Pelvic Region Anatomy

• The pelvic region includes the sacrum, coccyx, and two innominate bones, which are the ilium, ischium, and pubis
• The acetabulum is connected by the triradiate ligament

Sacrum

• Features include a sacral promontory, lateral mass, L-shaped articular surface, sacral cornu, sacral hiatus, median crest, and anterior and posterior sacral foramina

Coccyx

• Has a coccygeal cornu

S2

• Region represents the center of gravity from an anterior view

S2 to S4

• This describes the location in relation to "nutation" (bow of sacrum)
• "Counternutation" is when the coccyx goes upwards

Normal alignment

• PSIS and ASIS are at the same level

Anterior Superior Iliac Spine

• The sartorius muscle attaches to this
• It is aligned posteriorly with S2

Acetabulum

• Has a horseshoe-shaped surface that articulates with the lunate surface
• The acetabular fossa does not articulate with the femur
• The acetabular notch is bridged by the transverse acetabular ligament
• The acetabular labrum extends deep on the acetabulum

Iliac crest

• Features include the inferior gluteal line, a medial and posterior region, the highest point at L4, and the iliac tubercle at L5
• The dimple of Venus corresponds to the PSIS and is palpable

ASIS

• The sartorius muscle is attached

AIIS

• This is where the rectus femoris muscle attaches

PIIS

• This is non-palpable

Tensor fascia latae

• Located between the iliac crest and tibia (iliotibial tract)

Iliacus

• Found in the iliac fossa

Bones and Features

• The iliopectineal line, ischial spine, ischial tuberosity, body of ischium, and ramus of ischium

Ligaments

• The sacrospinous ligament forms the pelvic inlet, while the sacrotuberous ligament forms the pelvic outlet

Muscles

• Both the superior and inferior longus muscles, the superior longus is the abductor longus

Ischial tuberosity

• This is the insertion for the hamstring muscles

Ischial dorsal

• Irritation can arise from excessive sitting pressure

Sciatic nerve

• Located in the inferomedial quadrant, with the safest injection site being the superior part

Key Features

• Pubic crest and tubercle.

Pelvic Inlet vs. Pelvic Outlet

Pelvic inlet (pelvic brim)

• Separates the false and true pelvis
• Includes sacral promontory, iliopectineal line, and symphysis pubis

Pelvic outlet

• The pelvic floor below is also called the perineum

Pubic Arch

• Rounded in females
• Triangular in males

False Pelvis

• Features the lumbar vertebrae, iliac fossa, and abdominal wall
• Anterior tilting of the pelvis results in an increase in lumbar lordosis

True Pelvis

• Includes the pelvic brim and pelvic cavity

Anterior Pelvic Wall

• Includes bodies of the pubis, pubic rami, and symphysis pubis

Innominate Bone

• This is where only the hip bone moves; not the sacrum

Posterior Wall

• Includes the sacrum, coccyx, piriformis muscle, and parietal pelvic fascia

Lateral Wall

• Includes the lower pelvic inlet, obturator membrane (internus & ligament), and sacrotuberous ligament

Inferior Pelvic Wall

• Includes the pelvic floor/pelvic diaphragm
• The stability of the lumbar trunk is achieved by the levator rami and coccygeal muscles

Foramens in Pelvis

• The greater sciatic foramen connects the pelvis to the gluteal region
• The lesser sciatic foramen connects the gluteal region to the perineum, excluding the obturator internus tendon
• The Obturator foramen - obturator canal

Piriformis Syndrome

• This is when the sciatic nerve becomes impinged, causing sciatica (pain that travels)

Joints

• Includes sacroiliac joints

Ligaments

• Interosseous, Posterior sacroiliac, Anterior sacroiliac, Sacrospinous, Sacrotuberous, and T ligaments
• The anterior is thinner but stronger

T Ligament

• Connects the L5 to the iliac crest, preventing excessive nutation and counternutation

• Other Joints

• Sacrococcygeal, lumbosacral, and hip

Pelvic motion

• Anterior tilting involves flexion of the hip joint and lumbar extension
• Posterior tilting involves lumbar flexion

Impact of the Femur

• Right hip hiking is enabled by the gluteus medius, assisted by the gluteus minimus

• Pelvic drop when weak

• Left forward rotation creates internal rotation on the right side, backward creates external rotation on the right side

• Asymmetrical stands mean Trendelenburg sign where the right hip is weak and the left hip will drop

Counter Nutation

• Angat sacrum leads to an expanded inlet and a narrower outlet

Femur Anatomy

Notable Parts

• Head, fovea capitis, neck, greater and lesser trochanters, and intertrochanteric line (quadratic tubercle) and crest
• The Medial condyle is more mahaba than the lateral portion that is more umbok

Surfaces

• Patellar, popliteal, and intercondylar

Coxa

• Volga vs. Coxa Vera is more common in femoral fractures

Femoral Osteotomy

• Includes Femoral neck, Femoral shaft, and more

Femoral torsion

• Range is 13-18 and accompanied by out-toeing
• Larger internal rotation characterized anterversion

Ligamentum teres

• Contains conduit for vessels and nerves, and it has taut flexion with adduction

Bony Composition

• Two hip bones to form lateral/anterior walls
• Sacrum to form the back
• Coccyx to form the back

Pelvic brim

• The pelvic brim divides the pelvis into two parts
• False helps guide the fetus

Canal

• Bony canal through which the child passes during birth.

Pelvic Outlet

• Posterior coccух, Lateral ischial tuberosities, Anterior pubic arch

The Sacrotuberous ligament

• Runs superior to The PIIS

Sacrospinous ligament

• Attached to the spine of the ischium

Obturator membrane

• Almost closes the obturator

Anterior Pelvic Wall

• The shallowest

Posterior pelvic wall

• The most extensive

Sacrum

• Articulates with iliacs to form sacroiliac joints

Key features

• Lumbosacral joint to aid flexion

Hip Bone - the acetabulum

• Ilium - The iliopectineal line divides the false from the true pelvis

DIAPHRAGM

• Allows passage of urethra

Piriformis and sacral

Joint Movement

• Has Small but limited supply of movement