46 



FOOT. 



These tuberosities give origin to muscles and ligaments. The pos- 

 terior extremity^ is rough and prominent in its inferior half, into 

 which is inserted the tendo-achillis ; the superior half is smooth, 

 corresponding with the bursa. The anterior extremity presents two 

 processes, called the greater and lesser apophyses ; the greater is 

 external and below, and has a flat triangular articular surface for the 

 cuboid bone, surmounted by a rough projection, which is a surgical 

 guide in Chopart's amputation of the foot. The lesser ajjoj^hysis (sus- 

 tentaculum tali), is a blunt hook projecting forwards and upwards, 

 having an articular concavity above, constituting a portion of the 

 superior surface of the bone, which articulates with the astragalus ; 

 upon its inferior surface is a groove for the tendon of the flexor 

 longus pollicis. 



Astragalus.'^ — Is next in size to the os calcis. It consists of a 

 body and a head. The superior surface of the body presents a 

 large articular convexity for the tibia ; continuous with this, on 

 either side, is an articular surface for the malleoli; inferiorly is a 

 concavity, divided by a deep rough groove for the interosseous liga- 

 ment ; posteriorly., is a slight groove for the flexor longus pollicis. 



The head is upon the anterior portion of the bone. It presents a 

 large anterior convexity, the horizontal diameter of which is the 

 greatest. On the internal side of the head is a small triangular sur- 

 face, which rests upon the calcaneo-scaphoid ligament. The head 

 is united to the body by a narrow portion called the neck, which 

 has a depression superiorly and inferiorly. 



Scaphoid.* — Is oval, thicker above than it is below ; posteriorly, 

 it has a deep concavity for the head of the astragalus ; anteriorly, 

 an articular convexity, divided by ridges into three triangular facets 

 for the cuneiform bones. Internally, is a tubercle for the insertion 

 of the tibialis posticus tendon ; and externally, there is sometimes a 

 small articular face for the cuboid. 



Interred Ctmeiform.^ — Is the largest of the three cuneiform bones. 

 It is wedge-shaped, and is placed upon the inner side of the foot. 

 The small extremity of the wedge looks upwards. Its internal sur- 

 face is convex, and immediately beneath the skin ; its external sur- 

 face is concave, and has articular marks for the second cuneiform 

 and the second metatarsal bones ; anteriorly, is the largest arti- 

 cular surface, for the metatarsal bone of the big toe ; posteriorly, is 

 a triangular articular cavity, with the base downwards. The in- 

 ferior surface of the bone, or the base of the wedge, is rounded into 

 a tuberosity ; upon the inner side, is inserted the tendon of the tibialis 

 anticus. 



Middle Cujieiform.^^ — Is the smallest of the three, and placed with 

 the base of the wedge upwards ; ajiteriorly, it articulates with the 

 second metatarsal bone ; posteriorly, it is slightly concave, and arti- 



