Page 86 - untitled

AAAC37 21/5/05 10:48 AM Page 85
The forearm is enclosed in deep fascia which is continuous with that of
partment are supplied by the median nerve or its anterior interosseous
the arm. It is firmly attached to the periosteum of the subcutaneous bor-
branch (see Muscle index, p. 162).
der of the ulna. Together with the interosseous membrane this divides
• Arteries (Fig. 37.2): ulnar artery and its anterior interosseous branch
the forearm into anterior and posterior compartments each possessing of flexor digitorum profundus, all of the muscles of the anterior com-
its own muscles and arterial and nervous supplies. The superficial veins (via the common interosseous artery); radial artery.
and cutaneous sensory nerves course in the subcutaneous tissue • Nerve supply (Fig. 37.2): median nerve and its anterior interosseous
superficial to the deep fascia. branch; ulnar nerve; superficial radial nerve.
The interosseous membrane The contents of the posterior fascial (extensor)
• The interosseous membrane unites the interosseous borders of the compartment of the forearm
radius and ulna. The fibres of this tough membrane run obliquely down- • Muscles (Fig. 37.1): brachioradialis and extensor carpi radialis
wards and medially. A downwards force (e.g. fall on the outstretched longus arise separately from the lateral supracondylar ridge of the
hand) is transmitted from the radius to the ulna and from here to the humerus. They are innervated by the radial nerve. The remaining
humerus and shoulder. extensor muscles are considered in superficial and deep layers which
• The interosseous membrane provides attachment for neighbouring are innervated by the posterior interosseous branch of the radial nerve.
muscles. The muscles of the superficial layer arise from the common extensor
origin on the lateral epicondyle of the humerus. The muscles of the
The contents of the anterior (flexor) compartment of deep layer arise from the backs of the radius, ulna and interosseous
the forearm membrane (see Muscle index, p. 162).
• Muscles (Fig. 37.1): the muscles within this compartment are con- • Arteries: posterior interosseous artery (branch of the common
sidered in superficial, intermediate and deep layers. All of the muscles interosseous artery).
of the superficial group and part of flexor digitorum superficialis arise • Nerve supply: posterior interosseous nerve (branch of the radial
from the common flexor origin on the medial epicondyle of the nerve) (Fig. 37.3).
humerus. With the exceptions of flexor carpi ulnaris and the ulnar half

The forearm 85