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Overview of Female Pelvic Floor Muscle Anatomy and Physiology

Original Editor - Jess Bell based on the course by Ibukun Afolabi
Top Contributors - Jess Bell, Jorge Rodríguez Palomino, Kim Jackson, Rucha Gadgil and Stacy Schiurring

Introduction

The pelvic floor is part of a complex system that works synergistically with structures and systems both nearby and further away in the body, including the ankle/foot complex, the thorax and respiratory complex, the central nervous system and the brain.[1] The body is a dynamic, interrelated, fascially connected, biotensegral[2] system. Pelvic health physiotherapists must consider the contribution of all these systems and structures when assessing and treating pelvic health complaints.[1]

The Pelvic Floor

Health professionals might have differing views about what makes up the pelvic floor:[1]

  • Is it just comprised of the pelvic floor muscles?
  • Should the pelvic organs be included?
  • Is the hip joint part of the pelvic floor?
  • Are the contents of the lower abdominal cavity also included?

For the pelvic health physiotherapist, 'pelvic floor' is used broadly to refer to the pelvic region and all of its contents and associated structures, not just the pelvic floor musculature. This broader definition includes the pelvis itself (also called the pelvic ring or pelvic bowl), including the pelvic joints; the pelvic organs, such as the bladder, uterus and rectum in women; the pelvic ligaments; the endopelvic fascia and connective tissue; the nerves which innervate the pelvic region; the blood vessels and lymphatic system; the external genitalia; and the pelvic floor musculature. Pelvic health physiotherapists can treat all these structures either directly or indirectly.[1]

Bones of the pelvis.
Ligaments of the pelvis.
Muscles of the pelvic floor.

This page focuses on the anatomy of the female pelvic floor musculature. More information on the other structures within the pelvis is available here.

Pelvic Cavity

The abdominal and pelvic cavities are bordered at the front, top, back and bottom. The front border is the abdominal wall, the top border is the respiratory diaphragm, the back border is the spinal column, and the bottom border consists of the pelvic floor muscles.[1][3]

Pelvic Floor Muscles

The pelvic floor muscles act to close off the bony outlet completely, except for specific openings. The urogenital hiatus, positioned anteriorly, contains the urethra and vagina in women. The anal hiatus, positioned posteriorly, contains the anal canal.[1][3]

[4]
[5]

The muscles of the pelvic floor are divided into three layers.[6]

Muscles of the pelvic diaphragm.

Deep Layer - Pelvic Diaphragm

The deepest layer of the pelvic floor muscles is known as the pelvic diaphragm. It is a broad, funnel-shaped sling of fascia and muscle suspended from bony anchor points in the lesser pelvis[1][7] (i.e. the area of the pelvic cavity below the linea terminalis[8]).

The muscles of the pelvic diaphragm are the ischiococcygeus muscle (also known as the coccygeus muscle) and the levator ani.[1][9] [10]

Ischiococcygeus originates at the ischial spine and inserts into the lateral aspect of the coccygeal vertebrae.

The levator ani is a composite muscle that is traditionally divided into three parts. Pubococcygeus originates from the internal surface of the pubic ramus and inserts into the lower sacral and coccygeal vertebrae. Illiococcygeus originates at the arcus tendinous levator ani (ATLA) and fuses with the pubococcygeus. Puborectalis originates at the inner surface of the right and left sides of the pubic bone. The two muscles meet behind the rectum and form a continuous sling.[1][11]

In this deep part of the pelvic floor, it is also possible to palpate the obturator internus and piriformis muscles. These muscles are not, however, considered to be part of the pelvic diaphragm. Instead, they are rotators of the hip.[1]  

Middle Layer - Urogenital Diaphragm / Perineal Membrane

The middle layer has traditionally been called the urogenital diaphragm, but is often now referred to as the perineal membrane.[1]

There is controversy over whether this layer contains a transverse sheet of muscle called the deep transverse perinei muscle between an inferior and superior fascia, or three joined muscles and an inferior fascial layer (i.e. the perineal membrane).[10]

However, the middle layer stretches across the urogenital triangle (see below) and in women, houses the urethral and vaginal sphincters (i.e. the sphincter urethrovaginalis, the external urethral sphincter, and the compressor urethrae). These sphincters close the urethra and vagina, and maintain continence.[1][12] The entire perineal layer provides additional support for the deeper pelvic floor structures.[1][10]

Muscles of the superficial layer.

Superficial Layer

The most superficial layer of the pelvic floor muscles consists of bulbocavernosus and ischiocavernosus, the paired superficial transverse perineal muscles and the external anal sphincter.

The bulbocavernosus and ischiocavernosus assist with clitoral function during arousal and climax.[1] The superficial transverse perineal muscles provide additional support for the urogenital diaphragm. The external anal sphincter is a circular, layered muscle that closes off the anal canal.[1][13]

The perineum (perineal body) and superficial transverse perineal muscles divide into two triangles.[3] The anterior triangle, called the urogenital triangle, makes up the anterior half of the diamond-shaped perineum. The corners of the triangle are the pubic symphysis anteriorly and the ischial tuberosities anterolaterally.[14] The posterior triangle, called the anorectal triangle, makes up the posterior half of the perineum. The corners of this triangle are the tip of the coccyx posteriorly and the ischial tuberosities anterolaterally.[15]

Physiology of the Pelvic Floor

The pelvic floor muscles are, in many respects, just like any other skeletal muscle group. They can contract and relax, be shortened or lengthened, be weak or strong, and be stiff or supple. They can hold tension or move dynamically. They may be coordinated or lack coordination, either individually or in relation to other muscle groups. They can be normally regulated or "dysregulated".[1]

The pelvic floor muscles contain both fast- and slow-twitch fibres. Slow-twitch fibres make up 70 percent of the pelvic floor.[1][16] The high prevalence of slow-twitch fibres means that these muscles are able to maintain a degree of resting activation. They are, therefore, considered to be postural muscles.[17][18] This resting activation also enables the maintenance of continence.[1][19] The fast-twitch fibres allow the muscles to contract voluntarily when necessary (e.g. during an expected or unexpected increase in intra-abdominal pressure).[1][20]

The Nine S's of Pelvic Floor Muscle Physiology

While some authors discuss the Five S's,[21] Ibukun Afolabi describes Nine S's.[1]

Support: the pelvic floor provides support.[22][23][24]

Sexual arousal and orgasm: the superficial pelvic floor muscles cause engorgement and erection of the clitoris during arousal. The pelvic floor muscles also contract and relax rhythmically during climax.[1][24][25]

Sphincter action: sphincters are circular muscles that close off a space or lumen when they contract. They have a certain degree of resting tone, which is regulated by the nervous system, and can also be actively contracted. They maintain continence.[1][24][26]

Stability: the pelvic floor muscles play a key role in the inner core system (i.e. the deepest muscle layer surrounding the abdominal and pelvic cavities, which consists of transversus abdominis, multifidus, the respiratory diaphragm, and the pelvic floor).[1][18][27]

Synergy: the pelvic floor works synergistically with other muscles and organs (see videos below).[1][28] Together, the pelvic floor and diaphragm function like a piston. On inhalation, the diaphragm contracts and flattens, pushing the viscera inferiorly, while the pelvic floor absorbs this movement by eccentrically contracting. On exhalation, both the diaphragm and pelvic floor return to their starting position. The glottis above controls the passage of air in and out of the respiratory passages. It works synergistically with the pelvic floor and diaphragm.[29]

Spring: the pelvic floor needs to be able to lengthen under pressure, especially when this pressure is unexpected, such as during a sneeze, or when a high load is applied.[1]

Sump pump: the rhythmic movement of the pelvic floor muscles creates a pumping action that helps to move both blood and lymph through the vascular system, which decreases pelvic congestion and swelling.[1][21][24]

Stretch: during labour, the pelvic floor muscles must be able to stretch.[1][30] The pelvic floor muscles can reach a stretch ratio of 3.26 by the end of the second stage of labour.[31] During this stage, the levator ani muscles stretch more than 200 percent beyond what is considered the threshold for a stretch injury during the second stage of labour.[32]

Somatic: refers more to the “state of being” of the pelvic floor at any given time rather than a specific function of the pelvic floor. The “somatic reality” of the pelvic floor can provide insight into the relationship between mind, body, brain, and behaviour.[1][25]

[33]
[34]

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 Afolabi I. Overview of Female Pelvic Floor Muscle Anatomy and Physiology Course. Plus , 2021.
  2. ↑ Scarr G. Biotensegrity: what is the big deal? J Bodyw Mov Ther. 2020;24(1):134-7.
  3. ↑ 3.0 3.1 3.2 Chaudhry SR, Nahian A, Chaudhry K. Anatomy, Abdomen and Pelvis, Pelvis. [Updated 2021 Aug 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482258/
  4. ↑ Geeky Medics. Pelvic Floor Anatomy (3D Anatomy Tutorial). Available from: https://www.youtube.com/watch?v=I87G1dUcZng [last accessed 5/12/2021]
  5. ↑ Continence Foundation of Australia. Female pelvic floor muscle - 3D animation. Available from: https://www.youtube.com/watch?v=q0_JAoaM6pU&t=55s [last accessed 6/12/2021]
  6. ↑ Stoker J. Anorectal and pelvic floor anatomy. Best Pract Res Clin Gastroenterol. 2009;23(4):463-75.
  7. ↑ Eickmeyer SM. Anatomy and physiology of the pelvic floor. Physical Medicine and Rehabilitation Clinics. 2017;28(3):455-60.
  8. ↑ White TD, Black MT, Folkens PA. Chapter 11 - pelvis: sacrum, coccyx, and os coxae. In: White TD, Black MT, Folkens PA editors. Human Osteology (Third Edition). Academic Press. 2012. p219-40.
  9. ↑ McEvoy A, Tetrokalashvili M. Anatomy, Abdomen and Pelvis, Female Pelvic Cavity. [Updated 2021 Jul 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538435/
  10. ↑ 10.0 10.1 10.2 Herschorn S. Female pelvic floor anatomy: the pelvic floor, supporting structures, and pelvic organs. Rev Urol. 2004;6 Suppl 5(Suppl 5):S2-S10.
  11. ↑ A Karunaharamoorthy. Levator ani [Internet]. Kenhub. 2021 [cited 5 December 2021]. Available from: https://www.kenhub.com/en/library/anatomy/levator-ani
  12. ↑ Jung J, Ahn HK, Huh Y. Clinical and functional anatomy of the urethral sphincter. Int Neurourol J. 2012;16(3):102-6.
  13. ↑ Baramee P, Muro S, Suriyut J, Harada M, Akita K. Three muscle slings of the pelvic floor in women: an anatomic study. Anat Sci Int. 2020;95(1):47-53.
  14. ↑ Hacking C. Urogenital triangle [Internet]. Radiopaedia.org. 2021 [cited 10 December 2021]. Available from: https://radiopaedia.org/articles/urogenital-triangle?lang=us
  15. ↑ Hacking C. Anal triangle [Internet]. Radiopaedia.org. 2018 [cited 10 December 2021]. Available from: https://radiopaedia.org/articles/anal-triangle?lang=us
  16. ↑ Marques A, Stothers L, Macnab A. The status of pelvic floor muscle training for women. Can Urol Assoc J. 2010;4(6):419-24.
  17. ↑ Dsingh A., Kaur A. Role of postural control exercises and pelvic floor strengthening exercises on chronic low back pain of women with sitting jobs. In: Rebelo F, Soares M editors. Advances in ergonomics in design. Vol 955. Cham: Springer, 2020. p775-82.
  18. ↑ 18.0 18.1 Hodges PW, Sapsford R, Pengel LH. Postural and respiratory functions of the pelvic floor muscles. Neurourol Urodyn. 2007;26(3):362-71.
  19. ↑ Swash M, Petros P. The pelvic floor: neurocontrol and functional concepts. In: Santoro GA, Wieczorek AP, Sultan AH editors. Pelvic floor disorders. Cham: Springer, 2021. p57-70.
  20. ↑ Raizada V, Mittal RK. Pelvic floor anatomy and applied physiology. Gastroenterol Clin North Am. 2008;37(3):493-vii.
  21. ↑ 21.0 21.1 Thomas K. Pelvic Floor training for stress urinary incontinence: an update. Co-Kinetic Journal. 2019;(79):14-23.
  22. ↑ Peng Y, Miller BD, Boone TB, Zhang Y. Modern theories of pelvic floor support: a topical review of modern studies on structural and functional pelvic floor support from medical imaging, computational modeling, and electromyographic perspectives. Curr Urol Rep. 2018;19(1):9.
  23. ↑ Förstl N, Adler I, Süß F, Dendorfer S. Technologies for Evaluation of Pelvic Floor Functionality: A Systematic Review. Sensors. 2024 Jun 20;24(12):4001.
  24. ↑ 24.0 24.1 24.2 24.3 Fransson A, Hapidou EG, Anthonypillai J. Prevalence of pelvic floor symptoms among Veteran and civilian women participating in a chronic pain program. Journal of Military, Veteran and Family Health. 2025 Jun 1;11(3):122-7.
  25. ↑ 25.0 25.1 Prendergast SA, Mueller J. Pelvic floor physical therapy and female sexual dysfunction. Clinical Obstetrics and Gynecology. 2025 Mar 1;68(1):37-43.
  26. ↑ Bharucha AE. Pelvic floor: anatomy and function. Neurogastroenterol Motil. 2006;18(7):507-19.
  27. ↑ Soomro KU, Mughal SA, Hussain SA, Rajpar ZH, Shaikh AQ, Shaikh A. Pelvic Floor Muscle Exercise plus Core Stability Exercise on Urinary Incontinence in Females. Journal of The Society of Obstetricians and Gynaecologists of Pakistan. 2024 Jun 1;14(2):139-42.
  28. ↑ Ding S. Sources and streams of multidisciplinary pelvic floor practice: Development and interdisciplinary application of integral theory system (ITS). Pelviperineology A Multidisciplinary Pelvic Floor Journal. 2025 Aug 18.
  29. ↑ Rudavsky A, Turner T. Novel insight into the coordination between pelvic floor muscles and the glottis through ultrasound imaging: a pilot study. Int Urogynecol J. 2020;31(12):2645-52.
  30. ↑ Eggebø TM, Volløyhaug I. The pelvic floor during pregnancy and delivery: Can pelvic floor trauma and disorders be prevented?. Acta Obstetricia et Gynecologica Scandinavica. 2024 May 19;103(6):1012.
  31. ↑ Ashton-Miller JA, Delancey JO. On the biomechanics of vaginal birth and common sequelae. Annu Rev Biomed Eng. 2009;11:163-76
  32. ↑ Iglesia CB, Smithling KR. Pelvic organ prolapse. Am Fam Physician. 2017;96(3):179-85.
  33. ↑ JULIE WIEBE. The Diaphragm Pelvic Floor Piston Demo. Available from: https://www.youtube.com/watch?v=mLFfZfm7O7c [last accessed 5/12/2021]
  34. ↑ FemFusion Fitness and Pelvic Health. Can Singing Heal Your Pelvic Floor? The Pelvic Floor-Glottis Connection. Available from:https://www.youtube.com/watch?v=4dS7bc_4Mx0 [last accessed 5/12/2021]
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