Bony Framework of the Pelvis
The bony framework of the pelvis is formed by several key anatomical structures.
- Hip bones: consist of paired pubic, iliac, and ischial elements.
- Sacrum and coccyx: complete the formation of the bony framework posteriorly.
These structures provide reliable protection for internal organs and serve as support for the lower limb via the femurs.
Pelvic joints
The elements of the pelvic ring are firmly connected anteriorly and posteriorly.
- Anteriorly: the pubic symphysis (symphysis pubica) is located. Superiorly, it is additionally reinforced by the superior pubic ligament (lig. pubicum superius), and inferiorly by the arcuate pubic ligament (lig. arcuatum pubis).
- Posteriorly: the sacroiliac joint (articulatio sacroiliaca) is located, providing a minimally mobile but extremely strong connection between the axial skeleton and the lower limb girdle.
Ligamentous Apparatus and Foramina
Strong ligaments originating from the sacrum play a special role in pelvic anatomy:
- Lig. sacrospinale — extends to the ischial spine.
- Lig. sacrotuberale — runs to the ischial tuberosity.
By spanning across the notches of the hip bone, these structures close them off, forming two key anatomical openings: the greater and lesser sciatic foramina.
External Bony Landmarks
During clinical examination and topographic-anatomical study, a physician can palpate the following structures:
- Superior margin of the symphysis and pubic rami
- Pubic tubercles
- Anterior superior iliac spines
- Sacrum and Coccyx
- Ischial tuberosities
- Greater trochanters of the femurs
Briefly: answers to topical questions
Which muscles and neurovascular bundles pass through the greater sciatic foramen?
The piriformis muscle and several neurovascular bundles pass through the greater sciatic foramen.
- Piriformis muscle (m. piriformis) — divides the foramen into two apertures.
The suprapiriform foramen transmits:
- Superior gluteal neurovascular bundle.
The infrapiriform foramen transmits:
- Inferior gluteal neurovascular bundle;
- Sciatic nerve (n. ischiadicus);
- Posterior femoral cutaneous nerve (n. cutaneus femoris posterior);
- Pudendal neurovascular bundle.
Which articular surfaces form the sacroiliac joint?
The sacroiliac joint (articulatio sacroiliaca) is formed by the articulating bone surfaces of the sacrum and the hip bone.
- Auricular surface of the sacrum — located on the lateral parts of the sacrum.
- Auricular surface of the ilium — adjacent to the sacrum, forming a flat, slightly mobile joint (amphiarthrosis).
Which anatomical structures pass through the lesser sciatic foramen?
The following anatomical structures pass through the lesser sciatic foramen:
- Obturator internus muscle (m. obturatorius internus) — passes from the lesser pelvis into the gluteal region.
- Pudendal neurovascular bundle (a. et v. pudendae internae, n. pudendus) — returns from the gluteal region into the ischioanal fossa, passing under the sacrotuberous ligament.
Class and exam questions
Which bones make up the bony pelvis?
The bony framework is formed by the paired pelvic bones (ilium, pubis, and ischium), as well as the sacrum and coccyx.
What reinforces the pubic symphysis anteriorly and inferiorly?
Superiorly, the pubic symphysis (symphysis pubica) is reinforced by the superior pubic ligament (lig. pubicum superius), and inferiorly by the arcuate ligament of the pubis (lig. arcuatum pubis).
How are the greater and lesser sciatic foramina formed?
They are formed by the sacral ligaments (lig. sacrospinale and lig. sacrotuberale), which run to the ischial spine and ischial tuberosity, converting the greater and lesser sciatic notches into foramina.
What else to study on this topic
- Anatomy of the sacroiliac joint
- Topography of the greater and lesser sciatic foramina
- Clinical significance of palpating pelvic bony landmarks
- Structure and branches of the pubic bones
- Functional biomechanics of the pelvic ligamentous apparatus
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Other topics in the section "Topographic Anatomy of the Pelvis and Perineum"
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