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Landmarks, blood supply and innervation of the cuneiform bones.
Hey everyone! This is Nicole from Kenhub, and in this tutorial, we will be discussing the three cuneiform bones of the foot. So as we come back to our slide of the foot, I just want to talk a little bit about the name cuneiform. So the name cuneiform comes from the Latin meaning "wedge". And there are three cuneiform bones of the foot – the medial cuneiform, the intermediate cuneiform and the lateral cuneiform; and these three bones articulate with the navicular bone here proximally and with the first, second, and third metatarsals distally. And, so, here I'm just going to point out to you our first metatarsal, our second metatarsal, and our third metatarsal.
Now, the medial cuneiform is the largest cuneiform bone and it articulates with four bones – the navicular proximally here, the intermediate cuneiform laterally just here, and the first and second metatarsals distally just here. And the medial cuneiform provides a point of insertion for the tendon of the tibialis anterior muscle on the distal plantar angle of its medial face. So, just to explain that in English, on the plantar aspect of the foot around about here is where the tibialis anterior tendon inserts and on its distal lateral aspect, the medial cuneiform provides a point of insertion for the tendon of the fibularis longus muscle and that would just be round about here. And let's just remind ourselves that the tibialis anterior acts to dorsiflex and invert the foot while the fibularis longus muscle acts to plantarflex – so if you point the toe as if you're a ballerina – and everts the foot, which is turning the sole of the foot outward. And the medial cuneiform receives arterial blood supply from the dorsal arterial network and is innervated by the deep fibular and medial plantar nerves.
So our intermediate cuneiform bone is the smallest bone of our cuneiform bones, and I'll just show you with my mouse how it articulates with the medial cuneiform medially and lateral cuneiform laterally as well as the navicular bone proximally and the second metatarsal distally. The intermediate cuneiform provides a point of insertion for the tendon of the tibialis posterior muscle on its plantar surface just around about here if you can imagine it on the other side. And the tibialis posterior does a bit of a mix of what the tibialis anterior and fibularis longus muscle do – that is, it inverts and plantarflexes the foot which is very useful for those ballet dancers out there going en pointe. Like the medial cuneiform, the intermediate cuneiform receives arterial blood supply from the dorsal arterial network and is innervated by the deep fibular and medial plantar nerves.
The lateral cuneiform bone is situated in the center front row of the tarsal bones – and I'm just going to point it out with my mouse just here – and as you can see, it's bounded by the intermediate cuneiform medially, the cuboid bone laterally, the navicular bone proximally, and the third metatarsal distally. It also forms articulations with the second and fourth metatarsals. And the lateral cuneiform also provides a point of insertion for the tendon of the tibialis posterior muscle on its plantar surface. And the plantar surface of the lateral cuneiform is also the site of origin for the flexor hallucis brevis muscle which plantarflexes the big toe. Like the other two cuneiforms, the lateral cuneiform receives arterial blood supply from the dorsal arterial network, however, innervation is provided by branches of the deep fibular and lateral plantar nerves.