THE PATELLA. 223 
fetus. According to Hartman, it is absent in about 12 per cent of children at term, and 
may appear as early as the eighth month of foetal life in about 7 per cent. The superior 
extremity, entirely  carti- 
G . : Fuses with shaft Pn 
laginous at birth, comprises Se about AR GEMIGETO “reais ais 
early part o : Zs 
the head, neck, and _ tro- "gts Sa Be 
chanter major. <A centre Be 
i : Appears about a 
_ appears for the head during Bis Z 
: —— nD 
the early part of the first g 2 
year. That for the tro- 
_ chanter major begins to 
ossify about the second or 
third year, whilst the neck 
is developed as an upward 
extension of the shaft, which 
is, however, not confined to 
the neck alone, but forms the 
lower circumference of the 
articular head, as may be 
seen in bones up to the age 
of twelve or sixteen; after 
that, the separate epiphysis 
of the head begins to over- 
| lap it so as to cover it en- 
| tirely when fusion is com- Ustally anpears in Usually appear 
plete at the age of parte foetal life. 
or twenty. 
Appears 
_-about 
12-13 years 
Fuses with 
shaft about 
18 years 
Appears early in 2nd month of foetal life 
' The epiphysis of the creat Fuses with shaft about 20-22 years 
Je 5 c 
trochanter unites with the At birth. About 12 years. About 16 years. 
_ shaft and neck about eigh- Fic. 165.—OssiricaTIon OF FEMUR. 
teen or nineteen, whilst the 
_ epiphysis for the trochanter minor, which usually makes its appearance about the twelfth 
or thirteenth year, is usually completely fused with the shaft about the age of eighteen. 
The epiphysis. for the lower end, although the first to ossify, is not completely united to 
. the shaft until from about the twentieth to the twenty-second year. It is worthy of note 
that the line of fusion of the shaft and inferior epiphysis passes through the adductor 
_ tubercle, a point which can easily be determined in the living. 
: 
THE PATELLA. 
The patella, the largest of the sesamoid bones, overlies the front of the knee- 
joint in the tendon of the quadriceps extensor. Of compressed form and somewhat 
triangular shape, its 
lower angle projects 
downwards and forms 
a peak, called the apex 
(apex patellee), whilst 
its upper edge, or base 
(basis patellze), broad, 
thick, and _ sloping 
forwards and a little 
downwards, is divided 
into two areas by a 
transverse line or 
groove; the anterior 
EXTERNAL ARTICULAR FACET 
INTERNAL ARTICULAR FACET 
Surface for the ligamentum patelle area so defined 
Fic. 166.—RiIGcHT PATELLA serves for the attach- 
A, Anterior_surface. B, Posterior surface. ment of the common 
tendon of the Duges 
riceps extensor muscle, whilst the posterior, of compressed triangular shape, i 
covered by synovial membrane. The inner and outer borders, of curved ae 
' receive the insertions of the vastus internus and externus muscles respectively, the 
