Cuneiforms
Original Editor - Alex Benham Top Contributors - Rachael Lowe, Mohamed A Hassanin and Alex Benham
Description
They are located between the navicular bone and the first, second and third metatarsal bones and are medial to the cuboid bone.
There are three cuneiform ("wedge-shaped") bones in the human foot: the first or medial cuneiform, the second or intermediate cuneiform, also known as the middle cuneiform and the third or lateral cuneiform. Altogether with the five tarsals, navicular and cuboid bones form the midfoot compartment[1]
Structure
There are three cuneiform bones:
The first cuneiform (also known as the medial cuneiform) is the largest of the three bones, it is situated at the medial side of the foot, anterior to the navicular bone and posterior to the base of the first metatarsal.
Lateral to it is the intermediate cuneiform which articulates with four bones: the
navicular, second cuneiform, and first and second metatarsals. The intermediate cuneiform (second cuneiform or middle cuneiform) is shaped like a wedge, the thin end pointing downwards. The intermediate cuneiform is situated between the other two cuneiform bones (the medial and lateral cuneiforms) and articulates with the navicular posteriorly, the second metatarsal
anteriorly and with the other cuneiforms on either side.
The third cuneiform (also known as third cuneiform or external cuneiform) intermediate in size between the other two cuneiform bones, is also wedge-shaped, the base being uppermost. It occupies the center of the front row of the tarsal bones, between the intermediate cuneiform medially, the cuboid laterally, the navicular posteriorly, and the third metatarsal in front.
Function
The wedge shape of the cuneiform bones help to form and keep medial and transverse arches of
the foot keeping the foot dynamic with different terrains and compatible with different surfaces . Also the second metatarsal is strongly stabilized with the cuneiforms by dorsal tarsometatarsal ligament (to intermediate cuneiform) and Lisfranc ligament (to medial cuneiform) forming an axis on which the foot can be twisted creating the forefoot movement of supination and pronation[2].
Muscle and ligamentous attachments
Tibialis Anterior muscle inserts at the medial cuneiform bone.
Peroneus (Fibularis) Longus muscle inserts at the medial cuneiform bone.
Tibialis Posterior muscle inserts at the medial cuneiform,
Flexor Hallucis Brevis muscle originates from the medial cuneiform
Lisfranc ligament complex
Clinical relevance
Lisfranc injuries - where there is fracture dislocation of second tarsometatarsal joint lead to its instability due to disruption in two of three bands of Lisfranc ligament complex connected to medial cuneiform. This injury is common in sports e.g., football and occurs due to axial loading on planterflexion, patients complain from vague midfoot pain and maybe swelling[1].
Bipartite cuneiforms, a rare condition that can be mistaken for fractures in which the ossification centers are not completely fused but bound by a cartilage, commonly to be detected in medial cuneiform that in this case is divided horizontally into dorsal and planter portions characterized by the E-sign in MRI[1] [3].
References
- ↑ 1.0 1.1 1.2 MacGregor R, Byerly DW. Anatomy, Bony Pelvis and Lower Limb, Foot Bones [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557447/
- ↑ Huson, A. (1991). Functional anatomy of the foot. In M. H. Janss (Ed.), Disorders of the foot and ankle : medical and surgical treatment (Vol. 1, pp. 408-431). Saunders.
- ↑ Burnett S, D. Troy Case. Bipartite medial cuneiform: New frequencies from skeletal collections and a meta-analysis of previous cases. Homo-journal of Comparative Human Biology. 2011 Apr 1;62(2):109–25.