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APE 4: Muscles and their Actions – Tutor - 2016-17
Lesson Plan
Tutors
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Last week students covered the peripheral nervous system and learnt the
anatomy of the main limb nerves. They should now understand the difference
between a spinal nerve root and a peripheral nerve and should have learnt the
dermatomes.
This session should build on this to learn the myotomes and the motor
distribution of the nerves as well as learning to locate and test muscle groups.
They have been looking at muscles and tendons today in the DR and will have
covered origins and insertions
For All APE sessions
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The aim of APE is to teach clinical skills with surface anatomy. This is
not a re-teach of dissection room anatomy. Students must do this as
SDL and direct appropriate anatomical questions to the anatomists.
These sessions have been lovingly crafted by clinicians. If you have a
problem with the content or the way something is taught, please discuss
with me directly – we welcome your feedback – but do not change the
session
It is ok to say ‘I don’t know’ – you are not expected to know everything!
Ask me – I am always around
Please do not say ‘you need to do it this way for the OSCEs’. Exams are
important and motivate people, but this is not the point of these sessions.
Good clinical skills are for life, not just for OSCEs!
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APE 4: Muscles and their Actions – Tutor - 2016-17
Suggested
Timing
1
13.3013.35
(5 mins)
Activity
Introduction
 Introductions, register
 Run through objectives
Suggested
Timing
2
15.3015.35pm
(5mins)
13.3513.45
(10 mins)
Activity 1 – Muscles and tendon
 Help the students find the structures and help answer the
questions
15.3515.45
(10 mins)
13.4513.50
(5 mins)
13.5014.00
(10 mins)
Activity 2 – Muscle actions and compartments
 Work through the actions and questions with the students
Activity 3 – Revision of the PNS
 Using the ‘nerve roots’, conceptualise the PNS again
(done last week)
15.4515.50
(5 mins)
15.5016.00
(10 mins)
14.0014.15
(15 mins)
Activity 4 – Myotomes and PN - LL
 Introduce concepts
 Run through movements, naming nerves and myotomes
16.0016.15
(15 mins)
14.1514.30
(15 mins)
Activity 5 – Myotomes and PN - UL
 Introduce concepts
 Run through movements, naming nerves and myotomes
16.1516.30
(15 mins)
14.3014.45
(15 mins)
Activity 6 – Power testing
 Stage 2 demonstration of elbow flexion and extension
 Stage 4 in pairs; get them to do knee flexion and extension
 Ensure good technical practice
16.3016.45
(15 mins)
14.4515.00
(15 mins)
Activity 7 – Clinical context
 Work through the questions
 Keep concepts and terminology simple
16.4517.00
(10 mins)
Close and summarise
 Reiterate learning objectives, signpost SDL, answer any
questions
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APE 4: Muscles and their Actions – Tutor - 2016-17
Learning Objectives
At the end of this session, and with SDL, students should be able to:
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Identify certain landmark muscles and tendons
Identify key muscle groups and describe their actions
Define a muscle compartment
Understand the concept of a myotome
Identify the myotomes in the limbs
Know how to test muscle power
Dress Code
Shorts (or loose jogging bottoms) and t-shirts, so that legs can be
accessed from mid-thigh and arms from the shoulder.
PE
Overview
This session will explore the positions and actions of key muscles and tendons. You will
learn how muscles are arranged in groups and the principles of their nerve supply. You
will learn how to test a muscle.
Activity 1: Muscles and tendons (10 minutes)
You will have spent this morning naming and identifying muscles on the cadavers. You
also will have noted their attachment to the bones by tendons. We have found and
palpated some of these before…
With the help of your tutors, find the following on yourself and answer the questions
together:
Tutors –
Help them identify the following structures, get them to make the movements, and see and
feel the muscle contracting
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Patella tendon
o The patella is a sesamoid bone formed within the tendon substance.
o Other than the patella, what is the other bony landmark here?
o What muscle does this attach to? What is its action?
Tibial tuberosity = insertion of quadriceps – extension of the knee
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APE 4: Muscles and their Actions – Tutor - 2016-17
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Achilles tendon
o Which muscle does it attach to which bone?
o What is the action of this muscle?
Combined gastrocnemius and soleus tendons, attached to the calcaneus – plantarflexion
of ankle.
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Extensor hallucis longus tendon
o What is the action here? (the clue’s in the name!)
o Where is the muscle located?
Extension of the hallux/big toe; anterior lower leg – we will be using this landmark next
week.
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Sterno-cleido-mastoid
o What are the attachments here?
o This has a number of actions. Look over one of your shoulders. Which
muscle is working (left or right)? How would we describe this movement using
our technical nomenclature?
Help by breaking down name and deduction, Sterno= sternum, Cleido=clavicle and the
mastoid –get them to palpate all of these and ensure they have understood the 2 heads.
‘Contralateral’/opposite side SCM – get them to feel the muscle contacting. ‘Lateral
rotation of the head’ (other actions are lateral flexion and involved in flexion)
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Gluteus medius
o Get your tutor to help you find this by palpating the origin and insertion on the
right
o If the origin is fixed, what happens to the leg if the muscle contracts and
shortens?
o What now if the insertion is fixed? Ask your tutor why this is so important for
walking.
Tutors –
Get them all standing for this one
Origin = iliac crest, insertion = greater trochanter – get them to palpate these on the right.
If origin (ie pelvis) is fixed, a shortened, contracted muscle will abduct the leg – this one of
its main actions.
Get them to do this whilst feeling the muscle.
Now get them to put their weight on their RIGHT leg – the insertion is now fixed.
What happens to the pelvis if the muscle contracts? – it tilts, lifting up on the LEFT.
Get them to feel the muscle in action by raising and lowering the LEFT knee whilst feeling
the right Glut Med.
Please explain – with respect to walking, it is not so much that Glut Medius tilts the pelvis
up, but stops it from dropping on the left – this stabilizes the pelvis to allow us to …
Get them to walk feeling both Glut Med at once
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APE 4: Muscles and their Actions – Tutor - 2016-17
Activity 2: Muscle actions and compartments (5 minutes)
Muscles are often grouped in pairs that perform opposite actions, such as flexion and
extension, adduction and abduction. These are known as agonist and antagonist
muscles. As one contracts, the other relaxes.
1. Identify the flexors and extensors of the elbow. What compartments are these
located in?
Biceps brachii (brachialis, brachioradialis) – Anterior; Triceps brachii (Anconeus) Posterior
2. Do the same for the flexors and extensors of the knee – what are the muscles
called? What compartments are they in?
Flexors – hamstrings (biceps femoris; semi-membranosis; semi-tendinosis) –
posterior
Extensors – Quadriceps – anterior
What other compartment is there in the thigh? What does it contain?
Lateral - Hip adductors-adductor magnus, longus, brevis and gracilis. They can feel
these muscles contract using resisted hip adduction (push medial knee against hand)
It is important to note that most ‘compartments’ are supplied by the same nerves and
blood vessels.
3. Think back to the anatomy of the lower limb peripheral nerves from last week. Which
nerves do you think supply the flexor and extensor compartments of the thigh?
Extensors (anterior) – femoral; flexors (posterior) – sciatic (Lateral – obturaror)
We will come back to this idea later
Activity 3: Revision – Conceptualising the Peripheral Nervous
System (10 minutes)
Last week we used a model to help us visualize the peripheral nervous system – Let’s
do this again to remind us of the three main areas – nerve roots, plexus and
peripheral nerves.
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S3
S2
S1
L5
L4
L3
L2
Nerve Root
Lumbosacral Plexus
Sciatic
Femoral
Peripheral Nerve
APE 4: Muscles and their Actions – Tutor - 2016-17
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APE 4: Muscles and their Actions – Tutor - 2016-17
Tutors –
The aim of this exercise is to conceptualise the PNS more simplistically in 3 parts in order
to help understand the significance peripheral nerve testing in the neurology exam (i.e.
why we test certain areas and how this helps us localize pathology – reiterated in clinical
context activity
Last week we conceptualized the upper limb neurology; we will now consider the lower
limb (the principles remain the same):
Get them to draw the main peripheral nerves (in different colours)- give them the ‘root
values’/write on whiteboard (they do not need to know this by heart)
 Femoral L2, L3, L4
 Sciatic L4, L5, S1, S2, S3
There are many more peripheral nerves, but these are the main 2 we will be considering in
this session.
Once this has been done, please emphasise the 3 parts – Root/Plexus/Peripheral Nerve.
The pattern of loss for each area will be different on examination e.g. the sciatic nerve
contains fibres from a number of different roots, so if damaged will give different
examination findings compared with one nerve root being damaged.
As last week, please also remind them that these structures all contain both sensory
(afferent) fibres and motor (efferent) fibres, but today will be considering the motor part
only.
Activity 4: Myotomes and peripheral nerves – Lower Limb (15
minutes)
Tutors- please introduce the concepts below before moving on to the activity
Muscles have a segmental origin, like skin. The muscle tissue supplied by a single
spinal nerve root is a “myotome”. This is the motor equivalent of a dermatome.
Instead of testing areas of skin to assess integrity of a nerve root, we assess movements
and the power of the muscles performing those movements.
Look back to the answers you gave for the last question of Activity 2. Testing the
integrity of peripheral nerves is in the main straightforward, as one movement is mostly
supplied by one peripheral nerve.
Nerve roots however, as seen in the previous exercise, innervate a number of different
muscle groups and therefore will be involved in a number of movements.
Look at the picture below and run through all the movement with your tutor, reciting
the nerve roots (root value) and the peripheral nerve as you go.
Tutors- Run through below – get the students to do the movements, naming the main
peripheral nerve and root value of each
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APE 4: Muscles and their Actions – Tutor - 2016-17
Myotome groups of lower limb movements and respective nerve roots
Hip
Hip flexors
L2, L3
Knee
Hip extensors
L4, L5
Knee
extensors
L3, L4
Femoral
Hallux (Big Toe)
Ankle
Dorsiflexion of big toe
L5
Common peroneal
Dorsiflexion of foot
L4, L5
Common peroneal
Plantarflexion of foot
S1, S2
Tibial
Ankle inversion
L4
Knee flexors
L5, S1
Sciatic
Plantarflexion of
big toe
S1, S2
Tibial
Ankle eversion
L5, S1
Common peroneal
Reference: adapted from Last’s Anatomy - Regional & Applied, 11th Edition, pp16-17
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APE 4: Muscles and their Actions – Tutor - 2016-17
Activity 4: Myotomes and peripheral nerves – Upper Limb (15
minutes)
Now run through all the movements of the upper limb with your tutor, reciting the
nerve roots (root value) and the peripheral nerve as you go.
Myotomes of upper limb movements and respective nerve roots
Shoulder
Elbow
Flexors
C5, C6
Musculocutaneous
Abductors C5
Axillary
Supinators C6
Radial
Extensors
C7, C8
Radial
Adductors C6, C7
Pronators C7, C8
Median
Extensors C6, C7
Radial
Wrist
Flexors C6, C7
Median/Ulnar
Fingers
Extensors C7, C8
Radial
Abductors/ Adductors
T1
Ulnar
Flexors C7, C8
Median/Ulnar
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APE 4: Muscles and their Actions – Tutor - 2016-17
You may have noted the median and ulnar nerves have some overlap.
Specific testing for the median nerve often includes thumb abduction (abductor pollicis
brevis).
Tutors – Demonstrate this movement for them
Similar to dermatomes, there is some variation between different resources.
This is a lot to remember! Watch the YouTube video of the myotome dance to help
you recall the major movements innervated by each nerve root.
Tutors – signpost to ‘myotome dance’ SDL
Activity 6 – Muscle power testing (15 minutes)
To test the integrity of the nerves, making the movement is not enough, we also need to
test strength for detecting more subtle weaknesses. We are going to test the movements
we did in Activity 2.
Watch you tutor demonstrate elbow flexion and extension testing.
1. Now practice this in pairs. Please start with consent. Ensure you are giving your
‘patient’ instructions that they understand.
2. Use the same approach for testing knee flexion and extension.
Tutors –
Stage 2 demo of elbow flexion/extension only
Specific key points to address:
 Intro and consent – jargon free language
 Isolating the movement – with the student’s arm in a flexed position, see if they can
‘pull you towards them’ without using biceps (i.e. get them to use shoulder muscles) –
this highlights to importance of this
 Use equivalent force
 Compare side to side
Get the students to do in pairs (stage 4) – watch and give feedback for above points
Remember the important points:
- Use lay language and give clear instructions
- Isolate the movement
- Use an equivalent amount of force
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APE 4: Muscles and their Actions – Tutor - 2016-17
Clinical context
Work through the following questions with your tutor:
Tutors – get them to refer back to diagrams in handbook if struggling
1. A patient has radial nerve damage (‘mononeuropathy’ or ‘palsy’). What
movements will be weak?
Elbow, wrist and finger extension, supination – depending on where the lesion
occurs – see if they can recall where it may become damaged (fractured humerus –
mentioned last week)
Please emphasise that lack of wrist extension (wrist drop is often a prominent
feature of radial nerve palsy)
2. A patient has a compression of C5 nerve root.
a. What movements will be weak?
Shoulder abduction, (elbow flexion)
b. Where will they experience sensory loss?
C5 dermatome (covered last week) – lateral upper arm
3. A patient is unable to dorsiflex their foot.
a. Which peripheral nerve may be affected?
Common peroneal
b. Which nerve root may be affected?
L4/L5 – mostly ‘foot drop’ is associated with L5
c. How could we tell the difference between these on examination?
Very difficult!
Some other movements will be weak with nerve root – hip extension, knee
flexion (i.e. other actions in L5 myotome)
Sensory loss may help (but common peroneal/L5 distributions very similar)
d. How would the patient walk? (i.e. What would their gait look like?)
High-stepping gait, also ‘slapping’ gait – demonstrate!
4. A patient is unable to move or feel his whole left leg. Where (in the peripheral
nervous system) could the problem be?
Left lumbosacral plexus
5. Weakness is described medically as a paresis (Greek parienai – to let fall). The
patient in Q4 has a monoparesis.
a. What is a hemiparesis?
Half the body is weak one side of sagittal plane – e.g. in stroke. Most likely
location for pathology will be opposite (contralateral) side of the brain (will
be covered later with central nervous system)
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APE 4: Muscles and their Actions – Tutor - 2016-17
b. What is a quadraparesis?
Weakness in all 4 limbs
c. What is a paraparesis?
Weakness in both lower limbs (below the transverse plane) – though this
could be a problem in both plexuses, most likely location for para- and
quadraparesis is the spinal cord
6. A large weight has fallen on your patient’s thigh? It has badly crushed the
anterior compartment. Discuss the consequences of this with your tutor.
Compartment syndrome – swelling/bleeding from tissue damage increases
pressure within fixed enclosed compartment. This compresses nerves and blood
supply which can lead to tissue death and irreversible nerve damage.
The fascia of the compartment needs to be cut open as an emergency.
7. Your patient has a painful right hip due to arthritis and walks with a limp (antalgic
gait). This means they are using their right leg less to weight-bear.
a. What muscle do you think will become wasted (atrophy)?
Gluteus medius (right)
b. What will happen if they stand on their left leg? Ask your tutor for the
name of this sign
Right hip and leg will drop down – Trendelenberg sign (NOT test)
c. What if both muscles are weak – how will they walk?
‘Waddling gait’ – trunk swings from side to side to compensate for the hip
drop (Trendelenberg) – demonstrate!
This is common in muscle diseases (myopathies) especially those that
affect proximal muscles e.g. muscular dystrophies
Self- directed learning
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Practice naming the muscles, nerve root and nerves performing the
movements of the upper and lower limb
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Watch the ‘myotome dance’
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Find out:
o What is claw hand?
o What is Erb’s palsy?
Additional resources
O’Brien M. Aids to the Examination of the Peripheral Nervous System (5th Edition)
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