1. Hip biomechanics, Lumbosacral plexus, and Leg Musculature
Lower Extremity
Hip biomechanics, Lumbosacral plexus, and Leg Musculature

2. Objectives
Describe the gross anatomy for each system (circulatory, muscular, nervous, and skeletal) in the lower extremity.
Integrate the systems to discuss the lower extremity stability and mobility functions.
Analyze common injuries in the lower extremities.
For each muscle, describe how the attachment sites result in an action around a joint.
For each muscle, identify the innervation (peripheral nerve and nerve roots).
Pulled from syllabus

3. Announcements No office hours Thursday Lab closed Friday and Monday
Tag Test reminders

4. Presentations

5. Which of the following is incorrect pertaining to the patella?
It increases the mechanical advantage of the quadriceps femoris for extending the knee.
Pain felt deep to it may be associated with a condition known as chondromalacia patella.
Testing of its associated tendon reflex is done with the patient sitting and legs "dangling.“
It tracks superomedially on the femur. D

6. Your friend is diagnosed with trochanteric bursitis
Your friend is diagnosed with trochanteric bursitis. You explain to him that this bursa is between the:
iliopsoas tendon and the lesser trochanter, allowing the muscle to move freely across the neck of the femur.
obturator externus and the lesser trochanter, allowing the muscle to move freely across the trochanter.
gluteus maximus and medius at the site of the greater trochanter, allowing the muscles to move freely across one another.
skin and the gluteus maximus at the site of the greater trochanter, allowing comfortable sitting by distributing forces across the trochanter.
gluteus maximus and the greater trochanter, allowing the muscle to smoothly slide over the trochanter. E

7. In the following popliteal arteriogram, the arrow points to the:
popliteal artery.
anterior tibial artery.
fibular artery.
medial genicular artery.
fibular recurrent artery.

8. In the following coronal MRI of the ankle joint, the arrow points to the:
plantar calcaneonavicular (spring) ligament.
medial (deltoid) ligament.
long plantar ligament.
abductor hallucis longus.
flexor hallucis longus. B

9. Leg Musculature Anterior Compartment Lateral Compartment
Posterior Compartments
Superficial
Deep
Leg muscles primarily act on the ankle AND foot
Malleoli serve as pulleys for tendons
Tendons wrapped in synovial sheaths
Retinacula prevent bowstringing
General: two superficial veins outside thick and strong crural fascia
very little fatty tissue, thinner muscles for more control
fine motor control occurs at distal extremities – in the foot is necessary for balance and coordination during locomotion
compare to thigh muscles – much greater breakdown of movement in the foot than hamstrings are capable of
Function of compartments (review) – restrict total area to create pressure: muscular venous pump
Leg muscles primarily act on the ankle AND foot
Malleoli serve as pulleys for tendons
Tendons wrapped in synovial sheaths
Retinacula prevent bowstringing
Neurovasculature review
ant tibial artery runs with deep fibular n – anterior compartment
post tibial artery runs with tibial n – deep posterior compartment
fibular artery without a nerve – deep posterior compartment
superficial fibular nerve without an artery – lateral compartment

10. Anterior Compartment Tibialis anterior Extensor hallucis longus
Extensor digitorum longus
Fibularis tertius
Tibialis anterior
most medial origin -> inferior surface medial cuneiform & base of 1st metatarsal
dorsiflexes & inverts
Extensor hallucis longus
in the middle, deep on interosseous membrane -> base of distal phalanx
assists ankle dorsiflexion, extends great toe
Extensor digitorum longus
most lateral origin -> middle and distal phalanges of digits 2-5
extends toes, assists ankle dorsiflexion & eversion
Fibularis tertius
inferior fibula -> base of 5th metatarsal (only fibularis muscle that does not wrap lateral malleolus)

11. Lateral Compartment Fibularis longus Fibularis brevis Fibularis longus
superior fibula -> medial cuneiform and base of 1st metatarsal
everts foot & assists with plantarflexion
Fibularis brevis
inferior fibula -> base of 5th metatarsal
similar attachment sites as fibularis tertius, but posterior to malleolus

12. Posterior Compartments
Superficial
Triceps surae
Plantaris
Deep
Tibialis posterior
Flexor digitorum longus
Flexor hallucis longus
Popliteus
Superficial
Triceps surae (fused tendon)
gastroc – crosses knee joint
fast twitch fibers, essential for quick starts
tennis leg – medial gastroc tears at musculotendinous junction
soleus – soleal line, has a hiatus for popliteal artery and tibial nerve
slow twitch fibers, essential for standing and walking
medially directed muscle fibers
Plantaris - under lateral head of gastroc
not always present, inserts into plantar aponeurosis, can be used for grafts or transplants
Deep
Tibialis posterior
origin is between FDL and FHL and deep on interosseous membrane
inserts tuberosity of navicular and surrounding bones
plantarflexion & inversion
Flexor digitorum longus
most medial origin -> bases of distal phalanges digits 2-5
toe flexion, assists with plantarflexion
Flexor hallucis longus
largest muscle of posterior deep compartment, most lateral origin
inserts base of distal phalanx of big toe
flexes big toe – essential for push off
Popliteus
inferior to plantaris on lateral condyle of femur -> posterior tibia superior to soleal line
small muscle, very small moment arm and little biomechanical advantage
unlocks knee – internal rotation

13. Which of the following is incorrect pertaining to the calcaneal (Achilles) tendon?
It is the common distal attachment of the gastrocnemius, and soleus muscles.
It continues into the foot as the long plantar ligament.
It is used to test S1and S2 nerve function.
It is separated from the superior part of the posterior surface of the calcaneus by a bursa.
It spirals while passing inferiorly to its attachment on the calcaneus. B
Give hint that E is true

14. The tibialis posterior:
everts the foot.
attaches to the femur.
supports the medial longitudinal arch of the foot.
is an important swing phase muscle.
is innervated by the deep fibular nerve. C

15. Clinical relevance “Shin splints” Compartment syndrome
Stress fractures
Shin splints – small tears in periosteum
Causes: overpronation, inadequate stretching, worn shoes, excessive stress on one leg while running
treatments: rest and ice, decrease running (crosstrain instead), stretch regularly and gently
Compartment syndrome – not very common; mimics nerve damage since nerves are compressed
causes: overuse
treatments: extended rest or surgery
Stress fractures – often sudden onset, localized pain when palpated
causes: when beginning to train, muscles and nervous system adapt quickly but bones take longer to strengthen -> ramping up training too fast can lead to stress fractures
can only be diagnosed with imaging techniques
treatments: extended rest, possibly immobilization

16. Clinical relevance cont’d
Foot drop
Injury to common fibular nerve – most common nerve injury of lower limb
very superficial and exposed to trauma
can be severed when fibular neck fractures
can be severely stretched during knee dislocation
Results in paralysis of extensors and everters
Ask for demonstrators

17. Your patient is a runner complaining of leg pain
Your patient is a runner complaining of leg pain. Which of the following can you safely assume is not a likely diagnosis for this patient?
Shin splints
Tibia stress fracture
Compartment syndrome
Foot drop D

18. excessive flexion of the knee at heel-strike shortened stance phase
You see a patient in the emergency room with a fibular neck fracture subsequent to an automobile accident. You are fearful that the patient may have severed his common fibular nerve. To determine this, you ask him to walk. Which of the following walking abnormalities would suggest that the nerve has been severed?
excessive flexion of the knee at heel-strike
shortened stance phase
high-stepping (steppage) gait
lack of balance (use of a cane)
lack of effective hallux push-off C