Sheet no. 12

Lower appendicular skeleton

Lower appendicular skeleton consist of:
1-pelvic girdle

2-bones of lower limb

Pelvic girdle (pelvis) consists of 4 bones united by 4 joint.

The 4 bones are:

1- Right hip bone.

2- Left hip bone.

3- Sacrum.

4- Coccyx.

The 4 joints are:

1- Right sacroiliac joint: its synovial joint and it join ilium
And sacrum.

2- Left sacroiliac joint: its synovial joint and it join ilium
And sacrum.

3- Sacrococcygeal joint: it’s cartilaginous joint and it join sacrum and coccyx.

4- Symphysis pubis: it’s fibrous joint and joins left & right pubic bone.

Hip bone:

Ø It’s contributed from 3 bones that united at its lateral side on the outer surface at a cup-shape cavity called acetabulum that ossified at age 17.

Ø The site of union forming Y-shape which is cartilaginous before 17 & it allow the X-rays to pass through it.

Ø It’s an example of flat bone which contain large amount of bone marrow and it is the common site to take bone marrow biopsy for bone marrow transplant especially for the case of cancer.

Ø It has outer surface (for muscle of thigh or lower limb) & inner surface (for pelvis).
Ø The 3 bones are: ilium, pubic, ischium.

Ilium:

like oriental fan, and it has the following part:

1- body: where it’s united at the acetabulum.

2- Wing or (blade) (in Latin it’s called ala):
· It has outer concavoconvex surface creating 3 elevated lines (convexities) for muscles attachment, the lines are called: anterior, middle, posterior gluteal lines, which give origin in gluteal region.
· It has inner surface which is concave and form iliac fossa which give origin to a muscle called iliacus.

3- Free margin: it’s called iliac crest and it has:
A- Anterior end called anterior superior iliac spine (asis).
B- Posterior end called posterior superior iliac spine (psis).
(The iliac crest extends from (asis) to (psis)).
C- iliac tubercle: located 2 inches behind anterior superior iliac spine.

4- Anterior inferior iliac spine: it’s located below (Sais), it’s not in iliac crest.

5- Posterior inferior iliac spine: it’s located below (psis), it’s not in iliac crest.

Note: ilium has 4 spines: anterior superior iliac spine & posterior superior iliac spine & anterior inferior iliac spine & posterior inferior iliac spine.

Pubic bone:

It’s like a letter (V) on its side and it has 3 parts:
1- body: medial and it united with the opposite one at
Symphsis pubis.
2- Superior pubic ramus: it is united with ilium at acetabulum. (Ramus mean small/short limb).
3- Inferior pubic ramus: it’s united with ischium.

Ischium:

It’s comma-shape bone, and has the following parts:
1- body: that united at acetabulum.
2- ischial tuberosity: it’s the weight bearing site while sitting on a chair.
3- ischial ramus: that unit with inferior pubic ramus.
4- ischial spine: triangular bone projecting medially.
Acetabulum:
· Cup shape cavity at the outer surface of hip bone.
· It’s the site of union of the 3 bones forming Y-shape area which is cartilaginous before age 17.
· The acetabulum is defected inferiorly forming acetabular notch that allows arterial supply to head of femur to pass through.
· It articulates with head of femur to form hip joint.





To see more figure about this lecture see these books:
-Clinical anatomy /by Snell/8th Ed/ page (557,558,645)
-Principles of human anatomy/by Tortora/10th Ed/
Page (213,214,215).

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Finally, I want to dedicate this sheet to all my friends specially:
M7md alwazeer,m7md sboo3,m7md taycer,m7md yousef,m7md almomany, nader 3oad,hashem aboma7fo’6, shaker barham, wasem samara, omar allozi, yezan al3tom, omar abo baker, 3amer sameer, qasma, ahmed, 3bd alrahman al5ateb, qusai abo 3azam, abo 5adega, zaid, 3adnan, mo2mn ,7amza jassar, zakarea, zaedon abo 5raes, mo5tar.


احر التعازي لاخونا وزميلنا في كلية الطب محمد المومني الذي فقد عمته
Best wishes for all medical students in ju.
M7md bader