232 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM 



unite, and are inserted into the base of the terminal phalanx, 

 as in the case of the extensors of the fingers. 



Tendons to the second and fifth toes may be doubled; extra 

 slips from one or more tendons to the metatarsal bones, to 

 short extensor, or to interossei; a slip to the great toe. Slip 

 for the little toe may be separable to origin. 



4. M . Peroneus Tertius. Origin (below the extensor longus 

 digitorum, and united with it), lower third or more of the 

 anterior surface of the fibula, from the interosseous membrane, 

 from the septum between it and the peroneus brevis; insertion, 

 upper surface of the base of the fifth metatarsal, sometimes 

 the fourth. This muscle is peculiar to man. 



Nerves. All by the anterior tibial nerve. 



The Fibular or Peroneal Region 



1. M. Peroneus Longus. Origin, few fibers from the outer 

 tuberosity of the tibia, head and upper two-thirds of the 

 external surface of the fibula, fascia of the leg, and septa on 

 each side. It has an anterior and a posterior head with pero- 

 neal nerve between. Tendon begins in the lower half of the 

 leg, passes behind the external malleolus; then forward on the 

 outer side of the os calcis, winds around the tuberosity of the 

 cuboid, and enters its groove, crosses the sole obliquely, and 

 is inserted into the outer side of the tuberosity of the first 

 metatarsal, and slightly into the internal cuneiform; a frequent 

 offset to the base of the second metatarsal and first dorsal 

 interosseous. 



Both peroneal tendons are in the same sheath under the 

 annular ligament, but on the os calcis each has its own sheath, 

 separated by the peroneal spine, when it exists, and a fibrous 

 septum. A single synovial sac sends two processes down into 

 the special sheaths. 



A second synovial membrane is in the cuboid groove. A 

 sesamoid fibrocartilage or bone is on the tendon, playing over 

 the cuboid tuberosity. The special fascia binding down the 

 peroneal tendons is the retinaculum peronosorum inferius, p. n. 



2. M. Peroneus Brevis. It lies deeper than the peroneus 

 longus. Origin, lower two-thirds of the external surface of 

 the fibula from the septa and a flat tendon on the surface 

 turned toward the bone; insertion, tuberosity at the base of 



