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This video covers the muscles of the hand, including their origins, insertions, and functions.
Introduction
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What’s up.
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Meditay here and in this segment, we’ll be covering the muscles of the hand.
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Alright.
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So, the muscles of the upper limb are divided into 4 parts according to their anatomical
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location.
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The first group are muscles of the shoulder joint.
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Then we have the muscles of the arm, muscles of the forearm and then the muscles of the
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hand.
Division of the Hand Muscles
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So again, the muscles of the hand are what we’re gonna focus on.
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Now.
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Muscles of the hand are divided into specific regions.
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Some sources might differ in classification of them, but all the muscles are the same.
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So muscles of the hand can be divided into the Thermal Muscles, for the thumb, Hypothermal
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muscles for the pinky, and the middle hand muscles, which can be divided into interossei
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muscles and lumbrical muscles.
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So these are the muscles we’re gonna try to visualize today.
Thenar Muscles
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And we’ll start with the Thermal Muscles.
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Now the Thermal Muscles consist of 4 muscles.
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They’re the Abductor Pollicis Brevis, Opponens Pollicis, Flexor Pollicis Brevis and Adductor
1:04
Pollicis.
1:05
Now.
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Let’s turn the hand like this, and then remove a couple of layers until we get to
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the bone.
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Opponens Pollicis is this muscle right here.
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It originates from the Flexor Retinaculum and the Trapezium bone of the wrist.
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Flexor Retinaculum is a band of connective tissue that is formed by the fascia of the
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lower arm, we’ll talk more briefly about it when we covert he Fascia of the upper extremity,
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but for now just know that this muscle originates from this retinaculum.
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And then it inserts at the Base of the 1st metacarpal bone.
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And the function of it is opposition and flexion of the thumb, meaning pulling the thumb towards
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the little finger.
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So that’s this one.
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Next, we have the Flexor Pollicis Brevis, which is this muscle right here.
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It originates from the Flexor retinaculum as well, and the deeper part of it originate
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from the distal wrist bones, the Trapezium and Trapezoideum.
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It then inserts at the base of the proximal phalanx of the thumb.
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Its function is more or less the same as opponens pollicis.
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Next, we have the adductor Pollicis, which is this one.
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It has an Oblique head and a Transverse head.
2:12
The oblique head originate from the Capitate and he base of the 2nd to 3rd metacarpal bone,
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and the Transverse head originate from the 3rd metacarpal bone.
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And they both insert at the base of the proximal phalanx of the thumb.
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The function of this muscle is adduction of the thumb, more or less as the name says.
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That’s this one.
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The last thermal muscle is the Abductor Pollicis Brevis, which originates from the flexor retinaculum,
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and insert at the base of the proximal phalanx of the thumb.
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It’s called abductor pollicis brevis, so it abducts the thumb.
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So that was all the muscles of the thermal region,
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Now let’s do the Hypothenar muscles.
Hypothenar Muscles
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The first one is the Opponens digiti minimi.
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Which is this one.
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It originates from the Flexor Retinaculum and the Hamatum, and it Inserts at the base
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of the 5th metacarpal bone.
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The function of this muscle is opposition of the little finger, basically pulling it
3:07
towards the thumb.
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Next, we have the Flexor Digiti Minimi Brevis, which is this one.
3:13
This muscle originates from the Flexor Retinaculum and the hamatum, and it inserts at the base
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of the proximal phalanx of the little finger.
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It’s function it in the name, flexion of the little finger.
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Next we have the Abductor Digiti Minimi, which is this one.
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It originates from the flexor retinaculum, as well as the pisiform.
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And it inserts at the proximal phalanx of the little finger.
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And it’s function.
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Can you guess it?
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That’d be abduction of the little finger, pulling it away from the 3rd finger.
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The last muscle of the hypothermal region is the Palmaris Brevis.
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This muscle Originates from the Flexor Retinaculum as well, this one.
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And it originates from the palmar aponeurosis, which is the structure that Palmaris Longus
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inserts on.
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The palmar aponeurosis is primarily a fibrous triangle covering the palm to protect the
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neurovascular structures underneath it.
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And it also fuses with the superficial palmar fascia at some parts, we’ll talk about this
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one a little more when we cover the fascia of the upper limb.
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So it originates from these structures, and it inserts at the skin of the palm on the
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ulnar side.
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When this muscle contracts, it pulls the skin and produce wrinkles on the hypothermal side
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to mainly tense the palmar aponeurosis.
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So that was the muscles of the Hypothenar Region.
Middle Hand Muscles
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Now let’s talk about the middle hand muscles.
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And we’ll start with the interossei Muscles.
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There’s a Palmar interossei and a dorsal interossei, we’ll start with the palmar
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interossei first.
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The Palmar interossei are three muscles located in the 2nd to 4th interosseous space between
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the metacarpals, as you see here.
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So, let’s remove and fade a couple of structures to see them better.
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These muscles originates from the medial side of the 2nd metacarpal bone.
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The lateral side of the 4th metacarpal bone, and the Lateral side of the 5th Metacarpal
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bone.
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At it inserts at the Proximal phalanx of the 2nd 4th and 5th finger.
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When these muscle fibers contract, they Adduct the fingers, basically pulling the 2nd, 4th
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and 5th fingers towards the 3rd finger, as you see here.
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So that’s this one.
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Then we have the dorsal interossei muscles as we said earlier.
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There are four dorsal interossei muscles located in the 1st to 4th interosseous spaces between
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the metacarpals.
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As you see here.
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They originate between the metacarpal bones of thr 1st to 5th fingers, and they insert
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at the proximal phalanx of the 2nd to 4th fingers.
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When these muscle fibers contract, they abduct the fingers, as you see here.
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Meaning they pull the 2nd and 4th fingers away from the 3rd finger.
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Awesome, so that’s these two.
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Then we have a system of muscles called the lumbricals.
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Which are here.
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These are four muscles that correspond to the 2nd to the 5th fingers.
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They all originate from the tendons of the flexor digitorum profundus, and they insert
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at the proximal phalanx of the 2nd to 5th fingers.
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The lumbricals are actually a very practical muscle to have, because they give our fingers
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the possibility to flex the proximal phalanx, while extending the middle and distal phalanges
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of the fingers.
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So that was all the muscles of the middle group that I wanted to talk about.
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And now, we’ve covered all the muscles of the upper limb.
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