352 ge THE MUSCULAR SYSTEM. 
The tendon of origin is concealed by the gluteus maximus, and immediately 
beyond the ischium it is grooved by the common origin of the long head of the 
biceps and semitendinosus. In the back of the thigh it is covered by the semi- 
tendinosus, and lies upon the adductor magnus and great sciatic nerve. It forms 
part of the inner boundary of the popliteal space, and conceals the popliteal 
vessels. Its tendon passes over the inner head of the gastrocnemius on its way 
to its insertion. 
NERVE SuppLty OF THE MUSCLES OF THE THIGH AND Buttock. 
The innervation of the muscles described above is given in the following table :— 
| ) 
| | 
Muscles. | Nerves. Origin. | 
| Pectineus. Ib eS 
| Sartorius. | I, 33 
| Thacus T2735. 
| Psoas ; ; : 2 =| | Ib De By ab 
| Quadriceps extensor i : . | > Anterior crural L. 3. 4. | 
Vastus externus : : : 
Rectus femoris. | 
; - 1.3.4 
Crureus . é : : ; | 
Vastus internus ; F ah 
Tensor fasciz femoris. : | 
Gluteus minimus. : ; ; gases gluteal 1425s Sak 
Gluteus medius : ale. 
Gluteus maximus : : . | Inferior gluteal L558) 2 
Biceps (short head) . : : . | Peroneal Let SeSHle 
| Pyriformis . : : : . | Sacral plexus aul) OSes | 
| Adduetor longus. ; : il L, 2:3: | 
Saar 
racilis , F : ; L. 2. 3. 4. | 
Gracilis : Obturator . 3 | 
Adductor brevis | | L. 3. 4. | 
Obturator externus . L. 3. 4. 
Adductor magnus (leach eines ; ae 
POF ark \ Nerve to hamstrings » |) Ly Ais 1 
Semimembranosus . | | Ey 4.555513 
Semitendinosus -Nerve to hamstrings . 4) 5.8: 12: 
Biceps (long head) 5 : ; J ice totes 
Quadratus femoris and inferior ara 
sds On eel 
gemellus LQ Ee 
woeer : : Sacral plexus : : 4 
Superior gemellus and obturator ‘ 
7 5 S. 1.2.3 
internus / 
ACTION OF THE MUSCLES OF THE THIGH AND BUTTOCK. 
Most of the above muscles act on the pelvis and on the hip- and knee-joints. The psoas 
muscle acts in addition on the vertebral column. 
1. Movements at the Hip-Joint.—The movements of the thigh at the hip-joint are flexion 
and extension, adduction and abduction, internal and external rotation. The following table 
gives the muscles producing these movements :— 
a. Flexion and Extension. 
: | ; 
Sartorius Gluteus maximus 
Iliacus | 3 medius 
Psoas 55 minimus 
Rectus femoris | Biceps 
Pectineus | Semitendinosus 
Adductor longus | Semimembranosus 
Gracilis Adductor magnus 
Obturator externus | : 
