Clinical conditions of the upper limb Flashcards
What can cause injuries to the upper brachial plexus?
- Usually result from an excessive increase in the angle between the neck and the shoulder
- May occur in trauma
- During the birth of a baby if the shoulder becomes impacted in the pelvis and excessive traction is applied to the baby’s neck
Which parts of the upper brachial plexus gets injured?
- C5 and C6
What are the signs and symptoms of upper brachial plexus injury?
- Sensory alteration in these dermatomes (C5 and C6) and paralysis of muscles predominantly supplied by these nerve roots
What movements will be lost if the upper brachial plexus is injured?
- C5: shoulder abduction and external rotation
- C6: elbow flexion, wrist extension, supination, internal rotation of shoulder
Which muscles are paralysed in an upper brachial plexus injury?
- Deltoid (axillary nerve: C5-6)
- Teres minor (axillary nerve: C5-6)
- Biceps brachii (musculocutaneous nerve: C5-7)
- Brachioradialis (radial nerve: C5-T1)
- Brachialis (musculocutaneous nerve: C5-7)
- Coracobrachialis (musculocutaneous nerve: C5-7)
What happens as a result of upper brachial plexus injury?
- Limb hangs by the side in internal rotation with an adducted arm and extended elbow
- This is called the ‘waiter’s tip’ position
- Injury to the roots of the brachial plexus is called Erb’s palsy
What can cause injuries to the lower brachial plexus?
- Forced hyperextension or hyperabduction e.g. someone falling from a height and grabs onto a tree branch on the way down
What is injury to the lower roots of the brachial plexus known as?
- Klumpke’s palsy
Which nerve roots are affected by injury to the lower brachial plexus?
- C8 and T1
- Weakness affects the following movements
- C8: finger flexion/finger extension/thumb extension
- T1: finger abduction and adduction
What does paralysis caused by lower brachial plexus injury affect?
- Intrinsic muscles of the hand and flexors within the forearm that are supplied by the ulnar nerve
- Affects those muscles supplied by the C8 and T1 fibres within the median and radial nerves
What happens if the long thoracic nerve is damaged?
- Winging of the scapula
- Medial border of scapula is no longer held against chest wall, so protrudes posteriorly
How do we see winging of the scapula?
- Ask patient to place the palm of their hand on a wall and push
- Scapula lifts off the underlying ribs
What causes fractures of the scapula?
- Relatively uncommon
- Indicate severe chest trauma
- High speed road collisions, crushing injuries, high impact sport injuries
How do we treat a fractured scapula?
- Does not require fixation as tone of surrounding muscles holds fragments in place whilst healing occurs
What causes fracture of the surgical neck of the humerus?
- Blunt trauma to the shoulder
- FOOSH
Which key neurovascular structures are at risk when the surgical neck of the humerus is fractured?
- Axillary nerve
- Posterior circumflex artery
What is the classical presentation of a ruptured biceps tendon?
- Patient reports that they heard something snap in the shoulder whilst lifting
- Characteristically, flexion of the arm at the elbow produces a firm lump in the lower part of the arm (the unopposed contracted muscle belly of the biceps)
- This is ‘Popeye sign’
Why does the patient not notice much weakness in the upper limb following rupture of the biceps tendon?
- Action of the brachialis (flexion) and supinator muscles is in tact
- Management is usually conservative
What are the symptoms of a dislocated shoulder?
- Visible deformation of the shoulder
- Visible swelling and/or bruising around the shoulder
- Severe restriction of movement of the shoulder
What is the most common type of shoulder dislocation and why?
- Anterior (antero-inferiorly)
- Shallow glenoid fossa
- Joint is weak at its inferior aspect
- Displaces in an anterior direction due to pull of muscles
How is the arm held following an anterior shoulder dislocation?
- External rotation and slight abduction
What are the common mechanisms of anterior shoulder dislocation?
- Arm is abducted and externally rotated (hand behind head) and then forced posteriorly
- Or a direct blow to the posterior shoulder
What is a Bankart lesion or labral tear?
- Force of humeral head popping out of the socket causes part of the glenoid labrum to be torn off
- Sometimes a small piece of bone can be torn off with the labrum
What is a Hill-Sachs lesion?
- Anterior dislocation of the humeral head
- Tone of infraspinatus and teres minor means that posterior aspect of the humeral head becomes jammed against anterior lip of glenoid fossa
- Can cause a dent in the posterolateral humeral head
What can cause posterior shoulder dislocations?
- Violent muscle contractions due to epileptic seizure, electrocution, lightning strike
- Blow to anterior shoulder
- Arm is flexed across body and pushed posteriorly
How do patients usually present with posterior shoulder dislocation?
- Arm is internally rotated and adducted
- Patient demonstrates flattening/squaring of the shoulder with a prominent coracoid process
- Arm cannot be externally rotated into the anatomical position
How does a posterior shoulder dislocation appear on X-ray?
- Light-bulb sign
- Glenohumeral distance is increased
