Lower Appendicular Skeleton

Lower Appendicular Skeleton

Pelvic Girdle• Composed of sacrum, coccyx, and 2

coxae (hipbones)• Coxae have 3 distinct parts:

– Ilium– Ischium– Pubis

Pelvic Girdle, continued…..• Coxae parts fuse together in the

acetabulum, a cup-shaped area on the lateral surface of the hip that receives the head of the femur.

Ilium• Largest and uppermost portion of the

coxa• The upper edge is called the iliac crest• Joins the sacrum at the sacroiliac joint• Anterior superior iliac spine- the bony

prominence you feel as your “hipbone”

Ischium• Forms the lowest portion of the coxa• Ischial tuberosity

– Points posteriorly AND downward– Supports the weight of the body when

sitting• Ischial spine – a sharp projection above

the ischial tuberosity, near the junction of the ischium and ilium

Pubis• Anterior portion of the coxa• Two pubic bones join midline at the

symphysis pubis joint• Pubic arch

– Angle formed by pubic bones below the symphysis pubis

– Arch is wider in females

Female vs. Male Pelvis

Lower Limb• Femur• Patella• Tibia• Fibula• Tarsals• Metatarsals• Phalanges

Femur• Longest and strongest bone in the body• Head at top fits into __________of coxa• Greater trochanter – superior, lateral

process• Lesser trochanter – inferior, medial

process• Distal end:

– Two rounded processes posteriorly: lateral condyle and medial condyle

– Patella articulates anteriorly

Tibia• aka, “shin bone”• Proximal end:

– Medial and lateral condyles are concave and articulate with condyles of the femur

– Tibial tuberosity just below the condyles; attachment point for patellar ligament

• Distal end: medial malleolus forms prominent bony point of inner ankle

Fibula• Proximal: head

– Articulates with tibia just below the lateral condyle

– DOES NOT enter into knee joint or bear any weight

• Distal: lateral malleolus forms outer prominent bony part of ankle

Ankle (Tarsals)• “Tiger Cubs Need MILC”• Talus (A)

Calcaneus (“heal bone”) (K)Navicular (B)Medial cuneiform (D)Intermediate cuneiform (C)Lateral cuneiform (I)Cuboid (J)

Side View of the Bones of the Foot

Foot• 5 metatarsals

– numbered 1-5 starting medially– Heads at distal ends form the ball of the foot

• Phalanges– Toes– Each toe has 3 phalanges, except the big toe– What are the phalanges of each toe called?

(HINT: Just like the fingers)– Which phalanx is the big toe missing?

Joints• AKA “articulations” – functional

junctions between bones• Functions:

– Bind parts of the skeletal system– Make bone growth possible– Permit parts of the skeleton to change

shape during childbirth– Enable the body to move in response to

skeletal muscle contractions