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Morphological organization and contractile properties of the wrist flexor muscles in the cat.

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THE ANATOMICAL RECORD 199:321-339 (1981)
Mo rpho Iog ical 0rgan ization and Contractile
Properties of the Wrist Flexor Muscles
in the Cat
W.J. GONYEA, S.A. MARUSHIA, AND J.A. DIXON
Department of Cell Biology, The University of Texas Health Science Center at
Dallas, Dallas, Texas 75235
ABSTRACT
A comparison of the anatomy, fiber type profiles, and contractile
properties of the wrist flexor muscles was undertaken in the cat. Isometric contractile characteristics were measured for each muscle. Three muscle fiber types, FG,
FOG, and SO, were differentiated by staining cross sections of each muscle for
ATPase, NADH diaphorase, SDH, and a-GPD activities. The wrist flexor muscles
ranged from less than 1%to 4wo SO fiber content; with two of the five heads of the
flexor digitorium profundus (FDP) having 1%or less SO fibers (FDP,-l.07%,
FDPa4.81%) and the humeral head of the flexor carpi ulnaris muscle (FCU,)
having the greatest content of SO fibers. The mean contraction time (CT) plus
one-half relaxation time for an isometric twitch was correlated with the percentage
of SO fibers and ranged from 40.5 to 111.8 ms. Except for the FCU (37 ms), the CT
was less than 25 ms for the wrist flexor muscles. The uniarticular wrist flexor
muscles, the flexor carpi radialis (FCR),and the FCU had the highest percentage of
SO fibers and were more fatigue-resistant that the multiarticular muscles. Considerable differences exist in muscle structure, fiber type proportions, and contractile
properties between the FCR and FCU, which may be related to functional differences between the two sides of the wrist that may exist during the placement of the
foot during locomotion.
The structural organization, fiber type distribution, and the contractile properties of
skeletal muscle should reflect the complexity of
tasks that the neuromuscular apparatus of the
animal is called upon to perform. To study these
structural-functional interactions, a considerable volume of data on the structural organization and physiological properties of whole muscles and single motor units of the hindlimb
muscles have been collected (reviewed in Burke
and Edgerton, '75; Close, '72). While these
studies have yielded a great deal of information, resulting in a very rapid expansion of our
understanding of the function of the neuromuscular apparatus, a similar, thorough analysis of
the distal forelimb musculature has not been
performed. In the cat, increased motor control
for the forelimb musculature may be necessary
because this animal uses its forelimbs as prehensile organs to catch and manipulate food
(Gonyea and Ashworth, '75).
In a recent study of the elbow flexor and extensor muscles of the cat, it was observed that
deeply situated uniarticular extensor muscles
0003-276x/81/1993-0321$05.50
01981 ALAN R. LISS,INC.
consisted predominantly of slow twitch muscle
fiber types. It has also been demonstrated that
these muscles are used for postural support.
The larger extensor synergists and the elbow
flexor muscles, which are not used for postural
support, are composed primarily of fast twitch
muscle fibers (Collatos et at., '77, Smith et al.,
'77). Collatos and colleagues also demonstrated
that the frequency range over which fast twitch
muscles increase tension is much greater than
that for slow twitch muscles (Collatos et al.,
'77). Hence it could be assumed that for muscles
involved in a number of motor tasks, excluding
postural adjustments, fast twitch motor units
may be preferentially selected.
Although a recent detailed electromyographic (EMG) analysis of the forelimb
muscles of the cat has been published (English, '781, no information was included in this
study concerning the activity of the wrist
flexor muscles in maintaining standing posReceived June 6, 1980; accepted July 24, 1980.
322
W.J. GONYEA, S.A. IMARUSHIA, AND J.A. DMON
ture. This information would be useful in
elucidating the functional significance of differences in fiber type distribution of these muscles as it was for the elbow musculature (Collatos et al., '77, Smith et al., '77). However, our
preliminary studies have not demonstrated
any EMG activity of the wrist flexor muscles
during quiet standing (unpublished observations) and this has been confirmed by the observations of Dr. English (personal communication).
The purpose of this study was to establish the
fiber type composition and contractile properties of the wrist flexor muscles in the cat. In
this regard, some of these muscles are also the
long flexor muscles of the digits (Gonyea and
Ashworth, '75). Even though the forelimb has
the responsibility of supporting 3@%
of the body
weight (Manter, '38) and has a major role during propulsion (Smith et al., '77, English, '78),
its use as a prehensile organ suggests the possibility of a more complex motor control for the
wrist flexor muscles than that observed for
hindlimb muscles. Hence these studies were
undertaken to assess structural-functional correlations in the wrist flexor muscles that may
be useful in assessing different adaptive
strategies in motor control. A preliminary report on the contractile properties of two wrist
flexor muscles and a detailed anatomical analysis of the flexor carpi radialis (FCR) muscle
have appeared elsewhere (Gonyea and BondePetersen, '77; Gonyea and Ericson, '77).
METHODS
MYOkY
There are five muscles that cross the flexor
surface of the wrist: the flexor carpi radialis
(FCR), flexor carpi ulnaris (FCU), palmaris
longus (PLM), flexor digitorum superficialis
(FDS), and the flexor digitorum profundus
(FDP).The FDS is a small, rudimentarymuscle
in the cat (Crouch, '69);this muscle was therefore not included in this investigation. All other
wrist flexor muscles were studied in 24 adult
cats of both sexes. The muscles were stripped
from their osseous attachments, cleaned of all
extraneous tissue including all tendon not directly receiving muscle fibers, and weighed. A
brief description of the attachments of each
muscle and a general description of the gross
muscle fiber architectural arrangement is also
given.
Histochemistry
Muscles from six cats were prepared for
histochemical examination. Sections repre-
senting the total cross-sectional area from the
greatest girth of each muscle belly were taken
and mounted in tragacanth gum on a cork disc
and rapidly frozen by immersion in Freon
cooled with liquid nitrogen. Transverse serial
sections were cut a t 8 pm on a cryostat (-20°C)
and mounted on coverslips by thawing, and
stained for adenosine triphosphatase (ATPase)
activity (preincubations at pH 10.4 and 4.4,
Guth and Samaha, '701, reduced nicotinamid
adenine dinucleotide diaphorase (NADH
diaphorase, Novikoff et al., '611, succinate dehydrogenase (SDH, Pearse, '72), menadionelinked a-glycerophosphate dehydrogenase
(a-GPD, Wattenberg and Long, '60),and a modified Gomori trichrome technique (Engel and
Cunningham, '63).
Myofibers cut in serial section and using the
above histochemical procedures could be separated into three groups and classified according
to Peter et al. ('72) as fast-twitch glycolytic
(FG), fast-twitch oxidative glycolytic (FOG),
and slow-twitch oxidative (SO) (Fig. 1).
Microscopic fields from superficial, middle,
and deep regions of each muscle cross section
were photographed, and the three fiber types
were identified and counted. Distribution of
fiber types among the three fields was examined using a Kruskal-Wallis nonparametric
analysis of variance (Noether, '76; Zar, '74).
This was done to determine if there was a uniform distribution of fiber types throughout the
cross-sectional area of each muscle. A
Kruskal-Wallis analysis of variance and a nonparametric multiple comparison test was also
used to determine differences in fiber type distribution between the wrist flexor muscles.
When P < 0.05 was achieved the differences
were considered significant.
Contractile properties
These studies were made on a total of 24 cats.
The animals were given a n intraperitoneal injection of Nembutal anesthesia (35 mgkg).
Additional anesthesia was administered when
necessary throughout the experiment, using an
indwelling catheter placed in the femoral vein.
All of the insertion tendons of the wrist flexor
muscles were cut and the muscles were then
freed from surrounding connective tissue. Care
was used not to disturb the blood supply to the
muscles that were to be studied. A piece of the
pisiform bone was kept in connection with the
insertion tendon from the FCU. A steel hook
was attached to each muscle tendon that was
being prepared for recording using nylon suture. In this way, the muscle was ready for
ANATOMY AND PHYSIOLOGY OF FOREARM MUSCLES
323
Fig. 1. Serial sectionsof the FCR showing the three fiber types: SO, FOG, and FG. x 350. a) ATPasealkaline preincubation; b) ATPase-acid preincubation; c) NADHdiaphorase; d) a-glycerophosphatedehydrogenase.
324
W.J. GONYEA. S.A. MARUSHIA. AND J.A. DMON
attachment to a force transducer (Grass E"rl0).
The cat was placed on a Narishige cat frame
and a skin pool was erected on the limb to be
examined. The pool was filled with mineral oil,
which was maintained a t 37 2 1°C by a heating
lamp. The cat's body temperature was maintained at the same range by a heating pad. The
temperature of the oil and the rectal temperature were monitored by thermocouples. The
limb was securely fastened to the frame by
clamps placed on the humerus and around the
wrist. Both the medial and ulnar nerves were
dissected free and cut. The FCR, PLM, and the
radial three heads of the FDP are innervated by
the median nerve. The FCU and the ulnar two
heads of the FDP are innervated by the ulnar
nerve. Only one muscle per nerve was stimulated to fatigue. The nerve of the muscle to be
stimulated was placed on silver bipolar electrodes. Stimulation was by monophasic pulses
of 0.2 ms duration a t 2-3v in excess of the
voltage required to obtain peak twitch tension.
Each muscle studied was then set and maintained at optimal length for maximum twitch
tension.
The time to peak tension (CT), one-half relaxation time (%RT), and maximum tension
(Pt)of a single isometric twitch were measured
for each muscle. Tension-frequency curves
were generated by stimulating each muscle
nerve at 10 pulses/sec for about 2 sec. This procedure was continued every 60 sec with the
stimulus frequency increased in increments of
10 pulses/sec until the muscle being stimulated
exhibited a fused tetany. The preparation was
then stimulated at 300 pulses/sec to determine
maximum tetanic tension (Po)and the rate of
tension development (VJ. The maximum tension developed at each stimulus frequency was
also measured.
Fatigue characteristics for each muscle were
investigated by stimulating the muscle a t 40
pulses/sec for 330 ms at 1 sec intervals as described by Burke et al. ('71).The fatigue index
(FI) was calculated by expressing tetanic tension measured at 2 min as a percentage of the
maximum tension produced within the first 5
sec (Collatos et al., '77). All muscles were stimulated for a t least 30 min and the rate of fatigue
(FR) was calculated as a percentage of the
maximum tension taken a t 1 min intervals.
the total wrist flexor mass. The FCR tookorigin
from the medial epicondyle of the humerus by
tendinous fibers (partly external aponeurosis).
The muscle tapered gradually toward its insertion, and a n extensive aponeurotic sheet covered most of its deep surface. The terminal tendon (primarily internal aponeurosis) entered
the paw through an osteofibrous canal where it
was enclosed in a synovial sheath. At the metacarpus i t split into two strong tendons which
inserted onto the palmar proximal surface of
the second and third metacarpals. The FCR was
innervated by the median nerve.
The mean percentage of the three fiber types
for three different regions (fields) taken from
the cross-sectional area of each muscle were
compared in Table 1. For the FCR muscle there
was a significant difference in the distribution
of FG and SO fiber types (Table 1; Fig. 1) with
the SO fiber types concentrated in the deeper
regions of the cross-sectional area of the muscle. This fiber type distribution for the FCR is
similar to that previously described (Gonyea
and Ericson, '77). The FCR had 35%FG fibers,
29% FOG fibers, and 36% SO fibers (Table 2).
The contractile properties of the wrist flexor
muscles are given in Table 3. The FCR had a
short CT of 23 ms, but a much longer %RT of
31 ms. The Pt for this muscle was 0.27 kg while
the P, for the FCR was 2.23 kg. The V, for the
FCR was a slow 49 g ms-' while the PtP, was
a n unusually low 0.14 (Table 3).
The palmaris longus muscle (PLM)
This muscle had a unipinnate internal fiber
arrangement. The muscle weighed 1.90 rt
0.09 g, which was 12.1% of the flexor mass.
The PLM took origin from a restricted area
on the medial epicondyle (Fig. 2). In addition, it had the most superficial location of the
forearm flexor muscles. The muscle arose by
tendinous fibers (external aponeurosis) from
the deep surface of the muscle belly. The muscle
was fleshy for almost the entire length of the
forearm and formed a tendon very near the
carpus. Insertion was by a broad tendon formed
from a n extensive aponeurotic sheet covering
the distal half of the superficial surface of the
PLM. The insertion tendon expanded into four
or five incompletely separable tendons that
contribute to the formation of the palmar
aponeurosis. The PLM was innervated by the
RESULTS
median nerve.
The flexor carpi radialis muscle (FCR)
The PLM had an even distribution of all
The FCR had a bipennate fiber pattern (Figs. three fiber types throughout its cross-sectional
2 and 3) and weighed 1.04 0.09g (mean 2 area (Table 1).This muscle consisted of 5% FG
standard error of the mean) which was 6.59%of fibers, 29% FOG fibers, and 19% SO fibers
*
325
ANATOMY AND PHYSIOLOGY OF FOREARM MUSCLES
TABLE 1. Fiber type profile of wrist flexor muscles. Six animals were used for
each muscle sample.
% FG 5 t SEM)
(X t SEM)
Muscle
Field
FCR
1 (superficial)
2 (middle)
3 (deep)
47.1 t 4.3'.'
26.4 ? 5.0
23.4 2 3.9
30.8 t 4.5
35.0 t 3.2
22.4 2 3.1
22.1 t 3.0'.'
37.9 ? 3.5
54.2 t 3.0
PLM
1
2
3
60.0 ? 4.4
52.4 t 5.6
45.3 t 3.9
25.9 2 3.3
26.4 f 4.1
33.8 t 3.5
14.1 t 1.8
21.2 ? 2.5
20.9 t 2.8
FCUh
1
2
3
28.8 2 4.3
26.1 2 4.2
28.7 t 6.6
23.6 t 2.2
24.7 ? 3.4
20.2 t 1.2
47.6 2 4.9
49.2 t 7.1
51.1 t 6.1
1
2
3
43.6 t 5.7
34.2 t 5.3
39.0 t 5.8
24.7 t 3.1
27.4 f 3.0
24.7 t 4.0
31.7 ? 6.3
38.4 t 5.0
36.2 t 7.2
FDP,
1
2
3
71.8 2 1.6
69.4 i 0.64
72.6 2 1.5
26.6 t 2.2
29.2 ? 1.4
27.3 t 1.6
1.65 ? 1.7
1.50 t 1.2
0.10 f 0.06
FDP,
1
2
3
43.2 i 4.1
44.5 t 2.7
47.3 t 2.9
36.9 t 2.9
39.5 2 3.8
36.1 f 1.5
19.9 t 2.3
16.1 f 2.0
16.6 i 2.7
FDP,
1
2
3
58.1 2 3.2
52.9 2 4.7
56.7 t 3.4
31.3 t 3.0
37.1 ? 3.8
33.2 t 1.8
10.6 ? 0.90
10.0 t 1.0
10.1 ? 1.9
FDP,
1
2
3
50.7 t 4.3,J
40.2 2 4.3
52.9 f 5.1
40.3 t 4.6
45.0 2 4.7
39.9 ? 5.1
9.04 t 1.7'.4
14.7 i 2.6
7.30 i 1.1
FDP,
1
2
3
66.2 t 2.1
64.1 2 1.7
68.0 t 1.8
33.1 i 2.1
35.0 t 1.8
29.2 ? 2.2
0.63 t 0.40
0.73 t 0.48
2.73 ? 1.8
FCU,
% FOG
% SO (E t SEM)
lP<O.OOl
2Significantly different from all other fields
P<0.05
+Significantly different between fields 1 8 2
TABLE 2. Differences in fiber type distribution compared between
the wrist flexor muscles'
Muscle
FCU,
FCR-.
FCU,
FDP,
FDP,
PLM
FDP,
FDP,
FDP,
% FG
(a ? SEMI
27.9 i 2.8
35.2 +- 3.5
38.6 2 3 . 2 1
'"1
47.9
45'0 t
i- 2.8
52.6 ? 2.9
55.9 f 2.11
66.1 t 1.1
71.3 t 0.79
Muscle
FCU,
FCU[I
FDP,
PLM
FCR
FDP,
FDP,
FDP,
FDP,
% FOG
(E i SEMI
22.8 i 1.4
25.6 t 1.9 1
28.7 2 2.2
29.3 f 2.8
32.5 k 1.3
33.9 t 1.7
37.5 t 1.6)
41.7 ? 2.7
1
Muscle
FDP,
FDP
PLM
FCU.
FCU,
FCR
% SO
(X t SEM)
0.81 2 0.391
1.07 t 0.67J
10.4 ? 1.3
17.5 ? 1.3
18.7 ? 1 . 5 1
35.4 2 3.5
35.5 ? 3.7
49.3 t 3.3
3
*Means contained within brackets did not differ significantly. All comparisons outside brackets were significantly different, P i
0.05. Six animals
were used for each muscle sample.
(Table 3, Fig. 5).The PLM had a very short CT
The flexor carpi ulnaris (FCU)
of 24 ms. The %RTwas nearly the same as CT a t
26 ms. The Pt for the PLM was 0.43 kg,while P,,
This muscle consisted of two heads proxwas 2.95 kg. The Vt was a rapid 61 g m-' and imally which unite to insert by a single tendon (Fig. 3). The internal fiber arrangement
Pdg was 833 g.
326
W.J. GONYEA, S.A. MARUSHIA, AND J.A. DMON
TABLE 3. Contractile properties of wrist flexor muscles*
Muscle
CT, ms
FCR
23.2
FDP,
23.8(::0.98]
PLM
23.9
FDP,
?
Muscle
FDP,
0.85
FDP,
f 0.90
PLM
(24)
24.2 t 1.5 J FCR
(8)
FCU
Muscle
FCU
FCU
37.0 f 2.2
(16)
P,, kg
Muscle
2.15 t 0 . 3 4 7 FCR
FCR
FDP,
(24)
2.95 t 0.45J
(24)
4.43 & 0.46
FDP,
5.57 t 0.47 J FCU
PLM
(8)
16.7 c 1.2
(8)
18.0 2 1.3
(8)
26.3 2 2.3
(24)
30.5 c 2.6
(24)
73.5 f 6.5
(16)
m
Muscle
]
]
o
1 PLM
0.19 f 0.01
I
+ MRT, ms
Muscle
PLM
(24)
FCR
FCU
(24)
111.8 t 6.8
(16)
FDP,
Muscle
Vt, g * ms-l
Muscle
PLM
44.4
f
5.47
Pdg
FCU
7]
12 J
101
FDP,
]
0.95 ? 0.13
(8)
662 2 84
(15)
(24)
61.4 t 8 . 2 9 FDP,
124)
86.7 2 10
FCR
(8)
FDP,
Pt,kg
0.27 & 0.03
(24)
0.43 2 0.05
(24)
0.47 % 0.07
(16)
0.81 k0.08
FDP,
(8)
0.19 2 O . O ~ FDP,
(24)
0.22 f 0.01
(16)
CT
FDP,,
0.14 2 0.01 1 FCU
(24)
0.17 f 0 . 0 2 4 FCR
(8)
FDP.
~
(XI
%RT,ms
18)
(16)
1,146 f . l O 9 J
(8)
*Means contained within brackets did not differ significantly. All comparisons outside brackets were significantly different, P
muscles tested)
(8)
C
0.05. (Number of
primarily a unipennate fiber arrangement.
The first head (FDP,) arose by fleshy fibers
from the flexor surface of the ulna. Its fibers
converged to form the medial portion of the
common insertion tendon (Fig. 8). The first
head had a uniform fiber distribution (Table 1)
which consisted of 71% FG fibers, 28% FOG
fibers, and 1% SO fibers (Table 2; Fig. 9).
The second head (FDP,) arose by tendinous
fibers from the distal end of the medial epicondyle of the humerus just deep to FDP, (Fig. 8).
Its fibers joined with FDP,. This head had a
uniform fiber distribution (Table 1) which consisted of 45% FG fibers, 38% FOG fibers, and
17% SO fibers (Table 2; Fig. 4). Heads one and
two were innervated by the ulnar nerve. The
portion of the FDP innervated by the ulnar
nerve (FDP,) had a CT of 24 ms and a short
%RT of 18 ms. The Pt for this muscle was
0.81 kg while the P,,was 4.43 kg. The Vt was a
very fast 87 g ms-', while P,/g was 870 g.
The third head (FDP,) arose by a strong tendon (external aponeurosis) from the middle
portion of the medial epicondyle (Figs. 2 and 3).
It also shared an aponeurotic sheet with the
FCR a t the proximal end of that muscle. The
The flexor digitorum profundis (FDP)
FDP, had a uniform fiber type distribution
This muscle arose by five separate heads. The (Table 1) which consisted of 56%FG fibers, 34%
FDP weighed 9.48 % 0.78 g , which was 60.3% FOG fibers, and 10% SO fibers (Table 2; Fig.
of the wrist flexor muscle mass. The muscle had 11).
was unipennate and the muscle weighed
3.30 0.21 g, which was 21.0% of the total
wrist flexor mass. One head arose from the medial epicondyle of the humerus (FCU,,) by a
strong short tendon which was formed by a
broad aponeurotic sheet on the superficial surface of the muscle. The second head had a fleshy
origin from the medial surface of the proximal
third of the ulna (FCU,), and the origin extended onto the surface of the olecranon process. The FCU inserted onto the proximal surface of the pisifonn bone by tendinous and
fleshy fibers. The FCU was innervated by the
ulnar nerve.
Both FCUh and FCU, had uniform muscle
fiber type distributions (Table 1).The FCUh
had 28% FG fibers, 23% FOG fibers, and 4%
SO fibers (Table 2; Fig. 6). The FCU, had 3wo
FG fibers, 26%FOG fibers, and 35% SO fibers
(Fig. 7). The CT for the FCU was a long 37 ms
while the %RT was an even longer 74 ms. The
Pt was 0.47 kg and the P, was only 2.15 kg. The
Vt was a slow 44.4 g ms-I while P,,/gwas a low
662 g (Table 3).
-
ANATOMY AND PHYSIOLOGY OF FOREARM MUSCLES
327
\
J
Fig. 2. Diagrammatic representation of the cat’s superficial forearm flexor muscles.
Fig. 3. Diagrammatic representation of the cat’s intermediate forearm flexor muscles.
328
W J . GONYEA, S.A. MARUSHIA, AND J.A. DIXON
Fig. 4. Representation fiber type distribution in the second head of FDP. x 140. a) ATPase-alkaline preincubation;
b) NADH-diaphorase.
Fig. 5. Representative fiber type distribution in the PLM. x 140. a) ATPase-alkaline preincubation; b) NADHdiaphorase.
ANATOMY AND PHYSIOLOGY OF FOREARM MUSCLES
329
Fig. 6. Representativefiber type distributionin the humeral head of the FCU. x 140. a) ATPase-alkaline preincubation;
b) NADH-diaphorase.
Fig. 7. Representativefiber type distribution in the ulnar head of the FCU. x 140. a) ATPase-alkaline preincubation;
b) NADH-diaphorase.
330
WJ.GQNYEA, S.A. MARUSHIA, AND J.A. DIXON
\
Fig. 8. Diagrammatic representation of the cat’s deep forearm flexor muscles.
The fourth head (FDP,) also arose from the
medial epicondylejust medial and deep to that
of FDP, and deep to the origin of the PLM (Figs.
8 and 12). The FDP, had a nonuniform fiber
type distribution with a slight but significant
concentration of the FG fibers peripherally and
SO fiber concentration in the core of the muscle
(Table 1).The FDP, fiber type proportions were
48% FG fibers, 42% FOG fibers, and 1Wo SO
fibers (Table 2; Fig. 13).
The fifth head (FDP,) arose by fleshy fibers
from the flexor surface of the radius and the
adjacent parts of the interosseous membrane
(Figs. 8 and 12). This head lies deep to the
insertion tendon of the FCR and most of its
fibers join the tendinous portion of the FDP,.
The FDP, had a uniform fiber type distribution
(Table 1) which consisted of 66%FG fibers, 33%
FOG fibers, and 1%SO fibers (Table 2; Fig. 10).
These three heads were innervated by the median nerve (FDP,). The FDP, had a CT of
24 ms and a very short %RTof 17 ms. The P, for
the FDP, was 0.95 kg and the P, was 5.6 kg.
The V, was a very fast 101 g ms-I while the
P,/g was a very high 1,146 g.
All five heads form a large common insertion
tendon. The tendon divided into five strong
tendons which pass to the five digits, and inserted into the base of the terminal phalanx.
Fiber type distribution. It can be observed
that most of the wrist flexor muscles, except the
FCR and FDP,, had a uniform muscle fiber type
distribution throughout their cross-sectional
area. For the FDP, the very small percentage of
SO fibers were concentrated in the central region of the muscle. For the FCR, the SO fibers
were concentrated in the deep portion of the
muscle (Table 2).
A comparison was made of the percentage of
the three fiber types between all the wrist
flexor muscles (Table 2). The percentage of FG
fiber types ranged from 27.9%to 71.3%, and the
FCUhhad a significantly smaller concentration
of the FG fiber types and the FDP, had a significantly larger concentration of FG fiber types
when compared with the other wrist flexor
muscles (Table 2). Except for FCR and FCU,,
FDP, and FDP4,and PLM and FDP,, all other
possible combinations demonstrated a significantly different percentage of FG fibers (Table
2).
There was a dramatic reduction in the mean
range for the percentage of FOG fiber types
when compared with the range for the FG fibers
for the wrist flexor musculature (Table 2). The
percentage of FOG fibers ranged from 22.8 to
41.7. As was the case for the FG fibers, the
FCU, had the lowest percentage of FOG fiber
ANATOMY AND PHYSIOLOGY OF FOREARM MUSCLES
33 1
Fig. 9. Serial sections of the first head of the FDP fiber type distribution consisting of only fast twitch fibers. x 140.
a) ATPas+alkaline preincubation;b) ATPase-acid preincubationc).) NADH-diaphorase;d) a-GPD.
332
W.J. GONYEA, S.A. MARUSHIA, AND J.A. DIXON
Fig. 10. Representative sections of the fifth head of the FDP showing that it consists of nearly 100% fast-twitch fibers.
x 140. a) ATF'ase-alkaline preincubation;b) NADH-diaphorase.
Fig. 11. Representativefiber type distribution of the third head of the FDP. x 140. a) ATPaealkaline preincubation;
b) NADH-diaphorase.
ANATOMY AND PHYSIOLOGY OF FOREARM MUSCLES
333
Fig. 12. Diagrammatic representation of the deeply situated forearm flexor muscles.
types and this concentration was significantly
lower than all the other wrist flexor muscles
(Table 2). The FDP, (37.5%) and the FDP,
(41.7%)had the highest percentage of FOG fibers and these values did not differ significantly between these two muscles but were significantly higher than the other wrist flexor
muscles.
The percentage of SO fiber types for the wrist
flexor muscles ranged from 0.8 to 49.3. The
lowest concentration of SO fiber types was less
than 1%(0.81%)for FDPS,which did not differ
significantly with that for FDP, (1.07%). The
FCUh had the greatest relative number of SO
fibers with 49.3%0(Fig. 6), which was a significantly greater proportion of SO fibers than the
other wrist flexor muscles (Table 2).
The single joint wrist flexor muscles, FCUh,
FCU,, and FCR, were very similar in fiber type
composition, with a mean fast-twitch percentage of 51,64, and 65 (FG and FOG fibers), and
the oxidative percentage (SO and FOG fibers)
was 72, 61, and 65, respectively. However, the
FCR had compartmentalized fiber type distribution, whereas the other two muscles had a
uniform fiber type distribution (Tables 1and 2).
The six remaining multijoint flexor muscles
had a very high percentage of fast-twitch muscle fibers. The PLM and FDP, had 81% and
83%,the FDP, and FDP, both had 9Wo ,and the
FDP, and FDP, both had 99% fast-twitchfibers.
In addition, only the FDP, (55%) and FDP,
(5wo)had a proportion of oxidative fibers that
was greater than 50%. The PLM (47%) and
FDP, (44%) had just slightly less than 5@%,
whereas FDP, had only 33% and FDP, 29%
oxidative fiber composition.
Contractile properties. The mean CT for the
wrist flexor muscles was less than 25 ms, except
the FCU, which had a mean CT of 37 ms, and
this was a significantly longer CT than all
other wrist flexor muscles (Table 3). The mean
%RT was also significantly longer for the FCU
and significantly shorter for the FDP when
compared with the other wrist flexor muscles
(Table 3). The mean CT + Y2RT for the FCU
was more than twice as long (111.8 ms) as that
for the other muscles.
The maximum Pt was significantly smaller
for the FCR and greater for the FDP muscles
when compared with the other wrist flexor
muscles, which indicated the smallest and
largest muscle weights respectively for these
two muscles. However, only FDP developed a
significantly greater Po when compared with
that for the other muscles. The Poper gram of
muscle showed that all the wrist flexors were
similar i n tension development except the
FCU, which produced significantly less tension
334
W.J. GONYEA, S.A. MARUSHIA, AND J.A. DIXON
Fig. 13. ATPase and oxidative activity showing the oxidative (a, b) and glycolytic (c, d) region in the fourth head of the
FDP. x 140. a) ATPase-alkaline preincubation; b) NADHdiaphorase; c) ATPase-alkaline preincubation; d) NADH-diaphorase.
ANATOMY AND PHYSIOLOGY OF FOREARM MUSCLES
per gram of muscle than the other muscles
(Table 3). The ratio PJP, was significantly
higher for the FCU (0.22) and significantly
lower for the FCR (0.14) when compared between muscles. As would be expected for their
fiber type composition, the FDP (101 pms-I)
had the fastest V,, while the FCU had the slowest V, (44.4 g-ms-').
The fatigue index was plotted against the
mean percentage of SO fibers and mean percentage of oxidative fibers (SO + FOG) for
each muscle (Fig. 14). All of the wrist flexor
muscles had fewer than 50% SO fibers, and all
of the muscles except the FCU had a fatigue
index of less than 0.50. The inclusion of the
FOG fibers resulted in a smaller range for the
mean percentage oxidative composition for all
muscles (39-67%) than with just the SO fibers
(7-42%). Both the FCR and FCU were dominated by oxidative fibers; however, the relative
increase in SO fibers for the FCU when compared with the FCR resulted in a substantial
difference in the fatique index between these
two muscles (0.48 vs. 0.63; Fig. 14).
The wrist flexor muscles were stimulated for
30 min and the percentage tension lost was
measured (fatigue rate). It was observed (Fig.
15) that the FCU was the most fatigue-resistant and the FDP the most fatigable of the
wrist flexor muscles. The FCU lost 37% of its
tension after 2 min of stimulation and 52%
after 7 min of stimulation, after which point no
additional tension was lost. The FCR lost 51%
of its tension after 2 min of stimulation and
continued to lose tension for 10 min of stimulation, a t which time only 25% of the maximum
tension remained. At this point a steady state
was reached. The PLM lost 58%of its maximum
tension after 2 min and continued to lose tension gradually throughout the 30 rnin stimulation period, a t which point 30% of the
maximum tension remained (Fig. 15). The two
components of the FDP lost 60% of their
maximum tension after 2 min of stimulation.
The tension continued to decline throughout
the stimulation period with only 1Wc of the
max tension remaining a t the end of this
period.
The tension produced a t different stimulation frequencies was expressed as percentage of
mean P, for each muscle (Fig. 16). The FCU
developed a greater percentage of Po at the
lower stimulus frequencies when compared
with that of the other muscles. The FCR developed a relatively smaller percentage Po than
the other muscles.
335
DISCUSSION
The wrist joint of the cat was not simply a
hinge joint allowing flexion and extension; i t
also provided some rotation and ulnar and radial deviation. In fact, it has been demonstrated
that rotation a t the wrist joint is necessary to
facilitate foot placement during locomotion
(Gonyea, '78). It has also been demonstrated
that both forearm flexor and extensor muscles
of the cat that cross the wrist have monosynaptic excitatory connections of IA afTerents to
heteronomous motor neurons (Willis et al., '66).
This pattern of excitatory monosynaptic input
to supposedly antagonistic motor nuclei has
been correlated with the function of the retractile claw apparatus for the cat. Gonyea and
Ashworth ('75) have demonstrated that in
order for the cat to protrude its retractile
claws, both the flexor and extensor muscles
must act in a synergistic fashion to fix the wrist
and the metacarpolphalangeal and interphalangeal joints. This action was necessary
because of the FDPs protruding the claws
against the resistance of a n elastic retractor
ligament. This study has demonstrated that
the claw retractile muscles, the FDP, were
dominated by powerful fast-twitch fibers.
The FDP constituted 60.3%of the flexor muscle mass. All heads of this muscle were dominated by fast-twitch fibers. This muscle was
innervated by two major nerves; heads 1and 2
were innervated by the ulnar nerve and heads
3 , 4 , and 5, by the median nerve. The extreme
ulnar (FDP,) and radial (FDP,) heads had a
very similar fiber composition, as both had 1%
or less SO fibers and over 60%FG fibers. With
its insertion onto the distal phalanx and providing the force for claw protrusion, the FDP appeared to be organized for very powerful and
rapid movements with very little endurance.
Like the flexor muscles of the elbow, knee,
and ankle joints of the cat (Ariano et al., '73;
Burke et al., '74;Collatos et al., '771, most of the
muscles for the wrist joint can be characterized
as primarily fast (< 25% SO) on the basis of
their fiber type composition. Of the nine different muscle bellies constituting the four major
wrist flexor muscles, those that spanned several joints (multiarticular) all had less than
20%SO fibers. These included the five heads of
the FDP and the PLM. In fact, the extreme
ulnar head (FDP,) and the extreme radial head
(FDP,) of the FDP were found to have essentially 100%fast fibers for they contained 1%or
less SO fiber types. The two heads of the FCU
336
W.J. GONYEA, S.A. MARUSHIA, AND J.A. DIXON
.
0 FDP,
c
<
-
FOPm
FCU
A FCR
A PLM
0
0.60
,
FDP,
FCU
A FCR
..
A PLM
-
0.20-
0
80
60
20
100
40
X
Oxidotive Fibers
Fig. 14. Mean fatigue indexes (tetanictension at 2 min as
percentage maximum tension) from each muscle are plotted
against the mean percentage of SO fibers and oxidative fibers (SO and FOG) for each muscle.
2
4
6 8 10 20
Stimulus Time ( m i d
30
Fig. 15. Mean percent tetanic tensions for each muscle
are plotted against the time muscle has been stimulated at a
rate of 40 pulsedsec for 330 ms at 1-secintervals. Numbers of
observations are given in Table 3.
100
80
0 FDP,
FDPm
FCU
A FCR
A PLM
60
*a"
40
20
0
20
40
60
80
Stimulation Frequency
100 '3,
Fig. 16. Mean percent maximal tetanic tensions (% Po) for each muscle are plotted for different frequenciesof
stimulation. Numbers of observations are given in Table 3.
ANATOMY AND PHYSIOLOGY OF FOREARM MUSCLES
and the FCR are essentially uniarticular, and
even though FCUh and FCR arise from the
humeral epicondyle, they have no moment arm
a t this joint. All three muscles contain a significantly higher proportion of SO fibers than the
multiarticular muscles. However, these muscles cannot be characterized as predominantly
slow (8Wo SO) as has been observed for extensor muscles (Ariano et al., '73; Burke et al., '74;
Collatos et al., '77). A high density of SO fibers
has been correlated with postural muscles and
even though the wrist joint is fully extended
during quiet standing and rest, antihyperextension seems to be provided by ligamentous
support (Gonyea, '78) and not by muscle activity a s measured by EMG activity (unpublished observations).
Both the FDP, and the FCR had an uneven
fiber type distribution. The SO fibers for the
FDP, were concentrated in the core of the muscle. However, this muscle had only 10% SO
fibers, and therefore a slight concentration of
SO fibers in the core of the muscle may not be
important in the function of the muscle. For the
FCR, however, the SO fibers were found to be
concentrated in the deep region of the muscle
and the difference in fiber type distribution was
highly significant (Table 11, which supports our
earlier findings (Gonyea and Ericson, '77). The
muscle spindles have been shown to be concentrated in the oxidative compartment of the FCR
(region high in SO and FOG fiber types)
(Gonyea and Ericson, '771, and it has been postulated that the compartmentalization of fiber
types and spindles in the FCR may demonstrate a strong structure-function relationship
(Botterman et al., '79). Accordingly, motor
units may be spatially separated within the
FCR, being restricted to one of the fiber type
compartments. The significant difference in
the size of the muscle fiber types when compared between the oxidative and glycolytic
compartments (Gonyea, '79) and the presence
of intramuscular nerve branches that are
unique to each compartment (Galvas and
Gonyea, '80) lends support to the concept of
spatial separation of motor units. Intramuscular nerve branches have also been shown to
supply muscle fibers in a restricted territorial
volume in the gastrocnemius muscle of the cat
(Letbetter, '74). The control of wrist position
during locomotion and the necessity to maintain the wrist in a pronated position during
locomotion may, in part, require a more complex structural organization for the radial wrist
flexor, the FCR, than that observed on the
ulnar side. This organizational difference may
337
imply differences in the motor control between
the ulnar and radial sides of the wrist musculature. This hypothesis has been supported by our
finding a substantial difference in the rostrocaudal distribution of motor nuclei in the cervical cord for these two muscles (Iwamoto et al.,
'80). In this regard, the FCR had an extensive
longitudinal distribution for its motor nucleus,
whereas the FCU had a very confined distribution, which may reflect spatial separation of
afferent input to the FCR motor nucleus.
Each muscle belly had a reasonably distinct
muscle fiber type composition. There was far
less difference in the percentage of FOG fiber
types than the SO or FG fiber types when compared between muscles (Table 2). In a comparison of the fiber type distribution for the two
primary wrist flexor muscles, FCR and FCU,
there was no significant difference for all three
fiber types between the FCR and FCU,. However, the FCUhwas significantly different from
all other muscles in its fiber type composition,
for it was dominated by SO fibers (49.3%).
Hence there was one portion of FCU that had a
similar fiber type composition to t h a t of
the FCR. However, the FCU weighed 3.3g
while the FCR only weighed 1.04g. It appeared that the FCU had an additional oxidative component (FCUh) which resulted in
this muscle's having a uniquely oxidative fiber
composition when compared to the other muscles. The functional differences between the
FCR and FCU are unknown a t this time. Although during grasping, wrist flexion is also
accompanied by ulnar deviation which may require a fatigue-resistant capacity to maintain
this position and may account for the relative
increase in SO fibers in the FCU when compared with the other muscles; whereas ulnar
wrist control required a n oxidative component,
this property was not present on the radial side.
All of the wrist flexor muscles had a very
short CT (between 23 and 24 ms) except the
FCU, which had a CT of 37 ms. It has been
adequately demonstrated that CT increases
with greater percentages of SO fibers (Collatos
et al., '77; McPhedranet al., '65;Wuerkeret al.,
'65)as was the case in this study with the FCU.
In fact, the CT + %RT was over twice as long
for the FCU as any other wrist flexor muscle.
As would be expected, the smaller muscles produced less tension than the heavier muscles.
However, the ratio PJP, was significantly
higher for the FCU than the other wrist flexor
muscles, which was probably related to the relatively high percentage of SO fibers for that
muscle (Close, '72). The FCR, however, had a
338
W.J. GONYEA, S.A. MARUSHIA, AND J.A. DIXON
very low P+/P, ratio, which was significantly
smaller than all other muscles except the FDP,
and was quite low for the values of other fast
muscles that have been reported which usually
are near the value of 0.2 (Close, '72). This difference may be related to the differences in the
organization of the FCR with the compartmentalization of fiber types substantially altering
the mechanical properties of this muscleduring
a single isometric twitch.
It has been recently demonstrated that the
motor nucleus for the FCR had an extensive
rostrocaudal distribution in the cervical spinal
cord when compared with that of the FCU or to
the distribution of the motor nuclei in the lumbar cord for hindlimb muscles (Burke et al., '77;
Iwamoto et al., '80). The complex organization
of the FCR and the differences in morphological
and contractile properties between the FCR
and FCU may reflect the need for complex
motor programs for controlling the prehensile
movements of the distal limb musculature. It
has been demonstrated that cortical projections
are involved in the control of the highly flexible
yet precise movements of the distal limb and
hand, while it is probable that descending outputs of subcortical structures are used principally to control the activity of axial and proximal limb muscles during movement (Brinkman and Kypers, '73; Lawrence and Hopkins,
'76; Lawrence and Kuypers, '68). The prehensile motor skills of the cat argues for such a
complex motor control system. However, the
precise mechanisms involved have yet to be
elucidated.
ACKNOWLEDGMENTS
We extend our appreciation to Ms. Billie
Price for her assistance in typing this manuscript.
This work was supported by grant AM17615
from the National Institute of Arthritis,
Metabolism and Digestive Diseases.
LlTJ3RATURE CITED
Ariano, M.A., R.B. Armstrong, and V.R. Edgerton (1973)
Hindlimb muscles fiber populations of five mammals. J.
Histochem. Cytochem., 2 1 5 - 5 5 .
Botterman, B.R., M.D. Binder, and D.G. Stuart (1978)Functional anatomy of the association between motor units and
muscle receptors. Am. Zool., 18~135-152.
Brinkman, J., and H.G.J.M. Kuypers (1973)Cerebral control
of contralateral and ipsilateral arm, hand and finger
movements in split brain rhesus monkeys. Brain, 69:
653-674.
Burke, R.E., D.N. Levine, F.E. Zajac, P. Tsairis, and W.K.
Engel (1971) Mammalian motor units: Physiologicalhistochemical correlation in three types in cat gastrocnemius. Science, 174t709-712.
Burke, R.E., and V.R. Edgerton (1975)Motor unit properties
and selective involvement in movement. Exercise Sport
Sci Rev. 3:31-81.
Burke, R.E., D.N. Levine, P. Tsairis, and F.E. Zajac (1974)
Physiological types and histochemical profiles in motor
units of the cat gastrocnemius. J. Physiol., 234~723-748.
Burke, R.E., P.L. Strick, K. Kanda, C.C. Kim, and B.
Walmsley (1977) Anatomy of medial gastrocnemius and
soleus motor nuclei in cat spinal cord. J. Neurophysiol.,
40t667-680.
Close, RI. (1972)Dynamicpropertiesof mammalian skeletal
muscles. Physiol. Rev., 52(1/:12%197.
Collatos, T.C., V.R. Edgerton, J.L. Smith, and B.R. Botterman (1977) Contractile properties and fiber type compositions of flexors and extensors of elbow joint in c a t Implications for motor control. J. Neurophysiol., 40: 12921300.
Crouch, J.E. (1969) Text-Atlas of Cat Anatomy. Lea and
Febiger, Philadelphia, p. 399.
Engel, W.K., and G.C. Cunningham (1963) Rapid examination of muscle tissue. An improved trichrome method for
fresh frozen biopsy sections. Neurology, 13~919-923.
English, A.W. (1978) An electromyographic analysis of forelimb muscles during overground stepping in the cat. J.
Exp. Biol., 76:105-122.
Galvas, P.E., and W.J. Gonyea (In Press) Motor-end-plate
and nerve distribution in a histochemically compartmentalized pennate muscle in the cat. Amer. J. Anat.
Gonyea, W.J. (1978) Functional implications of felid forelimb anatomy. Acta Anat., 102t111-121.
Gonyea, W.J. (1979)Fiber size distribution inthe flexor carpi
radialis muscle of the cat. Anat. Rec., 195t447-453.
Gonyea, W., and R Ashworth (1975) The form and function
of retracticle claws in the Felidae and other representative
carnivorans. J. Morphol., 145t22S238.
Gonyea, W.J., and G.C. Ericson (1977) Morphological and
histochemical organization of the flexor carpi radialis
muscle in the cat. Am. J. Anat., 148t329-344.
Gonyea, W.J., and F. Bonde-Petersen (1977) Contraction
properties and fiber types of some forelimb and hindlimb
muscles in the cat. Exp. Neurol., 57:637-644.
Guth, L., and F.J. Samaha (1970) Qualitative differences
between actomyosin ATPase of slow and fast mammalian
muscle. Exp. Neurol., 25~138-152.
Iwamoto, G.A., L.H. Haber, J.A. Dixon, and W.J. Gonyea
(1980) Anatomical localization of the flexor carpi radialis
and flexor carpi ulnaris motor nuclei in the cat spinal cord.
Anat. Rec., 196:85-86A.
Lawrence, D.G., and D.A. Hopkins (1976) The development
of motor control in the rhesus monkey: Evidence concerning the role of corticomotoneuronal connections. Brain,
99:235-254.
Lawrence, D.G., and H.G.J.M. Kuypers (1968) The functional organization of the motor system in the monkey. I
and 11. Brain 9l:l-14, 1 5 3 6 .
Letbetter, W.D. (1974) Influence of intramuscular nerve
branching on motor unit organization in medial gastrocnemius muscle. Anat. Rec. 178:402.
Manter, J.T. (1938)Thedynamics ofquadrupedal walking. J.
Exp. Biol., 15~52Z-540.
McPhedran, A.M., R.B. Wuerker and E. Henneman (1965)
Properties of motor units in a homogeneous red muscle
(soleus) of the cat. J. Neurophysiol. 28~71-84.
Noether, G. (1976) Introduction to Statistics: A Nonparametric Approach. Houghton Mimin Co., Boston.
Novikoff, A.B., W.Y. Shin, and J. Drucker (1961) Mitochondrial localization of oxidative enzymes: Staining results
with two tetrazolium salts. J. Biophys. Biochem. Cytol.,
9~47-61.
Pearse, E. (1972) Histochemistry. Williams and Wilkins,
Baltimore, pp. 948-950.
Peter, J.B., R.J. Barnard,V.R. Edgerton, C.A. Gillespie, and
K.E. Stempel (1972)Metabolic profiles of three fibre types
ANATOMY AND PHYSIOLOGY OF FOREARM MUSCLES
of skeletal muscle in guinea pigs and rabbits. Biochemistry 11:2627-2633.
Smith, J.L., V.R. Edgerton, B. Betts, andT.C. Collatos (1977)
EMG of slow and fast ankle extensorsofcatduringposture
locomotion and jumping. J. Neurophysiol., 40:503-513.
Wattenberg, L.W., and J.L. Long (1960)Effects ofeoernyme
Q l O and m e n d o n e on succinic dehydrogenaw activity as
measured by tetrazolium salt reduction. J. Histochem.
Cytochem., 8;29&303.
339
Willis, W.D., G.W. Tate, R.D. Ashworth, and J.C. Willis
(1966) Monosynaptic excitation of motoneurons of individual forelimb muscles. J. Neurophysiol., 29:41&424.
Wuerker, R.B., A.M. McPhedran, and E. Henneman (1965)
Properties of motor units in a heterogeneous pale muscle
(m. gastracnemius) of the cat. J. Neurophysiol. 28.8599.
zar. J.H. (1974)Biostatistical Analysis. RenticeHall, Inc.,
Englewood Cliffs. New Jersey.
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