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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5833_Библиотеки_им_академика_М_И_Перельмана.pdf
4 Wrist
46
Fig. 4.1a Scheme of the proximal carpal tunnel. FCR, flexor carpi radialis tendon; FCU, flexor carpi ulnaris tendon;
m, median nerve; a, ulnar artery; u, ulnar nerve; FPL, flexor pollicis longus tendon; circles, flexor digitorum superfi-
cialis tendons ; *, flexor digitorum profundus tendons; arrowheads, retinaculum; ST, scaphoid tubercle; Pi, pisiform;
L, lunate; T, triquetral bone
Fig. 4.1b Scheme of the distal carpal tunnel. FCR, flexor carpi radialis tendon; m, median nerve; a, ulnar artery; s,
superficial sensitive branch of the ulnar nerve; d, deep motor branch of the ulnar nerve; FPL, flexor pollicis longus
tendon; circles, flexor digitorum superficialis tendons; *, flexor digitorum profundus tendons; arrowheads, retinacu-
lum; T, tubercle of trapezium; t, trapezoid; C, capitate; H, hook of the hamate
Palmar Side
47
Fig. 4.2 Position of the wrist to
evaluate the ventral compart-
ment
Fig. 4.3b Axial scan of the proximal section of carpal tunnel. Sc, scaphoid; Pi, pisiform; L, lunate. The arrow shows
the median nerve between flexor retinaculum (arrowheads) and flexor digitorum superficialis (circles) and profundus
(*) tendons. Note the “arched” appearance of the retinaculum and at the oval shape of the median nerve. FCR, flexor
carpi radialis tendon; ua, ulnar artery; UN, ulnar nerve; FPL, flexor pollicis longus tendon; FCU, flexor carpi ulnaris
tendon
Fig. 4.3a Probe position to eval-
uate the proximal section of the
carpal tunnel
4 Wrist
48
Fig. 4.4 This image series shows that a wrong
tilting of the probe (in a) can change the
echote
xture of the relevant tendons and nerves
due to sev
ere anisotropy artifacts (in b).
c and d show the correct probe position
and US image, respecti
vely
a
b
c
d
Palmar Side
49
Fig. 4.5a Probe position to eval-
uate the distal part of the carpal
tunnel
Fig. 4.5b Axial scan of the
distal carpal tunnel.
Arrow, median nerv
e;
H, hamate; T, trapezium.
The distal part of the tunnel
is smaller than the proximal
part, the flexor retinaculum
(arrowheads) is more flat
and the median nerve has a
smaller antero-posterior di-
ameter. a, ulnar artery;
FPL, flexor pollicis longus
tendon; circles, flexor digi-
torum superficialis tendons;
*, flexor digitorum
profundus tendons
Fig. 4.6 Longitudinal scan of the carpal tunnel shows the median nerve (*) over the flexor tendons (tt). Ca, capitate;
L, lunate
4.1.2 Guyon Tunnel and Ulnar Nerve
On the ulnar side of the carpal tunnel, the ulnar
artery can easily be detected (Figs. 4.7a, b).
The ulnar nerve courses along the artery with-
in the fibro-fibrous Guyon tunnel. Distally,
the ulnar nerve splits into a superficial sensi-
tive and deep motory branch (the latter run-
ning along the hook of the hamate).
4 Wrist
50
Fig. 4.7a Probe position to eval-
uate the Guyon tunnel
Fig. 4.7b Axial scan of ulnar nerve (arrowheads) between ulnar artery (Doppler signal in red) and pisiform (Pi)
4.2 Dorsal Side
4.2.1 Extensor Tendon Compartments
To maintain an anatomical order, the dorsal
extensor compartments are described below
from the radial to ulnar side, from the first to
sixth compartment (Fig. 4.8). However, note
that inexperienced operators should begin the
US evaluation of the dorsal aspect of the wrist
from a small bony landmark of the distal
radius (the Lister’s tubercle) that separates the
second and the third compartment. This is par-
ticularly true when common anatomical vari-
ants that change the number of tendons con-
tained in each compartment are encountered
(see below).
Palm must be placed on the table, in a neu-
tral position (Fig. 4.9), except for the evalua-
tion of the I and the VI compartments (see
below). A small pillow can be placed under
the wrist to improve the visibility of extensor
tendons (Fig. 4.10).
The probe must be placed on a transverse
plane on the dorsal side of wrist to detect the
six extensor tendon compartments on the short
axis. Compartments are numbered from I to
VI beginning from the radial side.
Each tendon must be scanned on the short
axis, followed up to its distal insertion and
also scanned during dynamic maneuvers (fin-
ger flexion and extension).
4.2.1.1 First Compartment
The first compartment contains the abductor
pollicis longus (radial) and extensor pollicis
brevis (ulnar) tendons (Fig. 4.11).
The position of tendons contained in the
first compartment can be easily detected by
visual inspection, as they form the radial edge
of the anatomical snuff box (Fig. 4.12a). The
wrist must be kept in an intermediate position
between pronation and supination and the
probe must be placed on the lateral side of
radial styloid (Fig. 4.12b). The retinaculum
contains the two tendons (Fig. 4.12c). Follow
the abductor pollicis longus up to its inser-
tion onto the scaphoid and check if there is an
accessory tendon.
Sometimes the tendon sheath is split into
two parts by a fibrous hyperechoic septum
that separates the two tendons. This septum
can be seen when evaluating the compartment
on the short axis.
The detection of accessory tendons and of
the fibrous septum is important as they can
favor the occurrence of tenosynovitis.
The abductor pollicis longus is the most lat-
eral of the deep muscles in the posterior com-
partment of the forearm. It arises from the
dorsal side of ulna, distally to the supinator
crest, from the interosseous membrane and
from the dorsal side of the radius. Its distal
tendon crosses the second extensor tendon
compartment and takes insertion on the first
metacarpal bone. Some fibers also insert onto
the trapezium and others join the extensor pol-
licis brevis tendon.
The extensor pollicis brevis is a deep mus-
cle of the posterior compartment of the
forearm. At this level, it is medial to the
abductor pollicis longus muscle. It arises
from the ulna, the interosseous membrane,
and the dorsal side of the radius. Its distal
tendon crosses the second extensor tendon
compartment and inserts on the proximal
phalanx of the thumb.
Dorsal Side
51
4 Wrist
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Fig. 4.9 Wrist position to
evaluate the dorsal side
Fig. 4.10 Position of the wrist on a small
pillow to improve the visibility of the
extensor tendons
Fig. 4.8 Panoramic anatomical scheme of the extensor tendon compartments. APL, abductor pollics longus tendon;
EPB, extensor pollicis brevis tendon; ECRL, extensor carpi radialis longus tendon; ECRB, extensor carpi radialis bre-
vis tendon; EPL, extensor pollicis longus tendon; EIP, extensor indicis proprius tendon; EDC, extensor digitorum
communis tendon; EDQ, extensor digiti quinti tendon; ECU, extensor carpi ulnaris tendon; R, radis; U, ulna
Dorsal Side
53
Fig. 4.12a Anatomical
snuff box (*). Radial side:
abductor pollicis longus
and extensor pollicis bre-
vis (arrowheads); ulnar
side: extensor pollicis
longus (arrows)
Fig. 4.12b Probe position
to evaluate the first exten-
sor compartment
Fig. 4.12c Axial scan of
the first compartment:
APL, abductor pollicis
longus tendon; EPB,
extensor pollicis brevis
tendon; V, cephalic vein;
R, radius. Note that the
location of the cephalic
vein can be extremely
variable
Fig. 4.11 Anatomical scheme of the first extensor
compartment; APL, abductor pollicis longus tendon;
EPB, extensor pollicis brevis tendon; R, radius
4.2.1.2 Second Compartment
The second compartment (Fig. 4.13) contains
the extensor carpi radialis longus (radial)
and the extensor carpi radialis brevis (ulnar)
tendons.
The wrist must be set with the palm placed
on the table. The probe must be aligned on an
axial plane on the radial side (Figs. 4.14a, b).
Move the probe cranially up to the
myotendinous junction, where tendons of the
first compartment cross over the tendons of
the second compartment (Fig. 4.15). This
intersection is critical, especially in subjects
that perform repetitive movements of the hand
(e.g., oarsmen), who develop the so-called
“intersection syndrome”. The presence of a
small bursa can also be detected. This patho-
logic condition can be confused with the more
common De Quervain tenosynovitis that typi-
cally affects the first compartment.
The extensor carpi radialis longus muscle
arises from the anterior aspect of the later-
al side of the humerus, the lateral epi-
condyle, and the lateral intermuscular sep-
tum. The muscle is very small and immedi-
ately becomes a tendon that runs on the lat-
eral side of the radius, reaching the second
extensor tendon compartment, finally
inserting on the dorsal aspect of the second
metacarpal bone.
The extensor carpi radialis brevis muscle
arises from the anterior aspect of the later-
al epicondyle, the antebrachial fascia, the
radial collateral ligament, and the intermus-
cular septum. The muscle is very small and
immediately becomes a tendon that runs on
the lateral aspect of the radius along with
the extensor carpi radialis longus tendon.
Distally, it inserts on the dorsal aspect of
the third metacarpal bone.
4 Wrist
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Fig. 4.13 Anatomical scheme of the second extensor
compartment: ECRL, extensor carpi radialis longus
tendon; ECRB, extensor carpi radialis brevis tendon
Dorsal Side
55
Fig. 4.14a Probe position to evaluate the second exten-
sor compartment
Fig. 4.14b Axial scan of the second compartment. ECRB, extensor carpi radialis brevis tendon; ECRL, extensor carpi
radialis longus tendon; EPL, extensor pollicis longus tendon; L, Lister’s tubercle
Fig. 4.15 Axial scans at the distal third of the forearm show the intersection between the first (I) and second (II) exten-
sor tendon compartment