• Assess swallowing with a water swallow test (p. 132).
Unilateral lower motor XII nerve lesions lead to tongue wasting
on the affected side and deviation to that side on protrusion (Fig.
7.14). Bilateral lower motor neurone damage results in global
wasting, the tongue appears thin and shrunken and fasciculation
may be evident. Normal rippling or undulating movements may be
mistaken for fasciculation, especially if the tongue is protruded;
these usually settle when the tongue is at rest in the mouth.
When associated with lesions of the IX, X and XI nerves, typically
in motor neurone disease, these features are termed bulbar
Unilateral upper motor XII nerve lesions are uncommon; bilateral
lesions lead to a tongue with increased tone (spastic) and the
patient has difficulty flicking the tongue from side to side. Bilateral
upper motor lesions of the IX–XII nerves are called pseudobulbar
palsy (see Box 7.5). Tremor of the resting or protruded tongue
may occur in Parkinson’s disease, although jaw tremor is more
common. Other orolingual dyskinesias (involuntary movements
of the mouth and tongue) are often drug-induced and include
tardive dyskinesias due to neuroleptics.
The principal motor pathway has CNS (corticospinal or pyramidal
tract – upper motor neurone) and PNS (anterior horn cell –
lower motor neurone) components (Fig. 7.15). Other parts of
The accessory nerve has two components:
• a cranial part closely related to the vagus (X) nerve
• a spinal part that provides fibres to the upper trapezius
muscles, responsible for elevating (shrugging) the
shoulders and elevation of the arm above the horizontal,
and the sternomastoid muscles that control head turning
The spinal component is discussed here.
The spinal nuclei arise from the anterior horn cells of C1–5.
Fibres emerge from the spinal cord, ascend through the foramen
magnum and exit via the jugular foramen (see Fig. 7.5), passing
• Face the patient and inspect the sternomastoid muscles
for wasting or hypertrophy; palpate them to assess their
• Stand behind the patient to inspect the trapezius muscle
• Ask the patient to shrug their shoulders, then apply
downward pressure with your hands to assess the
• Test power in the left sternomastoid by asking the patient
to turn their head to the right while you provide resistance
with your hand placed on the right side of the patient’s
chin. Reverse the procedure to check the right
• Test both sternocleidomastoid muscles simultaneously by
asking the patient to flex their neck. Apply your palm to
Isolated XI nerve lesions are uncommon but the nerve may
be damaged during surgery in the posterior triangle of the neck,
penetrating injuries or tumour invasion. Wasting of the upper fibres
of trapezius may be associated with displacement (‘winging’) of the
upper vertebral border of the scapula away from the spine, while
the lower border is displaced towards it. Wasting and weakness
of the sternomastoids are characteristic of myotonic dystrophy.
Weakness of neck flexion or extension, the latter causing head
drop, may occur in myasthenia gravis, motor neurone disease
and some myopathies. Dystonic head postures causing antecollis
(neck flexed), retrocollis (neck extended) or torticollis (neck twisted
to one side) are not associated with weakness.
The XII nerve innervates the tongue muscles; the nucleus lies
in the dorsal medulla beneath the floor of the fourth ventricle.
The nerve emerges anteriorly and exits the skull in the hypoglossal
canal, passing to the root of the tongue (see Fig. 7.5).
• Ask the patient to open their mouth. Look at the tongue at
rest for wasting, fasciculation or involuntary movement.
Fig. 7.14 Left hypoglossal nerve lesion. From Epstein O, Perkin GD, de
Bono DP, et al. Clinical Examination. 2nd edn. London: Mosby; 1997.
The group of muscle fibres innervated by a single anterior
horn cell forms a ‘motor unit’. A lower motor neurone lesion
causes weakness and wasting in these muscle fibres, reduced
tone (flaccidity), fasciculation and reduced or absent reflexes.
The basal ganglia are connected structures within the cerebral
hemispheres and brainstem (Fig. 7.16). They include the caudate
nucleus and putamen (collectively known as the striatum), globus
pallidus, thalamus, subthalamic nucleus and substantia nigra
(the latter in the brainstem). The basal ganglia receive much
information from the cortex and are involved in regulating many
activities, principally control of movement, but are also involved
in eye movement, behaviour and executive function control.
Disorders of the basal ganglia may cause reduced movement
(typically Parkinsonism; p. 135) or, less commonly, excessive
movement such as ballism or tics (p. 137).
Assess the motor system using the following method:
• assessment of stance and gait
• inspection and palpation of muscles
Stance and gait depend on intact visual, vestibular, sensory,
corticospinal, extrapyramidal and cerebellar pathways, together
with functioning lower motor neurones and spinal reflexes.
Non-neurological gait disorders are discussed in on page 259.
Certain abnormal gait patterns are recognisable, suggesting
diagnoses (Box 7.7 and Fig. 7.17).
• Ask the patient to stand with their (preferably bare) feet
• Swaying, lurching or an inability to stand with the feet
together and eyes open suggests cerebellar ataxia.
• Ask the patient to close their eyes (Romberg’s test) but be
prepared to steady/catch them. Repeated falling is a
Fig. 7.15 Principal motor pathways.
7.6 Features of motor neurone lesions
Inspection Usually normal (may
Weakness Preferentially affects
Deep tendon reflexes Increased Decreased/absent
Plantar response Extensor (Babinski
the nervous system, such as the basal ganglia and cerebellum,
have important modulating effects on movement. It is important
to distinguish upper from lower motor neurone signs to help
localise the lesion (Box 7.6).
If the lesion affects the CNS pathways, the lower motor neurones
are under the uninhibited influence of the spinal reflex. The motor
units then have an exaggerated response to stretch with increased
tone (spasticity), clonus and brisk reflexes. There is weakness but
not wasting (although atrophy may develop with longstanding
lesions). Primitive reflexes, such as the plantar extensor response
(Babinski sign), may be present.
Motor fibres, together with input from other systems involved in
the control of movement, including extrapyramidal, cerebellar,
vestibular and proprioceptive afferents, converge on the cell
bodies of lower motor neurones in the anterior horn of the grey
matter in the spinal cord (Fig. 7.15).
behind the patient, deliver a brisk push forwards or pull
backwards. You must be ready to catch them if they are
unable to maintain their balance. If in doubt, have an
assistant standing in front of the patient.
• Look at the patient’s shoes for abnormal wear patterns.
• Time the patient walking a measured 10 metres, with a
walking aid if needed, turning through 180 degrees and
• Note stride length, arm swing, steadiness (including
turning), limping or other difficulties.
• Look for abnormal movements that may be accentuated
by walking such as tremor (in Parkinson’s disease) or
• Listen for the slapping sound of a foot-drop gait.
• Ask the patient to walk first on their tiptoes, then heels.
Ankle dorsiflexion weakness (foot drop) is much more
common than plantar flexion weakness, and makes
walking on the heels difficult or impossible.
• Ask the patient to walk heel to toe in a straight line
(tandem gait). This emphasises gait ataxia and may be the
only abnormal finding in midline cerebellar (vermis) lesions.
Unsteadiness on standing with the eyes open is common in
cerebellar disorders. Instability that only occurs, or is markedly
worse, on eye closure (Romberg’s sign) indicates proprioceptive
sensory loss (sensory ataxia) or bilateral vestibular failure. Cerebellar
ataxia is not usually associated with a positive Romberg test.
Hemiplegic gait (unilateral upper motor neurone lesion) is
characterised by extension at the hip, knee and ankle and
circumduction at the hip, such that the foot on the affected
side is plantar flexed and describes a semicircle as the patient
walks. The upper limb may be flexed (Fig. 7.17A).
Bilateral upper motor neurone damage causes a scissor-like gait
due to spasticity. Cerebellar dysfunction leads to a broad-based,
unsteady (ataxic) gait, which usually makes walking heel to toe
impossible. In Parkinsonism, initiation of walking may be delayed;
the steps are short and shuffling with loss/reduction of arm
swing (Fig. 7.17D). A tremor may become more apparent. The
stooped posture and impairment of postural reflexes can result
in a festinant (rapid, short-stepped, hurrying) gait. As a doorway
or other obstacle approaches, the patient may freeze. Turning
involves many short steps, with the risk of falls. Postural instability
on the pull test, especially backwards, occurs in Parkinsonian
syndromes. Proximal muscle weakness may lead to a waddling
positive result. Swaying is common and should not be
• The ‘pull test’ assesses postural stability. Ask the patient
to stand with their feet slightly apart. Inform them that you
are going to push them forwards or pull them backwards.
They should maintain their position if possible. Standing
Fig. 7.16 Basal ganglia. A Anatomical location. B Coronal view.
Gait disturbance Description Causes
Gait apraxia Small, shuffling steps
Spastic Stiff ‘walking-throughmud’ or scissors gait
Foot drop Foot slapping Neuropathies
Central ataxia Wide-based, ‘drunken’
Functional Variable, often bizarre,
such as professional sports players, may have physiological
muscle hypertrophy. Pseudohypertrophy may occur in muscular
dystrophy but the muscles are weak.
Fasciculations are visible irregular twitches of resting muscles
caused by individual motor units firing spontaneously. This occurs
in lower motor neurone disease, usually in wasted muscles.
Fasciculation is seen, not felt, and you may need to observe
carefully for several minutes to be sure that it is not present.
Physiological (benign) fasciculation is common, especially in the
calves, but is not associated with weakness or wasting. Myokymia
– fine, involuntary fascicular contractions – involves rapid bursts
of repetitive motor unit activity that often affects orbicularis oculi
or the first dorsal interosseus, and is rarely pathological.
These are sudden, shock-like contractions of one or more muscles
that may be focal or diffuse and occur singly or repetitively.
Healthy people commonly experience these when falling asleep
(hypnic jerks). They may also occur pathologically in association
with epilepsy, diffuse brain damage and some neurodegenerative
disorders such as prion diseases. Negative myoclonus (asterixis)
is seen most commonly in liver disease (liver flap).
gait with bilateral Trendelenburg signs (see p. 259 and Fig. 13.37).
Bizarre gaits, such as when patients drag a leg behind them,
are often functional but some diseases, including Huntington’s
disease, produce unusual and chaotic gaits.
Inspection and palpation of the muscles
• Completely expose the patient while maintaining their
• Look for asymmetry, inspecting both proximally and
distally. Note deformities, such as flexion deformities or
• Inspect for wasting or hypertrophy, fasciculation and
Lower motor neurone lesions may cause muscle wasting. This
is not seen in acute upper motor neurone lesions, although
disuse atrophy may develop with longstanding lesions. A motor
neurone lesion in childhood may impair growth (causing a smaller
limb or hemiatrophy) or lead to limb deformity, such as pes
cavus. Muscle disorders usually result in proximal wasting (the
notable exception is myotonic dystrophy, in which it is distal,
often with temporalis wasting). People in certain occupations,
Foot is dragged or lifted high
C Sensory or cerebellar ataxia
based. Feet are thrown forward
In sensory ataxia, patients watch
steadily (positive Romberg sign)
In cerebellar ataxia, turns are
stand steadily with feet together
and patient is slow in getting
Caused by lesions in the basal
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