Fig. 198. Transverse (Frontal) Section through the Anterior Part 



of the Tarsus. 



Frozen Section. 



The Foot is arched both Antero-posteriorly and Transversely. The Trans- 

 verse Arch, shewn in the figure, begins posteriorly where the Os Calcis with its 

 Sustentaculum Tali forms a semicircle (v. Fig. 197). 



A little further forward the Scaphoid and Cuboid Bones form an arch, 

 whereas in front of these the arch becomes more definite as the Cuneiform Bones 

 with their broad Dorsal and narrow Plantar Surfaces closely resemble the stones 

 of an arch. 



The Longitudinal Arch is still more pronounced in the Metacarpal Bones. 

 The Plantar Vessels and Nerves run forward under cover of this arch which 

 serves to protect them from pressure (due to the weight of the body). 



Fig. 199. Longitudinal (Sagittal) Section through the Foot. 



Frozen Section carried through the middle of the Tibia and the oitter part 



of the 2nd Toe. 



This figure shows the Longitudinal Arch w^hich is most marked on the 

 inner side. The inner tubercle of the Os Calcis and the head of the ist Metatarsal 

 Bone form the PiUars of this Arch. On the outer side of the Foot the arch is 

 less curved; here its Anterior Pillar is formed by the base of the 5th Metatarsal 

 Bone. The Astragalus forms the Keystone of this Arch. Strong ligaments bind 

 together the bones on their Plantar Aspect and firmly brace up the arch; the 

 Plantar Fascia stretched across from the Inner Tubercle of the Os Calcis to the 

 Heads of the Metatarsal Bones acts Uke a bowstring. 



Mention must also be made of the assistance rendered by the Tendon of 

 the Posterior Tibial and other Muscles in keeping up the Arch. 



This figure further shews: a Bursa (alwa3's present) between the Os Calcis 

 and Tendo AchiUis. (A Bursa between the Tendo AchiUis and the Superficial 

 Fascia is rarely met with.) 



The cavity of the ankle-joint extends backwards nearlj' as far as the 

 Posterior Calcaneo-Astragaloid Articulation. In front it is Vsths inch distant from 

 the Astragalo-Scaphoid Joint. This explains why inexperienced persons, when per- 

 forming Chopart's disarticulation, easily open the ankle-joint instead of the 

 Astragalo-Scaphoid Articulation. 



The figure shews also that the Posterior Calcaneo-Astragaloid Articulation 

 is a complete joint, whereas the anterior is merely a part of the Astragalo-Scaphoid 

 Articulation. 



