Extensor hallucis brevis
Extensor brevis hallucis
Extensor hallucis brevis is the small medial slip of the short toe extensor, lying on top of the foot and lifting the big toe.
At a glance
- English
- Extensor hallucis brevis
- Latin (TA2)
- Extensor brevis hallucis
- System
- Muscle
- Region
- Lower limb
- Side
- Paired, left and right
About the extensor hallucis brevis
Extensor hallucis brevis is a little muscle on the dorsum of the foot. It is in effect the inner part of extensor digitorum brevis, and anatomists have long disagreed whether to call it a muscle of its own. Terminologia Anatomica lists it separately, and it has its own tendon and target, the big toe.
It arises with the rest of the short extensor from the upper and outer surface of the front of the calcaneus, close to the sinus tarsi, and from the nearby inferior extensor retinaculum. Its belly is the most medial and usually the largest of the short extensor's bellies. It runs forwards and inwards across the foot, and its tendon crosses over the dorsalis pedis artery on the way, then lies along the outer side of the extensor hallucis longus tendon. It attaches to the back of the base of the big toe's proximal phalanx.
The muscle extends the big toe at the metatarsophalangeal joint. It has no hold on the interphalangeal joint, which only the long extensor straightens. It is most useful when the ankle is already dorsiflexed, when the long extensor is short and pulls less well.
Because its tendon crosses the dorsalis pedis artery, it is a landmark for finding that pulse: the artery is felt between the long extensor tendon of the big toe and this short tendon. Like the rest of the short extensor, it is supplied by the lateral branch of the deep fibular nerve, so it weakens in lesions of that nerve or of the L5 root.
Attachments, action and supply
- Origin
- Upper lateral surface of the front of the calcaneus and the inferior extensor retinaculum, in common with extensor digitorum brevis.
- Insertion
- Dorsal surface of the base of the big toe's proximal phalanx.
- Action
- Extends the big toe at the metatarsophalangeal joint.
- Nerve supply
- Deep fibular nerve, lateral terminal branch (L5, S1).
- Blood supply
- Lateral tarsal artery and the dorsalis pedis artery, with the first dorsal metatarsal artery.
Anthromica
See the extensor hallucis brevis where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
