 2007, it moved to the new campus in Lushunkou District, Dalian, which is across Lushun South Road from Dalian University of Foreign Languages' new campus.

The school through its Dalian Medical University Plastination Co. subsidiary is the source of the cadavers which have undergone plastination to appear worldwide in the BODIES... The Exhibition.

Femoral nerve

The femoral nerve is a nerve in the thigh that supplies skin on the upper thigh and inner leg, and the muscles that extend the knee.

Gluteus maximus

The gluteus maximus (also known collectively with the gluteus medius and minimus, as the gluteal muscles, and sometimes referred to informally as the "glutes") is the main extensor muscle of the hip. It is the largest and most superficial of the three gluteal muscles and makes up a large portion of the shape and appearance of each side of the hips. Its thick fleshy mass, in a quadrilateral shape, forms the prominence of the buttocks.

Its large size is one of the most characteristic features of the muscular system in humans, connected as it is with the power of maintaining the trunk in the erect posture. Other primates have much flatter hips and can not sustain standing erectly.

The muscle is remarkably coarse in function and structure, being made up of muscle fascicles lying parallel with one another, and collected together into larger bundles separated by fibrous septa.

Gunther von Hagens

Gunther von Hagens (born Gunther Gerhard Liebchen; 10 January 1945) is a German anatomist who invented the technique for preserving biological tissue specimens called plastination.

Left coronary artery

The left coronary artery (abbreviated LCA) is an artery that arises from the aorta above the left cusp of the aortic valve and feeds blood to the left side of the heart. It is also known as the left main coronary artery (abbreviated LMCA) and the left main stem coronary artery (abbreviated LMS). It is one of the coronary arteries.

Mummy

A mummy is a deceased human or an animal whose skin and organs have been preserved by either intentional or accidental exposure to chemicals, extreme cold, very low humidity, or lack of air, so that the recovered body does not decay further if kept in cool and dry conditions. Some authorities restrict the use of the term to bodies deliberately embalmed with chemicals, but the use of the word to cover accidentally desiccated bodies goes back to at least 1615 AD (See the section Etymology and meaning).

Mummies of humans and animals have been found on every continent, both as a result of natural preservation through unusual conditions, and as cultural artifacts. Over one million animal mummies have been found in Egypt, many of which are cats. Many of the Egyptian animal mummies are sacred ibis, and radiocarbon dating suggests the Egyptian Ibis mummies that have been analyzed were from time frame that falls between approximately 450 and 250 BC.In addition to the well-known mummies of ancient Egypt, deliberate mummification was a feature of several ancient cultures in areas of America and Asia with very dry climates. The Spirit Cave mummies of Fallon, Nevada in North America were accurately dated at more than 9,400 years old. Before this discovery, the oldest known deliberate mummy was a child, one of the Chinchorro mummies found in the Camarones Valley, Chile, which dates around 5050 BC. The oldest known naturally mummified human corpse is a severed head dated as 6,000 years old, found in 1936 AD at the site named Inca Cueva No. 4 in South America.

Posterior atlantooccipital membrane

The posterior atlantooccipital membrane (posterior atlantooccipital ligament) is a broad but thin membrane. It is connected above to the posterior margin of the foramen magnum and below to the upper border of the posterior arch of the atlas.

On each side of this membrane there is a defect above the groove for the vertebral artery which serves as an opening for the entrance of the artery. The suboccipital nerve also passes through this defect.

The free border of the membrane arches over the artery and nerve and is sometimes ossified.

The membrane is deep to the Recti capitis posteriores minores and Obliqui capitis superiores and is superficial to the dura mater of the vertebral canal to which it is closely associated.

In 2015, Scali et al. revisited the anatomy of the posterior atlantooccipital membrane via plastination. Their findings revealed that the PAO membrane superiorly consisted of periosteum of the occiput, whereas inferiorly it formed part of the dura at the cerebrospinal junction, terminating at the level of the third cervical vertebra (rather than attaching to the posterior arch of the atlas). It is believed that this anatomical arrangement permits a superiorly located anchor point for epidural bridging structures and allows dural tensile forces to act in a summated synchronized manner. The author's hypothesize that this complex area assists with outflow of cerebrospinal fluid.

Premier Exhibitions

Premier Exhibitions Inc NASDAQ: PRXI is an Atlanta, Georgia-based company that organizes traveling exhibitions. As of January 2019, the company owned 5,500 Titanic relics with approximately 1,300 on display in various countries.Its two most prominent exhibits are artifacts from the RMS Titanic (for which it is the sole legal guardian of the artifacts) and BODIES... The Exhibition in which it displays cadavers arranged in lifelike poses via plastination from the Dalian Medical University (through its Dalian Medical University Plastination Company subsidiary) in China. It has multiple exhibits of both bodies and Titanic running at the same time in different venues. In 2008 it entered into a 10-year lease for more than 36,000 square feet (3,300 m2) at the Luxor Las Vegas for exhibits of Titanic and bodies there.In May 2015 the company opened Premier on 5th, a flagship exhibition space on Fifth Avenue in New York City that housed "Saturday Night Live: The Exhibition" and "The Discovery of King Tut." On June 14, 2016, Premier Exhibitions filed for Chapter 11.In late August 2018, at least three groups were vying for the right to purchase the 5,500 Titanic relics that were an asset of the bankrupt company in the case titled RMS Titanic Inc., 16-02230, U.S. Bankruptcy Court, Middle District of Florida (Jacksonville). Two of the offers for the collection were just under US $20 million, including one by museums in England and Northern Ireland, with assistance by James Cameron. Oceanographer Robert Ballard told the news media that he favored this bid since it would ensure that the memorabilia would be permanently displayed in Belfast and in Greenwich. A decision as to the outcome was to be made by Paul M. Glenn, a United States district court judge in Jacksonville, Florida.

Prosection

A prosection is the dissection of a cadaver (human or animal) or part of a cadaver by an experienced anatomist in order to demonstrate for students anatomic structure. In a dissection, students learn by doing; in a prosection, students learn by either observing a dissection being performed by an experienced anatomist or examining a specimen that has already been dissected by an experienced anatomist (etymology: Latin pro- "before" + sectio "a cutting")A prosection may also refer to the dissected cadaver or cadaver part which is then reassembled and provided to students for review.

Sartorius muscle

The sartorius muscle () is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh in the anterior compartment.

Spermatic cord

The spermatic cord is the cord-like structure in males formed by the vas deferens (ductus deferens) and surrounding tissue that runs from the deep inguinal ring down to each testicle. Its serosal covering, the tunica vaginalis, is an extension of the peritoneum that passes through the transversalis fascia.

Each testicle develops in the lower thoracic and upper lumber region and migrates into the scrotum during its descent it carries along with it vas deferens, its vessels, nerves etc it is one on each side.

Vastus lateralis muscle

The vastus lateralis (), also called the ''vastus externus'' is the largest and most powerful part of the quadriceps femoris, a muscle in the thigh. Together with other muscles of the quadriceps group, it serves to extend the knee joint, moving the lower leg forward. It arises from a series of flat, broad tendons attached to the femur, and attaches to the outer border of the patella. It ultimately joins with the other muscles that make up the quadriceps in the quadriceps tendon, which travels over the knee to connect to the tibia. The vastus lateralis is the recommended site for intramuscular injection in infants less than 7 months old and those unable to walk, with loss of muscular tone.

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