Biomedical Engineering Reference
In-Depth Information
over the ribs of the back, and the collarbone attaches in the front of
the body with the sternum.
• The scapula (2) is commonly called the shoulder blade. It is sup-
ported and positioned by the skeletal muscles. The scapula has no
bony or ligamentous bonds to the thoracic cage, but it is extremely
important for muscle attachment.
• The clavicle (2) is commonly known as the collarbone. It articulates
with the manubrium of the sternum and is the only direct connection
between the pectoral girdle and the axial skeleton.
• The upper limb or upper extremity (60) is the region in an animal
extending from the deltoid region to the hand, including the arm,
axilla, and shoulder. It may be divided into five main regions: an
upper arm bone (humerus), the forearm (radius and ulna), the wrist
(carpals), the metacarpals, and the phalanges.
• The humerus (2) is the bone of the shoulder and arm. It articu-
lates with the scapula at the shoulder and with the radius and
ulna at the elbow. The distal end of the humerus includes the
lateral and medial epicondyles and a condyle consisting of the
capitulum and trochlea. The lateral epicondyle gives origin to
the supinator and to the extensor muscles of the forearm. The
capitulum articulates with the head of the radius. The trochlea
is a pulley-shaped projection that articulates with the troch-
lear notch of the ulna. It is set obliquely, so that a “carrying
angle” exists between the arm and the extended and supinated
forearm. Radial and coronoid fossae are situated anterior and
superior to the capitulum and trochlea, respectively. A deeper
olecranon fossa is located posteriorly, superior to the trochlea.
The medial epicondyle gives origin to the flexor muscles of
the forearm. The ulnar nerve lies in a groove posterior to the
medial epicondyle and is palpable there (the “funny bone”). The
medial epicondyle gives an indication of the direction in which
the head of the humerus is pointing in any given position of the
arm. The distal end of the humerus is angled anteriorward, and
a decrease in the normal angulation suggests a supracondylar
fracture.
• The radius (2) lies along the lateral side (or thumb side) of the
forearm. The proximal end articulates with the humerus, the
medial aspect with the ulna, and the distal end with the carpus.
The distal end of the radius terminates in the styloid process lat-
erally. The process is palpable between the extensor tendons of
the thumb. It gives attachment to the radial collateral ligament.
The styloid process of the radius is about 1 cm distal to that
of the ulna. This relationship is important in the diagnosis of
