EXPLANATION OF PLATES
Plate 1, Fig. 1 is a view of the upper surface of the skeleton of the right foot. The bones are named as follows: — The Astragalus (talus or huckle bone) connects the foot with the leg, the large bone of which (tibia) rests upon it where the name is written, clipping it on the inner side by a projection downward as shown, in section, by fig. 16, Pl. 5, where the Fibula* or smaller bone of the leg, is seen to clip it on the outer side. The Astragalus rides on the Os calcis (calcaneum or heel bonea, while a large portion of the latter bone is, on the outer side, unconcealed by it. The two bones named come up to a fairly even line across the foot. A division at the joints is shown by fig. 9, Pl. 3. The smooth rounded head, enlongated in one direction into an oval form, fits into a corresponding hollow in the Scaphoid bone, so called from its boat-like form.† On the outer side is the Cuboid, having the form of a cube, though somewhate irregular. Extending from it to the inner margin of the foot are three wedge-like or cuneiform bones.
The seven bones of the foot, named, form the Tarsus, corresponding to the wrist or Carpus in the hand. The body of the foot is completed in front by five long Metatarsal bones, forming the Meta-tarsus, and fixed to the tarsus by an irregular line receding backward and outward. They are numbered 1 to 5, the fifth having a point projecting backward by the side of the cuboid bone. This point is concealed in the living foot, but a rounded projection outward (b) can always be felt.
The Metatarsal are united to the tarsal bones by their bases, while their heads form the supports at the roots of each of the five toes. Each bone of which the toes consist is called a phalanx, from a fancied resemblance to a phalanx of soldiers. These phalanges, two for the first or great toe, three for each of the others, have their bases or proximal ends toward the foot, their heads or distal ends pointing forward. They are numbered first (next the foot), second or middle and third or final; in the case of the great toe, first and second, or final, only. In the smaller toes, especially the fourth and fifth, the phalanges are often indistinct, being fused together.
The smooth articular surface on the first metatarsal bone which helps to form a joint with great should be noticed. It extends further back on the side next the second toe, so that the great toe in moving upward moves toward the position indicated by the dotted line. In the position as seen in the drawing it is supposed to be flat on the ground.
A line from A to B is seen to pass by the side of the heel, and to cut off from the rest of the foot the two outer toes and their metatarsal bones. The lines C D and E F mark the irregular lines of hinges formed by the joints. Their significance will be explained in the text.
Fig. 2 shows the same (right) foot turned over and the under surface seen. The very irregular projections of the bones contrast strongly with the smooth surface on the upper side. These exist for the attachment of muscles, for the guidance of tendons, and for the protection of blood vessels and nerves. The deep groove on the cuboid bone for a tendon, shown in fig. 14, pl. 5, is to be noted.
The manner in which the astragalus overhangs is clearly seen as well as the bracket-like projection of the os calcis to support it. The greater part of the head of the astragalus, as seen where the name is written, is unsupported by bone, and rests in the complete foot on a ligament only. Compare fig. 11, pl. 4, with fig. 5, pl. 2.
Fig. 3 is a section, in outline, of the three cuneiform and of the cuboid bones, taken obliquely across each foot. It marks a transverse arch in each foot, the two combining to form a larger arch.
Figs. 1 and 2, (adapted,) and fig. 3, (given in duplicate,) are taken from Holden's Osteology.
* The bones of the leg, Tibia and Fibula, are so called from their supposed resemblance, the former to a pipe or flute, the later to a clasp. [Back]
† For the same reason, sometimes called navicular, a name better avoided, because, in the horse, applied to an altogether different bone. [Back]
Plate 2, Fig. 4 shows the joints laid open as by taking a slice off the upper and outer surface of the foot. It will be seen that the astragalus and os calcis are united by two distinct joints. These are separated by a very strong ligament (interosseous) fitted into a groove in each bone so deep that, in the dried bones put together, the two grooves form a well-marked tunnel between the two joint surfaces.
Fig. 5 shows how the bones of the tarsus, seen on the inner margin, are bound to the leg bone, to the metatarsus and to each other by strong ligaments. These it is not necessary to name. The positions of the bones are indicated, and it will be noticed that the head of the astragalus unsupported by bone (Fig. 2, Pl. 1) is covered — it is in fact supported — by ligament. At the back of the os calcis is shown a small sac or bursa, which exists for the purpose of dimishing friction when the great tendon of the heel, attached below, slides over this surface.
Fig. 6 shows the heel uplifted. It is a sketch frequently given as expresive of the leverage of the foot, the power being the muscle acting on the heel, the body the weight and the ground the fulcrum. Taken alone, it conveys a wrong impression; other agency (to be explained) beyond the ligaments shown in fig. 5, are necessary to support the foot when in this position.
Figs. 4 and 5 are taken from Gray's Anatomy; fig. 6 from Holden's Osteology.
Plate 3, Fig. 7 represents the first or most superficial layer of the muscles* seen in the upturned sole. To give this view it is necessary to remove not only the skin, but also a cushion of soft tissue beneath and an expansion known as the plantar fascia. This consists of a strong layer of fibrous tissue, mostly arranged in a long longitudinal direction, which covers in and protects the muscles, these latter being made up of masses of the fleshy substance familiarly known as lean meat, sometimes united to fibrous cords or tendons which connect them with the bones, sometimes directly attached to the bone. A portion of the plantar fascia is seen in front of the os calcis or heel bone with which it is closely connected; between it and its extensions between the muscles, on the one hand, and the skin, on the other, is a cushion of soft material, make up of fat an fibrous tissues binding the whole together. The muscle which occupies the middle of the foot (flexor brevis digitorum) serves to draw down, as it bends or flexes, the four smaller toes. Its fleshy or muscular attachment is to the plantar fascia and to the heel bone (os calcis) behind. The tendons go forward to the four smaller toes where they divide in order to allow another deeper seated tendon, that of the long flexor, (10, Fig. 8) to go between the two divisions. They re-unite and again divide, being ultimately inserted into the two sides of the middle phalanges.
The tendons are bound down to the toes by sheaths of interlaced fibrous tissue. These sheaths are show entire on the fourth and fifth toes. In the middle toe the sheath has been laid open, and the tendon of the long flexor, passing between the two divisions, exposed. This latter tendon is, in the second toe, shown as cut through, revealing the smooth groove in which it runs.
The Abductor pollicis muscle, which draws the great toe towards the middle line of the body, away from the foot, and the Abductor minimi digiti, which draws the little toe outwards, are seen to be named with reference to an imaginary middle line of the foot, from which they abduct. Their muscular insertion is to the bones on the inner and outer sides of the foot respectively, and their tendons go forward to be inserted into the first phalanx of the great and of the litte toe.
Fig. 8 gives a view, so far as can be seen from the inner side, of the muscles* which belong to the leg and foot. The tendons are all held close to the ankle by a band of fibrous tissue, (a) which encircles the ankle like a ring, the annular ligament. The fibres of the flexor brevis pollicis are seen above b, coming from the deep part of the sole to join the abductor pollicis. Taking the muscles by their numbers, the anterior tibial, (Tibialis Anticus, 1) has a muscular insertion into the shin bone or tibia, and, by a tendon, into the inner and under side of the first cuneiform and the base of the first metatarsal bone. The tendons indicated by Nos. 2 and 3 are best seen in fig. 15, pl. 5, where 4, 5, and 6 are shown. The great calf-muscle narrowed down as it comes towards the heel, consists of two parts, the Gastro-cnemius and Soleus, indicated by 7' and 7''. These unite in the strong tendon of the heel (7), the tendon of Achilles or tendo Achillis. The number 8 indicates a tendon, not distinctly seen, really a relic of a muscle which plays a more important part in animals, and is mentioned in the text — the Plantaris.† The number 9 lies in the opening between the tendo Achillis and the other muscles; which is, in the complete foot, filled in with fat. It refers to the Flexor longus pollicis, the muscle above it, whose tendon is seen at the root of the great toe in front of and behind the joint at the base, the interval being occupied by one of the small bones, known as sesamoid, of which two are placed, one on the inner and one on the outer side of that joint, as explained in Fig. 14, pl. 5. The Long flexor common to the smaller toes (Flexor longus digitorum, 10) comes next, which has an upper muscular attachment to the leg, and goes, by tendons, along the sole to the four smaller toes. The posterior tibial muscle Tibialis Posticus, 11, also having a muscular attachment to the leg, is inserted by tendon beneath the inner margin of the foot, as seen in Fig. 14, pl. 5.
Fig. 9 is a view, seen from before, as given by a division of the foot through the joints immediately in front of the ankle. Above is seen the ankle joint itself exposed, the upper surface of the astragalus going up against and between the bones of the leg; this is better seen in a section taken a little further back (fig. 16, pl. 5), through the ankle. Below, on the inner side, is the head of the astragalus, which articulates with the scaphoid in front. On the outer side, nearer the sole, is that portion of the os calcis, which articulates with the cuboid. The tendency of the bones to become displaced inwards with the downward thrust caused by the weight of the body, a result (apparently) prevented only by the ligaments which bind them together, is obvious.
Fig. 7 is taken from Gray's Anatomy. Figs. 8 (the numbers being altered) and 9 (duplicated) are taken from Marshall's Anatomy for Artists.
* A complete list of muscles is given after the description of pl. 6 [Back]
† In the monkey tribes it tightens the plantar fascia (Fig. 7:) in man it is only rudimentary, and its tendon, merged in the tendo Achillis, does not even reach the sole. [Back]
Plate 4, Fig. 10 reveals a second layer of muscles,* the flexor brevis digitorum, abductor pollicis, and abductor minimi digiti having been removed. To the tendon of the flexor longus digitorum at its point of division is united a muscle which is attached by two heads to the two tuberosities of the os calcis, and to this tendon. In action it has the effect of throwing the tendon with which it is united in line with the long axis of the foot. It is an accessory flexor, Flexor accessorius. Outside this the tendon of the peroneus longus (pl. 5) muscle is seen crossing obliquely the sole from the outer to the inner side.
The four Lumbricales muscles, so called from their wormlike shape, are here marked: they were partly seen in fig. 7. These muslces are attached to the tendons of the flexor longus digitorum and, by means of tendons, to the base of the second phalanges of the four smaller toes; they join with the long extenson muscle, (pl. 6) and represent muscles in the hand of much importance.
Fig. 11 is a view of the bones forming the arch of the foot seen from the inner side. The astragalus is uplifted to show the bed in which it lies, transmitting the weight of the body backwards to the heel and forwards to the toes. The view of the under surface of the sole in fig. 2, pl. 1, shows the os calcis projecting over to the inner side, a rounded point being particularly prominent. This is here shown as the Sustentaculum tali, so-called from giving support to the astragalus or talus. A ligament stretching from this point to the scaphoid bone completes the joint in which the head of the astragalus moves. It is shown at this point in fig. 2, pl. 1, as unsupported by bone.
A deep groove separating the two articular surfaces on the upper surface of the os calcis corresponds with another on the under surface of the astragalus. These, filled up by ligament, are seen in fig. 4., pl. 2.
The heads of the metatarsal bones, numbered 1 to 5, are seen to recede backwards, which gives the arch the shape of a half-dome. Upon these, the anterior pillars of the arch, the whole weight of the body would fall when in the tip-toe position but for the relief afforded by muscles.
In the act of rising to tip-toe the tendons shown in fig. 10 (flexor longus pollicis and f. l. digitorum) are tightened. This draws the tips of the toes towards the points where the tendons turn below the ankle, (fig. 8, pl. 3) and so tends to throw upwards everything between those limits, as tightening a bow-string increases the convexity of a bow.
The effect of this action is to brace up the arch and to relieve the strain on the ligaments shown in fig. 5, pl. 2. But not only so; it lifts up the heads of the metatarsal bones, the anterior pillars, so that they rest on so many tightened cords, and injurious pressure against the ground is prevented. All this is most marked in the case of the great toe, where a small bone is seen beneath the head of the metatarsal bone; the use of this (sesamoid) bone is explained with fig. 14, pl. 5.
In this toe the phalanges are marked 1st and 3rd. This is the usual numbering. If, however, it be regarded in the light of the typical mammalian foot, the metatarsal bone is really a phalanx, although, as seen in pl. 1, it is ranged in line with the other metatarsals. Strictly, it is the first of these which is missing but it would be inconvenient to so consider it.
Fig. 12 marks the order in which the three tendons shown in fig. 8, pl. 3, come round the ankle. As seen in fig. 10, they cross in the sole, the second going below the third.
Fig. 13 marks the effect of this. The flexor longus pollicis being low down at the heel is picked up and drawn away from the sole line as C D is picked up by A D. Thus, as a greater space between C D and the ground line is obtained, so a similar effects results in the foot.
Fig. 10 is taken from Gray's Anatomy. Fig. 11 from Holden's Osteology.
The drawing on stone for this plate was used to illustrate my monograph on The Arch of the Foot in 1877, and has lost its softness.
* A complete list of muscles is given after the description of pl. 6. [Back]
Plate 5, Fig. 14 shows a third layer of muscles,* the flexor brevis, accessorius, and lumbricales having been removed. The manner in which the margin of the foot overhangs on the inner side is strikingly manifest. The tendon of the tibialis posticus muscle which has come down behind the inner ankle is shown. This tendon passes under the sustentaculum tali seen in fig. 13, supports the ligament which connects this and the scaphoid bone, and is inserted into that and the inner cuneiform bone. The groove next to it is for the flexor longus digitorum; the one next the heel for the flexor longus pollicis.
The sheath for the tendon of the peroneus longus, which, having come down behind the outer ankle, curves round the outer margin of the foot and crosses the sole, to be inserted on the inner side of the base of the first metatarsal bone, is seen across the sole.
Closely combined with this sheath is the long plantar ligament which unites the bones beneath in front with the heel behind. From this sheath attached to it, the short flexor muscle of the little toe (Flexor brevis minimi digiti) passes to be inserted into the first phalanx of the little toe. The tendon of the abductor (fig. 7, pl. 3) is seen cut through near its insertion. To this sheath is also attached the Adductor Pollicis muscle, which draws the great toe towards the middle line of the foot as the abductor (fig. 7, pl. 3) draws it from that imaginry line. The Flexor brevis pollicis is also united to the sheath of the peroneus longus, and, going forward, is divided: one half blends with the adductor to be attached to the one side of the base of the great toe, the other half blended with the abductor to be attached to the other side. A small muscle which crosses the foot, Transversalis Pedis also blends with the adductor.
The two little rounded eminences at these points of attachment represent two small bones embedded, one in each of the combined tendons, and serving to relieve the tendon of the flexor longus pollicis, which runs in the groove between them, from pressure by the weight of the body. They are called, from the resemblance to a grain (sesamum) sesamoid bones.
Fig. 15 is the outer view corresponding to fig. 8, but b here represents the short extensor muscle of the toes, better seen in fig. 18, pl. 7, and c indicates the flexor brevis minimi digiti already seen in fig. 14.
The numbers 2 and 3 indicate the long extensor muscles of the great and of the smaller toes, better seen in fig. 18, pl. 6. The Peroneus tertius (4) is also there seen. Attached to the leg above it is inserted, by a tendon, on the base of the Metatarsal bone of the little toe. Close to this is the tendon of the Peroneus brevis (5) which, however, comes from its attachment to the leg behind the ankle, curving round the end of the fibula. So, too, does the Peroneus longus, (6) but the tendon passes into and crosses the sole as seen in fig. 14.
The tendons of the flexor longus digitorum (10) are seen under the smaller toes.
Fig. 16 is a vertical, transverse section through the ankle. The interosseous ligament, shown in fig. 4, pl. 2, is seen filling up the groove in the astragalus and in the os calcis. The two leg bones, the tibia on the inner and the fibula on the outer sides, are also shown with the expanded lower ends cut through. The inclination inwards, showing an apparant disposition to give way, is very manifest.
Fig. 14 is taken from Gray's Anatomy. Figs. 15 (the numbers being altered) and 16 (duplicated) are taken from Marshall's Anatomy for Artists.
* A complete list of muscles is given after the description of plate 6. [Back]
Plate 6, Fig. 17 represents the fourth layer of muscles* found in examining the upturned sole, all those show in figs. 7, 10, and 14 having been removed. Three small muscles, between the Metatarsal bones, or interosseous (Interossei), are here seen. They are distinguished as plantar, because found in the sole, from the dorsal seen in fig. 19. The tendons are inserted on the inner side of the base of the first phalanx in the three outer toes. The action of these muscles is to draw the respective toes towards an imaginary line, show, running along the middle of the second toe.
Fig. 18 shows the muscles of a foot of the same (right) side examined from above. The encircling band or annular ligament is seen as at a in figs. 8 and 15. On the inner side is the tendon of the tibialis anticus, going down to be inserted on the inner side of the foot. Then the (special) long extensor muscle of the great toe, Extensor longus (proprius) pollicis, with its tendon inserted into the final phalanx. Outside this is the extensor muscle common to the four outer toes, Extensor longus digitorum, also going down to be inserted into the final phalanges. Finally, a tendon really coming from a part of this muscle, but knows as the Peroneus tertius, numbered 4, fig. 15, pl. 5, is seen to be attached to the base of the fifth metatarsal bone. Below the annular ligament, and beneath the tendons mentioned, is the fleshy mass of the short extensor muscle common to all the toes, the Extensor brevis digitorium — there is no special short extensor to the great toe — the tendons pass, one to the first phalanx of the great toe, and three others which unite with the tendons of the long extensor, going to the three middle toes. It has not connection with the little toe.
In fig. 19 all the superficial muscles seen in fig. 18 have been removed. Four interosseous muscles (Dorsal Interossei) are seen, each attached to two metatarsal bones by muscular or fleshy attachments. The tendons of the two first are inserted one on either side of the base of the first phalanx of the second toe. The third tendon goes to the outer side of the first phalanx of the third toe. The fourth has a corresponding relation to the fourth toe. They all draw in a direction from an imaginary line down the middle of the second toe, just as the plantar muscles in fig. 17 draw the three outer toes towards it.
Figs. 17, 18, 19 are taken from Gray's Anatomy.
* A complete list of muscles is appended. [Back]
MUSCLES OF THE FOOT AND OF THE FOOT AND LEG.
Latin Names English Equivalents Of the foot (figs. 7, 10, 14, 19) — Abductor pollicis Abductor of the great toe Abductor minimi digiti Abductor of the little toe Adductor pollicis Adductor of the great toe Flexor brevis pollicis Short flexor of the great toe Flexor brevis digitorum Short flexor of the smaller toes Flexor Accessorius Accessory flexor Lumbricales1 Lumbrical Transversalis pedis Transverse muscle of the foot Interossei Interosseous — plantar and dorsal Extensor brevis digitorum Short extensor of the toes Of the leg and foot (figs. 8, 15, 18) — 1 Tibialis2 anticus Anterior tibial 2 Extensor (longus3 ) proprius pollicis Extensor of the great toe 3 Extensor longus digitorum Long extensor of the toes 4 Peroneus4 tertius Third peroneal or fibular 5 Peroneus brevis Short peroneal or fibular 6 Peroneus longus Long peroneal or fibular 7' Gastro-enemius,5 and
7'' Soleus,6 uniting in the
7 Tendo Achillis
Calf muscles, uniting in the Tendon of Achilles 8 Plantaris7 Plantar or sole muscle 9 Flexor longus pollicis Long flexor of the great toe 10 Flexor longus digitorum Long flexor of the smaller toes 11 Tibialis2 posticus Posterior tibial
1. Or worm-like. [Back]
2. Attached to the tibia. [Back]
3. There is no special short extensor of the great toe. [Back]
4. Attached to the περόνη, Greek equivalent of fibula. [Back]
5. γαςτήρ belly and κνήμη leg; from its prominence in the calf. [Back]
6. Flat or sole-like, deep in the calf. [Back]
7. In man, only rudimentary. [Back]
Plate 7, fig. 20 represents impressions, taken with printer's ink, and reduced, from the sole of a boy æt 11½, in duplicate. The awkward look of a single sole print is not apparent when the two are seen together, the curves round the toes running into each other gracefully. The line, known as Meyer's line, is seen to run through the centre of the heel and along the middle line of the great toe. A line from the inner side of the heel to the inner side of the great toe will be found to pass clear of the joint at the root of the latter. The form of the area covered as by a dome or bell-shaped covering, when the two ankles are joined, is also evident.
Fig. 21 is from a photograph of the same feet as in fig. 20. Each of the inner lines indicates the tendons of the tibialis anticus muscle coming down to be inserted, and to fix the creasing point on the upper surface of the inner margin of the foot. The outer line (corresponding to Meyer's line in the sole) represents the leading line on the back of the foot, following the crest of the ridge.
The buttress-like appearance of the part of the foot corresponding to the two outer toes is clearly shown. See the lines A B in pl. 1.