ANATOMY IN A NUTSHELL. 



77 



Muscles. — It has fourteen muscles attached, Triceps, Anconeus, Flexor 

 carpi ulnaris, Brachialis anticus, Supinator brevis. Flexor sublimis digitorum, 

 Flexor profundus digitorum, Pronator quadratus, Extensor carpi ulnaris 

 Pronator radii teres, Extensor ossis metacarpi pollicis, Extensor longus 

 pollicis, Extensor indicis, and Flexor longus pollicis. 



PLATE XXV III 



DORSALIS SCAPULAE ARTERY 



GREAT TUBEROSITY 



POST. CIRCUMFLEX ARTERY 



CIRCUMFLEX N 



MUSCULO-SPIRAL N — 



THE QUADRILATERAL SPACE IS 

 BOUNOED ABOVE BY THE TERES MINOR; BELOW BY THE 

 TERES MAJOR; EXTERNALLY BY THE HUMERUS; INTER- 

 NALLY BY THE LONG HEAD OF THE TRICEPS. IT HAS THE 

 CIRCUMFLEX N. AND THE POST. CIRCUMFLEX ARTERY 

 PASSING THROUGH IT. THERE ARE TWO TRIANGUAL 

 SPACES FORMED BY THESE SAME BOUNDARIES. ONE 

 TRIANGLE HAS THE MUSCULO-SPIRAL N. PASSING 

 THROUGH IT. AND IS BOUNDED ABOVE BY THE TERES 

 MAJOR, EXTERNALLY BY THE HUMERUS. INTERNALLY BY 

 THE LONG HEAD OF TRICEPS. THE OTHER TRIANGLE HAS 

 THE DORSALIS SCAPULAE ARTERY PASSING PARTLY 

 THROUGH IT AND THEN PASSING BETWEEN THE SCAPULA 

 AND THE TERES MAJOR INTO THE INFRASPINOUS FOSSA. 



Showing the Quadrilateral Space and Structures Passing Through it 



Blood Supply. — The nutrienl vessel enters the shaft near the middle of 

 the anterior surface; it is derived from the anterior interosseous trunk, and is 

 directed towards the proximal end. The upper extremity receives branches 

 from the anterior and posterior ulnar recurrent and from the interosseous re- 

 current. The lower end receives twigs from the anterior and posterior inter- 

 osseous arteries. 



