It resembles the corresponding muscle of the third toe.

164. M. flexor phalangum proprius posterior (Fig. 91 F.ph.4′).

This extends from the plantar surface of the second phalanx to the anterior extremity of the third.

(VII.) Muscles of the small toe.

165. M. abductor dig. V (Fig. 91 a.b.5).

This muscle arises from the hinder extremity of the calcaneum, and is inserted into the outer surface of the fifth metatarsal.

166. M. adductor dig. V (Fig. 89 a.d.5).

This arises from the cartilage of the plantar aponeurosis, and is inserted into the hinder end of the fifth metatarsal.

167. M. flexor brevis dig. V (Fig. 89 F.5).

Arising from the same place as the preceding, it extends to the basal phalanx.

168. M. flexor dig. V. proprius (Fig. 91 F.p.5).

This muscle arises from the plantar and inner surfaces of the fifth metatarsal, and is inserted into the basal phalanx.

169. M. flexor phalangum proprius (Fig. 91 F.ph.5).

Its origin and insertion are as in the corresponding muscles of the second, third, and fourth toes, n. 159, 163, 164, 169.

170 to 172. MM. interossei (Fig. 91 t.m.).

These are three muscles with their fibres arranged transversely, which occupy the anterior portion of the spaces between the metatarsals, and approximate these. The first arises (tm′) from the edge of the plantar surface of the first metatarsal, and is inserted into the corresponding part of the second: the second (tm″) passes from this point to the third, and the third (tm‴) to the fifth.

B. Muscles of the Dorsal Surface.

173. M. flexor tarsi posterior (Ecker), (Fig. 92 F.t.).

This is a strong muscle, which has a narrow origin from the outer side of the tibio-fibula, directly over the distal extremity, and is inserted into the dorsal surface of the astragalus from the middle to the distal extremity.

Muscles of the first toe.

174. M. extensor longus dig. I (Fig. 92 e.l.1).

This lies to the outer side of and near the foregoing muscle; it arises by a long, strong head from the middle of the calcaneum, runs obliquely backwards and inwards to unite with a small head which arises from the common epiphysis of the astragalus and calcaneum, in common with the m. extensor dig. II. The muscle so formed passes into a flat tendon to be inserted into the basal phalanx of the first toe.

175. M. extensor brevis dig. I (Fig. 92 e.b.1).

A small, short muscle which arises from the os naviculare and is inserted into the dorsal surface of the first metatarsal.

176. M. abductor brevis dig. I (Fig. 92 a.b.1).

This small muscle is situated near the preceding; it arises from the first bone of the supplemental toe, and is inserted into the inner side of the first metatarsal.

Muscles of the second toe.

177. M. extensor dig. II longus (Fig. 92 e.l.2).

This arises from the calcaneum, in common with the m. extensor longus of the third toe, and is inserted into the basal phalanx of the second toe by a tendon.

178. M. extensor dig. II brevis (Fig. 92 e.b.2).

This is partly covered by the preceding muscle: it arises from the astragalus, and unites with the tendon of the preceding muscle.

Muscles of the third toe.

179. M. extensor dig. III longus (Fig. 92 e.l.3).

This arises with the extensor longus of the second toe from the calcaneum: its tendon unites with that of the following muscle.

180. M. extensor dig. III brevis (Fig. 92 e.b.3).

This muscle arises from the astragalus, and is inserted with the tendon of the preceding muscle into the dorsal surface of the basal phalanx.

Muscles of the fourth toe.

181. M. extensor longus dig. IV (Fig. 93 e.l.4).

A narrow muscle arising in common with the flexor tarsi inf., but external to it. It is inserted into the tendinous expansion on the dorsum of the toe.

182. MM. extensores dig. IV breves (Fig. 93 e.b.4 and e.b.4′).

These two small muscles arise from the calcaneum: one is inserted into the basal phalanx, the other, by means of a long thin tendon, passes along with the tendon of the corresponding m. interosseus to the second phalanx, to which it is attached.

Muscles of the fifth toe.

183. M. extensor dig. V longus (Fig. 93 e.l.5).

A strong muscle which covers almost the whole length of the calcaneum; it arises from the anterior extremity of this bone, runs backwards to the outer side of the dorsum of the foot, and is attached to the outer surface of the fifth metatarsal.

184. M. extensor dig. V brevis (Fig. 93 e.b.5).

This is a long thin muscle, which, together with the muscle last described, arises from the calcaneum and is inserted into the basal phalanx of the fifth toe.

185. M. abductor dig. V brevis (Fig. 93 i.10).

This, the last m. interosseus, arises from the outer side of the fifth metatarsal, and is inserted into the hinder extremity of the second phalanx of the same toe.

186 to 195. MM. interossei dorsales (Fig. 93 i.1 to i.10).

First toe.

(1) The analogue of the first m. interosseus is the m. abductor brevis dig. I (a.b.1).

(2) The second m. interosseus (i.2) arises from the outer side of the first metatarsal, and is inserted into the outer surface of the second phalanx of the same toe, dorsally to the m. opponens and flexor brevis dig. I.

Second toe.

(3) The third m. interosseus (i.3) takes origin from the anterior part of the outer surface of the first metatarsal by a thin tendon; it is inserted into the inner surface of the second phalanx by a similar tendon.

(4) The fourth m. interosseus (i.4) arises from the outer side of the second metatarsal, and is inserted into the outer surface of the second phalanx.

Third toe.

(5) The fifth m. interosseus arises from the outer surface of the second metatarsal, and is inserted by a thin tendon into the inner surface of the second phalanx of the same toe.

(6) The sixth arises from the outer surface of the third metatarsal, and is inserted laterally by a thin tendon into the hinder extremity of the second phalanx of the same toe.

Fourth toe.

(7) The seventh m. interosseus (i.7) arises by a thin tendon from the hinder extremity of the astragalus, and by fleshy fibres from the hinder extremity of the fourth metatarsal; it is inserted by a thin tendon into the inner surface of the second phalanx of the same toe.

(8) The eighth m. interosseus (i.8) takes its origin from the outer surface of the fourth metatarsal and from the inner surface of the fifth: it is inserted into the hinder extremity of the second phalanx.

Fifth toe.

(9) The ninth m. interosseus (i.9) arises from the inner surface of the fifth metatarsal, and is inserted into the hinder extremity of the second phalanx.

(10) The tenth m. interosseus has already been described as the abductor digiti V brevis (Fig. 94 i.10).

If we take the fourth toe as the axis of movement, the first, third, fifth, seventh, eighth, and tenth mm. interossei will abduct from an imaginary line which runs through this toe. The second, fourth, sixth, and ninth will adduct towards this line. If we compare them with those of man (in whose case the second toe affords the central line), those of the first group must be regarded as mm. interossei dorsales, of the latter as plantares. Dugès holds all these interossei (with the exception of the first, abductor brevis dig. I) to be mm. interossei dorsales (métatarso-sus-phalangettiens, n. 210, 211, 212, 214, 215, 216, 218, 219). Those which I have described as flexores proprii digitorum, he regards as interossei volares.

V. MUSCLES OF THE SKIN.

196. M. cutaneus pectoris (Fig. 95 cp).

This is an elongated quadrangular muscle, attached by its hinder margin to the side of the xiphisternum, and to the superficial surface of the aponeurosis of the m. obliquus externus. The fibres course forwards and slightly outwards to be inserted, at a very acute angle, into the skin: lying between the two muscles and attached to them on either side is a thin fascia, which, together with the muscles and the septum thoracicum, assists in closing a triangular space between these structures and the deeper muscles.

The thinness and transparency of this muscle render it especially suitable for the investigation of nerve-terminations‍49.

197. M. cutaneus dorsi (Fig. 96 cd).

This muscle has a narrow origin in the space between the muscles of the belly and of the thigh, and is here inserted into the fasciae, which are attached to the pubic symphysis; it passes inwards and upwards to the outer side of the anterior insertion of the m. rectus femoris anticus, then widens and is inserted by diverging fibres into the inner surface of the skin of the hinder portion of the back.

198. M. coccygeo-cutaneus.

The muscular fibres which Dugès has described under this name, lie covered by the m. pyriformis, behind the m. coccygeo-iliacus, etc., and above the muscles of the rectum. They arise from the hinder extremity of the urostyle: they appear to be connected with the rectal muscles, and pass outwards to be attached to the skin.

Among the cutaneous muscles may perhaps be included the m. submaxillaris (p. 62).

The fibrils passing from the flexor tendons to the warty bodies on the plantar surface of the toes are described‍50 with the skin (p. 373).