Pelvic floor definition:
pelvic floor are soft structures that fills the bony pelvic outlet.
Pelvic floor layers:
1. Pelvic peritoneum.
2. Pelvic fascia (endopelvic fascia).
3. Deep pelvic floor muscles (levator ani muscle).
4. Superficial pelvic floor muscles.
5. Perineal fascia (Colle’s fascia).
6. Perineal skin.
1. Pelvic peritoneum (Peritoneal covering of uterus)
1. Laterally: it forms the broad ligament.
2. Anteriorly: it forms the utero-vesical pouch.
3. Posteriorly: it forms the recto-vaginal pouch (Douglas pouch).
2.Pelvic fascia (Pelvic cellular tissue)
Def.: it is combination of C.T., blood vessels & muscle fibers that lines walls, floor of pelvic cavity & fills the area between pelvic organs.
Functions:
1. It provides additional support to these organs.
2. It’s thickened to form pelvic ligaments.
a) Pubocervical ligament.
b) Transverse cervical ligament.
c) Uterosacral ligament.
d) Round ligament.
3.Deep pelvic floor muscles
Levator ani muscle (bilateral sheets of muscles):
Parts:
1. Pubococcygeus: (main & inner part):
• Origin: 1) back of pubic bone.
2) Part of white line (which lies in front of obturator canal).
• Insertion: the muscle fibers sweep backwards as 3 distinct bands:
i. Most medial fibers (pubourethralis & pubovaginalis):
♦ Forms a U-shaped loop around the vagina & urethra & inserted into lateral, posterior walls of vagina & central point of perineum.
ii. Intermediate fibers (puborectalis):
♦ Forms U-shaped loop around anorectal junction & inserted into lateral, posterior walls of anal canal.
iii. Most lateral fibers (pubococcygeus proper ):
♦ Blend with fibers of the second part (Iliococcygeus)
♦ Inserted into the lateral margins of coccyx.
2.Iliococcygeus:
• Origin: white line of pelvic fascia.
• Insertion: it blends with lateral fibers of pubococcygeus & inserted into the lateral margin of coccyx.
3.Ischiococcygeus:
• Origin: pelvic aspect of ischial spine.
• Insertion: lateral border of coccyx & last sacral piece.
Gaps:
i. Anterior gap: for passage of
urethra & vagina.
ii. Posterior gap: for passage of anus
(behind perineal body).
Relations:
1. Pelvic surface (upper surface):
Covered by pelvic fascia. Related to UB, vagina & rectum.
2. Perineal surface (lower surface):
Covered by inferior fascia of pelvic diaphragm.
Related to superficial perineal muscles.
Blood supply:
A. Arterial: pudendal artery from internal iliac artery.
B. Venous: pudendal vein into internal iliac vein.
Nerve supply:
1) Perineal branch of S4 nerve: through its pelvic surface.
2) Pudendal nerve (S2,3,4):through its perineal surface.
Lymphatic drainage: inguinal L.Ns.
Special notes:
• Part of levator ani extending between rectum & coccyx is called levator plate (the upper vagina rests on this plate).
• Anterior border: separated from the opposite muscle by triangle occupied by urethra & vagina.
Functions:
1. Division of perineum into anal & urogenital triangles.
2. Support of pelvic organs.
3. Internal rotation of fetal head during labour.
4. Relaxation during micturition & defecation.
5. Sphincteric action for the urethra, vagina & rectum.
Applied anatomy:
1. Weakness of pelvic floor predisposes to genital prolapse & stress incontinence.
2. Too rigid or too lax pelvic floor: may interfere with internal rotation during labour.
4.Superficial pelvic floor muscles
Importance: provides additional support to deep structures (levator ani)).
Parts:
1. Transverse perineal muscle.
2. Bulbocavernous muscle.
• Allows erection of clitoris during sexual activity.
• Helps contraction of vaginal walls during sexual intercourse as they surround the vagina.
3. Ischiocavernous muscle.
4. External anal sphincter.
• Ring of voluntary muscle surrounding the lower 2/3 of anal canal.
• Formed of 3 parts:
− Subcutaneous part: surround the anal orifice.
− Superficial part: (the only part that has bony attachment): above subcutaneous part & surround the lower part of anal canal.
− Deep part: surround the lower part of internalsphincter.
5. External urethral meatus muscles:
• Opening in the distal urethra compressed by muscle fibres.
6.Triangular ligaments:
• Support the bladder neck.
5.Perineal fascia (Colle’s fascia).
6.Perineal skin
Pelvic floor videos:
The Pelvic Diaphragm – 3D Anatomy Tutorial
Perineal Membrane and Deep Perineal Pouch – 3D Anatomy Tutorial
Female Pelvic Floor Muscles