Bones of the forearm and hand pdf - Upper limb

378

CHAPTER 9

The Upper Limb

ligament of the elbow joint. It continues downward to enter

of the fossa is formed by the supinator muscle

floor

The

drawn between the two epicondyles of the humerus.

of the triangle is formed by an imaginary line

The

The pronator teres muscle

Medially:

The brachioradialis muscle

Laterally:

of the elbow (Figs. 9.47 and 9.48).

The cubital fossa is a triangular depression that lies in front

elbow joint.

brachial artery and take part in the anastomosis around the

superior and inferior ulnar collateral arteries arise from the

The

Superior and Inferior Ulnar Collateral Arteries

sis around the elbow joint.

supplies the triceps muscle, and takes part in the anastomo

It accompanies the radial nerve through the spiral groove,

arises from the brachial artery near its origin (Fig. 9.45).

The profunda brachii artery

Profunda Brachii Artery

(Fig. 9.23).

The ulnar nerve has an articular branch to the elbow joint

Branches

carpi ulnaris (see page 390).

the forearm between the two heads of origin of the flexor

The Cubital Fossa

Boundaries

■

base

bicipital

aponeurosis

basilic vein

palmaris

longus

flexor

digitorum

superficialis

flexor carpi

ulnaris

pisiform

bone

biceps

brachii

biceps brachii tendon

cubital fossa

brachioradialis

cephalic vein

flexor carpi

radialis

site fo

palpati

of radi

artery

FIGURE 9.48

The cubital fossa and anterior surface of the

forearm in a 27-year-old man.

laterally and the brachialis muscle medially. The

joint and with the head of the radius at the proximal

proximal end articulates with the humerus at the elbow

The ulna is the medial bone of the forearm (Fig. 9.49). Its

radius are shown in Figure 9.49.

The important muscles and ligaments attached to the

of the extensor pollicis longus (Fig. 9.49).

which is grooved on its medial side by the tendon

tubercle,

dorsal

terior aspect of the distal end is a small tubercle, the

articulates with the scaphoid and lunate bones. On the pos

the round head of the ulna. The inferior articular surface

which articulates with

ulnar notch,

medial surface is the

projects distally from its lateral margin (Fig. 9.49). On the

styloid process;

At the distal end of the radius is the

its lateral side.

tion of the pronator teres muscle, lies halfway down on

for the inser

pronator tubercle,

and ulna together. The

ment of the interosseous membrane that binds the radius

medially for the attach

interosseous border

has a sharp

of the ulna, is wider below than above (Fig. 9.49). It

The shaft of the radius, in contradistinction to that

for the insertion of the biceps muscle.

bicipital tuberosity

Below the neck is the

neck.

to form the

notch of the ulna. Below the head, the bone is constricted

The circumference of the head articulates with the radial

and articulates with the convex capitulum of the humerus.

(Fig. 9.49). The upper surface of the head is concave

head

At the proximal end of the radius is the small circular

radioulnar joint.

of the hand at the wrist joint and with the ulna at the distal

distal end articulates with the scaphoid and lunate bones

joint and with the ulna at the proximal radioulnar joint. Its

Its proximal end articulates with the humerus at the elbow

The radius is the lateral bone of the forearm (Fig. 9.49).

The forearm contains two bones: the radius and the ulna.

nodes (Fig. 9.40).

pass up to the axilla and enter the lateral axillary group of

the medial side of the forearm. The efferent lymph vessels

fourth, and fifth fingers; the medial part of the hand; and

(Fig. 9.40). It receives afferent lymph vessels from the third,

fascia over the upper part of the fossa, above the trochlea

lies in the superficial

supratrochlear lymph node

The

and the radial nerve and its deep branch.

ulnar and radial arteries, the tendon of the biceps muscle,

median nerve, the bifurcation of the brachial artery into the

tures, enumerated from the medial to the lateral side: the

The cubital fossa (Fig. 9.47) contains the following struc

aponeurosis.

formed by skin and fascia and is reinforced by the bicipital

roof

Contents

Bones of the Forearm

Radius

this

Ulna

Basic Anatomy

379

radioulnar joint. Its distal end articulates with the radius at

bone, however, should be studied, because it is commonly

unnecessary. The position, shape, and size of the scaphoid

A detailed knowledge of the bones of the hand is

when all the bones are ossified.

ers begin to ossify at intervals thereafter until the 12th year,

capitate begins to ossify during the first year, and the oth

The bones of the hand are cartilaginous at birth. The

fingers.

passage of the median nerve and the flexor tendons of the

is formed for the

carpal tunnel,

osteofascial tunnel, the

In this manner, an

flexor retinaculum.

band called the

medial edges of which is attached a strong membranous

on their anterior surface a concavity, to the lateral and

bones. Together, the bones of the carpus present

hamate

and

trapezium, trapezoid, capitate,

eral to medial) the

consists of (from lat

distal row

bones. The

pisiform

scaphoid, lunate, triquetral,

(from lateral to medial) the

consists of

proximal row

four (Figs. 9.51 and 9.52). The

There are eight carpal bones, made up of two rows of

ulna are shown in Figure 9.49.

The important muscles and ligaments attached to the

cess (Fig. 9.49).

which has projecting from its medial aspect the styloid pro

head,

At the distal end of the ulna is the small rounded

muscle.

that gives origin to the supinator

supinator crest

palpated throughout its length. Below the radial notch

border is rounded and subcutaneous and can be easily

attachment of the interosseous membrane. The posterior

laterally for the

interosseous border

9.49). It has a sharp

of the ulna tapers from above down (Fig.

The

radius.

for articulation with the head of the

radial notch

which has on its lateral surface

coronoid process,

of the humerus. Below the trochlear notch is the trian

which articulates with the trochlea

trochlear notch,

nence of the elbow. It has a notch on its anterior surface,

(Fig. 9.49); this forms the promi

olecranon process

The proximal end of the ulna is large and is known as

joint by the articular disc.

the distal radioulnar joint, but it is excluded from the wrist

the

gular
the

shaft

is the

Bones of the Hand

and

fractured. The ridge of the trapezium and the hook of the
hamate should be examined.

olecranon process

radial notch of ulna

head

neck

bicipital tuberosity

biceps brachii

oblique cord

supinator

flexor digitorum

superficialis

pronator teres

flexor pollicis

longus

pronator quadratus

brachioradialis

styloid process

aperture for anterior

interosseous artery

extensor indicis

extensor pollicis longus

flexor
digitorum

profundus

aponeurosis for extensor

and flexor carpi ulnaris

flexor pollicis longus

pronator teres

brachialis

coronoid process

capsule of elbow joint

triceps

anconeus

biceps

supinator

abductor pollicis

longus

extensor pollicis

brevis

dorsal tubercle of

radius

anterior surface

posterior surface

interosseous membrane

capsule of wrist joint

styloid process

aperture for anterior

interosseous artery

extensor indicis

extensor pollicis longus

flexor
digitorum

profundus

aponeurosis for extensor

and flexor carpi ulnaris

flexor pollicis longus

pronator teres

brachialis

coronoid process

anc

interosseous membrane

styloid process

FIGURE 9.49

Important muscular and ligamentous attachments to the radius and the ulna.

380

CHAPTER 9

The Upper Limb

Fractures of the Radius and Ulna

A small subcutaneous bursa is present over the olecranon pro

Colles’ fracture because the distal fragment is displaced anteri

is a fracture of the distal end of the radius

Colles’ fracture

process can be produced by the pull of the triceps muscle. Good

the pull of the triceps muscle, which is inserted on the olecranon

the proximal third of the radius is fractured

Galeazzi’s fracture,

the shaft of the ulna is fractured by a force applied from behind.

supination, the normal anatomic relationship of the radius, ulna,

fragment of the radius is pronated and pulled medially by the

can occur from falls on the

Fractures of the head of the radius

outstretched hand. As the force is transmitted along the radius,

the head of the radius is driven sharply against the capitulum,

splitting or splintering the head (Fig. 9.10).

Fractures of the neck of the radius occur in young children

from falls on the outstretched hand (Fig. 9.10).

Fractures of the shafts of the radius and ulna may or may

not occur together (Fig. 9.10). Displacement of the fragments is

usually considerable and depends on the pull of the attached

muscles. The proximal fragment of the radius is supinated by the

supinator and the biceps brachii muscles (Fig. 9.10). The distal

pronator quadratus muscle. The strength of the brachioradialis

and extensor carpi radialis longus and brevis shortens and angu-

lates the forearm. In fractures of the ulna, the ulna angulates

posteriorly. To restore the normal movements of pronation and

and interosseous membrane must be regained.

A fracture of one forearm bone may be associated with a dis-

location of the other bone. In Monteggia’s fracture, for example,

There is a bowing forward of the ulnar shaft and an anterior dis-

location of the radial head with rupture of the anular ligament. In

and the distal end of the ulna is dislocated at the distal radioulnar

joint.

Fractures of the olecranon process can result from a fall on

the flexed elbow or from a direct blow. Depending on the loca-

tion of the fracture line, the bony fragment may be displaced by

process (Fig. 9.10). Avulsion fractures of part of the olecranon

functional return after any of these fractures depends on the

accurate anatomic reduction of the fragment.

resulting from a fall on the outstretched hand. It commonly

occurs in patients older than 50 years. The force drives the dis-

tal fragment posteriorly and superiorly, and the distal articular

surface is inclined posteriorly (Fig. 9.50). This posterior displace-

ment produces a posterior bump, sometimes referred to as the

“dinner-fork deformity” because the forearm and wrist resemble

the shape of that eating utensil. Failure to restore the distal artic-

ular surface to its normal position will severely limit the range of

flexion of the wrist joint.

Smith’s fracture is a fracture of the distal end of the radius

and occurs from a fall on the back of the hand. It is a reversed

orly (Fig. 9.50).

Olecranon Bursitis

cess of the ulna, and repeated trauma often produces chronic

bursitis.

C L I N I C A L N O T E S

FIGURE 9.50

Fractures of the distal end of the radius.

of the medial cutaneous nerve of the forearm (Fig. 9.38).

neous nerve, and from the anterior and posterior branches

nerve of the forearm, a continuation of the musculocuta

the anterior and posterior branches of the lateral cutaneous

to the skin of the forearm is from

sensory nerve supply

The

hand and fingers are shown in Figures 9.51 and 9.52.

The important muscles attached to the bones of the

only two for the thumb.

There are three phalanges for each of the fingers but

surfaces are posterior, lateral, and medial.

concave forward and is triangular in transverse section. Its

and 9.52). The shaft of each metacarpal bone is slightly

knuckles, articulate with the proximal phalanges (Figs. 9.51

distal row of the carpal bones; the heads, which form the

The bases of the metacarpal bones articulate with the

surface is directed laterally and not backward.

rotated medially through a right angle so that its extensor

the others but occupies a more anterior position. It is also

est and most mobile. It does not lie in the same plane as

The first metacarpal bone of the thumb is the short

(Figs. 9.51 and 9.52).

head

There are five metacarpal bones, each of which has a

Smith’s fracture.

Colles’ fracture.

The Metacarpals and Phalanges

base,

a shaft, and a

The Forearm

Skin

A narrow strip of skin down the middle of the

ior

poster

surface of the forearm is supplied by the posterior cutaneous

lateral side of the dorsal venous arch on the back of the

arises from the

cephalic vein

ficial fascia (Fig. 9.39). The

of the forearm lie in the super

superficial veins

The

nerve of the forearm.