Chapter IX: Section II: The Muscles (2)

The muscles of this surface are arranged in two groups, so as to form, at the elbow-joint, a triangular depression (_plica cubiti_), into which the tendon of the _m. sternoradialis_ sinks.

A. Muscles of the Inner Group.

*57.* _M. flexor carpi I s. radialis_ (Fig. 74 _Fc_).

*Dugès*, sous-huméro-carpien, n. 83.

This represents either the _flexor carpi radialis longior_ or _radialis brevior_ of man; it has a broad origin from the inner border of the humerus above the epicondylus medialis. It becomes narrower as it passes downwards to be inserted by a tendon into the _os semilunare_ and _naviculare_. The muscle is much stronger in males than in females, and the crest from which it takes origin is correspondingly larger in the former sex (p. 42). Tendinous fibres connect it with the following muscles:--

*58.* _M. flexor carpi II s. ulnaris_ (Fig. 74 _Fc_′).

*Dugès*, epitrochlo-carpien, n. 84.

This muscle represents the _flexor carpi ulnaris_ or _ulnaris anterior_, and is close to the inner side of the foregoing. It arises from the _epicondylus medialis_, being connected by fibres with the _flexor digitorum communis_, and is inserted into the _os naviculare_.

Muscles of the right arm of _Rana esculenta_.

_ed_ M. extens. digitorum communis.
_ei_ M. abductor digiti II longus.
_Fa_′ M. flexor antibrachii lateralis superficialis.
_Fc_ M. flexor carpi radial.
_Fc_′ M. flexor carpi ulnar.
_Fd_ M. flexor digitorum communis.
_sr_ Tendon of the M. sternoradialis.
]

*59.* _M. flexor digitorum communis_ (Figs. 75, 76, 77 _Fd_).

*Dugès*, epitrochlo-sous-phalangettien, n. 118.

This muscle lies most internally, and corresponds to the _m. flexor digitorum sublimis_ of man. It arises in common with the foregoing muscle from the _epicondylus medialis_, and runs downwards to the palm of the hand. At its entrance into this it diminishes and passes into the flat _aponeurosis palmaris_. (See hand, B.)

*60.* _M. flexor antibrachii medialis_ (Ecker), (Fig. 75 _Fa_).

*Dugès*, epitrochlo-sous-radial, n. 79. (Frequently described as the
_pronator rotundus_, a description which cannot be retained, as the
implied movement does not occur in the frog.--Ecker.)

This muscle lies deeply on the inner side of the forearm, covered by the _flexores carpi_; it arises tendinously from the _epicondylus medialis_ and is inserted into the inner surface of the radial side of the radio-ulnar as far as the inferior articular extremity.

*61.* _M. flexor antibrachii lateralis superficialis_ (Ecker),
(Figs. 74, 75 _Fa_′).

*Dugès*, premier ex-huméro-radial, n. 76. (Usually described as
_supinator longus_, this, for reasons similar to those in the case
of _m. flexor antibrachii medialis_, cannot be retained.)

The situation of this muscle corresponds with that of the _supinator longus_ of man; it lies to the outer side of the tendon of the _m. sternoradialis_, and arises by two heads, the one, above from the outer edge of the humerus, the other deeper from the _epicondylus lateralis_. They unite and pass into a tendon which, running over the lower articular extremity of the radio-ulnar, is partly attached to the carpus and partly connected with the tendon of the _m. extensor digiti II proprius longus_. From its position and insertion, this muscle evidently flexes the forearm and extends the hand.

Muscles of the right arm of _Rana esculenta_, deep layer.

_ed_ Extensor digit. communis.
_Fa_ Flexor antibrachii medialis.
_Fa_′ Flexor antibrachii lat. superficialis.
_Fa_″ Flexor antibr. lat. profundus.
_Fc_ Flexor carpi radialis.
_Fc_′ Flexor carpi ulnaris.
_Fd_ Flexor digitorum communis.
]

*62.* _M. flexor antibrachii lateralis profundus_ (Ecker), (Fig. 75
_Fa_″).

*Dugès*, epicondylo-sus-radial, n. 78.--*Klein*, _flexor
antibrachii_. (_Supinat. brevis_ autt.)

This muscle arises under cover of the foregoing, from the _epicondylus lateralis_ of the outer surface of the humerus, it becomes broader and is inserted into the whole length of the lower (volar) ridge of the radio-ulnar. It is a powerful flexor of the forearm.

(II.) Muscles of the extensor surface.

*63.* _M. extensor digitorum communis longus_ (Fig. 75 _ed_).

*Dugès*, huméro-sus-digital, n. 95.

This muscle lies on the outer border of the forearm; it arises in common with the short head of the _flexor antibr. lateralis superficialis_ from the _epicondylus lateralis_, and from the surface above it; it runs downwards along the outer side of the forearm, in order to pass into an aponeurosis on the back of the hand, which expands upon the third, fourth, and fifth fingers, and ends between them in a free concave border. This aponeurotic expansion is connected with the tendons of the _extensor brevis digitorum_.

*63*.* _M. abductor digiti II_ (_i. e. pollicis_) _longus_ (Fig. 74
_ei_).

**Dugès*, cubito-métacarpien, n. 87.

This muscle lies between the foregoing and the _flexor antibrachii lateralis superficialis_, and appears superficially in the interval between them. It arises from the lateral surface of the radio-ulnar, and runs obliquely over the _m. flexor antibrachii lateralis profundus_ and the hinder extremity of the radio-ulnar towards the second finger into the metacarpal bones of which it is inserted.

*64.* _M. extensor carpi ulnaris s. ulnaris post._ (Fig. 76 _ec_).

*Dugès*, epicondylo-sous-carpien, n. 85.--*Klein*, _abductor carpi
internus_.

This muscle has a somewhat narrow origin from the _epicondylus lateralis_; during its course through the forearm, where it lies between the _mm. anconaei_ on the one side and the _extensor digitorum communi_ on the other, it becomes broader and is inserted into the outer surface of the carpus in the following manner. By one tendinous slip it is attached to the palmar border of the _os pyramidale_, by a second slip to the outer border of the _os capitato-hamatum_. This latter slip is usually connected in its dorsal portion with the _extensor digitorum communis brevis_.

Muscles of forearm of _Rana esculenta_, dorsal view.

_aa_ M. anconaei.
_ec_ M. extens. digit. communis.
_Fd_ M. flex. digit.
]

*65, 66.* _M. anconaei s. extensores antibrachii_ (Fig. 76 _aa_).

*Dugès*, epicondylo-cubital and epitrochlo-cubital, n. 80, 81.

Both these muscles lie on the extensor side of the forearm; they spring, the one from the _epicondylus lateralis_, the other from the _epicondylus medialis_; converging, they run downwards, enclose the olecranon, and are inserted into the upper (dorsal) border of the ulna, each forming a penniform muscle. They are extensors of the forearm and assist the _m. triceps_.

C. _MUSCLES OF THE HAND._

(I.) Muscles on the palmar surface.

(1) Muscles common to all the digits.

*67.* _M. flexor digitorum communis_ and _m. palmaris brevis_
(Fig. 77 _fd_, _pb_).

The origin and course of this muscle has been described above. At its entrance into the palm it suddenly diminishes in size and passes into a triangular aponeurosis, _aponeurosis palmaris_. Into the outer border of this aponeurosis is inserted the _m. palmaris brevis_ (Fig. 77 _pb_); this latter muscle arises from the posterior or ulnar border of the lower extremity of the radio-ulnar below the insertion of the _mm. anconaei_, and runs obliquely downwards to this insertion.

From the lower free border of the aponeurosis a number of muscles arise which will be described with the rest of the digital muscles.

(2) Muscles of the rudimentary thumb.

*68.* _M. abductor pollicis_ (Figs. 77, 78 _ap_).

*Dugès*, cubito-pollicien, n. 100.

This short muscle arises from the upper border of the lower extremity of the radio-ulnar, passes transversely outwards, and is then inserted into the anterior border of the rudimentary thumb.

*69.* _M. adductor pollicis_ (Figs. 77, 78 _ad.p_).

*Dugès*, sous-carpo-pollicien, n. 101.

This lies more superficially than the last, it arises from the palmar surface of the _os capitato-hamatum_, and is inserted together with the _abductor pollicis_ into the thumb. Several fibres of the _extens. dig. II brevis_ are also inserted into the thumb. As this member is completely covered with skin, the motions of which it is capable are very limited.

(3) Muscles of the second finger, which serves the purposes of a thumb.

*70.* _M. flexor digiti II longus s. sublimis_ (Fig. 77 _f2_).

*Dugès*, sous-carpo-phalangettien de l’index, n. 133.

Muscles of hand of _Rana esculenta_, volar surface, larger than nature.

_A_ Aponeurosis palmaris.
_ab5_ M. abductor dig. V primus.
_ab5_′ M. abductor dig. secundus.
_ac_ MM. anconaei.
_adp_ M. adductor pollicis.
_ap_ M. abductor pollicis.
_ec_ M. extensor digitorum communis.
_e5_ M. extens. dig. commun. brevis.
_f2_ M. flexor dig. II longus.
_f3_ M. flexor dig. III longus.
_f4_ M. flexor dig. IV longus.
_f5_ M. flexor dig. V longus.
_fb2_ M. flexor dig. II brevis.
_fb3_ and _fb3_′ MM. flexores dig. III breves.
_fb4_ and _fb4_′ MM. flexores dig. IV breves.
_fb5_ M. flexor dig. V primus.
_fd_ M. flexor digitorum communis.
_o_ M. opponens.
_pb_ M. palmaris brevis.
I First finger, rudimentary thumb.
II Second finger, functions as thumb.
III-V Third to fifth fingers.
]

This is a flat muscle, which arises for the most part by fleshy fibres from the hinder free border of the _aponeurosis palmaris_, also by a smaller part from the palmar surface of the _os capitato-hamatum_. It quickly passes into a thin long tendon which is inserted into the terminal phalanx of the thumb (second finger).

Second layer of muscles on volar surface of hand of _Rana esculenta_, larger than nature.

_ab5_ M. abductor dig. V primus.
_ab5_′ M. abductor dig. V secundus.
_ad2_ M. adductor dig. II.
_ad.p_ M. adductor pollicis.
_ap_ M. abductor pollicis.
_ec_ M. extensor carpi.
_fb2_ M. flexor dig. II brevis.
_fb2_′ M. flexor dig. II tertius.
_fp_ MM. flexores proprii phalangum.
_i3_ }
_i4_ } MM. interossei volares.
_i4_′}
_i5_ }
_o_ M. opponens dig. II.
_o_′ M. opponens dig. V.
_tt_ ′ MM. transversi metacarpi.
I-V as in Fig. 77.
]

*71.* _M. flexor digiti II brevis s. profundus_ (Fig. 77 _fb2_).

*Dugès*, sous-carpo-phalangien de l’index, n. 102.

This flat muscle, covered by the preceding, has a tendinous origin from the palmar surface of the _os capitato-hamatum_, together with one head of the _flexor sublimis_, and is inserted into the basal phalanx.

*72.* _M. flexor digiti II tertius_ (Fig. 78 _fb2_′).

*Dugès*, tendini-phalangien de l’index, n. 103.

A small, thin muscle which arises close to the foregoing from the _os capitato-hamatum_, and is inserted into the basal phalanx (see below, _m. interosseus volaris I_).

*73.* _M. adductor digiti II_ (Fig. 78 _ad2_).

*Dugès*, métacarpo-métacarpien de l’index, n. 90.

This muscle represents the _adductor pollicis_ of man; it arises from the base of the third os metacarpal and is inserted into the metacarpal of the second finger, which latter it draws towards the third finger.

*74.* _M. opponens digiti II_ (Figs. 77 and 78 _o_).

*Dugès*, sous-carpo-métacarpien de l’index, n. 90.

This muscle represents the muscle of like name in man. It arises from the palmar process of the _os capitato-hamatum_ by a narrow tendon and passes into a broad, flat muscle, which is inserted into the under surface and outer border of the metacarpal of the second finger throughout its length. It has, undoubtedly, the same action as the corresponding muscle in man.

(4) Muscles of the third finger.

*75.* _M. flexor digiti III longus s. sublimis_ (Fig. 77 _f3_).

The smaller portion of this muscle arises from the free border of the _aponeurosis palmaris_, the chief portion, together with the _flexor brevis_, from the palmar surface of the _os capitato-hamatum_. The two portions pass into one long tendon, which is inserted into the last phalanx.

*76, 77.* _MM. flexores digiti III breves s. profundi I, II_
(Fig. 77 _fb3_ and _fb3_′).

*Dugès*, tendini-phalangiens du medius, n. 104, 105.

These two muscles arise in part from the free border of the _aponeurosis palmaris_, in part from the volar surface of the _os capitato-hamatum_, and pass backwards on either side of the muscle last described, to be inserted into the basal phalanx. Dugès regards these as analogues of the _mm. lumbricales_.

*78.* _M. flexor metacarpi dig. III._

This is a somewhat strong muscle, which arises by fleshy fibres from the palmar surface of the _os capitato-hamatum_, and is inserted into the palmar surface of the metacarpal bone.

(5) Muscles of the fourth finger.

*79.* _M. flexor digiti IV longus s. sublimis_ (Fig. 77 _f4_).

It arises at the free border of the _aponeurosis palmaris_, and is inserted into the terminal phalanx by a thin tendon.

*80, 81.* _MM. flexores digiti IV breves s. profundi I, II_
(Fig. 77 _fb4_ and _fb4_′).

*Dugès*, tendini-phalangiens de l’annulaire, n. 108, 109.

Dugès regards these also as analogues of the _m. lumbricales_; they arise on either side of the foregoing muscle from the free border of the _aponeurosis palmaris_, and are inserted by tendons into the basal phalanx.

*82.* _M. flexor proprius phalangum dig. IV_ (Fig. 78 _fp_).

*Dugès*, phalango-phalangien, n. 115.

A small muscle which arises by two slips from the palmar surface of the basal phalanx, and is inserted into the base of the middle phalanx.

*83.* _M. flexor metacarpi dig. IV_ (Fig. 78 _i4_).

This somewhat strong muscle arises from the _os capitato-hamatum_, and is inserted into the palmar surface of the metacarpal bone.

(6) Muscles of the fifth finger.

*84.* _M. flexor dig. V longus s. sublimis_ (Fig. 77 _f5_).

This corresponds exactly with the corresponding muscle of the fourth finger.

*85.* _M. flexor dig. V brevis_ (Fig. 77 _fb5_).

This muscle arises from the free border of the aponeurosis and is inserted into the basal phalanx.

*86.* _M. flexor proprius phalangum dig. V_ (Fig. 78 _fp_).

*Dugès*, phalango-phalangien, n. 17.

It corresponds exactly with the corresponding muscle of the fourth finger.

*87.* _M. opponens dig. V_ (Fig. 78 _o_′).

*Dugès*, deuxième sous-carpo-métacarpien du digitule, n. 92.

This muscle has a narrow origin from the palmar surface of the _os capitato-hamatum_, it widens and is inserted into the outer border of the metacarpal of the small finger. It draws this finger towards the thumb.

*88.* _M. abductor dig. V primus_ (Figs. 77 and 78 _ab5_).

*Dugès*, sous-pyro-pré-métacarpien du digitule, n. 93.

This muscle arises from the palmar border and the outer surface of the _os pyramidale_, and is inserted into the basal phalanx by a thin tendon.

*89.* _M. abductor dig. V secundus_ (Figs. 77 and 78 _ab5_′).

*Dugès*, sous-pyro-post-métacarpien du digitule, n. 94.

It arises from the posterior part of the _os pyramidale_, is short, and is inserted into the outer side of the metacarpal.

(II.) Muscles on the dorsal surface.

_M. extensor digitorum communis longus_ (Figs. 75 _ed_ and 77 _ec_).

*90.* _M. extensor digitorum communis brevis_ (Fig. 79 _e_3, _e_4,
_e_5).

*Dugès*, sous-pyro-phalangettien du III, IV, V, n. 124, 128, 131.

Covered by the foregoing, this muscle arises from the _os pyramidale_ in conjunction with the _extensor pollicis_ and from the _os capitato-hamatum_. The part destined for the third finger, together with that for the fourth, arises from the _os pyramidale_, passes obliquely backwards into a tendon which runs along the inner side of the corresponding finger to be inserted into the last phalanx. That for the fifth finger arises from the inner projection of _os capitato-hamatum_ being here attached to the insertion of the _m. extensor carpi ulnaris_, and is inserted in a similar manner into the terminal phalanx of the fifth finger.

*91.* _M. abductor digiti II_ (_i.e._ _pollicis_) _longus_
(Figs. 74 _ei_ and 79 _ab.2_).

For the origin and course of this muscle in the forearm see No. 63. The muscle passes obliquely over the wrist-joint from the little finger towards the inner side and from before backwards, it is inserted into the metacarpal of the second finger (thumb). The place of insertion of this muscle into the metacarpal (compare p. 47) is, in the males, developed into a ridge and process, the muscle itself is enlarged during the breeding season. This muscle abducts the thumb and by this means presses upon the chest of the female when clinging to her.

*92.* _M. extensor digiti II proprius longus_ (Fig. 79 _e2_, _e2_′).

*Dugès*, cubito-radio-sous-phalangien de l’index, n. 96.

Muscles of hand of _Rana esculenta_. Dorsal view, twice natural size.

_ab.2._ M. abductor dig. II longus.
_ab.2_′ M. abductor dig. II brevis.
_ad.2_ M. adductor dig. II.
_e2_ }
_e2_′ } M. extensor dig. II longus.
_e3_ }
_e4_ } M. extensor digitorum communis brevis.
_e5_ }
_eb2_ M. extensor dig. II proprius brevis.
_ec_ M. extensor carpi ulnaris.
_fa_ M. flexor antibr. lat. superficial.
_i_′3 }
_i_′4 } MM. interossei.
_i_′5 }
II-V as in Fig. 77.
]

This muscle lies obliquely on the back of the hand, parallel with the _m. abductor digiti II_. It arises by two heads, one from the tendon of the _flexor antibr. lat. superf._ (n. 60) upon the hinder extremity of the radio-ulnar. This tendon conceals the hinder end of this bone by means of a patella-like thickening, and sends forth three tendinous prolongations; of these, the one is attached to the ulnar border of the radio-ulnar, the second to the _os naviculare_, while the third constitutes that portion of the _m. extens. dig. II proprius long._ which is under consideration. The second head arises from the _os pyramidale_ in connection with the _extensor digitorum communis brevis_ (n. 90). The heads unite to form a long muscle, which runs obliquely towards the second finger, passes into a tendon, which, after forming connections by some muscular fibres with the metacarpal, is inserted into the terminal phalanx.

*93.* _M. extensor dig. II proprius brevis_ (Fig. 79 _eb2_).

*Dugès*, sus-luno-phalangettien de l’index, n. 120.

This muscle lies between the preceding muscle and the _abductor dig. II longus_. It arises from the _os naviculare_, and also includes some fibres which arise from the second metacarpal. The tendon runs along the radial side and is inserted along with the last muscle into the terminal phalanx.

*94.* _M. abductor dig. II brevis_ (Fig. 79 _ab._2′).

*Dugès*, sus-luno-métacarpien de l’index, n. 88.

This represents the _abduct. pollic. brevis_ of man, lies on the outer side of the hand, arises from the _os naviculare_, and is inserted into the second metacarpal.

*95.* _M. extensor dig. III proprius._

*Dugès*, sus-luno-phalangettien du médius, n. 122.

This muscle has two heads of origin, from the _os naviculare_ and _lunatum_. These form one muscular belly, which rapidly diminishes and passes into a tendon; this, after receiving a few muscular fibres from the second metacarpal, runs to the outer part of the dorsal surface of this finger as far as the terminal phalanx, where it is inserted.

*96.* _M. extensor dig. IV proprius._

*Dugès*, sus-pyro-phalangettien de l’annulaire, n. 128.

By a somewhat broad base, this muscle arises from the _os naviculare_ and _lunatum_. The tendon receives fibres from the fourth metacarpal and runs on the outer half of the dorsal surface of this finger as far as the middle phalanx, where it is inserted.

(III.) _MM. interossei._

*97, 98.* [*a.*] _MM. transversi metacarpi_ (Ecker), (Fig. 78 _t_,
_t_′, _ad2_).

These lie transversely between the metacarpals. There are three; the first has been already described as _m. adductor digiti II_ (n. 73); the second is stretched between the third and fourth metacarpals, and the third between those of the fourth and fifth fingers.

*99, 100, 101.* [*b.*] _MM. interossei volares._

One may regard as such, four long, thin muscles, which take origin near one another on the palmar surface of the carpal bones, and diverge from this towards the second and fifth fingers.

1. The first of these muscles (Fig. 78 _fb2_′) has already been described above as the _m. flexor digiti II tertius_ (n. 72).

2. The second (Fig. 78 _i3_) passes from the origin already described to the palmar surface of the basal phalanx of the third finger.

3. The third (Fig. 78 _i4_) runs, in like manner, to the fourth finger.

4. The fifth (Fig. 78 _i5_) to the fifth finger[46].

[Footnote 46: Whether these muscles may be regarded as _mm. interossei_ is open to discussion, as they appear to act more as _mm. opponentes_.]

*102* to *108*. _MM. interossei dorsales._

These arise in common from the metacarpals, and are inserted into the basal phalanx of the corresponding surface on the finger.

1. The _third_ finger has two, one to the radial side (Fig. 79 _i_′3), one to the ulnar side.

2. The _fourth_ finger has three, the third (Fig. 79 _i_′4) arises from the carpus, and perhaps ought rather to be regarded as an extensor.

3. The _fifth_ finger has two.

IV. MUSCLES OF THE HINDER LIMB.

I. MUSCLES OF THE THIGH.

General arrangement (Figs. 80, 81).

*a.* The _m. triceps femoris_ forms the _outer border_ of the thigh, and extends on to both the dorsal and ventral surfaces. The outer border therefore corresponds with the anterior surface of the thigh of man, in consequence of the thigh in the frog being normally rotated outwards.

*b.* The _m. vastus internus_ (_v.i._) and a portion of the _adductor longus_ (_ad_′), the _sartorius_ (_s_), a portion of the _adductor magnus_ (_ad_‴), and the _rectus internus major_ (_r.i_′) are found on the _inner surface_ of the thigh.

*c.* The _rectus internus minor_ (_r.i_″) forms the _inner border_.

*d.* On the _dorsal surface_ are to be seen, nearest the trunk, the _glutaeus_ (_gl_), on the outer border the _vastus externus_ (_v.e._), the _pyriformis_ and _biceps_ (_p_ and _b_), then the _semimembranosus_ (_sm_), and lastly the _rectus internus minor_ (_ri_″).

*e.* By reflecting the _rectus internus major_ (compare Fig. 82) there are exposed to view: the _semitendinosus_ (_st_), the whole length of the _adductor longus_, _magnus_ (_ad_′ and _ad_‴), and _brevis_ (_ad_″). By reflecting the triceps, one sees (Figs. 84, 85) the _ilio psoas_ (_ip_), and beneath the _semimembranosus_, the _quadratus_ (_qf_), and _capsularis femoris_ (_og_).

_Description of the separate Muscles._

(A.) Muscles of the dorsal surface.

*109.* _M. glutaeus_ (Fig. 80 _gl_).

*Dugès*, ex-ilio-trochantérien.--*Zenker*, _glutaeus maior_.

The tendinous origin of this muscle is found on the outer surface and upper border of the two hinder thirds of the iliac bone. Thence it runs outwards and backwards between the head of the _m. vastus externus_ (_ve_) on the one side, and the _ilio-psoas_ and _rectus anticus_ (_ra_) on the other, to be inserted into a tubercle (trochanter) of the femur.

*110.* _M. Pyriformis_ (Fig. 80 _p_).

*Cuvier*, pyramidal.--*Dugès*, coccy-fémoral, n. 136.

A narrow, slender muscle, arising from the apex of the coccyx; it passes obliquely outwards and backwards to the thigh, to be inserted deeply between the _m. vastus externus_ and the _biceps_, into the inner surface of the femur, but towards the ventral surface.

_M. triceps femoris s. extensor cruris communis_ (Fig. 80).

*Dugès*, pelvi-fémoro-rotulien, n. 145, 146, 147.

This is a large, strong muscle, having three heads of origin, and inserted by a tendon into the tibio fibula. The three heads are the _caput longum_ or the _rectus femoris anticus_ (_r.a._), the _caput externum_ or the _vastus externus_ (_v.e._), and the _caput internum_ or the _vastus internus_ (Fig. 82 _vi_); of these, the first is situated on the outer border of the thigh, the second on the dorsal surface, and the third on the ventral surface.

Muscles of left thigh of _Rana esculenta_. Dorsal view.

_b_ M. biceps.
_ci_ M. coccygeo-iliacus.
_g_ M. gastrocnemius.
_gl_ M. glutaeus.
_p_ M. pyriformis.
_pe_ M. peroneus.
_r.a._ M. rectus anterior.
_ri_″ M. rectus internus minor.
_sm_ M. semimembranosus.
_t.a._ M. tibialis anticus.
_tr._ M. triceps fem.
_v.e._ M. vastus externus.
]

*111.* [*a.*] _M. rectus femoris anticus_ (Figs. 80, 82 _ra_).

This arises from the under (ventral) surface of the iliac bone about its middle and beneath the _m. glutaeus_. The muscular belly quickly passes into an aponeurosis, which covers the other two muscular masses and combines with their tendons.

*112.* [*b.*] _M. vastus externus_ (Fig. 80 _v.e._).

It arises from the upper and hinder extremity of the iliac bone (Fig. 42 _il_′) behind the _glutaeus_, which here sinks in between this muscle and the _rectus anterior_.

*113.* [*c.*] _M. vastus internus_ (Figs. 81, 82 _vi_).

It arises from the whole of the under and outer surfaces of the hip-joint capsule, and from tendinous slips which pass from this capsule downwards on the under surface of the muscle, (from the pubis and the femur I have not seen any fibres of origin, as stated by others). Anteriorly the _vastus_ may easily be separated into two heads. The two _vasti_ unite and form one muscular belly, in the formation of which, as above stated, the _rectus anticus_ takes no part. This united muscle passes into a tendon which, without the mediation of a patella, passes over the knee-joint to be inserted into the anterior extremity of the tibio fibula, and is prolonged into the fascia of the leg.

*114.* _M. ilio-fibularis s. biceps_ (Fig. 80 _b_).

*Dugès*, ilio-péronien, n, 149.--*Zenker*, flexor externus tibiae,
p. 42.

This is a long, somewhat narrow muscle, which lies to the inner side of, and partly covered by, the _vastus externus_, between which and the semimembranous it is placed. It arises by a tendon between the _ilio-psoas_ and _pyriformis_ from the ilium above the acetabulum and behind the origin of the _vastus externus_. From here it passes backwards, separated from the _vastus externus_ by a strong _ligam. intermusculare_. On the inner side of this muscle, between it and the _m. semimembranosus_, run the vessels of the thigh and the _N. ischiadicus_. The muscle then divides into two portions, of which one is inserted high up on the inner and under surface of the femur. This is probably the muscle which Klein (_l. c._, p. 61) describes as the _extensor brevis_. The other long muscular belly passes into a thin tendon, opposite the hinder extremity of the thigh, it divides into two portions; the anterior is inserted into the dorsal surface of the hinder extremity of the femur, the other into the dorsal surface of the tibio-fibula. Between the two is stretched an arch with the concavity outwards. This insertion of the biceps is covered by the stronger tendon of origin of the _m. gastrocnemius_ (compare Fig. 87).

*115.* _M. semimembranosus_ (Figs. 80, 86 _sm_).

*Dugès*, sus-ischio-poplité, n. 148.--*Klein*, p. 60, _extensor
femoris sublimis_.

This muscle lies on the dorsal surface of the thigh, to the inner side of the _biceps_ and _pyriformis_: it is a broad muscle, which takes a tendinous origin from the hinder and upper angle of the _symphysis ossis ilei_, and is inserted by a flat tendon into the dorsal surface of the ligaments of the knee-joint, and through these into the tibio-fibula. The tendon is formed rather abruptly from the muscle, and is surrounded (Fig. 86) by the concave arch, which forms the tendon of origin of the _gastrocnemius_ (_q. v._). A little behind its middle (compare Fig. 81) the muscle is divided obliquely into an anterior and a posterior portion by an aponeurotic septum. As all the fibres are interrupted by this structure, the muscle may very easily be torn through.

(B.) Muscles on the ventral surface.

*116.* _M. sartorius_ (Figs. 81, 82 _s_).

*Dugès*, sous-iléo-tibial, n. 150.--*Klein*, _gracilis_.

This long, flat muscle lies along the middle of the ventral surface of the thigh; it arises by a tendon from the anterior inferior angle formed by the symphysis of the innominate bones, and terminates in a tendon behind the knee-joint, forming a kind of _pes anserinus_ in the fascia of the leg, similar to that of the _semitendinosus_[47].

[Footnote 47: The sartorius has lately been used by Kühne in his researches on the nerve-endings in muscle and on muscle contraction without nerve supply (du Bois-Reymond’s and Reichert’s Archiv, 1859. Page 314).]

*117.* _M. rectus internus major_ (Ecker), (Figs. 81 _r.i_′, 82
_ri_′).

*Dugès*, post-ischio-tibial profond, n. 152.--*Klein*,
_semimembranosus_.

This is a broad and flat muscle, thinned out at either extremity; it occupies the inner half of the ventral surface of the thigh, and is in relation with the _adductor magnus_ externally and anteriorly, with the _sartorius_ posteriorly, and the _rectus minor_ muscle internally. The muscle arises by a tendon from the pubic symphysis; it covers in its course the _semitendinosus_, then passes into a strong tendon, which blends with the tendon of the _rectus minor_, to be inserted by a slip into a process of the tibio-fibula representing the _tuberositas tibiae_; first passing between the tendons of the _sartorius_ and _semimembranosus_, which here form an aponeurotic arch; a second slip passes under the tendon of the _m. semitendinosus_ to be inserted into the upper surface of the tibio-fibula, under it passes the _N. tibialis_. A third thread-like tendon passes to the _m. semimembranosus_. Somewhat behind its middle (Fig. 82) the muscle is traversed by an _inscriptio tendinea_, by which the whole of the fibres are interrupted.

Muscles of left thigh of _Rana esculenta_. Ventral surface.

_ad_′ M. adductor longus.
_ad_″ M. adductor brevis.
_ad_‴ M. adductor magnus.
_e.c._ M. extensor cruris.
_f.t._ M. flexor tarsi.
_g.c._ M. gastrocnemius.
_r.i_′ M. rectus internus major.
_r.i_″ M. rectus internus minor.
_s_ M. sartorius.
_t.a._ M. tibialis anticus.
_t.p._ M. tibialis posticus.
_v.i._ M. vastus internus.
]

*118.* _M. rectus internus minor_ (Ecker), (Figs. 80, 81 _r.i_″).

*Dugès*, post-ischio-tibial superficiel, n. 151.--*Zenker*, _flexor
tibiae magnus_.--*Klein*, _ischio-tibialis_.

Situated entirely on the inner surface of the thigh, this narrow muscle arises by a tendinous band which runs the whole length of the pubic symphysis, and is connected posteriorly with the _sphincter ani_, anteriorly with the _rectus abdominis_; posteriorly it passes into a thin tendon which is also connected with the muscle just described (117). In its course this muscle is attached to the skin by strands of vessels and connective tissue.

The vastus internus major and minor together undoubtedly correspond with rectus internus or gracilis of human anatomy. The rectus internus major is, however, regarded as corresponding with the adductor magnus by Dugès, and with the semimembranosus by Klein; by considering the position and attachments of these muscles one must arrive at a different conclusion.

_MM. adductores femoris._

*119.* [*a*] _M. adductor longus_ (Fig. 82 _ad_′).

*Dugès*, sous-ilio-fémoral, n. 141.

Without further dissection this muscle is only partially visible between the _m. sartorius_ and _vastus internus_ (Fig. 81 _ad_′). The muscle is flat and long, and arises by a tendon from the anterior inferior angle of the pubic symphysis (Fig. 42 _s_), partially covered by the origin of the _sartorius_. Thence the muscle passes between the _vastus internus_ and the _adductor magnus_, and finally is inserted below the middle of the femur, together with the latter muscle.

Muscles of the left thigh of _Rana esculenta_. Ventral surface.

_ad_′ M. adductor longus.
_ad_‴ M. adductor magnus.
_gl_ M. glutaeus.
_ip_ M. ilio-psoas.
_ra_ M. rectus fem. anticus.
_ri_′ M rectus int. major.
_s_ M. sartorius.
_st_ M. semitendinosus.
_vi_ M. vastus internus.
]

*120.* [*b*] _M. adductor magnus_ (Figs. 81, 82 _ad_‴).

*Dugès*, sous-ischio-pubi-fémoral (adductor 1 and 2), n. 142,
143.--*Klein*, _adductor magnus_ and _extensor femoris profundus_.

This muscle is visible between the _sartorius_ and _rectus internus major_ in the anterior half of the thigh, posteriorly it is covered by these muscles. It arises by a tendon from (_a_) the pubic symphysis and _ischii_, and is in this position divided into two portions, between which passes the tendon of one head of the _m. semitendinosus_ (Fig. 83 _st_″); (_b_) a second part arises from this same tendon (Fig. 83 _st_‴) and joins with the first part. Thus formed the muscle passes to be inserted into the distal half of the inner surface of the femur as far as the condyle. Near its hinder extremity, however, it passes on to the dorsal and outer surfaces, and thus forms a kind of muscular sheath surrounding the distal portion of the bone.

*121.* [*c*] _M. adductor brevis_ (Figs. 81, 83 _ad_″),

and

*122.* [*d*] _M. pectineus_ (Fig. 83 _pe_).

*Dugès*, sous-pubio-fémoral (analogue of the _pectineus_, possibly of
the _add. brevis_ also).

These two small muscles which lie under cover of the _sartorius_, _adductor longus_ and _magnus_, appear externally as one muscle, but may easily be separated (Fig. 83). They arise close together from the pubic symphysis, and are inserted into the inner surface of the anterior half of the femur. They are not attached to the _adductor magnus_.

Deep muscles of left thigh of _Rana esculenta_.

_ad_′ M. adductor longus.
_ad_″ M. adductor brevis.
_ad_‴ M. adductor magnus.
_ip_ M. ilio-psoas.
_pe_ M. pectineus.
_ra_ M. rectus anticus,
_ri_′ M. rectus internus major }
_ri_″ M. rectus internus minor } cut through.
_s_ M. sartorius.
_st_ Belly of m. semitendinosus.
_st_′ M. semitendinosus (cap. posticum).
_st_″ M. semitendinosus (cap. anticum).
_st_‴ Fibres passing into the adductor magnus.
_vi_ M. vastus internus.
]

*123.* _M. semitendinosus_ (Fig. 83 _st_, _st_′, _st_″).

*Dugès*, bis-ischio-tibial, n. 153.--*Zenker*, _biceps_.

This is a long thin muscle, only visible after removal of the _m. rectus internus_, by which it is entirely covered. It arises by two long thin tendons, one (_caput posticum_, _st_′) from the pubic symphysis, the other (_caput anticum_, _st_″) from the hollow between the symphysis and the acetabulum. The latter passes through a slit in the _adductor magnus_, and so affords this muscle another point of origin; then backwards between the _adductor magnus_ and the _rectus internus major_ and under the lower third of the thigh, and unites with the posterior head of origin. The muscle so formed passes into a thin tendon, and, together with that of the _sartorius_, forms an aponeurotic arch, connected with the fascia of the leg, under which the tendons of the _rectus internus major_ and _minor_ pass.

(C.) Deep muscles of the thigh.

To these, in addition to the _adductor brevis_, _pectineus_, and the portion of the _biceps_ already described, belong also the following:

Deep muscles of the left thigh of _Rana esculenta_. Dorsal view.

_ad_′ M. adductor brevis.
_ci_ M. coccygeo-iliacus.
_cx_ Coccyx.
_gl_ M. glutaeus.
_il_ Ileum.
_ip_ M. ilio-psoas.
_o.g._ M. obturatorius.
_qf_ M. quadratus femoris.
]

Left half of pelvis of _Rana esculenta_. Thigh turned forwards under the abdomen.

_gl_ M. glutaeus.
_og_ M. obturatorius.
]

*124.* _M. ilio-psoas_ (Figs. 82, 83, 84 _ip_).

*Dugès*, intra-ilio-fémoral (*_iliacus_ and _psoas_).--*Cuvier*,
*Zenker*, *Klein*, _iliacus internus_.

The fibres of this muscle take a broad origin from the pelvic surface of the ilium, pass outwards over the lower margin of the bone and form a flat muscle with its apex pointed posteriorly. It crosses the hip-joint between the _m. rectus_ and _vastus internus_, covering the hinder part of the _m. glutaeus_, and is inserted into the outer surface of the middle third of the femur.

*125.* _M. quadratus femoris_ (Fig. 84 _qf_).

*Dugès*, post-ilio-fémoral (Homologue of the _glutaeus maximus_), n.
197.--*Zenker*, _glutaeus minor_, p. 42.

This muscle is of a somewhat elongated, triangular shape, and arises, under cover of the _pyriformis_, from the ilium behind the acetabulum; it passes backwards over the joint to be inserted into the inner and under surfaces of the femur, between the _pyriformis_ and _ilio-psoas_; below, it is in direct relation with the _adductor brevis_.

*126.* _M. obturatorius_ (Figs. 84, 85 _og_).

*Dugès*, ischio-pubi-fémoral, n. 139 (?).--*Zenker*, _m. capsularis
femoris_.

This small muscle is deeply situated upon the hip-joint, and covered by all the other muscles that arise from the symphysis. Its origin from the innominate bone extends from the superior posterior angle of the _symph. ossis ilii_ to about the middle of the pubic symphysis; the muscle fills the space between the crest of the symphysis and the acetabulum. The fibres converge to pass into a strong tendon, which is inserted into the posterior and anterior surfaces of the head of the femur. The muscle appears to represent collectively the small rotators of human anatomy, _m. obturator externus_ and _internus_ and the _gemelli_.

II. MUSCLES OF THE LEG.

_General description._

On the outer surface (the anterior of man), covered by the _fascia cruris_, into which the tendon of the _extensor communis cruris_ or _triceps_ is prolonged, are found the following muscles: nearest to the bone, the _m. extensor cruris brevis_ (_ec_); externally, the _m. tibialis anticus_ (_ta_) and the _m. peroneus_ (_pe_). On the inner surface (the hinder of man) lie the _gastrocnemius_ (_gc_) and _tibialis posticus_ (_tp_), and deeply the _flexor tarsi sup._ (_ft_).

*127.* _M. gastrocnemius_ (Figs. 80, 81, 86).

*Dugès*, bi-fémoro-plantaire, n. 159.

This important muscle arises by two tendinous heads. The one (Fig. 86 _g_′) rather nearer the middle line of the popliteal space, is by far the stronger: it arises by a broad, tendinous expansion, which covers the knee-joint, and is attached to the femur and the tibio-fibula by anterior and posterior bands respectively; it ends internally in a concave aponeurotic arch: the second head is a thin, tendinous slip, arising from the common tendon of the _triceps_ as this lies on the knee-joint. The muscle is thickest near its origin, and then gradually diminishes in size as it passes backwards; the superficial surface is convex, the deep surface is flat. By tracing the tendons of origin, they are seen soon to unite and form a common flat tendinous surface, broad in front, contracted behind; this aponeurosis lies in a plane running obliquely from the deep surface towards the superficial surface, without, however, reaching this. The muscular fibres arise from both surfaces of the aponeurosis, the fibres of the two sides diverging slightly as they pass backwards so as to be inclined at a small angle to each other. The fibres are inserted into a fibrous expansion (_Ap_) which lies on the superficial surface of the muscle; thin and slight in front, this aponeurosis rapidly thickens posteriorly until it passes into the _tendo Achillis_.

Muscles of the right leg and foot of _Rana esculenta_. Dorsal view.

_a.h._ M. abductor hallucis.
_a.l1_ M. abductor longus digiti I.
_A.p._ Aponeurosis plantaris.
_b_ M. biceps.
_e.t._ M. extensor tarsi.
_F.l._ M. flexor digitorum III, IV, V longus.
_F.l_′. M. flexor digitorum I and II longus.
_g_ M. gastrocnemius, drawn towards the right.
_g_′ Tendon of origin of gastrocnemius.
_l.c._ Ligamentum calcanei.
_p_ M. plantaris.
_r.i._ MM. internus maior and minor.
_s.m._ M. semimembranosus.
_s.t._ M. semitendinosus.
_t.A._ Tendo Achillis.
_t.A_′. Thickening of tendo Achillis.
_t.p._ M. tibialis posticus.
_v.e._ M. vastus externus.
_v.i._ M. vastus internus.
]

*128.* _M. tibialis posticus_ (Fig. 86 _t.p._).

*Dugès*, cruro-astragalien, n. 160.

Covered by the _gastrocnemius_ this muscle occupies the whole of the inner and upper surfaces of the tibio-fibula, from which it arises by numerous fibres. Opposite the hinder extremity of the bone the muscle becomes free and passes somewhat abruptly into a tendon, which courses behind and over the _malleolus internus_, on to the dorsum of the foot, and is here inserted into the anterior extremity of the _astragalus_. I cannot agree with Dugès that this muscle corresponds with the _soleus_ (Ecker).

*129.* _M. extensor cruris brevis_ (Fig. 87 _ec_).

*Dugès*, pré-fémoro-tibial, n. 154.

Covered by the strong _fascia cruris_, and lying between the _m. tibialis anticus_ and the tibio-fibula, this muscle arises by a long tendon from the inner condyle of the femur; it passes backwards in the groove on the anterior extremity of the tibio-fibula, covered by the tendon of the triceps femoris, and is then inserted by muscular fibres into the outer surface of the tibio-fibula almost as far as the posterior third of the bone. (Dugès regards this muscle as the upper, i. e. anterior, portion of the _tibialis anticus_.)

*130.* _M. tibialis anticus_ (Figs. 80, 81, 87 _ta_).

*Dugès*, pré-fémoro-astragalien and pré-fémoro-calcanien, n. 156 and
157; the former he regards as one part of the _tib. anticus_, the
latter as the _peroneus longus I_.--*Zenker*, _tib. ant. biceps_.

The tendon of origin of this muscle is attached to the femur near the tendon of the _m. extensor cruris brevis_, and to the joint-ligaments. The muscle is placed under the _fascia cruris_, its long tendon of origin passing beneath the tendon of the _triceps_ in a special sheath through the joint; the tendon then gains a muscular belly which bifurcates at about the middle of the leg, forming two muscular masses, coursing along the outer and the inner side of the leg respectively. The latter is inserted into the dorsal surface of the _astragalus_ by a tendon, and the former into the dorsal surface of the _calcaneus_ in a similar manner. The muscle extends the foot and flexes the tarsus; the latter movement is very distinct on account of the insertion of the muscle being so near the _hypomochlion_.

*131.* _M. flexor tarsi anterior_ (Ecker), (Fig. 87 _Ft_).

*Dugès*, ex-tibio-astragalien, n. 155.--*Zenker*, _tibialis anticus
simplex_.

This muscle arises where the insertion of the _extensor cruris brevis_ ceases, from the middle of the under surface of the tibio-fibula, and passes backwards between the two tendons of the _m. tibialis anticus_ along the outer side of this muscle, to be inserted by a tendon into the inner side of the anterior articular extremity of the _astragalus_ and the _fascia dorsalis pedis_.

Muscles of leg and foot of _Rana esculenta_, seen from below.

_a.b.5_ M. abductor dig. V longus.
_ec_ M. extensor cruris brevis.
_e.d.1_ M. extensor digit I longus.
_e.d.4_ M. extensor digit IV longus.
_e.d.5_ M. extensor digit V longus.
_Ft_ M. flexor tarsi anterior.
_Ft_′ M. flexor tarsi posterior.
_g_ M. gastrocnemius.
_p_ M. peroneus.
_ta_ M. tibialis anticus.
_tF_ M. triceps femoris.
]

*132.* _M. peroneus_ (Figs. 80 _pe_, 87 _p_).

*Dugès*, génio-péronéo-calcanien, n. 158.

This is a strong muscle which is attached by a long tendon of origin to the hinder extremity of the femur and the ligaments of the knee-joint. The tendon runs in a sheath through the joint and posteriorly becomes muscular; the muscle passes downwards on the outer side of the tibio-fibula to be inserted into the _malleolus externus_ of this bone and into the anterior extremity of the _calcaneus_. It has an action similar to that of the _m. tibialis anticus_.

III. MUSCLES OF THE FOOT.

A. _MUSCLES ON THE PLANTAR SURFACE._

*133.* _Aponeurosis plantaris_ (Fig. 88 _A.p._).

As already mentioned, the tendon of the _m. gastrocnemius_ is, at the heel, continued into a strong aponeurosis, and possesses at this place a thickening[48]. The aponeurosis is of triangular form, the base directed towards the toes and attached to these. The lateral borders of this triangle are continued into weaker _fasciae_, which are attached to the two long tarsal bones. The inner border in particular gives a strong bundle of fibres to the astragalus, and is thus connected with the fascia of the dorsum of the foot; externally this aponeurosis is attached to a cartilage (Dugès, os sesamoïde, _l. c._, n. 66), situated on the plantar surface of the joint between the _calcaneus_ and the _os metatarsi IV_.

[Footnote 48: Lehmann, Ueber den Knorpel in der Achillessehene des Frosches, Zeitschs. f. U. Zool. XIV, p. 109. (See also literature on cartilage, Sect. VII.)]

*134.* _Ligamentum calcanei_ (Ecker), (Figs. 88, 89 _l.c._).

If the _tendo Achillis_ be divided and the _aponeurosis plantaris_ reflected towards the toes, there is seen, arising from the posterior head of the tibio-fibula, in its whole breadth, a ligament (between the _tib. posticus_ and _peroneus_). This ligament forms a firm surface on which the thickened portion of the _tendo Achillis_ may move, and which evidently represents the tuberosity of the heel bone. I have therefore named the entire structure the _ligamentum calcanei_.

Muscles of the right leg and foot of _Rana esculenta_. Dorsal view.

_a.h._ M. abductor hallucis.
_a.l_I M. abductor longus digiti I.
_A.p._ Aponeurosis plantaris.
_b_ M. biceps.
_e.t._ M. extensor tarsi.
_F.l._ M. flexor digitorum III, IV, V longus.
_F.l._′ M. flexor digitorum I and II longus.
_g_ M. gastrocnemius, drawn towards the right.
_g_′ Tendon of origin of gastrocnemius.
_l.c._ Ligamentum calcanei.
_p_ M. plantaris.
_r.i._ MM. internus maior and minor.
_s.m._ M. semimembranosus.
_s.t._ M. semitendinosus.
_t.A._ Tendo Achillis.
_t.A_′. Thickening of tendo Achillis.
_t.p._ M. tibialis posticus.
_v.e._ M. vastus externus.
_v.i._ M. vastus internus.
]

Several muscles arise from this ligament, viz.:--

*135.* _M. extensor tarsi_ (Klein), (Figs. 88, 89 _e.t._).

*Dugès*, tibio-sous-astragalien (regarded by him as the homologue of
the _tibialis posticus_).

Covered by the two succeeding muscles, this muscle arises from the _ligamentum calcanei_, runs backwards, and is inserted into the whole length of the plantar surface of the _astragalus_. It extends the foot.

*136.* _M. plantaris_ (Figs. 88, 89 _p_).

This takes its origin from the _ligamentum calcanei_ to the inner side and below the last muscle. It passes backwards and is inserted into the dorsal surface of the _aponeurosis plantaris_.

Muscles of the plantar surface of foot of _Rana esculenta_, twice natural size.

_A.p._ Aponeurosis plantaris, divided.
_ab.5._ M. abductor dig. V.
_ad.5._ M. adductor dig. V.
_ad.l.1._ M. adductor longus dig. I.
_e.t._ M. extensor tarsi.
_F.5._ M. flexor brevis dig. V.
_F.l._ M. flexor digitorum III, IV, V longus.
_F.l_′. M. flexor digitorum I, II longus.
_l.1._}
_l.2._}
_l3_ }
_l3_′ } Musculi lumbricales.
_l4_′ }
_14_″ }
_l.5._}
_l.c._ Ligamentum calcanei.
_p_ M. plantaris.
_t.A._ Tendo Achillis.
_t.A_′. Thickening in tendo Achillis.
_t.p._ M. transversus plantae posterior.
_t.p._′ M. transversus plantae anterior.
]

*137.* _M. flexor digitorum III_, _IV_, _V longus_ (Ecker),
(Figs. 88, 89 _F.l._).

*Dugès*, péronéo-sous-phalangettien (_flexor dig. longus_).

This muscle also arises from the _ligamentum calcanei_ to the outer side of the _m. plantaris_. It runs backwards over the _aponeurosis plantaris_, and at the free margin of this passes somewhat suddenly into a strong tendon, which traverses an aponeurotic canal, formed by fibres of the aponeurosis passing above and below the tendon, from the cartilaginous enlargement in the tendon to the median border of the aponeurosis. The tendon forms three slips for the fifth, fourth, and third toes: these are slightly attached to the aponeurosis, but reach beyond its free border to be inserted into the terminal phalanges of the toes mentioned, and are held down by fibrous bands. (The small _m. lumbricales_ arising from these tendons are described below.)

*138.* _M. flexor digitorum I_, _II longus_ (Ecker), (Figs. 88, 89
_F.l_′.).

The tendons, by means of which the terminal phalanges of the first and second toes are flexed, arise directly from the posterior border of the aponeurosis.

*139, 140.* _MM. transversi plantae_ (Ecker), (Fig. 89 _t.p._,
_t.p_′.).

The movements of the aponeurosis and through it the movements of the tendons attached to it are influenced not only by the _m. gastrocnemius_ and _plantaris_, but also by two other muscles, which together have been described as the _flexor dig. longus internus_ (Klein), or as the tarso-sous-phalangettien (Dugès, 221).

*a.* _M. transversus plantae posterior_ (_t.p._).

This takes its origin from the plantar cartilage, widens as it courses backwards and inwards to be inserted into the dorsal surface of the _aponeurosis plantaris_; from this the tendons for the first and second toes (_flexor dig. longus I_ and _II_) arise, thus there is no direct connection between the muscular fibres of the two muscles.

*b.* _M. transversus plantae anterior_ (_t.p_′.).

This muscle is covered by the last; broader anteriorly, it arises from the calcaneum, and is inserted to the inner side of the last muscle into the dorsal surface of the aponeurosis. This muscle, like that just described, is not continued directly into the tendon of the flexor of the toes, they cannot therefore be regarded as flexors of the toes.

*141* to *149*. _Musculi lumbricales_ (Fig. 89 _l.1–5_).

(A.) From the posterior border of the _aponeurosis plantaris_ arise:--

(1) _M. lumbricalis digiti I_ (_l.1_).

*Dugès*, tendini-sous-phalangien de pouce, n. 185.

This is inserted into the anterior extremity of the proximal phalanx.

(*2*) _M. lumbricalis digiti II_ (_l.2_).

*Dugès*, tendini-sous-phal. du I doigt, n. 186 (and 187), double
according to Dugès.

Similarly inserted.

(*3* and *4*) _MM. lumbricales digiti III_ (_l.3_).

*Dugès*, tendini-sous-phal. du III doigt, n. 188, single according to
Dugès.

One of these (_l3_) is inserted into the anterior extremity of the basal phalanx, the other (_l3_′) into a corresponding position on the middle phalanx.

(*5*) _M. lumbricalis digiti IV._

*Dugès*, tendini-sous-phal. du IV doigt.

Inserted into the anterior extremity of the basal phalanx.

(B.) Arising from the tendons of the _flexor longus III_, _IV_, _V_:

(*6* and *7*) _MM. lumbricales digiti IV_ (_l.4_′. and _l.4_″.).

*Dugès*, tendini-sous-phalanginien du IV doigt, n. 201, 202.

The first (_l.4_′) is inserted into the posterior end of the basal phalanx, the second (_l.4_″) in a similar position into the second phalanx.

(*8*) _M. lumbricalis digiti V_ (_l.5._).

*Dugès*, tendini-sous-phalangien du V doigt, n. 203.

This arises from the tendon for the fifth toe, runs backwards as a thin tendon alongside that of the flexor, and is inserted into the middle phalanx.

_Special Muscles of the Separate Toes._

(I.) Muscles of the rudimentary great toe.

*150.* _M. abductor hallucis_ (Figs. 88 _a.h._, 90).

*Dugès*, tibio-sous-tarsien, n. 163.

This muscle arises from the inner border of the _aponeurosis plantaris_, at the spot where the _m. plantaris_ is inserted, it may therefore almost be regarded as a continuation of this muscle; it is inserted into the anterior border of the rudimentary toe.

(II.) Muscles of the great and first toes.

*151.* _M. adductor longus digiti I_ (Figs. 89, 90 _ad.l1_).

*Dugès*, calcanéo-scaphoidien, n. 164.

This powerful muscle arises from the plantar surface of the calcaneum and astragalus; its fibres converge towards a tendon lying in its middle, which becomes free towards its posterior end; the tendon passing inwards under the _ligamentum tarsi transversum_ through a groove on the hinder extremity of the astragalus in an arched direction, to be inserted into the _os naviculare_, which bears the rudimentary great toe and the _os metatarsi I_.

(III.) Muscles of the first toe.

*152.* _M. abductor longus digiti I_ (Figs. 88 _al.1_, 90 _a.b.1_).

It takes its origin from the inner border of the _aponeurosis plantaris_, and lies on the plantar surface of the _abductor hallucis_. Its tendon runs in the hollow which the great toe forms, and is inserted into the inner side of the _os metatarsi I_.

*153.* _M. flexor brevis digiti I_ (Fig. 90 _F.b.1_).

A small, thin muscle, which arises from the anterior extremity of the _os metatarsi II_, and is inserted into the basal phalanx of the first toe. In this small muscle, and also in the _m. lumbrical. dig. V_ (Fig. 89 _l.5._), the nerve distribution may be very well seen.

*154.* _M. opponens dig. I_ (Fig. 90 _op_).

*Dugès*, sous-metatarso-phalangien du pouce, n. 192.

This is situated to the inner side of the preceding muscle, arises from the _os metatarsi II_ somewhat narrow, widens in a fan-like manner towards the _os metatarsi I_, into the anterior half of which it is inserted.

(IV.) Muscles of the second toe.

*155.* _M. flexor metatarsi dig. II_ (Fig. 90 _F.m.2_).

*Dugès*, sous-tarso-metatarsien du II doigt.--*Klein*, extensor
metatarsi.

By a narrow origin from the hinder end of the calcaneum, posteriorly this muscle becomes broader and is inserted, somewhat thinned out, into the plantar surface of the second _os metatarsi_.

*156.* _M. flexor dig. II proprius_ (Fig. 90 _F.p.2_).

*Dugès*, sous-metatarso-phalangien, n. 194.

It arises from the plantar surface of the _os metatarsi II_, and is inserted by a thin tendon into the plantar surface of the first phalanx.

Dugès describes this and the analogous muscles of the third, fourth, and fifth toes (_F.p.3_, _4_, _5_) as the _interossei plantares_, a nomenclature which, to me, does not appear correct, as these muscles lie entirely on the plantar surface, and do not adduct or abduct the toes, but flex them.

(V.) Muscles of the third toe.

*157.* _M. flex. metatarsi dig. III_ (Ecker), (Fig. 90 _F.m.3_).

*Dugès*, sous-calcaneo-métatarsien du III doigt, n. 174.--
*Klein*, _extensor metatarsi_.

Like the corresponding muscle of the second toe (n. 155), this arises by a small tendon from the hinder extremity of the calcaneum, runs backwards and is inserted into the plantar surface of the _os metatarsi III_. The greatest portion of the muscle lies beneath the _m. transversus metatarsi_ (_tm_), the most anterior portion, however, lies above this. Dugès has described this latter portion as a special muscle (n. 176, metatarso-métatarsien du III), the same description holds good for the second toe (n. 177, Dugès).

*158.* _M. flexor dig. III proprius_ (Ecker), (Fig. 91 _Fp3_).

*Dugès*, sous-métatarso-phalangien du III doigt, n. 195.

Like the corresponding muscle of the second toe, this arises from the plantar surface of the _os metatarsi III_, and is inserted by a thin tendon into the plantar surface of the anterior extremity of the first phalanx.

Muscles of plantar surface of foot of _Rana esculenta_.

_a.b.1_ M. abductor longus digiti I.
_ab5_ M. abductor digiti V.
_ad.l.1_ M. adductor longus digiti I.
_a.h._ M. abductor hallucis.
_F.b.1_ M. flexor brevis digiti I.
_F.m.2_, _3_, _4_ M. flexores metatarsi II, III, IV.
_F.p.2_, _3_, _4_, _5_ MM. flexor. proprii digit. 2, 3, 4, 5.
_F.ph.3_, _4_, _4_′, _5_ MM. flexor. phalang. digit. 3, 4, 5.
_op_ M. opponens digiti I.
_t.m_′ }
_t.m_″ } MM. transversi metatarsi 1, 2, 3.
_t.m_‴ }
]

*159.* _M. flexor phalangum proprius digiti III_ (Ecker), (Fig. 91
_F.ph.3_).

*Dugès*, phalango-phalangien, n. 204.

This arises by tendon from the plantar surface of the basal phalanx, and is inserted into the anterior extremity of the terminal phalanx.

(VI.) Muscles of the fourth toe.

*160.* _M. flexor metatarsi dig. IV_ (Fig. 91 _F.m.4_).

*Dugès*, métatarso-métatarsien, n. 175.

Similarly to the corresponding muscle of the third toe, this one arises from the hinder extremity of the calcaneum, and is inserted into the anterior portion of the plantar surface of the _os metatarsi IV_, but not into the greater portion of this surface, as in the second and third _os metatarsi_.

*161.* _M. flexor dig. IV proprius_ (Fig. 91 _Fp4_).

*Dugès*, sous-métatarso-phalangien du IV doigt (_interosseus
plantaris_), n. 196.

The origin and insertion are similar to those of the muscles of the second and third toes.

Muscles of plantar surface of foot of _Rana esculenta_.