Authors: Lewis, Steven L.
Title: Field Guide to the Neurologic Examination, 1st Edition
Copyright ©2004 Lippincott Williams & Wilkins
> Table of Contents > Section 2
– Neurologic Examination > Cranial Nerve Examination > Chapter 21
– Examination of the Sternocleidomastoid and Trapezius Muscles
– Neurologic Examination > Cranial Nerve Examination > Chapter 21
– Examination of the Sternocleidomastoid and Trapezius Muscles
Chapter 21
Examination of the Sternocleidomastoid and Trapezius Muscles
PURPOSE
The main purpose of the examination of the
sternocleidomastoid and trapezius muscles is to assess for dysfunction
of the spinal accessory (eleventh) nerve.
sternocleidomastoid and trapezius muscles is to assess for dysfunction
of the spinal accessory (eleventh) nerve.
WHEN TO EXAMINE THE STERNOCLEIDOMASTOID AND TRAPEZIUS MUSCLES
Testing of the sternocleidomastoid and trapezius muscles
does not need to be performed routinely, but they should be tested in
the rare situation when a unilateral lesion of the spinal accessory
nerve is suspected. It is also appropriate to test the function of
these proximal muscles when assessing for a myopathy or other diffuse
neuromuscular process.
does not need to be performed routinely, but they should be tested in
the rare situation when a unilateral lesion of the spinal accessory
nerve is suspected. It is also appropriate to test the function of
these proximal muscles when assessing for a myopathy or other diffuse
neuromuscular process.
NEUROANATOMY OF THE STERNOCLEIDOMASTOID AND TRAPEZIUS MUSCLES
The sternocleidomastoid and trapezius muscles are
innervated by the spinal accessory nerve (the spinal portion of the
eleventh cranial nerve); this is an unusual cranial nerve because its
nuclei originate in the high cervical cord rather than the brainstem.
The left sternocleidomastoid muscle turns the head to the right, and
the right muscle turns the head to the left; the trapezius muscles
shrug the shoulders upward.
innervated by the spinal accessory nerve (the spinal portion of the
eleventh cranial nerve); this is an unusual cranial nerve because its
nuclei originate in the high cervical cord rather than the brainstem.
The left sternocleidomastoid muscle turns the head to the right, and
the right muscle turns the head to the left; the trapezius muscles
shrug the shoulders upward.
EQUIPMENT NEEDED TO TEST THE STERNOCLEIDOMASTOID AND TRAPEZIUS MUSCLES
None.
HOW TO EXAMINE THE STERNOCLEIDOMASTOID AND TRAPEZIUS MUSCLES
-
To test sternocleidomastoid muscle
strength, ask the patient to rotate his or her head to one side. Hold
your hand on the patient’s chin, attempting to overcome the patient’s
head turn by pushing toward the opposite side. Repeat the same maneuver
with the patient turning the opposite direction. -
To test trapezius muscle strength, ask
the patient to shrug his or her shoulders upward. Push down on the
patient’s shoulders while asking the patient to resist your downward
pressure.
NORMAL FINDINGS
Normally, there should be symmetric and strong
resistance to your attempt to overcome the patient’s
sternocleidomastoid and trapezius strength.
resistance to your attempt to overcome the patient’s
sternocleidomastoid and trapezius strength.
P.65
ABNORMAL FINDINGS
-
Weakness of head turn to one side is
consistent with contralateral sternocleidomastoid muscle weakness. In
other words, weakness of head turn to the left is consistent with
weakness of the right sternocleidomastoid muscle due to a lesion of the
right eleventh nerve. -
Weakness of shoulder shrug on either side
is consistent with ipsilateral trapezius muscle weakness. In other
words, weakness of left shoulder shrug is consistent with weakness of
the left trapezius muscle due to a lesion of the left eleventh nerve. -
In addition to weakness, atrophy of the
sternocleidomastoid or trapezius muscles may be seen when there is a
lesion of the eleventh cranial nerve. -
Bilateral weakness of the
sternocleidomastoid and trapezius muscles may be seen as a result of
proximal muscle weakness from neuromuscular disease.
ADDITIONAL POINTS
-
Lesions of the spinal accessory nerve are
rare but may occur when the nerve is sectioned iatrogenically (such as
during a lymph node resection) or as a result of trauma. -
In the absence of a strong clinical
suspicion for a lesion of these nerves or a clinical suspicion for neck
and shoulder weakness due to neuromuscular disease, testing the
function of these muscles does not add much to the neurologic
examination and can usually be skipped.