FLOW OF BLOOD THROUGH BONES AND JOINTS 



[66l 



mmHg 



300 , vvrts,)..^ 



200 



T.rt 



i I 



fig. 7. Effect of injecting in- 

 travenously 1 ml of 1 150,000 

 Adrenalin on the femoral ar- 

 terial pressure (upper record) 

 and the marrow pressure (lower 

 record) in the femur of the cat. 

 [From Herzig & Root (60).] 



administration of ephedrine (82), Benzedrine (8, 60), 

 ergotamine tartrate (8) or nicotine (8). A reduction 

 in both systemic and marrow pressure follows the in- 

 jection of histamine (8, 82), acetylcholine (8), sodium 

 nitrate (8), and amyl nitrite (60). 



Patients with leukemia and multiple myeloma dif- 

 fer from nonleukemic patients in having elevated 

 mean marrow pressures and increased pulse pressures 

 (95). In patients with acute leukemia in whom the 

 highest pressures are found, dicrotic notches are pres- 

 ent in the pulse waves suggesting a lowered pe- 

 ripheral resistance in the marrow circulation. The 

 degree of anemia could not be correlated with the 

 mean pressures, nor with the pulse pressures in the 

 marrow. The pressure data confirm the increased 

 vascularity in the marrow in some forms of leukemia 

 as demonstrated by the clearance of I 131 from the 

 marrow (94). 



Temperature of Bone Marrow 



This subject is of some importance, for it is generally 

 believed that hematopoiesis requires the maintenance 

 of a high bone marrow temperature (33). According 

 to Huggins et al. (64), the more centrally placed 

 bones of the extremities, the cranial bones and the 

 sternum in the rat, rabbit, and pigeon have tempera- 

 tures similar to that of the peritoneal cavity, whereas 

 the temperature of the peripheral bone marrow of the 

 extremities may be lower by 4 to 8 C or more. In 

 adult man the red marrow is exclusively limited to 

 the bones of the body trunk and head as well as the 

 proximal portions of the limbs (92). Chemical ac- 

 tivity of the marrow does not affect the thermal con- 

 dition appreciably. On the other hand, the heat of 

 muscular activity of the limbs increases marrow 

 temperature. 



Huggins & Blocksom (63) showed that an increase 



in bone marrow temperature of the outlying bones 

 led to the replacement of yellow by red marrow. They 

 found a close correlation between the development of 

 cellular marrow and a temperature level similar to 

 that of the deep peritoneal cavity. However, they were 

 uncertain whether this is a primary effect upon tissue 

 metabolism, or a secondary vasomotor effect. 



Petrakis (93), who studied the temperature in the 

 sternum, iliac crest, tibia, spinous process, and verte- 

 bral body of ten patients, found temperatures ranging 

 from that of the rectum in the vertebral body mar- 

 row, to 4 C below this in other bones. He interprets 

 this to mean a lack of precise temperature regulation 

 in hematopoietically active bone marrow. No corre- 

 lation was found between temperature and cell type. 



JOINTS 



Gardner's excellent review (50) should be con- 

 sulted for general information concerning the physi- 

 ology of movable joints. 



The Blood Supply 



According to Davies (34) little has been added to 

 the first description of the circulus vasculosus by 

 William Hunter (66) who in 1743 wrote: "All around 

 the neck of the bone there is a great number of 

 Arteries and Veins which ramify into smaller Branches 

 and communicate with one another by frequent 

 Anastomoses like those of the mesenterv. This might 

 be called the Circulus vasculosus, the vascular border of 

 the Joint." 



At the articular margins, the capillaries form deli- 

 cate anastomosing loops comparable in pattern with 

 those seen in the mesentery. The blood supply of the 

 synovial membrane and capsule communicate freely 

 with the periosteal and epiphyseal supply; hence, the 



