SPINAL ACCESSORY NERVE,
CRANIAL NERVE XI
- Anatomy:The trapezius, the major muscle supplied
by the spinal accessory nerve, is a significant scapular
stabilizer and thereby critical for the maintenance of
efficient shoulder function (Ewing and Martin, 1952).
The spinal component of cranial nerve(CN) XI orig-
inates from the anterior horn cells of the cervical
spinal cord (C1–C5). Fibers enter the skull through
the foramen magnum and leave the skull through the
jugular foramen. There is somatotopical arrangement
with the fibers arising from C1 and C2 mainly inner-
vating the sternocleidomastoid muscles while those
arising from C3 and C4 constitute the nerve supply for
the trapezius. In the neck, the spinal accessory nerve
passes through the posterior triangle after giving off a
branch to the sternocleidomastoid muscle. It then sup-
plies the trapezius muscle. - Risk factors:Intracranial—head injuries. Intraspinal
cord—post traumatic syrinx.
1.Cervical:Sports injuries involving percussion or
compression in the posterior triangle of the neck,
such as through ill fitting shoulder pads in football
(stingers/burners) (Di Benedetto and Markey,
1984; Markey, Di Benedetto, and Curl, 1993),
blows to the shoulder (e.g., with a hockey stick),
compression with backpack straps, and shoulder
dislocation.
2. Traumatic penetrating injuries to the neck, atrau-
matic iatrogenic lesions, acute or delayed, mainly
after radical neck dissections or lymph node biop-
sies, cannulation of the internal jugular vein or after
carotid enterarterectomies (due to hemorrhages,
hematomas, malpositioned suction drainage, infec-
tion, or scarring).
3. Atraumatic weakness of trapezius must rule out
neurologic or myopathic disease. - Symptoms and signs:Shoulder syndrome (accessory
nerve lesion) consists of shoulder drooping, acromion
prominence, and limited lateral abduction, impaired
forward shoulder flexion, aberrant scapular rotation,
and abnormal scapulohumeral rhythm (Codman,
1934), pain and abnormal electromyographic findings.
Significant pain and tenderness over trapezius, exacer-
bated by shoulder movement, and a feeling of heavi-
ness in the affected arm may be present. Patients have
difficulty with overhead activities, heavy lifting, pro-
longed writing, or driving. The patient may have
impingement pain secondary to inability to rotate the
scapula, thereby causing the greater tuberosity to abut
the acromion (Bigliani et al, 1996). Late onset of pain
is mostly due to adhesive capsulitis, a common sequela
of spinal accessory nerve injury.- Test trapezius strength by resistance to lateral
abduction of the arm from about 100–180°with
the arm internally rotated and hand pronated
(Ewing and Martin, 1952) (check endurance).
Isolation of trapezius must be assured since shoul-
der elevation can also be accomplished with the
levator scapula and the rhomboids. Test strength of
sternocleidomastoid muscles by resisting head
turning, opposite to the side of the muscle tested.
Also test tilting. Resistance to head flexion tests
both sternocleidomostoid muscles at the same
time. Lateral scapular winging is not as pro-
nounced as with a long thoracic nerve lesion. The
scapula is laterally translocated with medial rota-
tion of the inferior angle.
- Test trapezius strength by resistance to lateral
- Treatment:Management includes range of motion
(ROM) exercises to prevent contractures. Resistive
exercises to restore strength to the shoulder girdle. If
no improvement, surgery. - Surgical intervention:Eden-Lange dynamic muscle
transfer is the procedure of choice. This consists of a
lateral transfer of the insertions of the levator scapu-
lae, rhomboids minor and rhomboids major muscles
(Lange, 1951; Wiater and Bigliani, 1999).
BRACHIAL PLEXUS- Brachial plexopathy secondary to sports or occupa-
tional injury mostly presents as compression, stretch,
or the combination of the two. - Other risk factors:Compression after prolonged anes-
thesia, postmedian sternotomy, coronary bypass sur-
gery, jugular vein cannulation, and Erb’s(birth) palsy.
Nontraumatic causes for sudden onset of shoulder pain
followed by weakness that has to be ruled out is
brachial plexitis (neuralgic amyotrophy) (Krivickas and
Wilbourne, 2000), which is believed to be a genetic dis-
order, or an inflammatory-immune response (Suarez et
al, 1996). In addition the brachial plexus may be
affected by space occupying lesions or radiation.
UPPER TRUNK PLEXOPATHY- Anatomy and origin:C5–C6 cervical nerve roots/
spinal nerves. In the upper trunk region the supras-
capular nerve and the nerve to the subclavius origi-
nate. The fibers to the musculocutaneous, axillary,
median, and radial nerve pass through. - The best known brachial plexus injury is the stinger
(burner) (Di Benedetto and Markey, 1984). - Risk factor:At risk are football players (highest inci-
dence in defensive backs), wrestlers and participants in
322 SECTION 4 • MUSCULOSKELETAL PROBLEMS IN THE ATHLETE