PHTY100 Lecture Notes - Lecture 11: Fibrocartilage, Coronal Plane, Abdominal Internal Oblique Muscle
ANAT week 11 LA Joints and Movements of the Pelvis
- Can ignore the movements with the muscles we haven’t done yet (greyed out bits)
Joints of the Pelvis
The Pelvic Girdle
- Closed osteoarticular ring
o4 bones:
2 x innominate bones
Sacrum fusion of 5 sacral vertebra
Quite variable
Articulates with the two innominate bones
Coccyx
o4 joints:
2 x sacroiliac
Pubic symphysis
Sacrococcygeal
- Supports abdomen
- Dynamic link between thoracic, lumbar spine and lower limb
Pelvis
- Pelvic inlet = pelvic brim (red circle in diagram)
oPubic crest – pectineal line – arcuate line – sacral alar and promontory
- Above the inlet = technically abdominal contents therefore called false pelvis, below
the inlet = true pelvis
- Pelvic outlet (blue dotted line)
oTip of coccyx at the back – ischial tuberosities – inferior part of pubic
symphysis
oShaped a bit like a diamond
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Functions of the (True) Pelvis
- Houses and protects the pelvic
contents (viscera)
- Supports the weight of the head, trunk and arms
- Allows for weight transference from trunk to lower limb
- Supports the birth canal and provides an exit for the foetus
- Provides extensive muscle attachment sites
Male and Female Pelves
- Inlet shape round in female, heart-shaped in male
- Ischial spines everted in female
- Sacral promontory more prominent in male
- Sub-pubic angles greater in female
- Alar of the ilium wider in female
- These slight variations are all about making the pelvic outlet bigger in a female to
allow the baby to get out
Orientation of the Pelvis
- In the anatomical position:
oASIS and the pubic tubercles are in the same coronal plane
oInferior coccyx and superior pubic symphysis in the same horizontal plane
oThe left and right ASIS are in the same transverse plane
oPelvic brim faces anteriorly
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Pubic Symphysis
- A fibrocartilage joint between the two medial symphyseal surfaces of the pubic
bones
- Fibrocartilaginous disc wedged between two layers of fibrocartilage
- Supported by ligaments
- Little to no movement between bones
oException is in pregnancy when the fibres soften under the influence of
hormones associated with pregnancy
Sacroiliac Joint
- Synovial, multiaxial, plane joint
- Between the auricular surface of the ilium and the corresponding surface of the
sacrum
oJoint surfaces are smooth in infants, but develop a series of complementary
ridges and depressions with age, more marked in male than female
oCartilage on the sacrum side is much thicker than iliac side
oCartilage on iliac side is more fibrous than sacrum side
- Complementary ridges and depressions interlock and aid joint stability
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Anat week 11 la joints and movements of the pelvis. Can ignore the movements with the muscles we haven"t done yet (greyed out bits) Dynamic link between thoracic, lumbar spine and lower limb. Pelvic inlet = pelvic brim (red circle in diagram: pubic crest pectineal line arcuate line sacral alar and promontory. Above the inlet = technically abdominal contents therefore called false pelvis, below the inlet = true pelvis. Pelvic outlet (blue dotted line: tip of coccyx at the back ischial tuberosities inferior part of pubic symphysis, shaped a bit like a diamond. Houses (true) pelvis and protects the pelvic contents (viscera) Supports the weight of the head, trunk and arms. Allows for weight transference from trunk to lower limb. Supports the birth canal and provides an exit for the foetus. Inlet shape round in female, heart-shaped in male. These slight variations are all about making the pelvic outlet bigger in a female to allow the baby to get out.
