HIP JOINT Flashcards
WK 10 (13 cards)
Functions of the pelvis
- Support and protect pelvic viscera (lower abd organs)
- Provide bony support for birth canal
- Provide area for muscle attachment
- Support weight of head trunk and upper limbs
- Allow for weight transfer:
- From trunk -> lower limb
- Standing -> weight to femurs
- Seated -> weight to ischial tuberosities
Pelvic inlet: (brim)
▪ Pubic crest
▪ Pectineal line
▪ Arcuate line
▪ Sacral alar + promo
* Promontory
Pelvic outlet
▪ Apex of coccyx
▪ Ischial tuberosities
Pubic symphysis (inf ridge)
True VS False Pelvis
True pelvis
- Inf to pelvic inlet
False pelvis
- Sup to pelvic inlet
Differences between male and female pelvis
Pelvic Inlet:
Male: Heart-shaped — narrower and more obstructed.
Female: Wider, oval or round — adapted for childbirth.
Ischial Spines:
Male: Closer together — makes the pelvic cavity narrower.
Female: Further apart — allows a wider birth canal.
Sacral Promontory:
Male: More prominent — reduces pelvic inlet space.
Female: Less prominent — creates a more open pelvic inlet.
Sub-Pubic Angle:
Male: Acute (less than 70–75°) — forms a V-shape.
Female: Obtuse (greater than 80–85°) — forms a U-shape.
Ala (Wings) of Ilium:
Male: Narrower and more upright.
Female: Wider and more flared laterally.
Hip joint - Pubic Symphysis
location
structure
classification
movement
location:
- bw symphyseal surf of pubic bones
structure:
- fibrocart disc
- supported by ligs
classification:
- 2ndary cart joint (symphysis)
movement:
- slightly
* Except in childbirth -> relaxin hormone softens the fibres
Hip Joint - Sacro-iliac Joint
anterior / posterior
articular surf
ligaments
Anteriorly: syonvial, plane, non-axial
* Auricular surface of the ilium and sacrum
- A sacro-liac lig
- Iliolumbar lig
- I/O sacroiliac lig
Posteriorly: fibrous due to I/O ligs
* Tuberosities for the fibrous part of the joint
- P sacroiliac lig
- Sacrotuberous lig
- Sacrospinous lig
Dorsal/Interosseous:
- Interosseous sacroiliac lig
Weight transfer thorugh the pelvis
- Weight t/ferred thru vert column
- Pushes sacrum inferiorly, generating shear forces.
- The sacrum to wedge between the ilia
- Irregular joint surfaces interlock.
- SI ligs become taut
- Self-locking mechanism -> stabilizes the pelvis.
Movements of the sacroiliac joint due to force
Nutation VS Counternutation
small gliding, slight rotation
Nutation:
* A/inf rotation of the sup sacrum to absorb shock
* P movement of the coccyx
* ↑ stability of the SI joint by tightening the SS + ST ligs,sacral wedge shape, & interlocking joint surfaces.
* Examples: Standing, squatting, childbirth
* ↑ pelvic outlet, ↓ pelvic inlet
Counternutation:
* A/sup rotation of the inf sacrum to lift it against gravity
* A movement of the coccyx
* ↑ mobility and unload SIJ
* Resisted by: posterior SI lig, supported by the multifidus muscle
* Examples: Trunk extension, early stance phase of gait
* ↑ pelvic inlet, ↓ pelvic outlet
Form closure (passive stability) VS force closure (active stability)
Form closure (passive stability):
what: Anatomical structures
eg:
- Interlocking joint surfaces of SIJ
- Wedge-like shape of the sacrum
- Ligament tension (SS, ST)
work to resist excesive movement @ SIJ t/f ↑ pelvic joint stab when under ↑ loads
Force closure (active stability):
what: Muscles and fascia
eg:
- Myofascial oblique sling system eg. Glutes, lats, internal obliques -> generate active tension -> compresses SIJ -> ↑ joint integrity when under ↑ laods, especially when passive structures alone (form closure) are inadequate.
Movements of the pelvis
Coronal plane
anteroposterior axis
Movements of the pelvis
Sagittal plane
transverse axis
Movements of the Pelvis
Transverse plane
Vertical axis
