

SURFACE MARKINGS OF THE LOWER EXTREMITY 1345 



tuberosity; it crosses the center of the acetabulum and the upper border of the 

 greater trochanter. Another surface marking of clinical importance is Bryant's 

 triangle, which is mapped out thus: a line from the anterior superior iliac spine 

 to the top of the greater trochanter forms the base of the triangle; its sides are 

 formed respectively by a horizontal line from the anterior superior iliac spine and 

 a vertical line from the top of the greater trochanter. 



Articulations. The posterior superior iliac spine overlies the center of the sacro- 

 iliac articulations. 



The hip-joint may be indicated, as described above, by the center of a horizontal 

 line from the pubic tubercle to the top of the greater trochanter; or more generally, 

 it is below and slightly lateral to the middle of the inguinal ligament. The knee-joint 

 is superficial and requires no surface marking. The level of the ankle-joint is that 

 of a transverse line about 1 cm. above the level of the tip of the medial malleolus. 

 If the foot be forcibly extended, the head of the talus appears as a rounded promi- 

 nence on the medial side of the dorsum; just in front of this prominence and behind 

 the tuberosity of the navicular is the talonavicular joint. The calcaneocuboid joint 

 is situated midway between the lateral malleolus and the prominent base of the 

 fifth metatarsal bone; the line indicating it is parallel to that of the talonavicular 

 joint. The line of the fifth tarsometatarsal joint is very oblique; it starts from the 

 projection of the base of the fifth metatarsal bone, and if continued would pass 

 through the head of the first metatarsal. The lines of the fourth and third tarso- 

 metatarsal joints are less oblique. The first tarsometatarsal joint corresponds to a 

 groove which can be felt by making firm pressure on the medial border of the foot 

 2.5 cm. in front of the tuberosity of the navicular bone; the position of the second 

 tarsometatarsal joint is 1.25 cm. behind this. The metatarsophalangeal joints are 

 about 2.5 cm. behind the webs of the corresponding toes. 



Muscles. None of the muscles require any special surface lines to indicate 

 them, but there are three intermuscular spaces which occasionally require defini- 

 tion, viz., the femoral triangle, the adductor canal, and the popliteal fossa. 



The femoral triangle is bounded above by the inguinal ligament, laterally by the 

 medial border of Sartorius, and medially by the medial border of Adductor longus. 

 In the triangle is the fossa ovalis, through which the great saphenous vein dips to 

 join the femoral; the center of this fossa is about 4 cm. below and lateral to the 

 pubic tubercle, its vertical diameter measures about 4 cm. and its transverse about 

 1.5 cm. The femoral ring is about 1.25 cm. lateral to the pubic tubercle. 



The adductor canal occupies the medial part of the middle third of the thigh; it 

 begins at the apex of the femoral triangle and lies deep to the vertical part of 

 Sartorius. The popliteal fossa is bounded: above and medially by the tendons 

 of Semimembranosus and Semitendinosus; above and laterally by the tendon of 

 Biceps femoris; below and medially by the medial head of Gastrocnemius ; below 

 and laterally by the lateral head of Gastrocnemius and the Plantaris. 



Mucous Sheaths. The positions of the mucous sheaths around the tendons 

 about the ankle-joints are sufficiently indicated in Figs. 1241, 1242 (see also page 

 489). 



Arteries. The points of emergence of the three main arteries on the buttock, 

 viz., the superior and inferior gluteals and the internal pudendal, maybe indicated 

 in the following manner (Fig. 1244). With the femur slightly flexed and rotated 

 inward, a line is drawn from the posterior superior iliac spine to the posterior supe- 

 ior angle of the greater trochanter; the point of emergence of the superior gluteal 

 artery from the upper part of the greater sciatic foramen corresponds to the junction 

 of the upper and middle thirds of this line. A second line is drawn from the poste- 

 rior superior iliac spine to the outer part of the ischial tuberosity; the junction 

 of its lower with its middle third marks the point of emergence of the inferior 

 gluteal and internal pudendal arteries from the lower part of the greater sciatic 

 85 





