Musculoskeletal: Anatomy - Bones of lower limb Flashcards
Components of the pelvic girdle
Sacrum
Right and left hip bones
Joined anteriorly at pubic symphysis
Function of the pelvic girdle
Attaches free lower limb to axial skeleton
Protective and supportive function for abdomen, pelvis, perineum and lower limbs
How are the femurs directed? What is the purpose?
Oblique orientation directed inferomedially
Returns centre of gravity following transfer of body weight from pelvic girdle to femurs
Two roles of the fibula
Muscle attachment
Formation of ankle joint
Does not bear or transfer weight (as it does not articulate with the femur)
Three primary bones which fuse to make the hip bone
- Ilium
- Ischium
- Pubis
When do the ilium, ischium and pubis fuse to create the hip bone?
End of teenage years
Describe the ossification and fusion of the hip bone
At birth: three primary bones joined by hyaline cartilage
Children: incomplete ossification
By age 9: ischiopubic rami fuses
By puberty: three bones separated by triradiate cartilage
Between 15-17yo: bones begin to fuse
Between 20-25yo: fusion complete
Describe the components of the acetabulum
Ilium forms superior part
Pubic forms anterior part
Ischium forms posteroinferior part
Where does a person’s body weight rest when sitting?
Ischial tuberosity
What makes up the boundaries of the obturator foramen?
Pubis and ischium and their rami
What closes the obturator foramen? Is this closure complete?
Obturator membrane
Not complete: small passageway (obturator canal)
What structures are carried within the obturator canal?
Obturator nerve and vessels
What is the name of the articular surface of the hip that receives the femoral head?
Lunate surface of the acetabulum
What is the longest and heaviest bone in the body?
Femur
What is the length of the femur in relation to a person’s height?
~1/4
What is the significance of the fovea?
Medially placed depression for the ligament of the head
In early life, the ligament gives passage to an artery supplying the epiphysis of the femoral head
Is the angle of inclination greater or smaller in females? Why?
Smaller
Increased distance between acetabula (due to the wider lesser pelvis) and greater obliquity of the femoral shaft
What is the effect of age on the angle of inclination?
Decreases
What is the normal angle of inclination in an adult?
126 degrees
What is the normal angle of torsion (or declination) in males and females?
Males: 7°
Females: 12°
Describe the normal pattern of bowing in the femur. How is this changed in rickets?
Slight convexity anteriorly
In rickets this may increase and proceed laterally as well as anteriorly due to weaking of the shaft
What vertebral level does the iliac tubercle correspond to?
L5
What muscular landmark does the gluteal fold correspond with?
Fat pad associated with the inferior border of gluteus maximus
What type of bone is the patella? How does it form?
Sesamoid
Forms within the tendon of quadriceps femoris
What two factors keep the patella centred in the intercondylar groove of the femur during extension at the knee?
Vertical ridge of posterior articular surface of patella
Balanced pull of vastus muscles
What is the second largest bone in the body?
Tibia
What are the three surfaces of the tibia?
Medial
Lateral-interosseous
Posterior
What makes up the shin?
Anterior border and medial surface of the tibia
Where does the patellar ligament attach distally?
Tibial tuberosity
Where is the tibial shaft thinnest?
Junction between middle and distal thirds
What replaces the interosseous border of the tibia inferiorly? What is this landmark’s purpose?
Fibular notch which accommodates and provides fibrous attachment to the distal fibula
What is the nutrient foramen?
Obliquely directed vascular groove immediately distal to the soleal line leads to the nutrient foramen
From it the nutrient canal runs inferiorly in the tibia before opening into the medullary cavity