Appendicular Skeleton: Lower Limb

Question 1

Lower Limb

Answer 1

Carries entire weight of body
Bones are thicker and stronger than the upper limbs
Femur (thigh bone) is the largest and strongest bone in the body

Question 2

Femur

Answer 2

Head of femur is carried on a neck that angles laterally to join shaft
Neck is weakest part of femur

Greater and Lesser trochanters are sites of muscle attachment.
Lateral and medial condyles articulate w/ tibia.
Lateral and medial epicondyles are the more raised parts of these condyles
The ridge along the posterior shaft (diaphysis) of the bone is the linea aspera. Used for muscle attachment

Condyles are separated anteriorly by a patellar surface
Condyles are separated posteriorly by intercondylar fossa

Question 3

Patella

Answer 3

Sesamoid bone (formed w/ CT)
Enclosed in tendon of quadriceps muscle
Protects knee joint and improves leverage of quadriceps muscles

Question 4

Tibia and Fibula

Answer 4

Tibia is larger and more sturdy. Located medially in leg

Fibula is thinner than tibia. Located laterally in leg.

Superior and inferior articulations, also connected by interosseous membrane

Tibia articulates w/ femur (at knee) and talus (at ankle)

Fibula does NOT articulate w/ femur at knee and is only for stabilization at ankle

Question 5

Tibia

Answer 5

Receives weight of body and transmits it to foot
Medial and lateral condyles articulate w/ condyles of femur
Diaphysis/shaft of tibia is triangular w/ a sharp anterior border (shin)
Distal end is flattened for articulation w/ talus; medial malleolus projects to form ankle bone

Question 6

Fibula

Answer 6

Thin
Head on superior end, lateral malleolus is on inferior end (ankle bone)
DOES NOT BEAR WEIGHT

Question 7

Ankle Fractures

Answer 7

Common: sports, skiing, running
Typically result of rolling or twisting
Ligaments crossing the joint are often so strong that they remain intact but the bones fracture

Question 8

Foot

Answer 8

Fxn: support weight of body, acts as lever for moving the body (walking/running)
Skeleton of foot includes tarsals, metatarsals, and phalanges

Question 9

Tarsals

Answer 9

7 bones
Body weight mostly carried by talus and calcaneus
Talus articulates w/ tibia and fibula anteriorly and calcaneus inferiorly

Calcaneus is the heel

Achilles tendon attaches to posterior surface and enables extension (plantar flexion) of foot

Question 10

Foot: Metatarsals and Phalanges

Answer 10

Metatarsus=5 small digits; numbered I-V

1st metatarsal at base of big toe (Hallux) is largest, helps support weight of body

There are 3 phalanges for each digit (digits II-V), ordered proximal, medial, and distal

Hallux has no middle phalanx

Question 11

Arches of the Foot

Answer 11

The bones of the foot form 3 arches:

• -transverse (side to side between longitudinal arches)
• -medial longitudinal (talus is key)
• -lateral longitudinal (cuboid is key)

This supports and distributes body weight so that about half goes to heel, half to metatarsals

Bones, ligaments, tendons all work together to maintain these

Overtime, tendons can begin to fail (under or overuse). This leads to “fallen arches”

Question 12

Disorders of the Foot

Answer 12

Plantar Fasciitis: very painful, results from inflamm/tiny tears to ligament. Pain at heel/bottom of foot

Common injury, typically overuse/standing a lot (ex: teachers)

Question 13

Name the 7 tarsal bones

Answer 13

Talus
Calcaneus
Cuboid
Navicular
3 Cuneiforms

Question 14

How many bones are in the lower limb?

Answer 14

30 (30/leg)

Femur
Patella
Tibia 
Fibula
26 bones in foot (tarsals, metatarsals, phalanges)