Muscles of the leg and foot Flashcards
gastrocnemius
- the most superficial posterior leg muscle
- Action:
knee flexion
primary plantarflexar of the foot
Innervation: tibial nerve
- it’s tendon merges with the soleus’ tendon to insert on the calcaneus bone of the foot
soleus
- sits deep to the gastrocnemius
- inserts on the calcaneus in the calcaneal tendon
- innervated by the tibial nerve
Action: plantarflexion of the ankle
calcaneal tendon
- the achilles tendon
- this is where the gastrocnemius and the soleus tendons merge
- this inserts onto the calcaneus bone of the foot
plantaris
a small muscle with a tiny muscle belly deep to the gastrocnemius
- not present in all individuals
- this is going across the posterior knee and extends down the leg to insert on the calcaneus
- Action: weak knee flexor and weak ankle plantarflexor
innervation: tibial nerve
tibialis posterior
this runs along the posterior aspect of the tibia
- this is lateral to flexor digitorum longus and medial to flexor hallucis longus
-its tendon crosses under flexor digitorum longus meaning that it crosses the medial malleolus the most anterior
- Action:
- plantarflexion and inversion of the ankle
- flexes the MTP, PIP, and the DIP joints in the toes
innervation: tibial nerve
flexor hallucis longus
- its tendon wraps around the medial aspect of the ankle before it reaches the distal great toe
- its tendon wraps around the medial malleolus the most posterior of three
- long path gives the muscle a mechanical advantage and makes it a powerful flexor of the first digit
- Action:
plantarflexion and weak inversion of the ankle
flexes the MTP and IP of the great toe
innervation: tibial nerve
popliteus
- It sits on the superior aspect of the tibia and crosses the knee joint
- It functions to medially rotate the tibia and “unlock” the knee from full extension in the first few degrees of flexion.
Action: knee flexion
innervated by tibial nerve
plantar fascia
- This thick layer of fascia is superficial to the muscles of the plantar aspect of the foot
- attaches to the calcaneus in anatomical position
flexor digitorum brevis
the muscle deep to the plantar fascia and flexes digits 2-4
- this is in the middle of the plantar aspect of the foot and has a big muscle body that then has tendons that branch out to the digits
innervation: medial plantar nerve
abductor hallucis
the large muscle on the medial aspect of the great toe
- travels from the calcaneus to the MTP
Action: abducts the great toe
innervation: medial plantar nerve
abductor digiti minimi
located on the lateral aspect of the 5th digit
Action: abducts the 5th digit
-innervation: lateral plantar nerve
Quadratus plantae
- this runs from the calcaneus to the tendons of flexor digitorum longus
- adjusts the angle of pull on these tendons
- aligns these tendons so that the toes flex within the sagittal plane
-innervation: lateral plantar nerve
lumbricals
- insert on to the flexor digitorum longus tendons
- in between the different branches of that tendon
Action: flex the MP and extend the PIP and DIP joints
Innervation:
- the first lumbircal is innervated by the medial plantar nerve but the rest are innervated by the lateral plantar nerve
adductor hallucis
- 7 shaped
- has transverse and oblique heads
Action: adducts the great toe
Innervation: lateral plantar nerve
flexor hallucis brevis
- lives completely within the foot
- lies along the medial side of the plantar aspect
Action:flexes the great toe
Innervation: medial plantar nerve
flexor digiti minimi brevis
- lives completely in the foot
- lies along the lateral side of the planter aspect
- a small muscle that is medial to the abductor digiti minimi
Action: flexes the fifth digit
innervation: lateral plantar nerve
Dorsal interossei
Abduct the toes
- the bellies of these muscles are on the outside of the toes (between the metatarsal bones)
- these can be seen from the plantar side and the dorsal aspect of the foot
- there are two of them on the second toe
innervation: lateral plantar nerve
Plantar interossei
Adduct the toes
- appear to only be on toes 3-5 and are on the medial side of the metatarsal
- can be seen from the plantar side of the foot
innervation: lateral plantar nerve
tibialis anterior
- this hugs the tibial bone
- this originates on the lateral side and then moves more medially while traveling inferiorly
-has a long tendon that crosses the medial side of the foot and this contributes to the arch of the foot
Action:
primary dorsiflexor of the foot
inverts ankle
innervation: deep fibular nerve
extensor digitorum longus
this is lateral to the tibialis anterior
- this branches into many tendons on the dorsal aspect of the foot that extend to digits 2-5
Action:
dorsiflexion and eversion of the ankle
extends the digits
innervation: deep fibular nerve
extensor hallucis longus
- this is deep to the tibialis anterior
- this crosses the ankle and travels to the hallucis (big toe)
Action:
extension of the big toe
dorsiflexion and inversion of ankle
innervation: deep fibular nerve
fibularis longus
- this is a long muscle that is on the lateral side with a long skinny tendon that causes the ankle and inserts at the metatarsal of digit 5
- this is part of the lateral compartment
- this sends its tendon under the arch on the foot to insert at the base of the first metatarsal (this gives it a mechanical advantage making it stronger with eversion)
Action: eversion of ankle with a little plantar flexion
-innervated by the superficial fibular nerve
fibularis brevis
- this is just deep to the fibularis longus
- has a shorter tendon than fibularis longus
Action: eversion of ankle with a little plantar flexion
- this inserts at the base of the 5th metatarsal on the lateral aspect of the foot
( this is important clinically because it can be the site of an avulsion fracture and a piece of the bone can break off rather than the tendon tearing)
-innervated by the superficial fibular nerve
fibularis tertius
- this is a small muscle that can be seen from behind the fibularis brevis when looking from the anterolateral side
- a minor muscle and not everyone has this muscle
inserts on the fifth digit
Action: dorsiflexion and weak eversion
innervation: deep fibular nerve
extensor digitorum brevis
Action: extends digits 2-4 (at the MTP and IP joints; does not travel to the distal phalanx)
- on the dorsal aspect of the foot
Innervation: deep fibular nerve
extensor hallucis brevis
Action: extends the big toe (the MTP joint)
innervation: deep fibular nerve
flexor digitorum longus
- these are the tendons that extend to the 2-5 digits
- this is the most medial of the three muscles in deep compartment and its tendon passes the medial malleolus in the middle of the other two tendons
Action:
- plantarflexion and weak inversion of the ankle
- flexes the MTP, PIP, and the DIP joints in the toes
innervation: tibial nerve
