Anatomy Lecture 9.2-12.2
Pelvic and hip joints
Join ts of t he pel vis
• Lumbosacral; secondary cartilaginous IV joint and synovial
zygapophyseal joints
o Between the L5/S1 facets
• Sacroiliac:
o Partly synovial joint/ partly syndesmosis between articular
surface of the sacrum and the ilium
o Strong weight-bearing joint
• Pubis symphyseal (with a disc)
o It is a secondary cartilaginous joint between the pubic
bones
▪ A primary cartilaginous joint is between epiphyses
and growing bones, a secondary is a joint that
usually does not allow much movement and there
is usually a fibrocartilaginous disc between the two ends of the bone which have hyaline
cartilage lining (and the disc in the middle)
Lumbosacral joints
• There is lordotic curvature of the lumbar
spine
• The body weight is slightly anterior to this
joint, where it is transferred laterally to
the head of the femur (slightly posterior
to it) so the sacrum (because of the
curvature) has much more weight-bearing
on the proximal end so S1 is quite
important and robust, especially in
transferring weight laterally
• There is a primary kyphosis at the sacrum for this purpose
• The IV discs allow this curvature so there is deep lumbar lordosis at this joint
o The discs are wider anteriorly and thinner posteriorly
• At the lumbar vertebrae, the superior facets are medially orientated (on the outside) and the inferior facets
sit within these facing laterally
o But at L5/S1 because this is transitional, the superior facet is facing internally (actually
posteromedially) and the inferior face is anterolaterally
o So the inferior facet of L5 stops forward movement of the whole spine because of its orientation and
this is where spondolysthesis occurs
• The accessory ligaments are:
o The iliolumbar ligaments from the transverse process of L5 to the iliac
o The anterior longitudinal ligament
o The lumbosacral ligament from the transverse process of L5 to the sacrum
Pelvic and hip joints
Join ts of t he pel vis
• Lumbosacral; secondary cartilaginous IV joint and synovial
zygapophyseal joints
o Between the L5/S1 facets
• Sacroiliac:
o Partly synovial joint/ partly syndesmosis between articular
surface of the sacrum and the ilium
o Strong weight-bearing joint
• Pubis symphyseal (with a disc)
o It is a secondary cartilaginous joint between the pubic
bones
▪ A primary cartilaginous joint is between epiphyses
and growing bones, a secondary is a joint that
usually does not allow much movement and there
is usually a fibrocartilaginous disc between the two ends of the bone which have hyaline
cartilage lining (and the disc in the middle)
Lumbosacral joints
• There is lordotic curvature of the lumbar
spine
• The body weight is slightly anterior to this
joint, where it is transferred laterally to
the head of the femur (slightly posterior
to it) so the sacrum (because of the
curvature) has much more weight-bearing
on the proximal end so S1 is quite
important and robust, especially in
transferring weight laterally
• There is a primary kyphosis at the sacrum for this purpose
• The IV discs allow this curvature so there is deep lumbar lordosis at this joint
o The discs are wider anteriorly and thinner posteriorly
• At the lumbar vertebrae, the superior facets are medially orientated (on the outside) and the inferior facets
sit within these facing laterally
o But at L5/S1 because this is transitional, the superior facet is facing internally (actually
posteromedially) and the inferior face is anterolaterally
o So the inferior facet of L5 stops forward movement of the whole spine because of its orientation and
this is where spondolysthesis occurs
• The accessory ligaments are:
o The iliolumbar ligaments from the transverse process of L5 to the iliac
o The anterior longitudinal ligament
o The lumbosacral ligament from the transverse process of L5 to the sacrum
