bro-cartilage. At this point it is prolonged
upwards as a pouch behind the lower extremity of the first phalanx.

THE ARTICULATION OF THE SECOND PHALANX WITH THE THIRD, THE PEDAL, OR THE
COFFIN JOINT.--This also is an imperfect hinge-joint, permitting only of
flexion and extension, which movements are more restricted than in the
previous articulation. Three bones enter into its formation: the second
phalanx, the third phalanx, and the navicular bone. The lower articulatory
surface is formed by the third phalanx and the navicular bone combined.
To effect this the navicular is closely and firmly attached to the third
phalanx by an interosseous ligament. The two bones, as one, are then
connected to the second phalanx by four lateral ligaments, an anterior and
a posterior on each side.

_The Interosseous Ligament_ consists of extremely short fibres running from
the extensively grooved portion of the anterior surface of the navicular
bone to become attached to the os pedis immediately behind its articular
surface.

_The Antero-lateral Ligaments_ are attached by their superior extremities
to the lateral surfaces of the second phalanx, and by their inferior
extremities into the depressions on either side of the pyramidal process of
the os pedis.

_The Postero-lateral Ligaments_.--As mentioned when describing the first
interphalangeal articulation, these are in reality continuations of the
lateral ligaments of that joint. Running obliquely downwards and backwards
from their point of attachment to the first phalanx they curve round the
lower part of the side of the second phalanx and end on the extremities and
posterior surface of the navicular bone. Having reached that position, they
send short attachments to the retrossal process of the os pedis and to the
inner face of the lateral cartilage.

[Illustration: FIG. 9.--LIGAMENTS OF THE FIRST AND SECOND INTERPHALANGEAL
ARTICULATIONS (VIEWED FROM BEHIND). (AFTER DOLLAR AND WHEATLEY.) 1,
Suspensory ligament; 2, innermost slip from complementary cartilage of
pastern joint; 3, middle slip from complementary cartilage of pastern
joint; 4, outermost slip from complementary cartilage of pastern joint; 5,
glenoid or complementary cartilage of pastern joint; 6, postero-lateral
ligaments of the pedal joint; 7, the navicular bone; 8, interosseous
ligaments of the pedal joint; 9, semilunar crest of os pedis; 10, plantar
surface of os pedis.]

_Synovial Membrane_.--This extends below th