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The upper limb
(Osciology)
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The upper limb…
The upper limb consists of
four segments:
• Shoulder
• Arm
• Forearm
• Hand
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The upper limb…
• The pectoral (shoulder) girdle is a bony ring, incomplete
posteriorly, formed by the scapulae and clavicles and
completed anteriorly by the manubrium of the sternum (part
of the axial skeleton).
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Bones of the Upper Limb
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Clavicle
• The clavicle (collar bone) connects the upper limb to the
trunk. The shaft of the clavicle has a double curve in a
horizontal plane.
• Its medial half is convex anteriorly, and its sternal end is
enlarged and triangular where it articulates with the
manubrium of the sternum at the sternoclavicular (SC) joint.
• Its lateral half is concave anteriorly, and its acromial end is flat
where it articulates with the acromion of the scapula at the
acromioclavicular (AC) joint. The medial two thirds of the shaft
of the clavicle are convex anteriorly, whereas the lateral third
is flattened and concave anteriorly. These curvatures increase
the resilience of the clavicle and give it the appearance of an
elongated capital S.
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Clavicle…
• The superior surface of the clavicle, lying just deep to
the skin and platysma muscle in the subcutaneous
tissue, is smooth.
• The inferior surface of the clavicle is rough because
strong ligaments bind it to the 1st rib near its sternal end
and suspend the scapula from its acromial end.
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Clavicle…
• Ossification of the Clavicle
• The clavicle is the first long bone to ossify (via
intramembranous ossification) and the last to be fully
formed, beginning during the 5th and 6th embryonic weeks
from medial and lateral primary centers that are close
together in the shaft of the clavicle. The ends of the clavicle
later pass through a cartilaginous phase (endochondral
ossification)
Applied Anatomy
Sometimes fusion of the two ossification centers of the clavicle fails to
occur; as a result, a bony defect forms between the lateral and the medial
thirds of the clavicle. Awareness of this possible congenital defect should
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prevent diagnosis of a fracture in anLufukuja
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normal clavicle
Scapula
• The scapula (shoulder blade) is a triangular flat bone that
lies on the posterolateral aspect of the thorax, overlying the
2nd and 7th ribs
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Scapula…
• The convex posterior surface of the scapula is unevenly
divided by a thick projecting ridge of bone, the spine of
the scapula, into a small supraspinous fossa and a
much larger infraspinous fossa.
• The concave costal surface of most of the scapula forms
a large subscapular fossa.
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Humerus
• The humerus (arm bone), the largest bone in the upper limb,
articulates with the scapula at the glenohumeral joint and the
radius and ulna at the elbow joint.
• The proximal end of the humerus has a head, surgical and
anatomical necks, and greater and lesser tubercles. The
spherical head of the humerus articulates with the glenoid
cavity of the scapula.
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Humerus…
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Humerus…
• The shaft (body) of the humerus has two prominent
features: the deltoid tuberosity laterally, for attachment
of the deltoid muscle, and the oblique radial groove
(groove for radial nerve, spiral groove) posteriorly, in
which the radial nerve and deep artery of the arm lie as
they pass anterior to the long and between the medial
and lateral heads of the triceps brachii muscle
• The inferior end of the humeral shaft widens as the
sharp
medial
and
lateral
supraepicondylar
(supracondylar) ridges form and then end distally in the
especially prominent medial epicondyle and the lateral
epicondyle, providing for muscle attachment
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BONES OF THE FOREARM
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Bones of the Forearm
• The ulna and radius together make up the second unit of a
two-unit articulated strut (the first unit being the humerus),
projecting from a mobile base (shoulder) that serves to
position the hand.
• Proximally, the larger medial ulna forms the primary
articulation with the humerus, whereas distally, the shorter
lateral radius forms the primary articulation with the hand
via the wrist.
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Applied anatomy
• Because the ulna does not reach the wrist, forces received
by the hand are transmitted from the radius to the ulna via
the interosseous membrane.
• A complete fracture of the distal 2 cm of the radius is called
a Colles fracture.
• - most common fracture of forearm
• - most common fracture in people older than 50 years
• - distal radial fragment is often comminuted (broken into
pieces)
• - ulnar styloid process is often avulsed (broken off)
• - posterior displacement of distal radial fragment results in a
“dinner fork deformity”
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BONES OF THE HAND
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Bones of the hand
• The wrist, or carpus, is composed of eight carpal bones
(carpals) arranged in proximal and distal rows of four.
• These small bones give flexibility to the wrist. The carpus
is markedly convex from side to side posteriorly and
concave anteriorly. Augmenting movement at the wrist
joint, the two rows of carpals glide on each other; in
addition, each bone glides on those adjacent to it
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Applied anatomy
• Fracture of the Scaphoid
• The scaphoid is the most frequently fractured carpal bone. It
often results from a fall on the palm when the hand is
abducted
• Pain occurs primarily on the lateral side of the wrist, especially
during dorsiflexion and abduction of the hand.
• Owing to the poor blood supply to the proximal part of the
scaphoid, union of the fractured parts may take at least 3
months. Avascular necrosis of the proximal fragment of the
scaphoid (pathological death of bone resulting from
inadequate blood supply) may occur and produce
degenerative joint disease of the wrist. In some cases, it is
necessary to fuse the carpals surgically (arthrodesis).
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