the glenoid cavity and the head of the humerus.
This bone consists of a large, flattened, triangular
body, two processes, the coracoid, and spine, which
ends in the acromial process, and at the apex a cavity
glenoid, for articulation with the head of the humerus.
THE BONES OF THE UPPER EXTREMITY 85
The Humerus (Arm Bone). This bone extends
from the shoulder to the elbow. It is divided into a
shaft, and an upper and lower extremity.
The Upper Extremity. This includes the head, a
neck, greater and lesser tuberosities. The head is
directed upward and slightly backward, and makes
an angle of 140 degrees with the shaft. The head is
round and articulates with the glenoid cavity of the
scapula, being held in apposition by the ligaments of the
shoulder-joint. Below the head is a depression pass-
ing around the bone called the anatomical neck. The
great tuberosity is an eminence of bone situated on
the outer and anterior aspect of the bone below the
anatomical neck. It gives attachment to the supra-
and infraspinatus and teres minor muscles, which
turn or rotate the shoulder-joint and arm outward.
Lying internal to the great tuberosity is the bicipital
groove, which lodges the tendon of the long head of the
biceps muscle. Internal to the groove is another
smaller eminence called the lesser tuberosity ; it receives
the tendon of the subscapularis muscle, which rotates
or turns the shoulder- joint inward.
The Shaft. This is cylindrical below the tuberosities
(and is known as the surgical neck) and triangular
below this portion. It is divided into external, internal,
arid posterior surfaces by anterior and lateral borders.
On the outer border, near the middle, is a rough
surface of bone called the deltoid eminence; it affords
attachment to the deltoid muscle. The middle of the
inner border receives the coracobrachialis muscle;
the lower three-fourths of the anterior aspect of the
shaft is covered by the origin of the brachialis anticus
muscle. The inner and outer borders become sharp
at the lower third, and are called the supracondylar
ridges. The posterior surface of the shaft is twisted
so that the upper part looks inward, its lower part
backward and outward. Its entire surface is almost
entirely covered by the origin of the inner and outer
86
OSTEOLOGY
heads of the triceps muscle, except a portion of bone
in the internal aspect of the surgical neck, and a narrow,
EXTERNAL
CONDYLE
SMALL
TUBEROSITY
MUSCULO-
SPIRAL GROOVE
INTERNAL
CONDYLE
The right humerus, front view. (Testut.)
THE BONES OF THE UPPER EXTREMITY 87
groove passing obliquely from within downward and
outward between the two portions of this muscle,
which is called the musculospiral groove and lodges the
musculospiral nerve and superior profunda artery.
The Lower Extremity. This is divided into an inter-
nal and external condyle, an articular surface sub-
divided into the trochlea and capitellum. The condyles
are rounded eminences of bone extending out beyond
the borders of the bone and can be always felt just
beneath the skin. Between the two condyles is
seen the articular facets, the outer the capitellum
is round and smooth and articulates with the cup-
shaped surface of the head of the radius; the inner
the trochlea presents a deep depression between two
well-marked borders and articulates with the sigmoid
cavity of the ulna. These articular surfaces mentioned
enter into the formation of the elbow-joint, and are
held in position by the capsular and internal and exter-
nal lateral ligaments of the elbow-joint. Above and
in front of the articular surface (trochlea) is a depres-
sion called the coronoid fossa, which receives the coro-
noid process of the ulna w r hen the arm is flexed; above
and behind the trochlear surface is a deep, triangular
depression, called the olecranon fossa, which receives
the olecranon process of the ulna when the forearm is
extended.
The Bones of the Forearm. The Ulna. This is
the internal of the two bones of the forearm. It
articulates above with the humerus, externally with
the radius, and below the triangular fibrocartilage at
the wrist. It presents an upper and a lower extremity
and a shaft.
THE UPPER EXTREMITY. It is divided into an olec-
ranon process, a coronoid process, and greater and
lesser sigmoid cavities. The olecranon process forms
the uppermost part of the ulna. It terminates supe-
riorly in front in a peak of bone, which overhangs the
greater sigmoid cavity; behind this is a rectangular,
88
OSTEOLOGY
thickened tuberosity, which forms the point of the
elbow, and can be felt just beneath the skin. The
FIG. 43
POSTERIOR
BORDER
STYLO ID
PROCESS
The bones of the right forearm, rear view. (Testut.)
posterior surface of the olecranon is triangular and
becomes narrowed below and extends into the posterior
border of the ulna. The anterior surface is concave
THE BONES OF THE UPPER EXTREMITY 89
and smooth, and forms the upper part of the greater
sigmoid cavity. The inferior surface is smooth and
attached to the shaft. The greater sigmoid cavity
articulates with the trochlear surface of the humerus.
The coronoid process is less marked than the olecranon
process; it is smooth, concave, and forms the base of
the greater sigmoid cavity.
The lesser sigmoid cavity is seen at the outer margin
of the greater cavity, with which it is continuous; it
is concave from before backward; and articulates with
the head of the radius held in position by the orbicular
ligament.
THE SHAFT. The shaft tapers from above, is three-
sided in its upper three-fourths, slender and cylindrical
in its lower fourth. It presents anterior, posterior,
and internal surfaces, and anterior, posterior, and
external borders.
THE LOWER EXTREMITY. This presents a rounded
head; from its inner and back part the styloid
process projects downward, giving attachments to
the internal lateral ligament and the triangular fibro-
cartilage of the wrist-joint. The head of the lower
extremity has an inferior articular surface, upon which
the triangular fibrocartilage plays, and an outer, nar-
row one, convex for the sigmoid cavity of the radius.
The styloid process of the ulna can always be felt
beneath the skin. The inner border of the ulna has
attached to its length the interosseous membrane, a
ligamentous septum stretching to the radius.
The Radius. It lies to the outer side of the forearm
alongside of the ulna. It is a long bone, and articulates
above with the capitellum of the humerus, the ulna,
internally; the scaphoid and semilunar bones of the
wrist, inferiorly. It presents for examination a shaft
and an upper and lower extremity.
THE UPPER EXTREMITY OR HEAD. It is disk-
shaped, convex in circumference, and its upper surface
has a depression for the capitellum of the humerus,
90
OSTEOLOGY
with which it articulates. It also internally rotates
within the lesser sigmotd cavity of the ulna. Below
the head is the neck, which is round and smooth, and
affords attachment to the supinator brevis muscle.
THE SHAFT. It is larger below than above, slightly
curved, and convex outward and backward. Below
the neck on the inner aspect is an elevation of bone
called the bicipital tuberosity, which receives the tendon
of the biceps muscle. Below this tuberosity the shaft
has three surfaces and three borders.
THE LOWER EXTREMITY. On the inner side of
the lower extremity at right angles to the inferior
articular surface is a concave articular facet which
articulates with the lower extremity of the ulna; the
two are held together by ligaments of the inferior
radio-ulnar articulation. To the smooth surface of
bone between these articular surfaces is attached the
interarticular fibrocartilage of the wrist-joint.
THE ARTICULATIONS OF THE CARPAL BONES
Superior.
External.
Inferior. Internal.
Ante-
rior.
Pos-
terior.
Num-
ber.
Scaphoid
Radius
Free
Trapezium
Os magnum
Free
Free
5
trapezoid
semilunar
Semilunar
Radius Scaphoid Os magnum
Cuneiform
Free
Free
5
unciform
Cuneiform
Triangular
Semilunar
Unciform
Free
Pisi-
Free
3
fib. cart.
form
Pisiform
Free
Free
Free
Free
Free
Cunei-
1
form
Trapezium
Scaphoid
Free j First meta-
Trapezoid
Free
Free
4
carpal
second met-
acarpal
Trapezoid
Scaphoid
Trapezium
Second meta-
Os magnum
Free
Free
4
carpal
Os magnum
Scaphoid
Trapezoid ! Second, third, Unciform
Free
Free
7
lunar
and fourth |
metacarpals '
Unciform
Lunar
Os mag-
Third and Cuneiform
Free
Free 5
num
fourth meta-
carpals :
The Bones of the Wrist (Carpus). The bones
of the wrist, eight in number, are arranged in two
rows. Those of the upper row, enumerated from the
THE BONES OF THE UPPER EXTREMITY 91
radial (outer side) to the ulnar (inner side), are: the
scaphoid, semilunar, cuneiform, and pisiform; those of
the lower row, enumerated in the same order, are:
Scaphoid - .^
Os magnum - .
Trapezium
Trapezoid-..
Metacarpal bo?2es_
FIG. 44
Bones of wrist
.Semilunar
... - Cuneiform
Pisiform
Unciform
Phalanx I"
j
PhelanxM-
Bones of the hand.
the trapezium, trapezoid, os magnum, and unciform.
Each bone presents six surfaces superior,, inferior,
anterior, posterior, internal, and external. The anterior
and posterior are rough for the attachment of ligaments.
92 OSTEOLOGY
The Metacarpal Bones or Bones of the Palm.
The metacarpal bones are five in number, from 1 to 5,
the first being the metacarpal bone of the thumb, the
fifth the metacarpal bone of the little finger. They
are long, cylindrical bones presenting a shaft, and an
upper and lower extremity.
Articulations of Metacarpal Bones.
First bone (proximal extremity) trapezium.
[Trapezium, trapezoid, os mag-
Second bone (proximal extremity) i num.
[Third metacarpal bones.
Third bone (proximal extremity) ( S m f gnum ' S , econd and fourth
\ metacarpal bones.
Fourth bone (proxi.al extre m it y ) * ^T'^ ?' b!
Fifth bone (proximal extremity)
The distal extremity of each metacarpal bone artic-
ulates with the corresponding proximal extremity of
the first phalanx below.
The Phalanges of the Hand (Four Fingers, One
Thumb). The phalanges are fourteen in number,
three for each finger and two for the thumb. They
consist of a shaft and upper and lower extremity.
They are similar in shape to the metacarpal bones,
only smaller, and are held together by ligaments, re-
inforced by the fibrous sheaths of the flexor and exten-
sor tendons. The first bone articulates with its meta-
carpal bone above, and the second phalanx 'below;
the second with the first or proximal phalanx above
and the third or distal phalanx below; and the third
phalanx with the second phalanx above. Of course,
the first phalanx of the thumb articulates with the
metacarpal bone above and the second phalanx below;
the second phalanx articulates with the first phalanx
above; there being no third phalanx.
All the long bones described have a nutrient canal
for the entrance of the nutrient artery.
THE BONES OF THE LOWER EXTREMITY 93
THE BONES OF THE LOWER EXTREMITY
Lower
Pelvis Ossa innominate (with sacrum and coccyx)
Thigh Femur
T /Tibia
Leg \Fibula
limb (Tarsus
Foot ] Metatarsus
( Phalanges (toes)
The Bones of the Pelvis. The Os Innominatum
(Hip Bone). This is so named from its bearing no
resemblance to any known object. There is one on
either side. It is irregular in shape, twisted, flat above,
expanded below, and constricted in the centre. With
its fellow of the opposite side it forms the lateral and
anterior walls of the pelvic cavity, which is completed
behind by the sacrum. In young subjects it consists
of three separate parts that meet to form the large
bone, and for purposes of description is divided into
the ilium, ischium, and pubis.
The ilium is the upper expanded portion and forms
less than two-thirds of the acetabulum (this is the
cavity which receives the head of the thigh bone).
The os pubis forms with its fellow of the opposite
side the anterior wall of the pelvic cavity, and bounds
the thyroid or obturator foramen above and partly
in front. It consists of a body and two rami; at the
inner extremity of the body is a roughened surface,
oval in shape for articulation with the opposite bone;
when the two bodies articulate they form the symphysis
pubis. The ascending and descending rami pass up-
ward and downward respectively from the body.
The ischium forms the lower and back part of the
hip bone, bounds the thyroid foramen below, and forms
over two-fifths of the acetabulum. It presents a body,
a ramus, and a tuberosity.
The Pelvis as a Whole. The pelvis (basin) is com-
posed of four bones: two ossa innominata (innominate
94
OSTEOLOGY
bones) on either side and in front and the sacrum and
coccyx behind. It is divided by an oblique line passing
through the prominence of the sacrum behind, and the
iliopectineal line and symphysis pubis in front, into
a false and true pelvis.
POSTERIOR SUPE-
RIOR SPINE
POSTERIOR IN-
FERIOR SPINE
ANTERIOR SUPE-
RIOR SPINE
ANTERIOR IN-
FERIOR SPINE
SPINE OF.
ISCHIUM
SMALL SCIATIC
NOTCH
'IUM
The right hip bone; outer surface. (Testut.)
THE FALSE PELVIS. This is the expanded portion
of the pelvic cavity above this plane. It is bounded
on each side by the iliac fossae of the iliac bones; in
front it is incomplete; the space of the basin between
the anterior superior spines is completed by the
abdominal wall; behind is a deep notch.
THE BONES OF THE LOWER EXTREMITY 95
THE TRUE PELVIS. This is the real bony basin,
situated below the oblique plane which divides the
prominence of the sacrum, iliopectineal line, and sym-
physis pubis. It is smaller than the false pelvis. For
description it presents a superior circumference or inlet,
an inferior circumference or outlet, and a cavity. The
superior circumference forms the brim of the pelvis,
the heart-shaped space being called the inlet.
FIG. 46
Crest fff ilium - -
Sup. spine of
Inf. spine of'iliu.
Obturator foramen, }
Body of ischiujJi
fuoerosity ofisckium ...
Ramus of ischium
-..Spine of ischium
ftamus of pubic tone
' -Symphysis pubes
Male pelvis from in front and below.
The cavity of the true pelvis is bounded in front by
the symphysis pubis; behind by the concavity of the
sacrum and coccyx, which, curving forward above and
below, contracts the inlet and outlet of the canal;
laterally it is bounded by the inner surface of the
ischium and that part of the ilium which is below
the iliopectineal line. It is shallow in front, measuring
If inches in depth at the symphysis, 3J inches in the
middle, and 4J inches posteriorly.
The'^lower circumference or outlet is irregular in shape.
Bounded by three eminences the point of the coccyx
behind, and the tuberosities of the ischia on either side.
The eminences are separated by three notches: one in
OSTEOLOGY
front, the pubic arch formed by the rami of the ischia
and pubes, and the symphyses. The other notches,
one on each side, are formed by the sacrum and coccyx
FIG. 47
of femur
Ant intcr/rvckantcric /I'M
" - .. Zesscr r/vchff/rfcr
.Int fubcrositij
-...Lit. condy/e
Right thigh bone, femur.
behind, the ischium in front, and the ilium above; the
latter notches are called the sacrosciatic notches; in
the recent state they are converted into foramina by
the lesser and greater sacrosciatic ligaments. When the
THE BONES OF THE LOWER EXTREMITY 97
ligaments are present, as in life, the real boundaries of
the outlet are the subpubic ligament and the rami of
the os pubis and ischium in front, the great sacro-
sciatic ligaments and the tip of the coccyx behind,
and the tuberosities of the ischia on each side.
The Femur. The femur (thigh bone) is the largest,
longest, and strongest bone of the skeleton. It is convex
in front and concave behind, and when the body is
erect the femur is inclined inward and slightly back-
ward. It is divisible into an upper and lower extremity
and a shaft.
The Upper Extremity. This presents a head, a neck,
and a great and small trochanter. The head is joined to
the shaft by the neck, it is round and forms more than
a half sphere. It articulates with the acetabulum of
the innominate bone. Just below and behind the centre
of the head is a depression for the interarticular or
round ligament of the hip- joint, which is attached
by its upper end to the centre of the acetabulum.
The neck is narrow just at the junction of the head,
constricted in the centre, and widens as the base is
approached; is flattened slightly anteriorly and poste-
riorly, concave above and below. The direction of
the neck is slightly upward, forward, and inward,
being set upon the shaft at an angle of 125 degrees.
The junction of the neck with the shaft shows in front
and behind a slight elevation or roughened surface of
bone called the anterior and posterior intertrochan-
teric lines, and they afford attachment to the capsular
ligament and ligament of Bigelow. The posterior
intertrochanteric line in the middle receives the
quadratus femoris. The small trochanter is a small
projection of the bone seen at the inferior aspect of
the base of the neck when it unites with the shaft.
The great trochanter is a projection of bone extending
upward beyond the neck. It can be felt under the skin.
It is quadrilateral in shape, with its base attached to
the shaft of the femur.
98 OSTEOLOGY
The Shaft. The shaft is long and rounded in front
and on the sides, is narrow in the centre, and enlarges
gradually above and below, being the broadest at the
lower extremity. It presents an anterior surface,
which is covered by a flat, yet large muscle on its
upper three-fourths the crureus and below this
two small spaces of bone give origin to the subcrureus
muscle. There are an internal and an external surface;
they are covered by the crureus and vastus internus
and externus respectively. The lateral surfaces are
separated posteriorly by a longitudinal rough ridge of
bone, about the middle of the shaft called the linea
aspera. It is divided into an inner and outer lip, and
a middle ridge.
The outer and inner lips of the linea aspera at the
junction of the middle with the lower third of the bone,
posteriorly, separate and include between their diverg-
ing borders a triangular-shaped, smooth surface of
bone, free from muscular attachments, called the pop-
liteal surface. The space is crossed by the popliteal
artery, vein, and the internal popliteal nerve, the artery
being next to the bone.
The Lower Extremity. This presents two condyles
internal and external and intercondylar notch, and
an inner and outer tuberosity or tubercle. The con-
dyles articulate with the upper articular facets of the
upper extremity of the tibia, and in front the articula-
ting surface is extended upon the shaft for a short
space (trochlear surface), to articulate with the patella
(knee-cap). The capsular ligament of the knee-joint
is attached just above the condyles on the shaft of the
bone. The intercondylar space is filled with fat and
has the crucial ligaments passing from the internal
surfaces of the condyles to the upper surface of the
tibia. These ligaments as they cross each other form
the letter X. The femur has an internal and external
rounded border.
THE BONES OF THE LOWER EXTREMITY 99
The Patella or Knee-cap. This is a flat, triangular
bone, situated at the anterior part of the knee-joint.
It is usually regarded as a sesamoid bone, developed
in the quadriceps extensor tendon (formed by the
rectus femoris, the vastus internus and externus, and
the crureus muscles).
The patella can always be felt beneath the skin and
fascia.
The right patella, ventral surface. (Testut.)
APEX
The right patella, dorsal surface. (Testut.)
Bones of the Leg. The bones of the leg are two,
the tibia and fibula.
The Tibia. This is situated at the inner and front
part of the' leg/ It is the longest, ai-.o. largest bone
100
OSTEOLOGY
in the body, excepting the femur. In the male its
direction is vertical; in the female inclined obliquely
OUTER TU
BEROSITYTt
STYLO ID.
PROCESS
UNTERO-EXTER-
NAL BORDER
ANTERO-INTER-
NAL BORDER
OUTER
MALLEOLUS
INNER
MALLEOLUS
The right tibiu and fibula in Lheir normal r^btiois 1 , f-ont view.
(Modified from Toflut.)
THE BONES OF THE LOWER EXTREMITY 101
downward and outward slightly. To its outer side is
the fibula.
The tibia presents an upper and lower extremity,
and shaft.
THE UPPER EXTREMITY OR HEAD. This is large
and expanded on either side into the internal and
external tuberosities. The superior surface of each
tuberosity presents a concave articular surface, which
receives the condyles of the femur above. The inner
facet is oval, the outer circular. Posteriorly the
external tuberosity presents a facet for articulation
with the head of the fibula. The anterior surfaces of
the tuberosities of the tibia are continuous with one
another, thus forming a surface which is triangular
in shape and at the lower part is the tubercle, which
receives the ligamentum patellae.
THE SHAFT. The shaft of the tibia is long and tri-
angular, broad above, gradually decreasing in size
to its most slender part the commencement of the
lower fourth; it then enlarges again at its lower ex-
tremity. It presents internal, external, and posterior
surfaces; internal, external, and anterior borders, the
anterior border forms the shin, so-called.
THE LOWER EXTREMITY. This, much smaller than
the upper, presents five surfaces anterior, posterior,
internal, external, and inferior. The anterior surface
is smooth and rounded above, and crossed by the ex-
tensor tendons of the toes and tibialis anticus muscle.
The external surface is a rough, triangular depression for
the attachment of the interosseous membrane above, at
its lower part is a smooth hollow surface covered by car-
tilage, for articulation with the lower end of the fibula.
The inferior surface is quadrilateral and articulates with
the upper aspect of the astragalus, one of the tarsal
bones; this surface is continuous with the articular
surface of the internal malleolus. The internal surface
is practically the internal malleolus, a pyramidal process
of bone, flattened from without inward. The inner
102 OSTEOLOGY
surface is convex and just beneath the skin. The outer
surface of the malleolus is smooth and articulates with
the astragalus bone. The posterior surface is flattened
and crossed by the flexor tendons of the toes and the
tibialis posticus muscle.
The Fibula. The fibula (clasp) or peroneal bone,
nearly equal in length to the tibia, is the thinnest long
bone in the body. It lies parallel with the tibia at the
outer side of the leg. It articulates by its upper ex-
tremity with the outer tuberosity of the tibia, by its
lower extremity with the astragalus. The two articu-
lating extremities are held in place by ligaments, all
entering into the formation of the superior and infe-
rior tibiofibular articulation. The inner border has
attached to it the outer edge of the interosseous mem-
brane, stretching between the titya and fibula. The
fibula is the most irregular bone in the body as its
surfaces and borders are not evenly defined.
The outer aspect of the lower extremity is subcuta-
neous and is grooved behind for the lodgement of the
tendons of the peroneus longus and brevis muscles
the latter tendon being next to the bone. The lower
extremity forms the external malleolus.
The Bones of the Foot. The bones of the foot con-
sist of three divisions the tarsus, metatarsus, and
phalanges (toes).
The Tarsus. This consists of seven irregular-shaped
bones held in position by ligaments and reinforced by
the inserted sheaths of the tendons of muscles. The
bones are, viz., the os calcis or calcaneum, astragalus,
cuboid, scaphoid, internal, middle, and external cuneiform.
The os calcis forms the heel, and is the largest of the
seven bones. It articulates above, with the astragalus;
in front, with the cuboid. It presents six surfaces
superior, inferior, internal, external, anterior, and pos-
terior.
The astragalus or ankle bone (talus) receives the