Muscles and Fascia of Pelvic Wall Dr. Sama-ul-Haque

Objectives Describe the origin, insertion, nerve supply and actions of the Piriformis, obturator internus & levator ani. Describe the pelvic fascia organization.

Pelvic Walls Anterior pelvic wall: Formed primarily by the bodies and rami of the pubic bones and the pubic Symphysis Lateral pelvic walls: Formed by 1- the hip bones and the 2-Obturatorinternus muscles: Origin: Proximal surface of the ilium & ischium; obturator membrane Insertion: Greater trochanter of the femur

Nerve supply: N to Obturator internus ( L5, S1, S2) Action: Lateral Rotation of the thigh

Obturator Internus Muscle

Pelvic Walls Posterior Pelvic Wall: Formed by the sacrum, coccyx, adjacent parts of the ilia, Sacroiliac joints and Piriformis muscle: Origin: Pelvic surface of 2nd and 4th sacral segments, superior margin of the greater sciatic notch and sacrotuberous ligament. Insertion: Greater trochanter of femur

Piriformis Muscle

Pelvic Floor Formed by the funnel shaped pelvic diaphragm Consists of the levator ani and coccygeus muscles and their fascia Stretches between the pubis anteriorly and the coccyx posteriorly and from one lateral pelvic wall to the other.

Levator Ani Three parts Pubococcygeus Puborectalis Iliococcygeus Origin: Collectively they run from the body of the pubis, the tendinous arch of the obturator fascia and the Ischial spine. Insertion: To the perineal body, the coccyx, the anococcygeal ligament, the walls of the prostate or vagina, the rectum and the anal canal

Levator Ani Nerve supply: Nerve to levator ani (S4) Pudendal nerve Action: 1- Forms most of the pelvic diaphragm that helps to support the pelvic viscera; 2- Acting together they raise the pelvic floor and 3- Assist the abdominal muscles in forced expiration activities.

Pelvic Walls

The anteroinferior pelvic wall: Is formed primarily by the bodies and rami of the pubic bones and the pubic symphysis. Participates in bearing the weight of the urinary bladder.

The lateral pelvic walls: Have a bony framework formed by the hip bones, including the obturator foramen ; the obturator foramen is closed by the obturator membrane . Are covered and padded by the obturator internus muscles .Each obturator internus passes posteriorly from its origin within the lesser pelvis, exits through the lesser sciatic foramen, and turns sharply laterally to attach to the femur.

The medial surfaces of these muscles are covered by obturator fascia, thickened centrally as a tendinous arch that provides attachment for the pelvic diaphragm Have the obturator nerves and vessels and other branches of the internal iliac vessels located on their medial aspects (medial to obturator internus muscles).

The posterior pelvic wall: Consists of a bony wall and roof in the midline (formed by the sacrum and coccyx) and musculoligamentous posterolateral walls (formed by the sacroiliac joints and their associated ligaments and piriformis muscles). Each piriformis muscle leaves the lesser pelvis through the greater sciatic foramen to attach to the femur . Is the site of the nerves forming the sacral plexus; the piriformis muscles form a muscular bed for this nerve network

Pelvic Diaphragm

Pelvic Floor (Male)

Pelvic Floor (Female)

Female Pelvic Floor (Medial view)

Perineal Body

Coccygeus Muscle Origin: Ischial spine Insertion: Lower end of the sacrum and coccyx Nerve supply: Branches of S4 and S5 Action: Forms a small part of the pelvic diaphragm that supports the pelvic viscera, flexes the coccyx.

Pelvic Fascia

1- Membranous pelvic fascia: Parietal and visceral 2- Endopelvic fascia: Loose and condensed

Pelvic Fascia

Thank you