Topic 10: The Pelvis Flashcards
(61 cards)
1
Q
The Pelvis bones
A
- Right & Left hip Bones
- sacrum
- joints
- hip x2
- symphysis pubis
- sacroiliac x2
2
Q
Pelvic girdle bones
A
- hip bones
- many texts also say sacrum
3
Q
Orientate the pelvis (anatomical position)
A
- ASIS and pubic tubercles line up in the same coronal plane
- inferior part sacrum/top of coccyx lies just above symphysis
- right and left ASIS line up in the horizontal plane (usually)
- Acetabulum directed inferolaterally
4
Q
Functions of the pelvis
A
- support and protect pelvis viscera (& lower abd viscera)
- provides bony support for the birth canal (provides an exit for foetus)
- provides extensive muscle attachment sites
- supports the weight of the head, trunk, and upper limbs
- allows for weight transfer
- from trunk to lower limb
- standing – weight to femora
- seated – weight to ischial tubs
5
Q
How many muscles attach to the pelvis?
A
36
6
Q
Pelvic inlet
A
junction between the greater and lesser pelvis (bony edges = pelvic brim)
7
Q
Pelvic Inlet (brim) functions
A
- Marks the boundary between the greater & lesser pelvis
2. determines the size & shape of the birth canal, with the prominent ridges a key site for attachment of muscles & ligs
8
Q
Pelvic Inlet (brim) bones
A
- pubic crest
- pectineal line
- arcuate line
- sacral alar and promontory
9
Q
Pelvic Outlet location
A
end of the lesser pelvis, and the beginning of the pelvic wall
10
Q
Pelvic outlet bones
A
- coccyx (tip of)
- ischial tuberosities
- pubic symphysis (inferior part)
11
Q
False (greater) pelvis
A
Superior to pelvic inlet
12
Q
False (greater) pelvis function
A
Supports the lower abd viscera
13
Q
True (lesser) pelvis
A
inferior to pelvic inlet
14
Q
True (lesser) pelvis function
A
Within the lesser pelvis reside the pelvic cavity and pelvic viscera
15
Q
Male Pelvis inlet shape
A
Heart
16
Q
Male Pelvis sacral promontory (inlet)
A
more prominent
17
Q
Female pelvis inlet shape
A
Round
18
Q
Female pelvis ischial spines
A
further apart
19
Q
Female sub-pubic angles
A
greater
20
Q
Alar of female ilium
A
wider
21
Q
Pubic Symphysis classification
A
Secondary cartilaginous joint
22
Q
Pubic symphysis features
A
- fibrocartilage disc in between the 2 symphyseal surfaces of both pubic bones
- supported by ligaments
- osteitis pubis (inflammation of the bone of the pubis)
23
Q
Pubic symphysis ligaments
A
- superior ligament
- arcuate ligament
- anterior ligament
24
Q
Pubic symphysis mvmts
A
Limited movement
- exception in pregnancy when the fibres soften (separation of the joint)
- under the influence of the hormone relaxin
25
Sacroiliac Joint classification
```
Anteriorly
- synovial, plane joint
Posteriorly
- fibrous joint
--> due to massive interosseus ligaments
```
26
Sacroiliac Joint Joint surfaces
- are smooth in infants
- develop a series of complementary ridges and depressions with age
- -> these interlock and aid joint stability
- joint cavity obliterated with advancing age
27
Sacroiliac Joints articular surfaces (synovial part)
- auricular surface of the ilium
- auricular surface of the sacrum
- tuberosities for fibrous part of the joint
28
Sacroiliac ligaments (anterior) functions
1. provides stability + attenuates forces to lower extremities
2. prevents sacrum + spine from moving inferiorly
3. prevents tendency of ilium to move laterally
29
Interosseus sacroiliac ligament functions
1. slightly movable (syndesmosis)
2. stability
3. keeps jt together
4. fills space at the back of joint
5. limits nutation
6. divides the sacroiliac joint into ant + post
30
Iliolumbar ligament function
1. stabilises lumbosacral spine on the pelvis
| 2. supports the lower lumbar spine; they join the 4th and 5th lumbar vertebrae to the iliac bone crest @ back of pelvis
31
Sacroiliac ligament (posterior/ dorsal)
Long & short fibres
32
Sacroiliac ligament (posterior/ dorsal) functions
1. provides stability and attenuates forces down to the lower extremities
2. prevents sacrum + spine from moving inferiorly
3. prevents tendency of ilium to move laterally
33
Sacrotuberous ligament (post) function
1. stability
2. limits nutation
3. locks inferior sacrum
4. reinforced by biceps fem
on ischial tub
34
Sacrospinous ligament functions
1. limits nutation
- - when you bring sacrum forward, the ligament = more tense
2. connects ischial spine to sacrum
35
Weight transfer through the pelvis
Sacrum= suspended between innominate bones
- weight pushes the sacrum inferiorly (shear force)
- sacrum becomes 'wedged' in
- irregular joint surfaces interlock
- ligaments come under tension
- ligament attachments mean the ilia are pulled towards the sacrum
- sacroiliac joint self-locks
36
Sacroiliac Joint movements - due to FORCES not MUSCLES
Movements:
- small magnitude of gliding rotation movements
- nutation
- counter-nutation
37
Nutation
Anterior rotation of superior sacrum
38
Counter-Nutation
Anterior rotation of inferior sacrum/ posterior rotation of superior sacrum
39
Which ligaments resist nutation
1. Sacrotuberous ligament
| 2. Sacrospinous ligament
40
Form and Force Closure
The stability for the high loads transferred through the jts of the pelvis come from both form & force closure
41
Form Closure
Stability of the joint from pelvic anatomy design (passive structures)
42
Force Closure
Describes the other forces acting across pelvic jts to create stability (active structures incl. fascia)
43
Form Closure (passive structures)
- joint configuration- ridged, interlocking surfaces
- Joint surface alignment relative to
1. gravity and bodyweight - “keystone-like” shape
- Tension in the restraining ligaments associated with normal
alignment of the segments
44
Force Closure (active structures)
- refers to the interaction of multiple muscles
- which act across the joint to enhance compression on the joint surfaces
- this assists in joint stability
- is the so-called active myofascial oblique sling system
45
Myofascial oblique sling system
Holds things together and maintains posture (muscles and fascia)
46
Movements of the pelvis in the coronal plane
- Around an A-P axis
1. pelvic lift (tilt)
2. pelvic drop (tilt)
- corresponding lateral flexion of the lumbar spine (contralateral flexion with pelvic drop)
- corresponding hip abduction with pelvic drop
47
Pelvic Drop produced by:
Ipsilateral gluteus medius
| Contralateral hip adductors
48
Pelvic Lift produced by:
Contralateral Gluteus medius
| Ipsilateral hip adductors
49
Pelvic drop movement controlled by:
Contralateral Gluteus Medius
| Ipsilateral Hip adductors
50
Pelvic lift movement controlled by:
Ipsilateral gluteus medius
| Contralateral hip adductors
51
Movements of the pelvis in the sagittal plane
1. anterior pelvic tilt
2. posterior pelvic tilt
Corresponding increase lumbar lordosis with anterior pelvic tilt
Corresponding hip flexion pelvic tilt
52
Pelvic tilt vs nutation/ counter-nutation:
nutation/ counter-nutation = rotation of the SACRUM
| anterior/ posterior pelvic tilt = rotation of the ENTIRE pelvis
53
Anterior Pelvic tilt produced by
hip flexors
54
Posterior pelvic tilt produced by
hip extensors
55
Anterior pelvic tilt controlled by
hip extensors
56
Posterior pelvic tilt controlled by
hip flexors
57
Movements in the horizontal (transverse) plane
1. Rotation to the right
2. Rotation to the left
Corresponding contralateral hip ER i.e. rotate to the right = left hip will externally rotate
58
Pelvic rotation to the R produced by:
Left hip lateral rotators
| Right hip medial rotators
59
Pelvic rotation to the L produced by:
Left hip medial rotators
| Right hip lateral rotators
60
Pelvic rotation to the R controlled by:
Right hip lateral rotators
| Left hip medial rotators
61
Pelvic rotation to the L controlled by:
Right hip medial rotators
| Left hip lateral rotators
