L2 - Pelvis & Hip Joint Flashcards
What is the function of the pelvic girdle?
How does it compare to the shoulder girdle?
it connects the vertebral column to the femurs
it is much stronger and less flexible than the shoulder girdle
What are the 3 bones and 3 joints of the pelvic girdle?
Bones:
- left and right innominate (hip) bones
- sacrum
Joints:
- 2 sacroiliac joints
- pubic symphysis joint
What is the main function of the pelvis?
it bears the weight of the upper body when walking
the vertebral column transfers body weight to the lower limbs through the pelvis
What is the secondary function of the pelvis?
it protects the pelvic viscera and blood vessels
it protects the foetus during pregnancy
What are the articulations of the innominate bones?
the innominate bones articulate posteriorly with the sacrum
they articulate anteriorly at the pubic symphysis joint
Label the features of the pelvic girdle
What are the 3 bones that fuse together to form the innominate (hip) bone?
What do they form when they fuse?
- ileum
- ischium
- pubis
These fuse at the acetabulum
What does the acetabulum articulate with?
the acetabulum articulates with the femoral head
this is the hip joint
Label the bones and articulation of the hip joint
What are the 2 main ligaments in the pelvis?
What structures do they form?
Sacrospinous ligament:
this runs from the sacrum to the ischial spine
this forms the greater sciatic foramen
Sacrotuberous ligament:
this runs from the sacrum to the ischial tuberosity
this forms the lesser sciatic foramen
How does the sciatic nerve pass through the pelvis?
it passes from inside the pelvis out into the lower limb via the greater sciatic foramen
Which colours represent the ligaments and the foramina of the of the pelvis?
red - greater sciatic foramen
green - lesser sciatic foramen
pink - sacrotuberous ligament
purple - sacrospinous ligament
What is the function of the acetabular labrum?
it is a lip of cartilage that deepens the articular surface
this makes the acetabulum a better fit for the femoral head
Label the features of the acetabulum
What is the role of the fibrous capsule?
it is a strong and dense fibrous capsule that surrounds the femoral head within the acetabulum
even if the femoral head is moving within the acetabulum, the fibrous capsule surrounding it keeps it stable
What are the proximal and distal attachments of the fibrous capsule?
proximal attachment:
rim of the acetabulum
distal attachment:
femoral neck (intertrochanteric line and greater trochanter)
What are the three ligaments of hip joint?
- pubofemoral ligament
- iliofemoral ligament
- ischiofemoral ligament
What is the role of the pubofemoral ligament?
it prevents excessive abduction
What is the role of the iliofemoral ligament?
it is the strongest ligament
it prevents hyperextension of the hip during standing as it “screws in” the femoral head
What is the weakest ligament of the hip joint?
ischiofemoral ligament
What is the function of the hip joint ligaments?
How do they acheive this?
- they spiral around the hip joint
- they become taut when the hip is extended
- they pull the femoral head into the acetabulum
THIS IMPROVES STABILITY
Which ligaments are shown in the diagram?
Which ligament is this?
ischiofemoral
What are the 3 factors that provide stability of the hip joint?
- the anatomy of the acetabulum
- fibrous capsule
- the ligaments - iliofemoral, ischiofemoral and pubofemoral
What are the typical injuries that occur to the hip?
- fractures to the pelvic ring
- dislocation of the hip joint
- fracture to the neck of the femur - ‘hip fracture’
What happens in a congenital hip problem?
children can have problems with development of the hip joint, leading to joint laxity, subluxation and dislocation of the hip
if this is not detected and treated early, the hip fails to develop
Label the features on the AP pelvis X-ray
Which points of the pelvis are common sites for fracture in elderly people?
the superior and inferior pubic rami
What is Shenton’s line?
Why is this clinically significant?
it is a smooth line along the medial aspect of the femur, over and around the top of the obturator foramen
in a hip fracture, Shenton’s line is often disrupted and no longer smooth