318 THE MUSCULAR SYSTEM. 
The intermuscular septa are processes of the deep fascia attached to the 
supracondyloid or epicondylic ridges of the humerus. 
INSERTION OF 
__— PECTORALIS 
MINOR 
DELTOID 
a —Axillary artery 
Musculo- 
—~eutaneous nerve 
“> Median nerve 
(outer head) 
———— Median nerve 
INSERTION OF (inner head) 
PECTORALIS 
MAJOR 
CoRACO-BRACHIALIS \\ 
~ Ulnar nerve 
SHORT HEAD OF BICEPS ~ 
LONG HEAD OF BICEPS 
BRACHIALIS ANTICUS 
TRICEPS (inner head) 
Musculo-cutaneous nerve 
Musculo-spiral nerve 
—Semilunar fascia of biceps 
f5\\ 
BRACHIO-RADIALIS 
PRONATOR RADII TERES 
Deep fascia of forearm 
EXTENSOR CARPI RADIALIS_! 
LONGIOR —FLEXOR CARPI RADIALIS 
PALMARIS LONGUS 
Radial artery (cut) FLEXOR CARPI ULNARIS 
FLEXOR SUBLIMIS DIGITORUM 
_— FLEXOR LONGUS POLLICIS 
EXTENSOR osst ___— PRONATOR QUADRATUS 
D INS SSIS 
METACARPI POLLICIS —> Ulnar artery 
Radial artery (cut)- 
Anterior annular 
‘ Inar nerve 
ligament Dies 
4 oy 
&, 
a 
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Fic. 236.—SuPERFICIAL MuscLes ON THE FRONT OF THE ARM 
AND. FOREARM. 
The internal and stronger 
septum is placed between 
the brachialis anticus in 
front and the inner head 
of the triceps behind, and 
gives origin to both. It 
extends upwards to the 
insertion of the coraco- 
brachials (which is often 
continuous with it). The 
external septum is thinner 
and of less extent. It 
separates the brachialis 
anticus and brachio-radialis 
in front from the inner 
and outer heads of the 
triceps behind, and gives 
origin to these muscles. 
It extends upwards to the 
insertion of the deltoid, 
and is pierced by the 
musculo-spiral nerve and 
superior profunda artery. 
MUSCLES. 
The coraco-brachialis 
is a rudimentary muscle 
placed on the front and 
inner aspect of the arm. 
It arises in common with 
the short head of the biceps 
from the tip of the coracoid 
process of the scapula, and 
is commonly connected at 
its origin with the insertion 
of the pectoralis minor. The 
muscle is partially sub- 
divided into two parts by 
the musculo-cutaneous 
nerve, and ends in a tendon 
inserted into a faint linear 
impression about an inch 
in length on the middle of 
the inner border of the 
humerus. 
The muscle hes on the 
inner side of the biceps, 
and is concealed at first by 
the deltoid and pectoralis 
major. In the lower part 
of its extent it 1s super- 
ficial, and forms a swelling 
beneath the skin on the 
inner side of the arm which serves as a guide to the axillary and brachial arteries. 
The coraco-brachialis is the remains of a threefold muscle, of which only two elements are 
usually present in man, but of which in anomalous cases all the parts may be more or less fully 
developed. The passage of the musculo-cutaneous nerve through the muscle is an indication of 
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