A secondary centre appears in the cartilage of the lower extremity about the second or 
third year; this does not unite with the shaft until the twentieth or twenty-fifth year, 
somewhat earlier in the female. From this the carpal and ulnar articular surfaces are 
formed. The centre for the head appears from the fifth to the seventh year, and fuses 
with the neck about the age of eighteen or twenty. It forms the capitellar articular 
surface and combines with the neck to form the area for articulation with the small 
sigmoid cavity of the ulna. A scale-like epiphysis capping the summit of the bicipital 
tubercle has been described ; this appears about fourteen or fifteen, and rapidly fuses with 
that process. 
THE BONES OF THE HAND. 197 
THE BONES OF THE HAND. 
The bones of the hand, twenty-seven in number, may be conveniently divided 
into three groups :— 
(1) The bones of the wrist or carpus—erght in number. 
(2) The bones of 
the palm or meta- 
carpus— five in 
number. 
(3) The bones of 
the fingers and 
SCAPHOID 
SEMILUNAR 
TRAPEZOID 
UNCIFORM 
<\) Os MAGNUM 
Abductor pollicis 
CUNEIFORM 
HO TRAP EZIUM 
thumb or phalan- Opponensi poles Ey ieee 
ges—fourteen In actanaow ose oa Abductor minimi digiti 
number. metacarpi pollicis 
Flexor carpi ulnaris 
Flexor carpi radialis 
a x i Adductor obliquns 
THE CARPUS. pollicis 9 
Flexor brevis 
and 
>Opponens minimi digiti 
The carpal bones |, meracarrar—/ 
(Ossa Carpl) are ar- _ __ 
: : 5 ae: ates SESAMOID BONES 
ranged in tWOTrows: abductor 
Palmar interossei 
the first or proxi- Pa V. METACARPAL 
: Flexor brevis 7 
mal row comprises Steoal) 
from without in- — Adductor 
transversus ff 
wards the scaphoid pollicis 
(os naviculare), : 
semilunar (os luna- 
tum), cuneiform (os 
triquetrum), and 
pisiform (0s _ pisi- 
forme); the second 
or distal row in- 
_Flexor brevis 
and 
Abductor 
minimi digiti 
Palmar 
interossei 
FIRST PHALANX 
Flexor longus 
cludes the trapezium polis Sree 
(os multangulum ees 
majus), trapezoid (0s 
. 3 oy THIRD OR 
multangulum min- TERMINAL 
us), OS magnum (0s Flexor ) ene 
: . sublimis Yigg 
Capitatum), and Ai citanar 
unciform (os hama- 
tum). Trregularly Flexor 
six-sided, each of HIATT Be 
digitorum 
these bones possesses 
non-articular — pal- 
mar and dorsal sur- 
faces. In addition, 
the marginal bones | 
are non-articular ae 
along their ulnar Fia. 139.—TaE BONES OF re Gs a AND HAND AS SEEN FROM 
and radial aspects ne hats 
according as they form the inner or outer members of the series. 
| 
| 
| 
| 
; 
Note. —In the illustrations (Figs. 141 to 148) the bones are represented in the centre of 
