THE PHALANGEAL BONES 



383 



Os PEDIS {the bo7ie of the foot, formerly called the coffin-buue). In form it 

 is semilunar, divided into wall, sole, articulatory surface, and retrossal 

 processes, commonly called wings (see Fig. 31). 



The wall, the semicircular prominent part, possesses some degree of 

 declivity, increasing in circumference from above, downwards. It is full of 

 foramina, and rough. Superiorly, the bone bulges out, forming the coronal 

 process (8, 8). The middle part of it terminates in a peak, which looks 

 slightly backwards — the cacumen coronse (the peak of the coronet). 



The wall terminates posteriorly in wings ; the retrossal processes 



Pio. 31. — Posterior View of Phalanges. 



A. Os suffraginis. 



1. 1. Surfaces articulating -witli the 



lower extremity of the large meta- 

 carpal bone. 



2. Groove. 



3. Rough surface for the i in plantation 



of ligaments. 



4. 4. Inferior extremity articulating 



with 



B. Os coronffi. 



5. 5. Superior articulatory surfaces. 

 0. 6. Inferior articulatory surfaces. 



C. Os pedis. 



7. 7. Articulatory surfaces. 

 S. S. Coronal process. 

 9. 9. Scutiform processes. 



10. 10. Retrossal processes. 



11. Surface articulating with a corre- 



sponding one on the navicular 

 bone (12.) 



D. Os naviculare. 



12. Surface articulating with the os 



coronffi. 



13. Surface over which the flexor pedis 



perforans tendon glides. 

 1 14. 14. Points nttaclied to the pedal 

 bone by ligaments. 



(10,10); each wing is divided into two parts by a groove, which runs 

 through it from before, backwards. 



The inferior surface or sole is divided into an anterior semilunar 

 plantar surface, and into a posterior sharp semicircular edge which divides 

 it from the tendinous portion. The former is slightly concave, porous, and 

 bounded by the inferior circumferent edge of the wall. 



The superior articulatory surface, semilunar in form, presents two 

 lateral concavities, separated by an eminence. The eminence is bounded 

 anteriorly by the cacumen coronte, which stands before it, the point looking 

 backwards. Posteriorly, it is bevelled off for articulation with the os 

 naviculare. 



Os Naviculare (navis, a ship), sometimes called the shuttle-bone, in form 

 is semilunar and elongated. It is divided into four surfaces and two 

 extremities. 



The superior surface presents, in its centre, an eminence, which declines 

 laterally, leaving two slight concavities. 



