Muscles of the Leg – Part 2 – Anterior and Lateral Compartments – Anatomy Tutorial

Muscles of the Leg – Part 2 – Anterior and Lateral Compartments – Anatomy Tutorial


Okay so this is the second tutorial on the
muscles of the leg, so in this tutorial I’m going to cover the muscles of the anterior
and lateral compartments. So these compartments are supplied by the common peroneal branch
of the sciatic nerve. So the sciatic nerve splits into two branches at the popliteal
fossa. The tibial branch supplies the posterior compartment, and then you’ve got the common
fibular, or common peroneal branch, which winds round laterally, over the head of the…the
lateral head of the gastrocnemius, over the neck of the fibula, where it’s vulnerable
to impact injuries and fractures, and then it splits into two branches which supply the
anterior and the lateral compartments. So I’ll just fade away the muscles and then you
can see how this nerve splits. So you’ve got the common fibular branch coming around laterally,
and then it splits into these two branches: you’ve got the superficial branch, which supplies
the muscles of the lateral compartment, and you’ve got the deep branch, which supplies
the anterior compartment. So the muscles of the anterior compartment mainly act to dorsiflex,
extend to the toes, and to invert the foot, and there are four muscles in this compartment,
and this compartment is supplied by the deep branch of the common fibular nerve. The lateral
compartment only has two muscles, and these muscles mainly act to evert the foot. And
this compartment is supplied by the superficial branch of the common fibular nerve. Okay so
you have two muscles in the lateral compartment of the leg, you’ve got the peroneus longus,
or the fibularis longus, which is this muscle here. And you’ve got the fibularis brevis,
which lies deep to the fibularis longus, and it attaches a bit lower down on the fibula.
So I’ll just show you the fibularis longus muscle. So the fibularis longus muscle, as
you can see its origin, attaches on the upper lateral surface of the fibula, and also on
the lateral side of the head of the fibula, and it has an interesting tendon, because
it actually crosses over underneath the foot to insert medially at the distal end of the
medial cuneiform bone, and at the base of the proximal, sorry, the base of the first
metatarsal here. So if we just follow this tendon round, you can see it runs down behind
the lateral malleolus and then it descends and curves forwards on the lateral side of
the calcaneus and then passes under the foot. And it then passes under the cuboid bone,
and in this bone there’s a groove for the…for the tendon. So I’ll just show you that. So
if we just look, I’ve just rotated the model and we’re looking at the underside of the
foot – the plantar surface of the foot, so this is the cuboid bone, which is one of the
tarsal bones that sits laterally. So the tendon of the peroneus longus actually runs in a
groove in this cuboid bone. I think it’s a little bit out of place here, but you can
see this groove here, so the tendon runs underneath the foot, through the groove on the cuboid
bone and attaches to the base…base of the first metatarsal and also distally on the
medial cuneiform bone. So you can just see that tendon coming across, and it inserts
distally on the medial cuneiform, and at the base of this first metatarsal. So what this
muscle does is that it actually everts the foot and it can also assist in plantarflexion.
So you can just imagine, so seeing the insertion point here, you could just visualise if this
muscle were to contract it would pull this, pull the foot round into eversion. So eversion
is when the soles of the feet face away from each other, and inversion is when you bring
the soles of the feet to face each other. So another point about the peroneus longus
is that it actually provides support for the arches of the foot. So it mainly supports
the lateral and transverse arches, and if you remember in my last tutorial, the tibialis
posterior also provided support to the arch, due to its insertion on the medial aspect
of the foot, and there’s another muscle which I’ll come on to talk about later in this tutorial,
called the tibialis anterior, which also inserts medially on the foot, and contributes to arch
support. So I’ve just brought back in all the muscles, and this muscle here is the tibialis
anterior, which I’ll talk about later, and you can see its tendon which winds round and
inserts also on the base of the first metatarsal. And if I just remove this muscle here, you
can see the tibialis posterior tendon. So you’ve got these three tendons coming in to
attach to the underside on the medial aspect of the foot, and these sort of act to support
the arches. So you’ve got the tibialis anterior tendon here, you’ve got the tibialis posterior
tendon, and you’ve got the peroneus longus tendon, or the fibularis longus tendon coming
in from this side. So these all function to support the arches of the foot. So next we’ve
got the peroneus brevis muscle, the fibularis brevis, so if we just remove the…this muscle.
So this lies deep to the fibularis longus, and this lies on the lower two thirds, on
the lateral surface of the shaft of the fibula, and you can see this tendon here, it winds
round behind the lateral malleolus, just like the fibularis longus, and it curves round
and inserts onto the base of the fifth metatarsal. So what this muscle does is it everts the
foot. So the peroneus brevis and peroneus longus, or fibularis brevis/fibularis longus
if you want, are innervated by the superficial branch of the common peroneal or common fibular
nerve. So next we’ve got the muscles of the anterior compartment of the leg, and there
are four muscles in this compartment, you’ve got the tibialis anterior, the extensor hallucis
longus, the extensor digitorum longus, and the fibularis tertius. So these muscles mainly
act to dorsiflex, extend the toes, and to invert the foot. So I’ll start with this muscle
here, the tibialis anterior, which is the most superficial muscle. So I’ve just isolated
this muscle and you can see its attachment on the tibia, on the lateral side of the tibia,
and on the adjacent interosseus membrane. So this muscle forms a tendon which runs down
the front of the leg and inserts medially on the foot. So this, this muscle actually
provides support for the arch of the foot, as well as the tibialis posterior and the
fibularis longus. So you can see its attachment on the foot here, so it inserts on the medial,
the sort of lower surface of the medial cuneiform bone and on the adjacent base of the first
metatarsal. So you can see by this medial attachment on the foot, that if this muscle
contracts, it would pull the foot up, so that it will invert the foot, so again inversion
is when you bring the foot up so both the soles face each other. And it will also dorsiflex
the foot, so it will pull the…pull the toes up in this direction towards the head. So
that’s the tibialis anterior, and it’s innervated by the deep branch of the common peroneal
nerve, so the deep, or the fibular nerve, the deep fibular nerve – so all the muscles
in the anterior compartment are innervated by the deep fibular nerve. So next we’ve got
the two extensor muscles of the digits and of the great toe. So you’ve got the extensor
digitorum longus, and the extensor hallucis longus. So just like in the posterior compartment,
where you’ve got the flexor of the toes and the flexor of the big toe, in the extensor
compartment, the anterior compartment, you’ve got the extensor of the big toe – extensor
hallucis longus and the extensor of the digits – so extensor digitorum longus. So I’ve just
removed the tibialis anterior, and we’ll just have a look at this muscle here, the extensor
hallucis longus. So if I just isolate that, so you can see it now here, it sits, it’s
not quite shown here, but it actually sits medially on the fibula, on the middle half
of the fibula and it also attaches to the bit of the interosseus membrane that’s adjacent
to the fibula, so it attaches here – its origin, and it descends along, anteriorly on the leg
and crosses over medially to insert here, at the base of the distal phalanx of the great
toe. So because of this muscle attachment, when this muscle contracts it extends the
big toe and because of its…because it’s anchored here at the ankle, it can also dorsiflex
the ankle, so when it contracts it brings the toes up. So if I just bring the other
muscles back into view, you can see, well you can see these two retinaculum, these are
the extensor retinaculum, so you’ve got a superior and inferior retinaculum. So these
extensor retinaculum, they hold the extensor tendons in place, so I’ll just remove them
for now, and you can look at the…well we’ll look at the other side, we’ll look at the
left side because I haven’t removed the tibialis anterior. So you can look at the relationship
of these tendons, so the tibialis anterior tendon is most medial, then you’ve got the
extensor hallucis longus tendon in between the tendon of the extensor digitorum longus,
which I’ll just talk about now, so it sits between the extensor digitorum longus tendon
and the tibialis anterior tendon on the anterior aspect of the distal leg, so just worth noting
that relationship. So next we’ve got the extensor digitorum longus muscle, so the name gives
away its function – it extends, it’s the long extensor of the digits. So it attaches superiorly
to the extensor longus muscle, so it’s this muscle here, I’ll just isolate it. So if we
just take a look at the attachment, so we can see the extensor hallucis longus muscle
a bit inferiorly with its origin, and the extensor digitorum longus attaches higher
up on the proximal, medial surface of the proximal tibia, and it’s also got this attachment
on the lateral condyle of the tibia – so that’s its origin, and if we follow the muscle down
we can see that it splits to form four tendons which then attach to the digits. So the insertion
point of these, of the extensor digitorum longus is on the bases of the intermediate
and the distal phalanges. So I’m not sure if it’s actually shown on this model…no
it’s not, but the, this tendon attaches to the bases of the middle and the distal phalanges.
So what this muscle does is it extends the lateral four digits, and it can also dorsiflex
at the ankle. Okay, so the final muscle that I’m going to talk about is the, a small little
muscle called the fibularis tertius, or the peroneus tertius. So I’ll just remove away
the other muscles, so we can take a look at this. So I’ve just zoomed in a little bit
and you can see this muscle here, this is the fibularis tertius, or the peroneus tertius,
and this muscle originates as you can see distally on the medial surface of the fibula,
so it’s not that clear on this model here, but the peroneus tertius, or fibularis tertius
is often considered a part of the extensor digitorum longus, and it’s sometimes actually
joined together with this muscle, so it runs down into the foot and this tendon inserts
medially on the base of the fifth metatarsals. So what this muscle does is that it everts
the foot and assists in dorsiflexing the foot. So those are the muscles in the anterior compartment
of the foot, sorry the leg. So you’ve got the tibialis anterior, which you can see here.
You’ve got the extensor of the four toes, called the extensor digitorum longus, the
extensor of the big toe, the extensor hallucis longus and you’ve got the little peroneus
tertius, which is often thought of as part of the extensor digitorum longus. So the way
I remember the muscle of the anterior and posterior compartments is that the deep layer
of the muscles in the posterior compartment is quite similar to the muscles of the anterior
compartment. So you’ve got the tibialis muscles. So in the anterior compartment you’ve got
the tibialis anterior, and in the posterior compartment you’ve got the tibialis posterior.
And then you’ve got the muscles which act on the toes, the four toes, the four digits,
so you’ve got the extensor digitorum longus in the anterior compartment and in the posterior
compartment you’ve got the flexor digitorum longus. And then you’ve got the muscle which
acts on the big toe, so you’ve got the extensor hallucis longus in the anterior compartment,
and correspondingly you’ve got the flexor hallucis in the posterior compartment. And
then you’ve got a little small muscle, so in the anterior compartment, the little small
muscle is the peroneus tertius, and in the posterior compartment the little small muscle
is the popliteus. So that’s just one way of thinking of these things, to help you remember
different muscles and how they act.

100 thoughts on “Muscles of the Leg – Part 2 – Anterior and Lateral Compartments – Anatomy Tutorial

  1. I could not get through anatomy without 3D models. A one dimensional textbook pictures just do not speak to my brain. Thank you for posting these videos. I can't tell you how helpful it has been for me to get through school. You're awesome!

  2. i can use ur videos as a lectures instead of my lecs in my college ๐Ÿ˜€

    thank you .. these videos are so helpful especially in the origin and insertion coz i always face problems in memorizing them :
    thank you

  3. Sometimes i hear animals and sometimes water drops. You must be in some cave. My question; are you Batman?

  4. Im a medical student and these videos have been amazing for orienting everything and learning the muscles. Thank you so much!

  5. What application are you running for these tutorials? I am a MS1 and would love to play around with them to get a better idea of the body. Thanks

  6. if you people wish to get ripped much faster without spending a single another minute in the gym, then you have to keep an eye on this online video SIXPP.COM

    Victory gave us such insane delusions of grandeur that we helped start a world war we hadnโ€™t a chance of winning

  7. Your videos are amazing. It is really helpful but wish watched it bit earlier. well its never too late ๐Ÿ™‚ Thank u so much! the speed is awesome and wording are clear to understand! Awesome Awesome Awesome!

  8. Between 1:00 and 1:15 you said that the superficial branch of the common fibular nerve supplies the lateral compartment, whilst the deep branch supplies the anterior.
    Then between 1:25 and 1:40 you say that both compartments are supplied by the superficial branch

    Your tutorials are nevertheless very helpful ๐Ÿ™‚

  9. superficial fibular branch ->lateral compartment
    deep fibular branch -> anterior compartment
    extensor retinaculum holds extensor tendons in place

    -fibularis longus; lateral head of fibula to distal cuneiform and 1st metatarsal
    -fibularis brevis (deep); lateral lower 2/3 fibula to 5th metatarsal lateral base

    -extensor hallucis longus; medial interosseus membrane +medial fibula to base of distal phallanx of great toe
    -extensor digitorum longus; medial surface of proximal tibia, lateral condyle of tibia, hallucis longus, to bases of intermediate and distal phalanges
    -fibularis tersius: distal surface of medial fibula, to medial base of 5th metatarsal

  10. Thanks a lot for your great work…….I just hoped you could upload tutorials about the blood supply….. I don't want to move around between so many channels.Thanks againย 

  11. I'd just like to say that I put on chill music in the background as I watch these and it's amazing! Thank you for posting such awesome videos!ย 

  12. My only video I've disliked. Maybe Ive listened incorrectly you firstly said that the superficial branch supplies the lateral and deep branch of common peroneal supplies anterior then you switched this around later on

  13. What's the name of the program or application you are using to describe the anatomy it's pretty amazing

  14. I have a tight muscle behind my leg in calve area but on the inside of leg up rite below my knee. I can't straighten out my leg and very hard to walk. What to do. i have put ice and heat. Heat seems to do better. I ride my bike every where I have no car. it's been 2days.

  15. At 1:12 you say that the DEEP branch or the common perineal nerve supplies the ANTERIOR compartment.
    And at 1:30 you say that the ANTERIOR compartment is supplied by the SUPERFICIAL branch.
    You're right the first time.
    Please check this. Great videos btw. ๐Ÿ™‚

  16. I couldn't understand muscles of the leg however now I do perfectly I have a favour to ask if next time you could add the artery supply that would be great thanks!

  17. his voice suckssssss his words are not clear at alllllll and because of that i had to replay video 10 times to make myself undertsand > it seemed he just woke up from sleep hoeee

  18. Thank you!ย 

    I know the names of all the muscles in the leg but I'm having serious trouble identifying them and their attachments…they are very random and very complex….is there an easy way to remember where these muscles attach?

  19. Because of your accent I could understand the words you said ๐Ÿ˜ก๐Ÿ˜ก๐Ÿ˜กyou had better use international accent.

  20. It was fun watching your video. On what platform you guys make this video? Are you taking some professionals help? I need more this information ASAP. Thanks a lot!

  21. May God Bless you for your amazing talent in teaching anatomy! Thank you so much for helping us medstudents ๐Ÿค—๐Ÿ˜‡

  22. People without legs are disliking ๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…๐Ÿ˜…

Leave a Reply

Your email address will not be published. Required fields are marked *