WEBVTT

1
00:00:03.643 --> 00:00:09.894
Webtoon Advanced
Structural Understanding of Arms and Legs

2
00:00:09.903 --> 00:00:12.550
GCC Academy

3
00:00:25.424 --> 00:00:27.763
Hello, I am Webtoon artist Uksoo

4
00:00:28.053 --> 00:00:33.334
As we explored in the previous lecture, the arm,
unlike the torso, has a significantly wider range of motion

5
00:00:34.336 --> 00:00:36.298
and consists of multiple muscle layers

6
00:00:36.665 --> 00:00:41.004
This results in highly dynamic silhouette changes
depending on the movement direction and angles

7
00:00:41.474 --> 00:00:43.159
In this session, we will examine

8
00:00:43.578 --> 00:00:48.089
how muscles change through wrist rotation,
specifically pronation and supination of the forearm

9
00:00:48.383 --> 00:00:51.126
We will also look into shoulder changes
when the arm is raised

10
00:00:51.127 --> 00:00:55.453
and muscle transformations
during arm flexion and extension

11
00:00:55.454 --> 00:00:59.433
These aspects will be analyzed through various poses

12
00:00:59.732 --> 00:01:02.697
It's like the practical application
of arm anatomy for drawing

13
00:01:03.442 --> 00:01:04.355
Let’s get started

14
00:01:04.532 --> 00:01:08.578
Arm Muscles

15
00:01:08.699 --> 00:01:10.451
Before diving in, let’s do a quick review

16
00:01:11.074 --> 00:01:15.383
The arm performs not only flexion and extension
but also wrist rotation,

17
00:01:15.383 --> 00:01:18.121
known as pronation and supination

18
00:01:18.945 --> 00:01:23.768
The default position is when the palms face forward,
which is called supination

19
00:01:24.780 --> 00:01:29.554
We previously learned that wrist rotation follows the radius

20
00:01:29.557 --> 00:01:31.845
and that the radius follows the thumb

21
00:01:32.865 --> 00:01:34.548
Please keep that in mind

22
00:01:34.548 --> 00:01:37.031
However, when we studied muscles last time,

23
00:01:37.032 --> 00:01:39.807
we only looked at the muscles in the supinated state,

24
00:01:40.083 --> 00:01:42.927
that is, we only observed them in their default position

25
00:01:43.194 --> 00:01:46.449
What happens when we rotate the wrist
while keeping the same muscles?

26
00:01:46.640 --> 00:01:51.966
The forearm muscles, for wrist and hand movements,
will undergo significant shape transformations

27
00:01:52.300 --> 00:01:54.109
Here’s an arm in supination,

28
00:01:54.507 --> 00:01:55.507
the default

29
00:01:56.082 --> 00:02:00.233
Looking at the side view,

30
00:02:00.234 --> 00:02:03.007
the brachioradialis and wrist extensor muscles
extend toward the thumb side

31
00:02:04.298 --> 00:02:07.194
For the purpose of this session,
when I refer to the brachioradialis,

32
00:02:07.743 --> 00:02:09.844
please understand that I am including

33
00:02:10.033 --> 00:02:14.392
both the brachioradialis and wrist extensors as a single unit

34
00:02:14.936 --> 00:02:19.896
In general, many forearm muscles are relatively
aligned horizontally in this neutral state

35
00:02:20.460 --> 00:02:22.883
Meanwhile, in the upper arm,

36
00:02:22.883 --> 00:02:27.121
the biceps brachii is prominent,

37
00:02:27.121 --> 00:02:28.428
while the triceps brachii

38
00:02:28.428 --> 00:02:31.171
at the back is barely visible

39
00:02:31.597 --> 00:02:35.199
The deltoid, as its name suggests,
maintains a clear triangular shape

40
00:02:35.677 --> 00:02:40.082
Now, let’s rotate the forearm into pronation,
with the back of the hand facing forward

41
00:02:40.986 --> 00:02:42.708
Many things change

42
00:02:42.924 --> 00:02:44.226
Let's look at the forearm

43
00:02:44.657 --> 00:02:47.901
The brachioradialis, which was straight in supination,

44
00:02:48.548 --> 00:02:51.749
now curves inward, following the thumb’s movement

45
00:02:52.586 --> 00:02:57.045
The proximal part of the brachioradialis,
which was previously hidden, becomes more visible

46
00:02:57.707 --> 00:03:00.337
From a side view, this shape transformation
is even more noticeable

47
00:03:00.707 --> 00:03:05.602
Additionally, muscles that were barely visible before,
such as the triceps brachii at the back of the upper arm

48
00:03:05.604 --> 00:03:07.498
and hand extensors, become more pronounced

49
00:03:08.500 --> 00:03:14.042
The deltoid also thickens, creating a more rounded shape

50
00:03:14.384 --> 00:03:19.452
The interaction between the biceps
and triceps becomes more distinct

51
00:03:20.527 --> 00:03:23.499
When drawing pronation, the brachioradialis line

52
00:03:23.499 --> 00:03:25.797
is one of the most noticeable aspects to depict

53
00:03:26.134 --> 00:03:29.772
In supination, this line drops straight down

54
00:03:29.772 --> 00:03:33.131
In pronation, it curves inward,
creating a more dynamic appearance

55
00:03:34.003 --> 00:03:36.430
Other muscles in the forearm
follow a similar rotational arc

56
00:03:37.122 --> 00:03:42.768
In reality, we rarely hold our palms or backs

57
00:03:43.456 --> 00:03:46.637
of the hands completely forward for long

58
00:03:47.413 --> 00:03:48.887
That’s because it requires muscle effort and feels unnatural

59
00:03:49.499 --> 00:03:52.485
When the arm is relaxed,

60
00:03:53.299 --> 00:03:56.804
the brachioradialis follows the thumb’s inward curve,

61
00:03:56.804 --> 00:03:58.194
creating a triangle shape

62
00:03:59.200 --> 00:04:04.237
Below that, hand and wrist muscles extend horizontally

63
00:04:05.139 --> 00:04:06.876
Now it's the upper arm

64
00:04:07.462 --> 00:04:12.460
Unlike before, where only the biceps
or triceps were visible,

65
00:04:12.460 --> 00:04:14.871
both now appear equally from this perspective

66
00:04:15.037 --> 00:04:19.365
The deltoid follows the arm’s contours,
blending into the silhouette

67
00:04:19.956 --> 00:04:23.710
If we were to define the most natural arm pose,
this neutral position would be a strong candidate

68
00:04:24.358 --> 00:04:29.468
So far, I have explained pronation and supination
using the brachioradialis as the reference point

69
00:04:29.810 --> 00:04:34.467
So, how do we handle the rest of the forearm muscles
when drawing?

70
00:04:36.530 --> 00:04:37.868
Here’s a shortcut I often use

71
00:04:38.456 --> 00:04:40.568
Draw two straight lines

72
00:04:40.910 --> 00:04:44.594
to define the brachioradialis and wrist extensor bundle

73
00:04:44.594 --> 00:04:48.058
These two muscle groups undergo dramatic changes
during rotation,

74
00:04:48.496 --> 00:04:51.026
making their outlines more pronounced

75
00:04:51.900 --> 00:04:56.146
In contrast, other forearm muscles have weaker outlines

76
00:04:56.915 --> 00:04:59.480
and less noticeable transformations

77
00:04:59.779 --> 00:05:01.991
Trying to master every single muscle detail
here is extremely difficult

78
00:05:02.687 --> 00:05:03.725
So I simply treat them

79
00:05:04.708 --> 00:05:06.190
as two main lines for clarity

80
00:05:06.664 --> 00:05:07.756
This isn’t a perfect anatomical approach,

81
00:05:08.179 --> 00:05:13.244
but it’s practical when dealing
with the complexity of forearm anatomy,

82
00:05:13.250 --> 00:05:16.067
which I cannot pull myself to master

83
00:05:16.464 --> 00:05:17.862
That's about it

84
00:05:19.055 --> 00:05:22.110
If you do manage to fully master all forearm
and hand muscles, I sincerely respect you

85
00:05:22.208 --> 00:05:23.831
You deserve a double thumbs-up

86
00:05:24.144 --> 00:05:26.240
Now, let’s briefly explore how shoulder muscles

87
00:05:26.550 --> 00:05:30.189
Imagine you’re stretching with one arm raised high

88
00:05:31.380 --> 00:05:32.604
Like this

89
00:05:35.435 --> 00:05:38.183
How does this affect the deltoid and surrounding muscles?

90
00:05:38.943 --> 00:05:42.863
The deltoid previously fit between the biceps and triceps,

91
00:05:43.317 --> 00:05:44.873
so in between them?

92
00:05:45.475 --> 00:05:46.214
That's not true

93
00:05:46.601 --> 00:05:49.400
The deltoid now moves back

94
00:05:50.233 --> 00:05:53.234
The visible front muscles now include the pectoralis major

95
00:05:53.850 --> 00:05:57.576
and coracobrachialis or the small shoulder muscle

96
00:05:58.319 --> 00:06:00.265
The arm girdle bones we previously examined,

97
00:06:00.632 --> 00:06:03.076
that is, the scapula and clavicle, 
do you remember how they functioned?

98
00:06:03.495 --> 00:06:07.013
In order to lift the arm, the scapula must fully expand,

99
00:06:07.013 --> 00:06:08.810
and the clavicle follows this movement upward

100
00:06:09.569 --> 00:06:13.236
As a result, the muscles attached to these bones
also shift accordingly

101
00:06:13.826 --> 00:06:16.288
This is why the deltoid muscle,
which was originally visible, is no longer in view

102
00:06:16.980 --> 00:06:18.716
This is really fascinating

103
00:06:19.008 --> 00:06:20.474
I remember when I first saw this,

104
00:06:20.854 --> 00:06:24.990
I thought, wow, it changes like this? So cool!

105
00:06:25.293 --> 00:06:29.093
The deltoid muscle, which is clearly
visible when the arm is down,

106
00:06:29.102 --> 00:06:31.028
tilts backward when raising the arms

107
00:06:31.256 --> 00:06:33.363
I doubt you’ll easily forget this either

108
00:06:33.739 --> 00:06:35.801
Now, let’s take a look at the upper arm

109
00:06:37.430 --> 00:06:39.504
Focusing so much on pronation and supination,

110
00:06:39.504 --> 00:06:42.907
I feel like we’ve neglected the key muscles
of the upper arm

111
00:06:43.661 --> 00:06:45.604
As I mentioned before,

112
00:06:45.604 --> 00:06:48.021
muscles can only actively contract

113
00:06:48.022 --> 00:06:49.834
They cannot actively relax

114
00:06:50.371 --> 00:06:52.913
This is why we have flexor and extensor muscles,

115
00:06:52.914 --> 00:06:55.488
which usually exist in pairs

116
00:06:55.937 --> 00:06:59.728
For the arm, the brachialis
and biceps brachii handle flexion,

117
00:07:00.050 --> 00:07:03.141
while the triceps brachii is responsible for extension

118
00:07:03.739 --> 00:07:05.487
Now, let’s flex the arm with some force

119
00:07:05.719 --> 00:07:06.356
Like this

120
00:07:08.660 --> 00:07:11.813
The biceps, our familiar biceps brachii,

121
00:07:11.965 --> 00:07:15.685
swells up as if it’s flexing in anger

122
00:07:16.671 --> 00:07:18.895
What happens when we extend the arm?

123
00:07:19.731 --> 00:07:23.174
At this moment, the triceps brachii,

124
00:07:23.174 --> 00:07:26.777
finally getting its turn,
expands and makes its presence known

125
00:07:27.820 --> 00:07:30.141
While this may seem obvious,

126
00:07:30.142 --> 00:07:32.274
breaking it down by principle

127
00:07:32.275 --> 00:07:34.346
makes it feel like a new discovery

128
00:07:34.810 --> 00:07:38.605
The elbow is the protruding part at the head of the ulna,
forming the joint

129
00:07:39.971 --> 00:07:41.967
You’re all familiar with this part

130
00:07:43.007 --> 00:07:45.209
This section is covered by fascia,

131
00:07:45.209 --> 00:07:47.686
leaving the bone directly exposed under the skin

132
00:07:47.904 --> 00:07:52.752
If you follow the elbow line down, it connects to the ulna

133
00:07:53.299 --> 00:07:55.883
Remember how we said that the radius
follows the thumb side?

134
00:07:56.794 --> 00:08:00.603
The ulna, on the other hand, extends
toward the protruding area of the pinky finger

135
00:08:00.934 --> 00:08:01.819
That's right

136
00:08:02.222 --> 00:08:05.672
WThe ulna, on the other hand, extends toward

137
00:08:05.672 --> 00:08:08.283
the protruding area of the pinky finger

138
00:08:08.284 --> 00:08:11.245
It creates a natural arm boundary

139
00:08:11.597 --> 00:08:14.448
Next, let’s draw an outstretched arm pose

140
00:08:14.811 --> 00:08:17.357
From the front, the arm won’t be very visible

141
00:08:18.143 --> 00:08:19.152
since it’s overlapping

142
00:08:19.519 --> 00:08:23.637
Just like with the torso, we tend to assume
the cross-section of the arm is a perfect circle

143
00:08:24.140 --> 00:08:26.794
However, as you can see,
it often takes an elongated oval shape,

144
00:08:26.803 --> 00:08:29.903
more like a flattened baguette

145
00:08:31.140 --> 00:08:35.955
In other words, avoid drawing it as a perfect circle

146
00:08:37.262 --> 00:08:41.240
For the upper arm, since the muscle layers
stack more vertically than horizontally,

147
00:08:41.240 --> 00:08:42.709
it takes on a taller oval shape

148
00:08:43.020 --> 00:08:46.331
 Conversely, the forearm connects to the hand,

149
00:08:46.331 --> 00:08:48.767
where the palm is wider horizontally,

150
00:08:48.767 --> 00:08:51.091
so the forearm also follows this shape

151
00:08:51.525 --> 00:08:56.420
Keeping these muscle shapes in mind is crucial
when depicting overlapping arms

152
00:08:56.778 --> 00:08:59.748
That said, there’s no need to be overly precise

153
00:08:59.972 --> 00:09:04.396
In many cases, exaggerated proportions
are used in such scenes,

154
00:09:04.773 --> 00:09:08.444
and bold exaggeration is often more effective
than strict accuracy

155
00:09:08.900 --> 00:09:10.603
If you understand the basic form

156
00:09:10.603 --> 00:09:13.450
and can adapt it to your desired composition,

157
00:09:13.851 --> 00:09:16.287
that alone is enough

158
00:09:16.776 --> 00:09:20.338
Exaggeration is more about energy than precision

159
00:09:20.637 --> 00:09:21.962
The same goes for the armpit

160
00:09:22.267 --> 00:09:23.642
It’s a familiar area,

161
00:09:23.895 --> 00:09:25.956
yet when trying to draw it after studying

162
00:09:26.568 --> 00:09:28.753
arm and torso anatomy, it can be confusing

163
00:09:28.900 --> 00:09:30.315
At least, that was my experience

164
00:09:30.950 --> 00:09:31.732
Take a look

165
00:09:32.635 --> 00:09:37.020
The armpit is essentially a meeting point
for the upper arm and torso muscles

166
00:09:37.552 --> 00:09:40.929
The pectoralis major, coracobrachialis, latissimus dorsi,

167
00:09:41.256 --> 00:09:43.252
biceps brachii, and triceps brachii

168
00:09:43.775 --> 00:09:46.159
all converge here on the armpit

169
00:09:47.081 --> 00:09:51.946
The most influential lines in shaping this area
are the pectoralis major,

170
00:09:52.136 --> 00:09:53.574
biceps brachii, and latissimus dorsi

171
00:09:54.102 --> 00:09:55.795
These three form the primary intersections

172
00:09:56.340 --> 00:10:00.650
For added detail, the coracobrachialis
runs through the middle,

173
00:10:01.145 --> 00:10:04.751
and the triceps at the back also influences the contour

174
00:10:05.270 --> 00:10:08.308
Many artists simplify this area

175
00:10:08.308 --> 00:10:11.519
into the intersection of the biceps and chest muscles

176
00:10:12.219 --> 00:10:14.123
But if you need to depict a muscle-bound character,

177
00:10:14.575 --> 00:10:17.732
adding detail becomes important

178
00:10:18.179 --> 00:10:22.012
Now, we’ve examined the various muscle lines
and details of the arm

179
00:10:22.342 --> 00:10:23.157
How do you feel?

180
00:10:23.805 --> 00:10:26.525
Personally, I now feel much more confident
in drawing arms

181
00:10:26.797 --> 00:10:30.916
Teaching is truly one of the best ways to learn

182
00:10:31.109 --> 00:10:33.548
Now, let’s move on to the grand finale, the hands

183
00:10:33.728 --> 00:10:37.652
Muscles and Bones of the Hand

184
00:10:37.981 --> 00:10:38.754
Here’s the hand

185
00:10:39.238 --> 00:10:40.387
Yes, the hand

186
00:10:41.299 --> 00:10:44.202
Since I specialize in romance illustrations,

187
00:10:44.775 --> 00:10:47.012
I consider the hand to be a second face

188
00:10:47.589 --> 00:10:50.878
Of course, in action genres,
hand details are also important

189
00:10:50.878 --> 00:10:55.228
However, in romance, conversations
often drive the story rather than action

190
00:10:55.710 --> 00:10:58.459
This results in many close-ups and bust shots

191
00:10:59.026 --> 00:11:01.183
As I mentioned earlier,

192
00:11:01.189 --> 00:11:05.520
such compositions limit expressive movement
in the upper body

193
00:11:05.776 --> 00:11:07.773
If two characters are conversing,

194
00:11:07.774 --> 00:11:10.070
they can’t suddenly twist their torsos

195
00:11:10.500 --> 00:11:12.228
into unnatural poses

196
00:11:12.935 --> 00:11:15.766
At most, changes in the neck and shoulders are possible

197
00:11:16.500 --> 00:11:19.833
This is where hands play a crucial role
in setting the mood

198
00:11:20.336 --> 00:11:24.013
Hands can also express a wide range of emotions
in close-ups, just like the face

199
00:11:24.400 --> 00:11:25.531
A clenched fist,

200
00:11:25.533 --> 00:11:26.841
trembling fingers,

201
00:11:26.841 --> 00:11:27.965
grasping a cup,

202
00:11:27.965 --> 00:11:28.937
pointing a finger

203
00:11:29.916 --> 00:11:32.209
All of these gestures carry specific connotations

204
00:11:32.484 --> 00:11:33.581
How was it?

205
00:11:33.960 --> 00:11:35.995
A close-up that might seem plain or dull

206
00:11:35.995 --> 00:11:40.320
can gain a sense of presence and action
when a hand is added,

207
00:11:40.692 --> 00:11:43.874
In drama and romance genres, with many dialogues,

208
00:11:43.874 --> 00:11:46.151
the ability to draw hands becomes especially important

209
00:11:46.960 --> 00:11:49.493
However, hands are incredibly difficult to draw

210
00:11:50.321 --> 00:11:53.255
Even as an artist with 15 years of experience,
I still struggle with them at times

211
00:11:53.255 --> 00:11:54.723
So I can only imagine how challenging it must be for you

212
00:11:55.761 --> 00:11:58.545
Just drawing a single finger is difficult,

213
00:11:58.547 --> 00:12:02.169
but there are five of them, one of them
slightly different in size and shape

214
00:12:02.911 --> 00:12:06.578
The palm that connects them isn’t flat

215
00:12:06.578 --> 00:12:08.825
It’s thick in some areas, thin in others,

216
00:12:09.191 --> 00:12:11.528
and has irregular contours, making it hard to grasp

217
00:12:11.960 --> 00:12:15.142
You know there are five fingers on a palm,

218
00:12:15.348 --> 00:12:17.738
but when you actually try to draw them,
you often get stuck

219
00:12:18.239 --> 00:12:21.798
This is a drawing of a hand I made
when I was in first or second grade

220
00:12:22.335 --> 00:12:25.548
If only we could get away with this,
life would be so much easier

221
00:12:25.560 --> 00:12:26.495
But we can't

222
00:12:26.840 --> 00:12:30.873
If readers are admiring a beautifully drawn face,

223
00:12:30.873 --> 00:12:32.563
they might lose immersion in an instant with the hand

224
00:12:32.765 --> 00:12:34.862
You need to be able to draw hands
at least somewhat convincingly

225
00:12:35.107 --> 00:12:37.556
This is even more important
if you’re aspiring to work in the romance genre

226
00:12:38.236 --> 00:12:39.114
It’s tough,

227
00:12:39.871 --> 00:12:41.323
but let’s tackle it together

228
00:12:42.320 --> 00:12:45.723
Before diving into anatomy,
let’s first get an overview of the hand

229
00:12:46.000 --> 00:12:49.473
To start, let’s separate the thumb from
the other four fingers and examine them individually

230
00:12:49.928 --> 00:12:51.450
Starting with the four fingers

231
00:12:51.679 --> 00:12:54.834
The most fundamental function of the hand
is grasping objects

232
00:12:55.288 --> 00:12:57.647
This involves flexion and extension movements

233
00:12:58.242 --> 00:12:59.542
Flexion occurs toward the palm,

234
00:12:59.545 --> 00:13:02.155
while extension is controlled on the back of the hand

235
00:13:02.479 --> 00:13:03.994
Try raising your hand and observing its movement

236
00:13:04.640 --> 00:13:06.274
Although drawing hands is incredibly difficult,

237
00:13:06.275 --> 00:13:08.698
the advantage is that visual references
are always readily available

238
00:13:09.075 --> 00:13:15.273
Each of the four fingers is divided into three sections,
the proximal, the middle, and the distal phalanx

239
00:13:15.732 --> 00:13:18.564
If the hand were just one large, single finger,

240
00:13:19.359 --> 00:13:21.326
it would still be able to grasp objects,

241
00:13:21.767 --> 00:13:24.227
but its versatility would be greatly limited

242
00:13:24.900 --> 00:13:27.956
Instead, having four separate fingers allows
for more diverse

243
00:13:27.957 --> 00:13:31.958
and adaptable grips, making it
evolutionarily advantageous

244
00:13:32.466 --> 00:13:35.150
Given that hands evolved from feet,

245
00:13:35.168 --> 00:13:38.232
it makes sense that fingers developed as multiple segments

246
00:13:38.641 --> 00:13:41.886
Another notable characteristic is
that because grasping is so important,

247
00:13:41.886 --> 00:13:47.136
the palm side is much thicker compared
to the back of the hand

248
00:13:47.503 --> 00:13:51.553
Even just comparing the palm and the back of the hand,
you can see a significant difference in muscle mass,

249
00:13:51.875 --> 00:13:53.027
especially around the thumb

250
00:13:53.285 --> 00:13:55.198
So why do we have a thumb?

251
00:13:55.639 --> 00:13:58.491
Picture yourself hanging onto
something with only four fingers

252
00:13:59.411 --> 00:14:00.589
You’re managing for now,

253
00:14:01.479 --> 00:14:04.808
but your grip is weakening, and the fingers begin to slip

254
00:14:05.079 --> 00:14:05.917
Oh no!

255
00:14:06.441 --> 00:14:10.719
his is where the thumb comes in

256
00:14:10.719 --> 00:14:12.663
It locks in place, securing the grip

257
00:14:13.865 --> 00:14:17.888
The thumb is like the biggest brother of all fingers

258
00:14:18.212 --> 00:14:18.939
It's amazing

259
00:14:19.687 --> 00:14:24.723
The thumb serves as a crucial stabilizer,
dramatically increasing grip strength

260
00:14:25.080 --> 00:14:28.735
Try imagining gripping something without your thumb

261
00:14:29.440 --> 00:14:32.047
You’ll immediately realize how essential it is

262
00:14:32.400 --> 00:14:35.112
That said, the thumb is just one against four

263
00:14:35.919 --> 00:14:39.098
It needs enough strength to counterbalance
the weight of the other four fingers

264
00:14:39.679 --> 00:14:43.115
Unlike the other fingers, the thumb only has two joints,

265
00:14:43.599 --> 00:14:44.825
while others have three

266
00:14:45.159 --> 00:14:47.153
This means it has a more limited range of motion,

267
00:14:47.333 --> 00:14:49.449
but in return, it can focus its strength more effectively

268
00:14:50.000 --> 00:14:52.047
Additionally, the muscles around the base of the thumb

269
00:14:52.805 --> 00:14:56.602
are significantly larger compared
to other areas of the hand

270
00:14:57.119 --> 00:15:00.861
With the emergence of the thumb, the hand
became capable of opposition

271
00:15:01.410 --> 00:15:04.113
Think of a LEGO minifigure’s hand

272
00:15:04.890 --> 00:15:06.716
The opposition between the thumb and the four fingers

273
00:15:06.716 --> 00:15:08.876
That's what the opposition means

274
00:15:09.311 --> 00:15:13.353
This ability is the foundation of how we grasp objects

275
00:15:13.884 --> 00:15:16.106
Now that we’ve covered the basics of the hand,

276
00:15:16.670 --> 00:15:18.593
let’s move on to the bones

277
00:15:19.505 --> 00:15:25.324
The bones of the hand can be divided into three major groups:
Carpal bones, metacarpal bones, and phalanges

278
00:15:25.718 --> 00:15:28.878
The carpal bones connect the hand to the forearm

279
00:15:28.889 --> 00:15:31.838
They are arranged in a compact, clustered formation,
like a collection of small pebbles

280
00:15:32.280 --> 00:15:34.621
You don’t need to memorize all their individual names,

281
00:15:35.280 --> 00:15:37.911
but keep in mind

282
00:15:37.911 --> 00:15:39.872
that the curved shape of the palm

283
00:15:39.873 --> 00:15:42.487
is largely determined by the structure of these wrist bones

284
00:15:42.789 --> 00:15:44.529
Please remember that

285
00:15:44.993 --> 00:15:47.551
The metacarpal bones form
the boundary between the wrist and the palm,

286
00:15:47.820 --> 00:15:49.905
as well as between the palm and the fingers

287
00:15:50.719 --> 00:15:51.937
Here’s an interesting detail

288
00:15:52.488 --> 00:15:55.011
The point where the metacarpal bones
connect to the phalanges

289
00:15:55.280 --> 00:15:59.173
is not the same as where our fingers
visually appear to begin

290
00:15:59.760 --> 00:16:01.478
The actual joint between

291
00:16:01.900 --> 00:16:06.424
the palm and the fingers is lower than it seems

292
00:16:06.446 --> 00:16:08.323
So when you bend your fingers,

293
00:16:08.732 --> 00:16:11.173
they don’t fold exactly at the point
where they appear to separate,

294
00:16:11.173 --> 00:16:13.561
but rather at a lower point in the hand

295
00:16:14.280 --> 00:16:17.698
I actually discovered this while preparing for this lecture

296
00:16:18.280 --> 00:16:20.338
It makes drawing hands both

297
00:16:20.338 --> 00:16:22.020
more fascinating and more challenging

298
00:16:22.559 --> 00:16:27.096
Rather than bending precisely here,
the fingers fold at a slightly recessed area lower down

299
00:16:27.104 --> 00:16:29.010
I had been unconsciously drawing it this way,

300
00:16:29.679 --> 00:16:32.479
but now that I understand the structural reason behind it,

301
00:16:32.479 --> 00:16:35.181
I can finally see why hands form those distinctive lines

302
00:16:36.009 --> 00:16:37.293
That was my revelation

303
00:16:38.039 --> 00:16:39.298
But anyhow, we now know

304
00:16:39.640 --> 00:16:41.626
The boundary between the bone joints
and the visible finger segments is different

305
00:16:41.996 --> 00:16:42.669
Please take note of it

306
00:16:43.400 --> 00:16:46.336
One of the most prominent landmarks of the hand

307
00:16:46.349 --> 00:16:48.688
is the protruding metacarpophalangeal (MCP) joints

308
00:16:49.479 --> 00:16:54.490
When drawing the back of the hand or a clenched fist,
you often depict these knuckle ridges as small hills

309
00:16:55.200 --> 00:16:59.026
These hills correspond to the MCP joints
located at the end of the metacarpal bones

310
00:17:00.000 --> 00:17:04.199
When making a fist, the fingers fold at this point,

311
00:17:04.199 --> 00:17:07.545
and the MCP joints become visibly prominent

312
00:17:07.800 --> 00:17:11.359
Properly depicting this part can emphasize either
the delicate nature of a hand

313
00:17:11.359 --> 00:17:14.383
or the strength of a clenched fist

314
00:17:14.760 --> 00:17:17.479
Each finger consists of three phalanges,

315
00:17:17.479 --> 00:17:20.642
the proximal, middle, and distal phalanx

316
00:17:21.277 --> 00:17:23.479
The proximal phalanx connects to the metacarpal bone,

317
00:17:23.479 --> 00:17:26.680
the middle phalanx links the first and second joints,

318
00:17:26.680 --> 00:17:30.180
and the distal phalanx forms the tip of the finger,
where the fingernail is located

319
00:17:30.680 --> 00:17:34.239
Many people simplify fingers as long, straight cylinders,

320
00:17:34.239 --> 00:17:36.069
but the distal phalanx actually

321
00:17:36.622 --> 00:17:39.581
has a subtle curve that follows the shape of the fingernail

322
00:17:40.119 --> 00:17:44.566
In contrast, the thumb has only two segments,

323
00:17:45.140 --> 00:17:47.959
which, as mentioned earlier,

324
00:17:47.959 --> 00:17:50.213
allows it to oppose and support the four fingers

325
00:17:50.680 --> 00:17:55.349
As a result, the fingertip appears to
have a slight additional bend

326
00:17:56.000 --> 00:18:00.359
Since the fingernail is halfway down the distal phalanx,
it creates a small inward dip

327
00:18:00.359 --> 00:18:02.199
Although fingers technically have three joints,

328
00:18:02.199 --> 00:18:05.845
think of the fingertip as having
an extra unbending segment

329
00:18:05.845 --> 00:18:07.011
to better capture the natural curve

330
00:18:07.494 --> 00:18:11.293
There are also differences in how the knuckles and fingers
are depicted between male and female hands

331
00:18:11.680 --> 00:18:14.599
Generally, men’s knuckles tend to

332
00:18:14.599 --> 00:18:17.169
be more pronounced than women’s

333
00:18:17.919 --> 00:18:21.400
On the other hand, female fingers are usually thinner

334
00:18:21.400 --> 00:18:22.803
and longer,

335
00:18:22.803 --> 00:18:26.258
with less emphasis on the knuckles

336
00:18:26.421 --> 00:18:30.400
To emphasize the roughness of a male hand,
artists often exaggerate the prominence of the knuckles

337
00:18:30.400 --> 00:18:33.636
and depict fingers as thick with minimal spacing

338
00:18:34.092 --> 00:18:37.160
Conversely, elegant or beautiful hands

339
00:18:37.160 --> 00:18:40.055
are typically drawn with long, slender fingers
and greater spacing between them

340
00:18:41.319 --> 00:18:43.956
Now that we’ve examined these hand characteristics,

341
00:18:44.760 --> 00:18:49.190
let’s take a look at the muscles of the hand and wrist,
which we briefly covered in the previous session

342
00:18:50.040 --> 00:18:52.654
It may seem complex, but we’ll break it down simply

343
00:18:53.520 --> 00:18:56.378
The muscles of the hand can be broadly categorized into two types

344
00:18:57.000 --> 00:18:58.719
Flexor muscles and extensor muscles

345
00:18:58.719 --> 00:19:03.982
The flexor muscles include the flexor digitorum profundus
and the flexor pollicis longus,

346
00:19:04.479 --> 00:19:06.479
both located on the palm side of the hand

347
00:19:06.479 --> 00:19:08.260
to contribute to finger flexion

348
00:19:09.239 --> 00:19:11.920
Previously, I mentioned the knuckle ridges

349
00:19:11.920 --> 00:19:13.628
that become prominent when making a fist

350
00:19:14.280 --> 00:19:18.239
In contrast, when the fingers are extended upward,

351
00:19:18.239 --> 00:19:20.145
the tendons of the extensor muscles become visible

352
00:19:21.027 --> 00:19:24.312
By emphasizing these lines,
you can add detail to the back of the hand

353
00:19:24.880 --> 00:19:30.520
Additionally, the thumb
has the extensor pollicis longus and extensor pollicis brevis,

354
00:19:30.520 --> 00:19:33.490
which cross over each other and form
a noticeable groove known as the anatomical snuffbox

355
00:19:34.400 --> 00:19:37.415
These details are particularly useful
for depicting slender or bony hands

356
00:19:37.719 --> 00:19:40.387
So far, we’ve covered the basic anatomy of the hand

357
00:19:40.800 --> 00:19:43.596
However, when drawing hands,

358
00:19:43.597 --> 00:19:48.062
understanding the overall flow of movement
is more effective than focusing solely on muscle details

359
00:19:48.319 --> 00:19:52.196
Unlike other parts of the body,
the hand’s muscle structure is not as prominently visible

360
00:19:52.479 --> 00:19:54.362
Instead, its shape follows a defined structure,

361
00:19:54.640 --> 00:19:57.069
which is guided by opposition,

362
00:19:57.069 --> 00:19:59.295
extension, and flexion movements,

363
00:19:59.920 --> 00:20:02.355
which prioritizes that flow of movement

364
00:20:02.790 --> 00:20:07.806
In other words, drawing hands is less about anatomy
and more about capturing dynamic motion

365
00:20:07.806 --> 00:20:10.325
With that in mind, let’s move on to practical examples
of drawing hands

366
00:20:10.800 --> 00:20:13.978
Before drawing fingers, let’s divide the palm
into different regions

367
00:20:15.079 --> 00:20:17.520
This is similar to how we first analyze the torso

368
00:20:17.520 --> 00:20:20.011
before drawing body movements

369
00:20:20.599 --> 00:20:22.012
Since fingers branch out like tree limbs,

370
00:20:22.560 --> 00:20:24.382
it’s best to start with the foundation

371
00:20:25.520 --> 00:20:28.298
We can divide the palm into four key regions

372
00:20:29.280 --> 00:20:32.269
This division can also be understood as
following the crease lines of the palm

373
00:20:32.599 --> 00:20:35.766
First, there is the thenar eminence,

374
00:20:36.640 --> 00:20:39.395
something we're familiar with palm reading

375
00:20:40.040 --> 00:20:43.948
Next, there is the broad palm area next to the thumb

376
00:20:45.319 --> 00:20:48.400
As mentioned earlier
when discussing the back of the hand, this section,

377
00:20:48.400 --> 00:20:51.905
along with the thenar eminence,
contributes significantly to the overall volume

378
00:20:52.719 --> 00:20:55.655
Then, we have the junction
where the four fingers connect to the palm

379
00:20:56.439 --> 00:21:00.818
Again, the fingers and the palm do not align exactly
with the points where the fingers bend

380
00:21:01.599 --> 00:21:06.330
nstead, the fingers slightly overlap the palm,
forming curved junctions

381
00:21:07.160 --> 00:21:12.245
When the fingers curl inward, this section folds
along with them, completely covering the palm,

382
00:21:13.002 --> 00:21:14.797
which is why a clenched fist has no visible gaps

383
00:21:15.680 --> 00:21:19.832
Finally, there is the central hollow of the palm,

384
00:21:20.800 --> 00:21:23.066
the deepest point of opposition between
the fingers and the thumb

385
00:21:24.119 --> 00:21:26.187
This section isn’t something you need to draw explicitly

386
00:21:26.839 --> 00:21:30.861
Rather, like the supraclavicular fossa,
it forms as a result of depicting the surrounding areas

387
00:21:31.760 --> 00:21:33.284
Not necessarily, though

388
00:21:33.920 --> 00:21:36.732
One particularly important aspect to note

389
00:21:37.168 --> 00:21:39.527
is the curved boundary
where the four fingers meet the palm

390
00:21:40.439 --> 00:21:44.856
As you can see, fingers do not attach to the palm
in a straight line but rather form a gentle arc

391
00:21:45.800 --> 00:21:48.079
If you fail to account for this curve when drawing,

392
00:21:48.079 --> 00:21:51.261
the hand will appear stiff and unnatural,
like a robotic hand

393
00:21:52.199 --> 00:21:53.705
So be sure to keep it in mind

394
00:21:54.079 --> 00:21:56.168
It's a critical factor in drawing natural-looking hands

395
00:21:56.997 --> 00:22:00.507
Looking back, I realize that even the crude hands
I drew as a child

396
00:22:00.507 --> 00:22:02.062
contained an unexpected level of insight

397
00:22:02.959 --> 00:22:04.686
Of course, I wasn’t inventing anything

398
00:22:04.687 --> 00:22:07.021
I was simply copying the work of professional artists

399
00:22:07.027 --> 00:22:08.661
Perhaps it's something obvious

400
00:22:09.239 --> 00:22:12.924
Now, let’s move on to some
practical hand-drawing exercises

401
00:22:13.520 --> 00:22:15.529
First, stretch out your hand

402
00:22:15.920 --> 00:22:17.009
as wide as you can

403
00:22:17.880 --> 00:22:21.514
Notice how, when fully extended, all the fingertips

404
00:22:22.319 --> 00:22:25.794
and knuckles fan out in a radial pattern from the wrist

405
00:22:26.040 --> 00:22:29.808
Let’s begin by defining the palm’s basic shape
and confidently sketching out the primary structures

406
00:22:30.359 --> 00:22:32.839
When the fingers are fully extended,

407
00:22:32.839 --> 00:22:34.158
the indentations between them straighten out,

408
00:22:34.158 --> 00:22:36.554
forming smooth, linear separations

409
00:22:37.239 --> 00:22:41.839
The line extending from the palm to the thumb
should also be drawn as a continuous straight line

410
00:22:41.839 --> 00:22:44.920
Similarly, all other fingers should be fully stretched out,

411
00:22:44.920 --> 00:22:46.622
and their forms should be carefully
sketched in a natural arc

412
00:22:47.079 --> 00:22:47.770
That's it

413
00:22:50.040 --> 00:22:51.352
Now, let’s flip it over and examine the back of the hand

414
00:22:51.680 --> 00:22:53.203
The fundamental structure remains the same

415
00:22:53.439 --> 00:22:55.788
However, there’s something interesting to note

416
00:22:57.079 --> 00:23:01.903
The boundaries between fingers on the palm
side and the back of the hand do not align perfectly

417
00:23:02.719 --> 00:23:04.959
If you spread your fingers wide open, you’ll notice

418
00:23:04.959 --> 00:23:09.599
a web-like membrane between them,

419
00:23:09.599 --> 00:23:11.353
somewhat resembling the webbing on a frog’s feet

420
00:23:12.400 --> 00:23:15.555
This webbed section marks the finger boundaries
on the palm side

421
00:23:16.479 --> 00:23:21.608
Now, if you close your fingers
while looking at the back of your hand

422
00:23:22.668 --> 00:23:25.199
the webbing becomes hidden,

423
00:23:25.199 --> 00:23:28.657
making the boundaries between fingers appear
longer on the back than on the palm

424
00:23:29.520 --> 00:23:30.224
See that?

425
00:23:31.280 --> 00:23:32.026
That's right

426
00:23:32.719 --> 00:23:37.128
The separation between fingers is more pronounced
on the back than on the palm

427
00:23:37.680 --> 00:23:40.319
his was something I had not consciously realized before,

428
00:23:40.319 --> 00:23:41.618
but preparing for this lecture made me aware of it

429
00:23:42.239 --> 00:23:44.350
Now, returning to the drawing,

430
00:23:44.959 --> 00:23:46.738
let’s refine some details by highlighting
key tendon structures:

431
00:23:47.225 --> 00:23:48.354
Extensor digitorum, extensor pollicis longus,

432
00:23:48.544 --> 00:23:50.625
and extensor pollicis brevis

433
00:23:50.959 --> 00:23:52.737
These tendons will add depth and realism to the drawing

434
00:23:53.359 --> 00:23:56.604
Now, let’s relax the fully extended hand

435
00:23:57.101 --> 00:23:59.294
If you gradually release tension,

436
00:23:59.305 --> 00:24:02.315
the hand will naturally curve into a shape
that resembles gripping a small ball

437
00:24:03.119 --> 00:24:03.951
That's right

438
00:24:03.954 --> 00:24:05.022
Opposition again

439
00:24:05.920 --> 00:24:09.280
You may have noticed that in 3D modeling or animation,

440
00:24:09.280 --> 00:24:13.074
characters often start in a stiff T-pose,

441
00:24:13.959 --> 00:24:15.385
which, at first glance, looks unnatural and uncomfortable

442
00:24:16.357 --> 00:24:18.640
Earlier, we discussed how
the most natural resting position

443
00:24:18.640 --> 00:24:21.108
for the arms is slightly bent rather than fully extended

444
00:24:21.560 --> 00:24:22.756
The same applies to the hand

445
00:24:23.560 --> 00:24:26.719
Instead of staying stiff and flat,

446
00:24:26.719 --> 00:24:29.295
a slightly curved, C-shaped opposition stance

447
00:24:29.295 --> 00:24:30.405
feels much more natural

448
00:24:30.959 --> 00:24:32.839
When drawing an opposed hand position, note that

449
00:24:32.839 --> 00:24:35.520
the thumb and index finger form a C shape

450
00:24:35.520 --> 00:24:38.040
and the middle, ring, and pinky fingers

451
00:24:38.040 --> 00:24:43.207
follow a gradually increasing curve towards the palm

452
00:24:43.207 --> 00:24:46.993
There's anther crucial detail for hands

453
00:24:47.280 --> 00:24:51.381
Earlier, I mentioned that the finger boundaries
on the palm curve naturally

454
00:24:51.760 --> 00:24:53.160
Many assume that

455
00:24:53.160 --> 00:24:56.653
the palm itself is a flat surface, but that’s not entirely true

456
00:24:57.000 --> 00:25:00.277
In reality, the cross-section of the palm is subtly curved

457
00:25:00.560 --> 00:25:02.880
Even in a relaxed state, the metacarpal bones

458
00:25:02.880 --> 00:25:05.630
are arranged in a gentle arc rather
than a completely flat plane

459
00:25:05.800 --> 00:25:09.895
Of course, you can force the palm into a flat shape,

460
00:25:10.148 --> 00:25:13.190
but that would be similar to the unnatural T-pose for arms

461
00:25:13.319 --> 00:25:15.719
A natural palm shape should always retain a slight curve

462
00:25:15.719 --> 00:25:18.014
It's essential point to remember when drawing hands

463
00:25:18.520 --> 00:25:20.341
Next is a fist

464
00:25:20.880 --> 00:25:22.974
A common approach is to simply sketch it
as a boxy shape

465
00:25:23.680 --> 00:25:25.880
with visible knuckles

466
00:25:25.880 --> 00:25:26.699
So good!

467
00:25:27.010 --> 00:25:28.199
You may end with this

468
00:25:29.079 --> 00:25:33.372
But we just learned that the palm has a natural curvature

469
00:25:33.721 --> 00:25:38.181
So we know that the fingers do not fold inward
in a perfectly straight line when forming a fist

470
00:25:39.000 --> 00:25:42.160
Instead, the fingers gradually curl inward,

471
00:25:42.160 --> 00:25:44.798
with the pinky finger tucking in
more deeply than the others

472
00:25:45.439 --> 00:25:46.680
One, two, three, four

473
00:25:46.680 --> 00:25:49.212
Notice how the fingers disappear in that order

474
00:25:49.839 --> 00:25:52.506
Let’s now examine a side view of a clenched fist

475
00:25:53.320 --> 00:25:55.287
The knuckles serve as the pivot points for the fingers

476
00:25:56.079 --> 00:25:58.113
The palm itself also folds slightly,

477
00:25:58.760 --> 00:26:01.839
as the first finger joint curls into the palm

478
00:26:02.959 --> 00:26:05.160
The second finger joint bends inward,

479
00:26:05.160 --> 00:26:08.160
and the third joint disappears completely inside the fist,

480
00:26:08.160 --> 00:26:10.898
not leaving any space inside

481
00:26:11.079 --> 00:26:15.581
The thumb presses firmly against
the index and middle fingers,

482
00:26:16.135 --> 00:26:20.280
This, too, happens because
the first metacarpal bone moves the palm

483
00:26:20.280 --> 00:26:22.184
to cover a larger portion of the four fingers

484
00:26:23.199 --> 00:26:26.035
From this angle, only the first segment
of the thumb is visible

485
00:26:26.479 --> 00:26:28.809
Looking at the fist from the pinky’s side,

486
00:26:29.560 --> 00:26:33.246
the pinky is the most visible finger of the four

487
00:26:34.280 --> 00:26:35.304
Like so

488
00:26:35.920 --> 00:26:39.427
Also, the thumb firmly secures the grip over
the front of the fist

489
00:26:40.119 --> 00:26:44.217
Now, let’s integrate what we’ve learned into
a full arm movement analysis

490
00:26:45.131 --> 00:26:49.199
It shows how the arm bends and extends
through coordinated muscle contractions

491
00:26:49.199 --> 00:26:53.228
And how the wrist naturally rotates
between supination and pronation

492
00:26:54.079 --> 00:26:59.439
Also, how key forearm muscles,
like the brachioradialis and wrist extensors,

493
00:26:59.439 --> 00:27:01.795
shift dynamically with movement is important here

494
00:27:02.359 --> 00:27:05.334
With this, we’ve now completed

495
00:27:05.920 --> 00:27:10.317
our two-part study on arms and hands

496
00:27:10.959 --> 00:27:12.800
For those of you who have followed along this far,

497
00:27:12.800 --> 00:27:15.447
I want to say: great job! You’ve put in a lot of effort

498
00:27:15.900 --> 00:27:19.732
In Webtoon and comic art, dialogue-heavy scenes
make up about 60% of most stories

499
00:27:20.059 --> 00:27:21.840
During these scenes,

500
00:27:21.840 --> 00:27:24.480
close-up shots of shoulders,

501
00:27:24.480 --> 00:27:26.731
upper bodies, and hands are frequently used

502
00:27:27.199 --> 00:27:28.736
Since facial expressions are crucial,

503
00:27:29.239 --> 00:27:32.598
understanding the upper body is also crucial

504
00:27:33.199 --> 00:27:37.432
You have now conquered about 80% of
the anatomy knowledge essential for Webtoon illustrations

505
00:27:38.160 --> 00:27:41.855
In our next lesson, we will focus
on the anatomy of the legs and feet

506
00:27:42.400 --> 00:27:47.199
Legs and feet are key elements in defining

507
00:27:47.199 --> 00:27:51.756
a character’s posture, movement, and balance

508
00:27:52.160 --> 00:27:55.000
We will explore the anatomical structure of the legs

509
00:27:55.000 --> 00:27:59.084
and the foot movement and its impact
on silhouette and posture

510
00:27:59.839 --> 00:28:02.359
Great job everyone

511
00:28:02.359 --> 00:28:03.062
Thank you

512
00:28:05.133 --> 00:28:06.970
Arm Muscles
Supination
Brachioradialis + wrist extensors extend toward the thumb
Biceps prominent, triceps barely visible

513
00:28:06.970 --> 00:28:08.331
Pronation: Brachioradialis wraps inward along the thumb
Triceps and wrist extensors more visible

514
00:28:08.331 --> 00:28:11.327
Neutral: Brachioradialis curves around
the thumb (triangular shape)
Biceps + triceps visible together

515
00:28:11.327 --> 00:28:14.731
Elbow
Ulna head protrudes
Follow pinky direction for arm contour

516
00:28:14.731 --> 00:28:18.362
Armpit
Major muscle convergence: Pectoralis major,
coracobrachialis, latissimus dorsi, biceps, triceps

517
00:28:18.362 --> 00:28:19.841
Hand Muscles and Bones
Flexor muscles: Palm side; deep finger flexor, long thumb flexor

518
00:28:19.842 --> 00:28:20.842
Extensor muscles: Dorsal side; finger extensors, long & short thumb extensors

519
00:28:20.842 --> 00:28:22.267
Bones
Wrist bones connect hand & arm
Metacarpal bones form palm structure

520
00:28:22.267 --> 00:28:24.218
Phalanges (finger bones):
Three segments, proximal, middle, distal