THE FIBULA. 
serves for articulation with the external tuberosity of the tibia. 
lateral ligament, together with the 
remainder of the tendon of the 
biceps muscle which surrounds it, 
is attached to the outer and upper 
side of the head in front of the 
styloid process. In front and behind 
the head thereare usually prominent 
tubercles. The anterior of these 
is associated with the origin of the 
peroneus longus muscle; the pos- 
terior, whilst furnishing an origin 
for the upper fibres of the soleus, 
serves to deepen the groove, behind 
the superior tibio-fibular articula- 
tion, in which the tendon and fleshy 
part of the popliteus muscle play. 
The constricted portion of the shaft 
below the head is often referred to as 
theneck; around theoutersideofthis 
the external popliteal nerve winds. 
The shaft of the fibula (corpus 
fibule) presents many varieties 
of shape and form, being ridged 
and channelled in such a way as 
greatly to increase the difficulties 
of the student in recognising the 
various surfaces described. The 
most important point is first to 
determine the position of the in- 
terosseous ridge. Holding the bone 
in the position which it normally 
occupies in the leg, it will be 
noticed that the external surface 
of the lower extremity is limited 
in front and behind by two lines, 
which, converging above, enclose 
between them a triangular sub- 
cutaneous area which lies im- 
mediately above the outer ankle. 
From the summit of the triangle 
_ so formed a well-defined ridge may 
be traced up the front of the shaft 
to reach the anterior aspect of the 
head. This is the anterior border, 
and must not be mistaken for the 
interosseous ‘ridge, which is now 
easy to find, for the next ridge 
which lies immediately internal to 
the anterior border, or towards the 
tibial side on the anterior aspect of 
the bone, is the line to which the 
interosseous membrane is attached. 
As a rule these two lines are 
separated by a considerable interval 
in the lower half of the bone, but 
tend to run much closer together 
Semimem- 
Flexor longus digitormm— 
229 
The long external 
SPINE 
INT. CONDYLIC 
SURFACE 
Ext. CONDYLIC SURFACE 
oN PoPLITEAL 
SS T|!|!#«CNNOTCH 
SN 
yi) a —sSTYLOID 
branosus ie: 
Popliteus Soleus 
NECK 
OBLIQUE LINE 
ARTERIAL 
Tibialis posticus 
FORAMEN 
INTEROSSEOUS 
RIDGE 
INTERNAL BORDER- 
~~~ Peroneus longus 
SURFACE FOR EX- 
f TENSORS OF ANKLE 
# —— Flexor longus 
hallueis 
ARTERIAL 
FORAMEN 
Peroneus brevis 
PRRONEAL 
SURFACE 
GROOVE FOR 1 
is] 
& 
AND 
GROOVE FOR 
I 
INTERNAL ii i SecGeenS.. 
NTERNAL_1 a hh ‘UA PERONEUS 
MALLEOLUS f \ Teh ! LONGUS AND 
oy BREVIS 
GROOVE ae EXTERNAL 
FLEXOR LONGUS 
HALLUCIS MALLEOLUS 
Fra. 170.—Ricut TipiA AND FIBULA AS SEEN FROM 
BEHIND. 
above ; indeed it is not uncommon to find that they coalesce to form a single crest. 
2 Let it therefore be clear that the interosseous line is that which lies immediately 
