PELVIS 607 



thus arises directly from the sacral plexus, it usually perforates 

 the piriformis muscle on its way out of the pelvis. 



In addition to the two main bands into which the plexus 

 resolves itself (sciatic and pudendal) various other branches 

 are given off. They are : 



1. Superior glutaeal. 



2. Inferior glutaeal. 



3. Posterior cutaneous of the thigh (O.T. small sciatic). 



4. Nerve to the obturator internus and superior gemellus. 



5. Nerve to the quadratus femoris and inferior gemellus. 



6. Perforating cutaneous nerve. 



7. Branches to the piriformis muscle. 



8. Branches to the pelvic viscera. 



Nervus Glutaeus Superior (Superior Glutaeal Nerve). The 



superior glutaeal nerve arises from the posterior aspect of the 

 plexus and contains fibres of the fourth and fifth lumbar 

 and first sacral nerves. It passes, with the superior glutaeal 

 artery, above the upper border of the piriformis muscle, and 

 leaves the pelvis through the upper part of the great sciatic 

 foramen. It is distributed, in the glutaeal region, to the 

 glutaeus medius and glutaeus minimus, and to the tensor fasciae 

 latae muscles. 



Nervus Glutaeus Inferior (Inferior Glutaeal Nerve). This 

 is the special branch of supply to the glutaeus maximus. It also 

 springs from the back of the plexus, and contains fibres of 

 the fifth lumbar and the first and second sacral nerves. It 

 passes below the piriformis and through the great sciatic 

 foramen into the buttock. 



Nervus Cutaneus Femoris Posterior (O.T. Small Sciatic). 

 This nerve arises from the back of the plexus and contains 

 fibres of the second and third sacral nerves. It passes between 

 the piriformis and coccygeus, and leaves the pelvis through 

 the lower part of the great sciatic foramen. 



The Nerve to the Obturator Internus springs from the 

 anterior aspect of the plexus, and contains fibres of the fifth 

 lumbar and the first and second sacral nerves. It leaves the 

 pelvis with the pudendal nerve, and, after giving a twig to the 

 superior gemellus in the glutaeal region, it reaches the obturator 

 internus by passing through the small sciatic foramen. It 

 sinks into the medial aspect of the muscle. 



The Nerve to the Quadratus Femoris springs from the 

 anterior aspect of the plexus, receiving fibres from the fourth 

 and fifth lumbar and the first sacral nerves. It accompanies 



