Foot




Surface landmarks of the foot


Surface landmarks of the left foot





From the front and above (dorsal surface, dorsum)







From behind







From the front, in inversion







From the front, in eversion with abduction of toes







From below (plantar surface, sole)







Imprint of sole when weight-bearing (viewed through a glass plate)






  • 1

    Medial malleolus


  • 2

    Great saphenous vein and saphenous nerve


  • 3

    Tibialis anterior


  • 4

    Extensor hallucis longus


  • 5

    Extensor digitorum longus


  • 6

    Lateral malleolus


  • 7

    Extensor digitorum brevis


  • 8

    Dorsalis pedis artery


  • 9

    Dorsal venous arch


  • 10

    Fibularis ( peroneus ) longus and brevis


  • 11

    Small saphenous vein and sural nerve


  • 12

    Tendo calcaneus


  • 13

    Flexor hallucis longus


  • 14

    Posterior tibial artery and tibial nerve


  • 15

    Flexor digitorum longus and tibialis posterior


  • 16

    Tuberosity of calcaneus


  • 17

    Sesamoid bones under head of first metatarsal


  • 18

    Base of first metatarsal


  • 19

    Head of fifth metatarsal


  • 20

    Tuberosity of base of fifth metatarsal


  • 21

    Tuberosity of navicular






Definitions of movements are as follows:




  • Extension: from the Latin for straightening out, but as far as the ankle and foot are concerned it means bending the foot and/or toes upwards, and is also known as dorsiflexion.



  • Flexion: from the Latin for bending. In the ankle and foot it means bending the foot and/or toes downwards, which is also known as plantarflexion.



  • Abduction: from the Latin for moving away. In the foot it means spreading the toes apart (the corresponding movement of the fingers is much more extensive).



  • Adduction: from the Latin for moving towards. In the foot it means drawing the toes together.



  • Inversion: from the Latin for turning in—turning the foot so that the sole faces more inwards (medially).



  • Eversion: from the Latin for turning out—moving the foot so that the sole faces more outwards (laterally) (a more limited movement than inversion).



For further details see pp. 87 and 99 .






From the medial side







In dorsiflexion (extension)







In plantarflexion (flexion)







From the lateral side







In dorsiflexion (extension)







In plantarflexion (flexion)






  • 1

    Tendo calcaneus


  • 2

    Flexor hallucis longus


  • 3

    Posterior tibial artery and tibial nerve


  • 4

    Flexor digitorum longus and tibialis posterior


  • 5

    Medial malleolus


  • 6

    Great saphenous vein and saphenous nerve


  • 7

    Tibialis anterior


  • 8

    Extensor hallucis longus


  • 9

    Head of first metatarsal


  • 10

    Sesamoid bone


  • 11

    Tuberosity of navicular


  • 12

    Sustentaculum tali


  • 13

    Tuberosity of calcaneus


  • 14

    Small saphenous vein and sural nerve


  • 15

    Fibularis (peroneus) longus and brevis


  • 16

    Lateral malleolus


  • 17

    Extensor digitorum brevis


  • 18

    Extensor digitorum longus


  • 19

    Tuberosity of base of fifth metatarsal


  • 20

    Head of fifth metatarsal









  • Pulsation in the dorsalis pedis artery ( p. 78 , 14 ) is normally palpable between the tendons of extensor hallucis longus ( 8 ) and extensor digitorum longus ( 18 ), on a line from the midpoint between the medial and lateral malleoli to the proximal end of the first intermetatarsal space. However, the artery is absent in about 12% of feet (see p. 79 ).



  • Pulsation in the posterior tibial artery ( 3 ) is normally palpable behind the medial malleolus ( 5 ), 2.5 cm in front of the medial border of the tendo calcaneus.



  • The sustentaculum tali ( 12 ) is palpable about 2.5 cm below the tip of the medial malleolus ( 5 ).






Skeleton of the foot


Bones of the left foot, from above







The talus and calcaneus remain articulated with each other but the remainder have been disarticulated.




  • 1

    Calcaneus


  • 2

    Talus


  • 3

    Navicular


  • 4

    Medial cuneiform


  • 5

    Intermediate cuneiform


  • 6

    Lateral cuneiform


  • 7

    Cuboid


  • 8

    First metatarsal


  • 9

    Second metatarsal


  • 10

    Third metatarsal


  • 11

    Fourth metatarsal


  • 12

    Fifth metatarsal


  • 13

    Proximal phalanx of great toe


  • 14

    Distal phalanx of great toe


  • 15

    Proximal phalanx of second toe


  • 16

    Middle phalanx of second toe


  • 17

    Distal phalanx of second toe














  • Bones of the tarsus


    Calcaneus


    Talus


    Navicular bone


    Cuboid bone


    Medial, intermediate and lateral cuneiform bones



  • Bones of the metatarsus


    First to fifth metatarsal bones, numbered from medial to lateral



  • Bones of the toes or digits


    Phalanges—a proximal and a distal phalanx for the great toe; proximal, middle and distal phalanges for each of the second to fifth toes



  • The hindfoot consists of the talus and calcaneus.



  • The midfoot consists of the navicular, cuboid and cuneiform bones.



  • The forefoot consists of the metatarsal bones and phalanges.



  • Sesamoid bones —two always present in the tendons of flexor hallucis brevis. For others see pp. 44 , 46 .



  • Origin and meaning of some names associated with the foot are as follows (some older names for bones are given in parentheses):




















































Tibia: Latin for a flute or pipe; when held upside down, the shin bone has a fanciful resemblance to this wind instrument.
Fibula: Latin for a pin or skewer; the long thin bone of the leg. Adjective fibular or peroneal, which is from the Greek for pin (see the last note on p. 3 ).
Tarsus: Greek for a wicker frame, in the basic framework for the back of the foot.
Metatarsus: Greek for beyond the tarsus; the forepart of the foot.
Talus: (astragalus) Latin (Greek) for one of a set of dice; viewed from above the main part of the talus has a rather square appearance.
Calcaneus: os calcis, ( calcaneum ) From the Greek for heel; the heel bone.
Navicular : (scaphoid) Latin (Greek) for boat-shaped; the navicular bone roughly resembles a saucer-shaped coracle.
Cuboid: Greek for cube-shaped.
Cuneiform: Latin for wedge-shaped.
Phalanx: Greek for a row of soldiers; a row of bones in the toes. Plural phalanges.
Sesamoid: Greek for shaped like a sesame seed.
Digitus: Latin for finger or toe. Digiti and digitorum are the genitive singular and genitive plural—of the toe(s).
Hallux: Latin for the great toe. Hallucis is the genitive singular—of the great toe.
Dorsum: Latin for back; the upper surface of the foot. Adjective dorsal.
Plantar: Adjective from planta, Latin for the sole of the foot.



Articulated bones of the left foot





From above (dorsal surface)







From below (plantar surface)






  • 1

    Calcaneus


  • 2

    Talus


  • 3

    Navicular


  • 4

    Medial cuneiform


  • 5

    Intermediate cuneiform


  • 6

    Lateral cuneiform


  • 7

    Cuboid


  • 8

    First metatarsal


  • 9

    Second metatarsal


  • 10

    Third metatarsal


  • 11

    Fourth metatarsal


  • 12

    Fifth metatarsal


  • 13

    Proximal phalanx of great toe


  • 14

    Distal phalanx of great toe


  • 15

    Proximal phalanx of second toe


  • 16

    Middle phalanx of second toe


  • 17

    Distal phalanx of second toe


  • 18

    Sesamoid bones
















Ossification of Foot Bones


All the tarsal bones are ossified from one primary center: calcaneus at the third fetal month, talus at the sixth fetal month, cuboid just before or just after birth, lateral cuneiform at 1 year, medial cuneiform at 2 years, intermediate cuneiform and navicular at 3 years.


The calcaneus is the only tarsal bone to have a secondary center: a thin plate of bone on the posterior surface, appearing at about 7 years and fusing during puberty.


The metatarsal bones and phalanges have primary centers for their shafts at the second to fourth fetal months, and one secondary center: at the base of the first metatarsal and bases of all the phalanges, but at the heads of the other metatarsals. These begin to ossify at 2 to 6 years and fuse at about 18 years.


All dates given are subject to considerable variation, and ossification tends to occur earlier in females.





  • During the preparation of dried bones, the hyaline cartilage on articulating surfaces is lost, so that when rearticulating bones an exact fit is not possible. The thickness of the cartilage on joint surface is best appreciated in sections of bones, as on pp. 20 , 21 and 92–104 .



  • The talus ( 2 ) is the uppermost foot bone, forming the ankle joint with the tibia and fibula. For details see pp. 52 , 61 .



  • The calcaneus ( 1 ) is the most posterior and the largest foot bone, forming the heel. For details see pp. 62 , 63 .



  • The navicular bone ( 3 ) lies in front of the talus, on the medial side of the foot. For details see p. 64 .



  • The cuboid bone ( 7 ) lies in front of the calcaneus, on the lateral side of the foot. For details see p. 64 .



  • The three cuneiform bones —medial, intermediate and lateral ( 4 , 5 and 6 )—lie in front of the navicular bone. For details see p. 65 .



  • The first, second and third metatarsal bones ( 8 , 9 and 10 ) are in front of the three cuneiforms, and the fourth and fifth metatarsal bones ( 11 and 12 ) are in front of the cuboid bone. For details see pp. 66 , 67 .



  • The phalanges ( 13–17 ) are the bones of the toes. Each proximal phalanx articulates with the head of a metatarsal bone. Each phalanx has a base (at the proximal end), body and head (at the distal end). The body is convex on the dorsal (upper) surface, and concave on the plantar surface. See pp. 42 , 50 .




Attachments of muscles and major ligaments to the bones of the left foot





From above (dorsal surface)












From below (plantar surface)











  • 1

    Tendo calcaneus


  • 2

    Plantaris


  • 3

    Area for bursa


  • 4

    Extensor digitorum brevis




  • 7

    Fibularis (peroneus) brevis


  • 8

    Fibularis (peroneus) tertius




  • 13

    Abductor hallucis


  • 14

    Extensor hallucis brevis


  • 15

    Extensor hallucis longus


  • 16

    Extensor digitorum longus and brevis


  • 17

    Extensor digitorum longus




  • 21

    Abductor digiti minimi


  • 22

    Flexor digitorum brevis


  • 23

    Quadratus plantae


  • 24

    Long plantar ligament


  • 25

    Plantar calcaneocuboid (short plantar) ligament


  • 26

    Plantar calcaneonavicular (spring) ligament


  • 27

    Tibialis posterior


  • 28

    Tibialis anterior


  • 29

    Flexor hallucis brevis


  • 30

    Flexor digiti minimi brevis


  • 31

    Adductor hallucis


  • 32

    Flexor hallucis longus


  • 33

    Flexor digitorum longus


  • 34

    Opponens digiti minimi (occasional part of 30 )


  • 35

    Fibularis ( peroneus ) longus



Sesamoid and accessory bones





Sesamoid Bones


The patella is by far the largest sesamoid bone in the lower limb and its close association with tendons and a bony joint (the knee) gives a conceptual focus as to the function of sesamoid bones.


In the Foot:




  • They usually vary in shape and size but in general are ovoid and normally only a few millimeters in diameter ( p. 44 , B18 ).



  • They are not always ossified but may consist of fibrous tissue or cartilage, or a combination of all three.



  • They are usually found embedded in tendons at the point where the tendons angle acutely around bony surfaces to their point of insertion ( p. 92 , 16 and p. 93 , 33 ).



  • Sesamoids have articular cartilage on the surface which is in direct relationship to the bone that they are proximate to.



Although not proved, it is thought that sesamoid bones protect tendons from wear, and by their strategic position to joints, alter the angle of insertion of a tendon into bone and thus provides a greater mechanical advantage to the joint.


Accessory Bones


Bones within the human body gradually begin to form during the early developmental phases of the fetus by the initial formation of central areas of ossification within the cartilaginous and membranous skeleton. These ossified areas continue to grow, unite and eventually form solid adult bones, some during late childhood and some as late as early adulthood.


On occasions however the centres of ossification fail to fuse completely, often at the ends of bones, and thus a separate (accessory or supernumerary) bone is formed.


The foot is a common place for accessory bones to form and there are common sites for them to occur. It is important to be aware of their possible presence because on a radiographic image they can be easily mistaken for a fractured bone or ‘chip’.


Common accessory bones in the foot are:




  • Dorsum of foot




    • Os intercuneiforme



    • Os talonaviculare dorsale



    • Os calcaneus secondarius



    • Os intermetatarsal I




  • Posterior part of foot




    • Os trigonum




  • Lateral part of foot




    • Os calcaneus secondarius



    • Os vesalianum pedis




  • Medial part of foot




    • Os tibiale externum (Os naviculare accessorium)



    • Os sustentaculi




  • Plantar aspect (sole) of foot




    • Pars peronea metatarsalis I



    • Os cuboides secondarius








Common locations of sesamoid ( red ) and accessory ( blue ) bones




Articulated bones of the left foot





From the medial side







From the lateral side






  • 1

    Body of calcaneus


  • 2

    Sustentaculum tali part of calcaneus


  • 3

    Body of talus


  • 4

    Head of talus


  • 5

    Navicular


  • 6

    Tuberosity of navicular


  • 7

    Medial cuneiform


  • 8

    Intermediate cuneiform




  • 18

    Sesamoid bone


  • 19

    Lateral cuneiform


  • 20

    Cuboid




  • 25

    Tarsal sinus









  • When standing (as can be seen from the imprint of a wet foot on the floor or when viewed through a glass plate—see p. 39 , F ) the parts of the foot in contact with the ground are the heel, the lateral margin of the foot, the pads under the metatarsal heads and the pads under the distal part of the toes.



  • The medial margin of the foot is not normally in contact with the ground because of the height of the medial longitudinal arch (see pp. 50 and 51 ). In flat foot the medial arch is lower with an increasingly large imprint on the medial side.



  • The body weight when standing is borne by the tuberosity of the calcaneus and the heads of the metatarsals, especially the first (with the sesamoid bones underneath it) and the fifth. As the foot bends forward in walking the other metatarsal heads take increasingly more of the load. With further raising of the heel the toe pads become pressed to the ground and so take some of the weight off the metatarsals.



  • Although the forearm and hand have many muscles similar in name and action to those of the leg and foot, their normal use in everyday life is different. In the upper limb the muscles work from above to produce intricate movements of the thumb and fingers in a free limb. In the lower limb the toes must be stabilized on the ground so that muscles can work from below to produce the propulsive movements of walking.














Bones of the left longitudinal arches, transverse tarsal joint and other joints





Bones of the medial longitudinal arch, from above







Bones of the lateral longitudinal arch, from the lateral side

















The transverse tarsal joint, disarticulated, from above















  • The bones of the medial longitudinal arch ( A ) are the calcaneus, talus, navicular, the three cuneiforms and the medial three metatarsal bones.



  • The bones of the lateral longitudinal arch ( B ) are the calcaneus, cuboid and the two lateral metatarsal bones.



  • The transverse arch is formed by the cuboid and cuneiform bones and the adjacent parts of the five metatarsals (those of each foot forming one half of the whole arch). At the level of the metatarsal heads the arched form is no longer present.



  • The medial longitudinal arch is higher than the lateral.



  • While the shape of the individual bones determines the shapes of the arches, the maintenance of the arches in the stationary foot (standing in the normal upright position) depends largely on the ligaments in the sole (where they are larger and stronger than those on the dorsum). As soon as movement occurs the long tendons and small muscles of the sole assume importance in maintaining the curved forms.



  • The many joints of the foot contribute to its function as a flexible lever, and the word arch suggests an architectural rigidity that does not exist.



  • On the medial side the plantar calcaneonavicular ligament (spring ligament) is of particular importance in supporting the head of the talus, and other structures that help to maintain the medial arch include the plantar aponeurosis, flexor hallucis longus, tibialis anterior and posterior, and the medial parts of flexor digitorum longus and brevis.



  • The transverse tarsal joint (midtarsal joint) is the collective name for two joints—the calcaneocuboid joint, and the talonavicular part of the talocalcaneonavicular joint.






  • 1

    Calcaneus


  • 2

    Talus


  • 3

    Navicular


  • 4

    Medial cuneiform


  • 5

    Intermediate cuneiform


  • 6

    Lateral cuneiform


  • 7

    First metatarsal


  • 8

    Second metatarsal


  • 9

    Third metatarsal


  • 10

    Phalanges of great toe


  • 11

    Phalanges of second toe


  • 12

    Phalanges of third toe


  • 13

    Cuboid


  • 14

    Fourth metatarsal


  • 15

    Fifth metatarsal


  • 16

    Phalanges of fourth toe


  • 17

    Phalanges of fifth toe


  • 18

    Talocalcanean joint


  • 19

    Talonavicular part of talocalcaneonavicular joint


  • 20

    Cuneonavicular joint


  • 21

    Intercuneiform joints


  • 22

    Tarsometatarsal joints (cuneometatarsal and cuboideometatarsal)


  • 23

    Intermetatarsal joints


  • 24

    Metatarsophalangeal joints


  • 25

    Interphalangeal joints


  • 26

    Calcaneocuboid joint


  • 27

    Cuboideonavicular joint


  • 28

    Cuneocuboid joint





Skeleton of the foot


Bones of the left foot, from above







The talus and calcaneus remain articulated with each other but the remainder have been disarticulated.




  • 1

    Calcaneus


  • 2

    Talus


  • 3

    Navicular


  • 4

    Medial cuneiform


  • 5

    Intermediate cuneiform


  • 6

    Lateral cuneiform


  • 7

    Cuboid


  • 8

    First metatarsal


  • 9

    Second metatarsal


  • 10

    Third metatarsal


  • 11

    Fourth metatarsal


  • 12

    Fifth metatarsal


  • 13

    Proximal phalanx of great toe


  • 14

    Distal phalanx of great toe


  • 15

    Proximal phalanx of second toe


  • 16

    Middle phalanx of second toe


  • 17

    Distal phalanx of second toe














  • Bones of the tarsus


    Calcaneus


    Talus


    Navicular bone


    Cuboid bone


    Medial, intermediate and lateral cuneiform bones



  • Bones of the metatarsus


    First to fifth metatarsal bones, numbered from medial to lateral



  • Bones of the toes or digits


    Phalanges—a proximal and a distal phalanx for the great toe; proximal, middle and distal phalanges for each of the second to fifth toes



  • The hindfoot consists of the talus and calcaneus.



  • The midfoot consists of the navicular, cuboid and cuneiform bones.



  • The forefoot consists of the metatarsal bones and phalanges.



  • Sesamoid bones —two always present in the tendons of flexor hallucis brevis. For others see pp. 44 , 46 .



  • Origin and meaning of some names associated with the foot are as follows (some older names for bones are given in parentheses):




















































Tibia: Latin for a flute or pipe; when held upside down, the shin bone has a fanciful resemblance to this wind instrument.
Fibula: Latin for a pin or skewer; the long thin bone of the leg. Adjective fibular or peroneal, which is from the Greek for pin (see the last note on p. 3 ).
Tarsus: Greek for a wicker frame, in the basic framework for the back of the foot.
Metatarsus: Greek for beyond the tarsus; the forepart of the foot.
Talus: (astragalus) Latin (Greek) for one of a set of dice; viewed from above the main part of the talus has a rather square appearance.
Calcaneus: os calcis, ( calcaneum ) From the Greek for heel; the heel bone.
Navicular : (scaphoid) Latin (Greek) for boat-shaped; the navicular bone roughly resembles a saucer-shaped coracle.
Cuboid: Greek for cube-shaped.
Cuneiform: Latin for wedge-shaped.
Phalanx: Greek for a row of soldiers; a row of bones in the toes. Plural phalanges.
Sesamoid: Greek for shaped like a sesame seed.
Digitus: Latin for finger or toe. Digiti and digitorum are the genitive singular and genitive plural—of the toe(s).
Hallux: Latin for the great toe. Hallucis is the genitive singular—of the great toe.
Dorsum: Latin for back; the upper surface of the foot. Adjective dorsal.
Plantar: Adjective from planta, Latin for the sole of the foot.



Articulated bones of the left foot





From above (dorsal surface)







From below (plantar surface)






  • 1

    Calcaneus


  • 2

    Talus


  • 3

    Navicular


  • 4

    Medial cuneiform


  • 5

    Intermediate cuneiform


  • 6

    Lateral cuneiform


  • 7

    Cuboid


  • 8

    First metatarsal


  • 9

    Second metatarsal


  • 10

    Third metatarsal


  • 11

    Fourth metatarsal


  • 12

    Fifth metatarsal


  • 13

    Proximal phalanx of great toe


  • 14

    Distal phalanx of great toe


  • 15

    Proximal phalanx of second toe


  • 16

    Middle phalanx of second toe


  • 17

    Distal phalanx of second toe


  • 18

    Sesamoid bones
















Ossification of Foot Bones


All the tarsal bones are ossified from one primary center: calcaneus at the third fetal month, talus at the sixth fetal month, cuboid just before or just after birth, lateral cuneiform at 1 year, medial cuneiform at 2 years, intermediate cuneiform and navicular at 3 years.


The calcaneus is the only tarsal bone to have a secondary center: a thin plate of bone on the posterior surface, appearing at about 7 years and fusing during puberty.


The metatarsal bones and phalanges have primary centers for their shafts at the second to fourth fetal months, and one secondary center: at the base of the first metatarsal and bases of all the phalanges, but at the heads of the other metatarsals. These begin to ossify at 2 to 6 years and fuse at about 18 years.


All dates given are subject to considerable variation, and ossification tends to occur earlier in females.





  • During the preparation of dried bones, the hyaline cartilage on articulating surfaces is lost, so that when rearticulating bones an exact fit is not possible. The thickness of the cartilage on joint surface is best appreciated in sections of bones, as on pp. 20 , 21 and 92–104 .



  • The talus ( 2 ) is the uppermost foot bone, forming the ankle joint with the tibia and fibula. For details see pp. 52 , 61 .



  • The calcaneus ( 1 ) is the most posterior and the largest foot bone, forming the heel. For details see pp. 62 , 63 .



  • The navicular bone ( 3 ) lies in front of the talus, on the medial side of the foot. For details see p. 64 .



  • The cuboid bone ( 7 ) lies in front of the calcaneus, on the lateral side of the foot. For details see p. 64 .



  • The three cuneiform bones —medial, intermediate and lateral ( 4 , 5 and 6 )—lie in front of the navicular bone. For details see p. 65 .



  • The first, second and third metatarsal bones ( 8 , 9 and 10 ) are in front of the three cuneiforms, and the fourth and fifth metatarsal bones ( 11 and 12 ) are in front of the cuboid bone. For details see pp. 66 , 67 .



  • The phalanges ( 13–17 ) are the bones of the toes. Each proximal phalanx articulates with the head of a metatarsal bone. Each phalanx has a base (at the proximal end), body and head (at the distal end). The body is convex on the dorsal (upper) surface, and concave on the plantar surface. See pp. 42 , 50 .




Attachments of muscles and major ligaments to the bones of the left foot





From above (dorsal surface)












From below (plantar surface)











  • 1

    Tendo calcaneus


  • 2

    Plantaris


  • 3

    Area for bursa


  • 4

    Extensor digitorum brevis




  • 7

    Fibularis (peroneus) brevis


  • 8

    Fibularis (peroneus) tertius




  • 13

    Abductor hallucis


  • 14

    Extensor hallucis brevis


  • 15

    Extensor hallucis longus


  • 16

    Extensor digitorum longus and brevis


  • 17

    Extensor digitorum longus




  • 21

    Abductor digiti minimi


  • 22

    Flexor digitorum brevis


  • 23

    Quadratus plantae


  • 24

    Long plantar ligament


  • 25

    Plantar calcaneocuboid (short plantar) ligament


  • 26

    Plantar calcaneonavicular (spring) ligament


  • 27

    Tibialis posterior


  • 28

    Tibialis anterior


  • 29

    Flexor hallucis brevis


  • 30

    Flexor digiti minimi brevis


  • 31

    Adductor hallucis


  • 32

    Flexor hallucis longus


  • 33

    Flexor digitorum longus


  • 34

    Opponens digiti minimi (occasional part of 30 )


  • 35

    Fibularis ( peroneus ) longus



Sesamoid and accessory bones





Sesamoid Bones


The patella is by far the largest sesamoid bone in the lower limb and its close association with tendons and a bony joint (the knee) gives a conceptual focus as to the function of sesamoid bones.


In the Foot:




  • They usually vary in shape and size but in general are ovoid and normally only a few millimeters in diameter ( p. 44 , B18 ).



  • They are not always ossified but may consist of fibrous tissue or cartilage, or a combination of all three.



  • They are usually found embedded in tendons at the point where the tendons angle acutely around bony surfaces to their point of insertion ( p. 92 , 16 and p. 93 , 33 ).



  • Sesamoids have articular cartilage on the surface which is in direct relationship to the bone that they are proximate to.



Although not proved, it is thought that sesamoid bones protect tendons from wear, and by their strategic position to joints, alter the angle of insertion of a tendon into bone and thus provides a greater mechanical advantage to the joint.


Accessory Bones


Bones within the human body gradually begin to form during the early developmental phases of the fetus by the initial formation of central areas of ossification within the cartilaginous and membranous skeleton. These ossified areas continue to grow, unite and eventually form solid adult bones, some during late childhood and some as late as early adulthood.


On occasions however the centres of ossification fail to fuse completely, often at the ends of bones, and thus a separate (accessory or supernumerary) bone is formed.


The foot is a common place for accessory bones to form and there are common sites for them to occur. It is important to be aware of their possible presence because on a radiographic image they can be easily mistaken for a fractured bone or ‘chip’.


Common accessory bones in the foot are:




  • Dorsum of foot




    • Os intercuneiforme



    • Os talonaviculare dorsale



    • Os calcaneus secondarius



    • Os intermetatarsal I




  • Posterior part of foot




    • Os trigonum




  • Lateral part of foot




    • Os calcaneus secondarius



    • Os vesalianum pedis




  • Medial part of foot




    • Os tibiale externum (Os naviculare accessorium)



    • Os sustentaculi




  • Plantar aspect (sole) of foot




    • Pars peronea metatarsalis I



    • Os cuboides secondarius








Common locations of sesamoid ( red ) and accessory ( blue ) bones




Articulated bones of the left foot





From the medial side







From the lateral side






  • 1

    Body of calcaneus


  • 2

    Sustentaculum tali part of calcaneus


  • 3

    Body of talus


  • 4

    Head of talus


  • 5

    Navicular


  • 6

    Tuberosity of navicular


  • 7

    Medial cuneiform


  • 8

    Intermediate cuneiform




  • 18

    Sesamoid bone


  • 19

    Lateral cuneiform


  • 20

    Cuboid




  • 25

    Tarsal sinus









  • When standing (as can be seen from the imprint of a wet foot on the floor or when viewed through a glass plate—see p. 39 , F ) the parts of the foot in contact with the ground are the heel, the lateral margin of the foot, the pads under the metatarsal heads and the pads under the distal part of the toes.



  • The medial margin of the foot is not normally in contact with the ground because of the height of the medial longitudinal arch (see pp. 50 and 51 ). In flat foot the medial arch is lower with an increasingly large imprint on the medial side.



  • The body weight when standing is borne by the tuberosity of the calcaneus and the heads of the metatarsals, especially the first (with the sesamoid bones underneath it) and the fifth. As the foot bends forward in walking the other metatarsal heads take increasingly more of the load. With further raising of the heel the toe pads become pressed to the ground and so take some of the weight off the metatarsals.



  • Although the forearm and hand have many muscles similar in name and action to those of the leg and foot, their normal use in everyday life is different. In the upper limb the muscles work from above to produce intricate movements of the thumb and fingers in a free limb. In the lower limb the toes must be stabilized on the ground so that muscles can work from below to produce the propulsive movements of walking.














Bones of the left longitudinal arches, transverse tarsal joint and other joints





Bones of the medial longitudinal arch, from above







Bones of the lateral longitudinal arch, from the lateral side

















The transverse tarsal joint, disarticulated, from above















  • The bones of the medial longitudinal arch ( A ) are the calcaneus, talus, navicular, the three cuneiforms and the medial three metatarsal bones.



  • The bones of the lateral longitudinal arch ( B ) are the calcaneus, cuboid and the two lateral metatarsal bones.



  • The transverse arch is formed by the cuboid and cuneiform bones and the adjacent parts of the five metatarsals (those of each foot forming one half of the whole arch). At the level of the metatarsal heads the arched form is no longer present.



  • The medial longitudinal arch is higher than the lateral.



  • While the shape of the individual bones determines the shapes of the arches, the maintenance of the arches in the stationary foot (standing in the normal upright position) depends largely on the ligaments in the sole (where they are larger and stronger than those on the dorsum). As soon as movement occurs the long tendons and small muscles of the sole assume importance in maintaining the curved forms.



  • The many joints of the foot contribute to its function as a flexible lever, and the word arch suggests an architectural rigidity that does not exist.



  • On the medial side the plantar calcaneonavicular ligament (spring ligament) is of particular importance in supporting the head of the talus, and other structures that help to maintain the medial arch include the plantar aponeurosis, flexor hallucis longus, tibialis anterior and posterior, and the medial parts of flexor digitorum longus and brevis.



  • The transverse tarsal joint (midtarsal joint) is the collective name for two joints—the calcaneocuboid joint, and the talonavicular part of the talocalcaneonavicular joint.






  • 1

    Calcaneus


  • 2

    Talus


  • 3

    Navicular


  • 4

    Medial cuneiform


  • 5

    Intermediate cuneiform


  • 6

    Lateral cuneiform


  • 7

    First metatarsal


  • 8

    Second metatarsal


  • 9

    Third metatarsal


  • 10

    Phalanges of great toe


  • 11

    Phalanges of second toe


  • 12

    Phalanges of third toe


  • 13

    Cuboid


  • 14

    Fourth metatarsal


  • 15

    Fifth metatarsal


  • 16

    Phalanges of fourth toe


  • 17

    Phalanges of fifth toe


  • 18

    Talocalcanean joint


  • 19

    Talonavicular part of talocalcaneonavicular joint


  • 20

    Cuneonavicular joint


  • 21

    Intercuneiform joints


  • 22

    Tarsometatarsal joints (cuneometatarsal and cuboideometatarsal)


  • 23

    Intermetatarsal joints


  • 24

    Metatarsophalangeal joints


  • 25

    Interphalangeal joints


  • 26

    Calcaneocuboid joint


  • 27

    Cuboideonavicular joint


  • 28

    Cuneocuboid joint





Foot bones


Left talus





From above












From below












From the medial side












From the lateral side












From the front












From behind











  • 1

    Head with articular surface for navicular


  • 2

    Neck


  • 3

    Trochlear surface of body, for inferior surface of tibia


  • 4

    Surface for medial malleolus




  • 8

    Surface for lateral malleolus


  • 9

    Anterior calcanean articular surface


  • 10

    Surface for plantar calcaneonavicular (spring) ligament


  • 11

    Middle calcanean articular surface


  • 12

    Sulcus tali


  • 13

    Posterior calcanean articular surface


  • 14

    Lateral process






Talus





  • The uppermost foot bone, forming the ankle joint with the tibia and fibula.



  • Formerly known as the astragalus.



  • Articular facets on the upper surface and sides for the tibia and fibula, on the under surface for the calcaneus, and on the anterior surface (head) for the navicular.



  • Unique among the foot bones in having no muscles attached to it.




Left talus and the lower ends of the tibia and fibula





The talus, tibia and fibula, articulated, from the front












The tibia from the lateral side












The fibula from the medial side












The talus, tibia and fibula, articulated, from behind












The tibia and fibula, articulated, from below













  • 16

    Posterior surface of tibia


  • 17

    Groove for flexor hallucis longus tendon


  • 18

    Groove for tibialis posterior tendon


  • 19

    Groove for fibularis (peroneus) brevis tendon


  • 20

    Inferior surface of tibia



Left talus and the lower ends of the tibia and fibula, with ligamentous attachments in the ankle region





The talus, tibia and fibula, articulated, from the front

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Aug 10, 2019 | Posted by in ORTHOPEDIC | Comments Off on Foot
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