344 THE HORSE. 
rently intended to lighten the bone, being filled up by a strong mem- 
brane, the obturator ligament. Above this opening is the ramus of the 
ischium, which bone also enters into the composition of the hip joint 
as already described. Posteriorly the ischium terminates in a rough 
protuberance, the tuberosity (9-9, Fig. 32), which is the rounded pro- 
jection felt and seen on each side the root of the tail in the living horse. 
Below the foramen is the os pubis, the anterior part of which is the 
ramus, and the small section of the cotyloid cavity which it forms, while © 
posteriorly the body unites with the os ischii, to form, with the corre- 
sponding bones of the opposite’ side, the symphysis, or connecting joint 
between them. 
By rap consunction of the tw ossa innominata an oval ring is nearly 
completed, the deficiency being supplied by the sacrum above. The 
anterior margin of this ring is the brim of the pelvis, and it is upon the 
size of this as compared with the foal that parturition is in general ren- 
dered easy or difficult. 
THE FEMUR (ROUND-BONE) AND PATELLA, 
Tue Os Femonis, the strongest and heaviest bone in the body, is 
situated between the os innominatum and the tibia. It takes an oblique 
direction from above downwards and forwards, and presents a central 
part or body, and two extremities. It was formerly called the round-bone, 
from being in the centre of the part called by butchers “ the round.” 
THE Bopy, although compressed, is nearly cylindrical towards its 
centre ; anteriorly, the bone is convex and smooth ; posteriorly, flattened 
and rough ; superiorly and inferiorly, it is expanded to meet the enlarged 
extremities. 
THE SUPERIOR EXTREMITY is prolonged into a thick, flattened neck, 
directed upwards and inwards, so as to form an obtuse angle with the 
shaft. At the point of union are two eminences (trochanters, zpoydr, to 
run or roll); one on the outer, and the other on the inner side ; and it is 
from between these that the neck arises. 
The trochanter major is prolonged from the postero-external margin of 
the body, and nearly in a line with its axis: it is a large irregular pro- 
jection, rising into a pyramidal eminence. Posteriorly, at its base, it 
presents an oval cavity, the digital fossa, for the attachment of several 
small muscles. Inwardly it presents a concavo-convex smooth surface ; 
outwardly, a convex and rough one. From the back of the great tro- 
chanter a prominent line runs vertically down, terminating in the tro- 
chanter minor externus (7, Fig. 33); and from this again a roughened 
ridge descends, taking a course downwards and slightly forwards to the 
oval fossa situated above the external condyle (8). 
The neck is surmounted by a hemispherical smooth head, coated with 
cartilage, and lodged in the acetabulum ; on it is a deep ovoid fossa, 
which gives attachment to the ligamentum teres. 
The trochanter minor internus, a conical rounded eminence, arises from 
the posterior and internal side of the bone. It is placed above the tro- 
chanter minor externus, which is on the opposite side. 
THE INFERIOR EXTREMITY has on each side an eminence (the external 
and internal condyles), separated by a deep fossa. Between tnese ante- 
riorly two articular surfaces occur (external and internal), separated by a 
semicircular groove, in which the patella plays. 
The external condyle is larger and projects moro forwards than the 
