From the top of the shoulder to the point of the elbow is as far as
from that point to the joints of the four fingers with the palm of
the hand, and each is 2 faces.

[5]_a e_ is equal to the palm of the hand, _r f_ and _o g_ are equal
to half a head and each goes 4 times into _a b_ and _b c_. From _c_
to _m_ is 1/2 a head; _m n_ is 1/3 of a head and goes 6 times into
_c b_ and into _b a_; _a b_ loses 1/7 of its length when the arm is
extended; _c b_ never alters; _o_ will always be the middle point
between _a_ and _s_.

_y l_ is the fleshy part of the arm and measures one head; and when
the arm is bent this shrinks 2/5 of its length; _o a_ in bending
loses 1/6 and so does _o r_.

_a b_ is 1/7 of _r c_. _f s_ will be 1/8 of _r c_, and each of those
2 measurements is the largest of the arm; _k h_ is the thinnest part
between the shoulder and the elbow and it is 1/8 of the whole arm _r
c_; _o p_ is 1/5 of _r l_; _c z_ goes 13 times into _r c_.

[Footnote: See Pl. XX where the text is also seen from lines 5-23.]

The movement of the arm (350-354).