This little piggy went to anatomy prac. This little piggy went to microbiology lab. This little piggy went to clinical tutorials. This little piggy went to study group. And this little piggy cried, “hee, hee, hee”… as he abducted and flexed his little head all the way home.
What? It’s never too early to start preparing for medical school, is it? Today, we’re talking all things pinky, and by that, I mean your pinky toe. Have you ever stopped and wondered what muscles help you bend and wiggle your little toe? Well, today, we’ll find out the answers to this rather random question.
Welcome to our video tutorial on the functions of the lateral plantar muscles of the foot in 3D.
So, in today’s video tutorial, we’re going to be exploring the functions of two small muscles of the foot and these are the abductor digiti minimi muscle which is this long superficial muscle seen here along the lateral border of the foot, and the flexor digit minimi brevis muscle, a smaller, deeper muscle also located along the lateral aspect of the plantar surface of the foot.
Now, of course, we cannot learn about the functions of any muscle without first refreshing our memories of its anatomy. So, we’re going to do just that by beginning first with the abductor digiti minimi muscle.
So as you can see on our awesome model here, the abductor digiti minimi is a long thin muscle located along the lateral border of the plantar aspect of the foot. If you happen to learn your plantar muscles by layers, well, you can make a note that this muscle is found in the first layer of plantar muscles.
The abductor digiti minimi muscle has its origin or proximal attachment point at both the medial and lateral processes of the calcaneal tuberosity in addition to a soft tissue structure known as the plantar aponeurosis. From here, its long tapered belly courses distally towards the lateral border of the foot where this muscle finds its insertion or distal attachment point at the base of the proximal phalanx of the little toe. And you may also see it described as having an additional attachment at the tuberosity located at the base of the fifth metatarsal bone.
So, let’s move a little deeper into the plantar muscles now, and check out our second muscle of interest, the flexor digit minimi brevis muscle. And this muscle is much smaller compared to the abductor digiti minimi and is located in the third layer of plantar muscles of the foot. It has its origin on the medial plantar surface of the base of the fifth metatarsal bone and it may also have an attachment to another structure known as the long plantar ligament.
From its origin, the short muscular belly of the flexor digiti minimi brevis then continues distally to find its insertion also at the base of the proximal phalanx of the fifth digit.
And just like that, we’ve discussed the anatomy of both lateral plantar muscles of the foot.
Of course, when we discuss the anatomy of any muscle, it’s important for us to identify which joint it acts upon, and luckily for us, both of our star muscles primarily act upon the same joint, which is the metatarsophalangeal joint of the little toe.
Before we move on to talk about some functions, it wouldn’t be right to talk about the anatomy of a muscle without giving their nerve supply I mentioned. So, in the case of both the abductor digiti minimi and the flexor digiti minimi brevis, both of them received their nerve supply via the lateral plantar nerve which is one of the terminal branches of the tibial nerve.
Okay, so now that we’ve mastered the anatomy of the two lateral plantar muscles of the foot, it’s time for us now to check out their functions. Then let’s begin once again with the abductor digiti minimi muscle. So, despite its name, the primary function of this muscle is actually flexion of the little toe occurring at the metatarsophalangeal joint. Flexion of any toe, of course, means the bending towards the plantar surface of the foot.
The second function of the abductor digiti minimi is its namesake – abduction of the little toe – again, occurring at the metatarsophalangeal joint. Now, abduction and adduction can be confusing when it comes to the toes, so I’ll quickly explain what both terms mean. So, when we speak about abduction and adduction of the toes, we’re talking about their position in reference to a long axis which runs through the second toe. Abduction means to move away from the second toe, while adduction means to move towards the second toe. So going back to our muscle, the abductor digiti minimi, we now know that this movement means that the little toe is moving away from the second toe.
And finally, the last function of the abductor digiti minimi is related to the support of the lateral longitudinal arch of the foot. So when weight is applied down on the foot, the abductor digiti minimi works to counteract this by raising the lateral longitudinal arch of the foot just like this.
And that covers the three primary functions of the abductor digit minimi.
So, let’s now look at our other lateral plantar muscle – the flexor digiti minimi brevis. So, the primary function of this muscle as you probably have correctly guessed is flexion of the little toe at the metatarsophalangeal joint. So this means that the flexor digit minimi brevis works to assist the abductor digit minimi and other muscles to flex our little toe. Now, not many muscles in the body can be described as a one-trick pony, but the flexor digiti minimi brevis is exceptional as a flexion of the little toe is its one and only function.
This means just like that we’ve learned about the functions of the lateral plantar muscles of the foot.
So before we finish, let me quickly review what we’ve learned today. So, today, we focused on the two lateral plantar muscles of the foot – the first of these was the abductor digiti minimi muscle, which had three main functions. The first was flexion of the little toe occurring at the metatarsophalangeal joint of the same toe, the next function was abduction of the little toe occurring at the same joint – and this movement involved the little toe moving laterally or away from the other toes of the foot – and finally the abductor digiti minimi helps to support the lateral longitudinal arch of the foot.
We then moved on to the smaller flexor digiti minimi brevis muscle which had just one function for us to consider and that was flexion of the little toe, once again, happening at the metatarsophalangeal joint.