Week 2 - The Pelvis: Bony Features, Joints And Ligs Flashcards
What does the pelvis consist of
The hip bone and sacrum which are connected via the sacroiliac joint
What is the hip bone also know as
Pelvic girdle
What is the hip bone composed of
Three fused bones - ilium, ischium and the pubic bone
What is the pelvic spine
It is the posterior portion of the pelvis below the lumbar spine
What is the pelvic spine composed of
The sacrum and coccyx
What do the sacrum and coccyx form
They are connected anteriorly by the pubic symphsis and posteriorly, they articulate with the pelvis spine to form the SACROILIAC JOINTS
What are some functions of the pelvis
- it carries the entire weight of of the upper body
- stabilises and transmits the upper body to the lower limbs which allows various actions to occur
- it provides the attachment point for muscles and reproductive organs
What are the ilium, ischium and pubis known as
- innominate bones
- pelvic bones
- coxal bones
What are the two surfaces of the hip bone
Lateral and medial
What does the lateral surface comprise of
Its most prominent landmark of the bone of the acetabulum
What is the acetabulum ?
It is a socket shaped articular surface via which the hip bones articulates with femur and makes the hip joint. It has a “C” shaped acetabulur labrum and is completed inferiorly by the transverse acetabular ligament.
What three bones are arranged within the acetabular ?
- ilium
- ischium
- pubic bone
Describe the ilium as a characteristic arrangement of the acetabulum
It extends superiorly to the hip joint, therefore, it comprises the superior portion of the acetabulum
Describe the ischium as a characteristic arrangement of the acetabulum
It is the massive posteroinferior part of the hip bone which fits into the posterioinferior third of the acetabulum
Describe the pubic bone as a characteristic arrangement of the acetabulum
It builds the anterioinferior third of acetabulum and is the anterioinferior part of the bone that articulates with the contralateral hip bone
What is the obturator foramen ?
It is an important landmark which is a large opening located anteroinferior to the acetabulum, bounded by the ischium and pubis
What is the function of the obturator foramen
It serves as the communication between pelvic and thigh regions through which neurovacular structures pass
What is the ilium ?
It is a blade-shaped bone found superior to the hip joint
What does the ilium consist of?
- the body of ilium: a smaller, inferior part which contributes to the formation of the acetabulum
- ala = the superior part which is a large, flat portion of the bone that has 4 borders and 3 surfaces
What is the ASIS?
It is located at the anterior end of the iliac crest. It serves as a point of attachment for the inguinal ligament
What is the AIIS?
It is located anterior to the supra-acetabular groove and acetabular margin. It provides points of attachment for the rectus femoris and proximal part of the iliofemoral ligament. It is separated front the ASIS by a short, vertical slope.
What is the PSIS?
It is located at the posterior end of the iliac crest. It is laterally related to the iliac tuberosity and sacropelvic surface
Where is the PIIS located
Inferior to the the PSIS
What is the iliac crest ?
It is a rough, crescentic surface that starts at the PSIS posteriorly and arches forward to end at the ASIS anteriorly. It has inner and outer lips
What is the anterior border of the ilium
It extends from ASIS to the acetabulum. It features the AIIS just superior to its acetabular end. The part of the border between the spines is concave anteriorly
What is the posterior border of the ilium
It begins at the PSIS and extends to the posterior border of ischium. It features a PIIS.
What is the gluteal surface ?
It is bounded superiorly by the outer lip of the iliac crest and inferiorly by the inferior gluteal line
What does the gluteal surface represent ?
The posterolateral face of the bone
What are 3 features of the gluteal surface
It features 3 gluteal lines that provide attachment points for the gluteal and thigh muscles
What is the inferior gluteal line
It runs just above the acetabular margin
Where is the posterior gluteal line located?
Just above and anterior to the greater sciatic notch and both posterior iliac spines
Where is the anterior gluteal line located?
It travels obliquely along the gluteal surface from the tubercle of the iliac crest toward the posterior gluteal lien
What is the iliac fossa
It is bounded superiorly by the inner lip of the iliac crest, inferiorly by the arcuate line and posteriorly by the anterior borders of the the iliac tuberosity and auricular surface of ilium
What is the iliac tuberosity
It provides a point of attachment for ligaments and muscles of the back and lower limb
Where is the ischium located?
It is found posteroinferiorly to the hip joint
What is the ischium
It is an ‘L’ shaped bone continuous superiorly with the ilium and anteriorly with the pubic bone. It consists of two parts - the body and ramus
What is the body of ischium
It is rough and broad with 3 bony surfaces - medial/pelvic, lateral/femoral and posterior surfaces
What is the ramus of the ischium
It is a roughly cylindrical, branch-like part of the ischium which extends anteromedially from the interior aspect of the body to meet the inferior pubic ramus. These bony rami form the inferior border of obturator foramen
What is the pubic bone/pubis
It has a small body located medially and two rami (superior and inferior) extending posterolaterally.
What is the pubic crest
It separates the anterior and posterior surfaces of the bone. It features the pubic tubercle ofn its lateral end. It also serves as a point of attachment for the inguinal ligament and can be used clinically to locate the rings of the inguinal canal
Where is the pubic arch?
It is the curved area below the pubic symphysis. It is one of the sexually dimorphic areas of the pelvis as it shape differs form male to female
Where is the superior pubic ramus located?
It starts at the pubic tubercle and extends posterolaterally and upwards to the acetabulum
Where is the obturator surface of superior ramus located
It faces posteroinferiorly and is bounded anteriorly by the obturator crest and inferiorly by its own sharp inferior border
Where is the pelvic surface located ?
It faces posterosuperiorly and is relatively smooth compared to the anterior surface. It is limited by pecten pubis above and the inferior border below
Where is the inferior pubic ramus located
It projects posteroinferiorly and laterally front the superolateral angle of the pubic body. It continues and unites with the ischial ramus to complete the obturator foramen
What is the sacrum
It is a triangular bone that consist of five fused sacral vertebrae
What is the sacrum comprised of
- anterior (pelvic) surface: smooth and concave
- posterior (gluteal) surface: rough, irregular and convex
- a base
- 2 alae
- an apex
What is the sacral promontory
It is at the base of the sacrum and features a slight projection at the midline.
What is the function of the sacral promontory ?
It helps in defining the pelvic diameters
What is the sacroiliac joint
It is a synovial joint between the ala of sacrum and the auricualr surface of the ilium
What movement does the sacroiliac joint prevent
It allows for very little mobility through slight gliding and rotation movements
What is the sacrococcygeal joint
It is an amphiarthrodial (limited mobility) joint between the 5th sacral and 1st coccygeal segment
What movements does the sacroccoygeal joint have
It allows flexion and extension of the coccyx - these movements are rather passive as they occur during child birth and defecation
What is the pubic symphysis
It is a secondary cartilaginous joint between the medial surface of the pubic bones
What movements occur at the pubic symphysis
There tends to be no movement on this joint, expect during pregnancy when the ligaments and cartilage soften which allows the increase of pelvic diameters during labor
