48 LIGAMENTS. 



TOES, 



There are five on each foot. Each consists of three phalanges^ 

 with the exception of the first or great toe, which, like the thumb, 

 has but two. 



The first row^^ of phalanges are smaller than those of the fingers, 

 and readily distinguished by the narrowness of their bodies. The 

 bases have a single concavity ; the anterior extremities have two 

 convexities, separated by a groove. 



The second row.^^ — These phalanges have hardly any body ; the 

 posterior extremities have two concavities, separated by a ridge ; and 

 the anterior, two convexities separated by a groove. 



The third row.^* — These phalanges are very small ; their bases 

 have two concavities and a ridge. The anterior extremity is flat 

 and rough. 



Sesamoid Bones. — These are two small sections of a sphere of 

 bone, imbedded in the tendon of the flexor brevis pollicis of each foot. 

 The flat surface plays on the inferior part of the head of the meta- 

 tarsal bone of the great toe. 



SECTION II. 



ARTICULATIONS. 

 LIGAMENTS. 



An articulation or joint is the connexion of one bone with another. 

 If motion be intended, it is necessary that cartilage, ligaments, and 

 synovial membranes should be employed in the mechanism. 



Cartilage. — Is white, flexible, elastic and hard. Its chemical 

 composition is, gelatine 44*5 ; water 55 ; phosphate of lime 0-5. 

 By boiling it becomes yellow, swells, and the gelatine is dissolved. 

 It resists mortification and putrefaction longer than any tissue except 

 bone. When dried it becomes hard and contracted, and semi-trans- 

 parent, resembling common glue. Soaking in water restores its 

 appearance. It contains no red blood-vessels, nor can nerves nor 

 lymphatics be traced in it. Old age disposes it to ossify, particularly 

 in the ribs and larynx. 



Perichondrium is the fibrous investing membrane of cartilage 

 corresponding to the periosteum of bone. 



Articular cartilages. — ^^These cover the extremities of bone and 

 obviate or equalize pressure. Those lining the cavity are thicker 

 on the edges ; those covering a convexity are thicker in the middle. 

 Inter -articular cartilages are free and movable in the joint, not 

 covering a bony surface, and held in their places by connexion with 

 ligaments : they are called menisci, from their shape. 



Fibro-cartilage. — Is stronger and tougher than cartilage ; it is 



