Sacrum: Description
The sacrum is an element of the bony pelvis
Location: forms the posterior aspect of the pelvic ring
Function: transmission of force between the pelvis and the spinal column
Sacrum: Gross anatomy
Inverted triangle in shape
Formed by the fusion of 5 sacral vertebrae
Concave anterior
Sacrum: Features
Sacrum: Articulation
Sacrum: Ligaments
Sacrum: Neurovasculature
Blood supply:
Venous drainage:
Lymphatics:
Sacrum: Variants
Hip bone: Description
The hip bone is a large paired flat bone of the pelvis.
Function: Forms the lateral and anterior aspects of the bony pelvis
Ilium
Superior part of the hip bone
Made up of a body and wing separated by the arcuate line
Forms the sacroiliac joint with the sacrum via the articular surface
Forms the superior aspect of the acetabulum
Anterior and posterior, superior and inferior iliac spines
Forms most of the greater sciatic notch
Ischium
Posterior inferior part of the hip bone
Made up of a body and a ramus
Forms the lower acetabulum
Forms the posterior part of the obturator foramen
Forms the lower part of the greater sciatic notch and all of the lesser sciatic notch with the ischial spine between them
Inferiorly is the ischial tuberosity
Pubis
Anteromedial body with a superior and inferior ramus
Forms the anterior aspect of the obturator foramen
Symphysial surface of the body of the pubis forms the pubic symphysis
Pubis tubercle located superior and lateral to the pubic symphysis
Forms the anterior aspect of the acetabulum
Sacroiliac Joint: Description
Paired symmetrical synovial and fibrous joint between the ilium and the sacrum
Location: S1-S3 level oblique plane
Movement: little movement, main function is transfer of weigh between the axial and lower appendicular skeletons.
Sacroiliac joint: Articulation
Sacroiliac joint: Ligaments
Sacroliac joint: Relations
Sacroiliac joint: Neurovasculature
Arterial:
Venous: same named veins
Innervation: Branches of the lumbar and sacral plexus
Sacroiliac joint: Variant
Accessory sacroiliac joints
Pubic symphyisis
The pubic symphysis is a midline secondary cartilaginous joint between the articular surfaces of the pubic bodies
Movement: minimal shift and rotation, may widen during pregnancy and child birth
Pubic symphysis: Gross anatomy
Pubic Symphysis: Ligaments
Pubic symphysis: Muscles
Symphysis pubis: Relations
Anterior – proximal penile/clitoral shafts
Inferior – Urethra, deep dorsal vein of the penis/clitoris
Posterior – Bladder, retropubic fat, Prostate and prostate venous plexus
Pubic symphysis: Neurovasculature
Blood supply:
Obturator and inferior epigastric arteries
Innervation:
Pudendal nerve
Levator ani: Description
The lavator ani also known as the muscular pelvic diaphragm is the musculotendinous sheet that forms the majority of the pelvis floor.
Function: supports the pelvic viscera and aided in urinary and faecal continence