UL1 - Clinical Flashcards
which nerve is commonly affected in a surgical neck fracture of the humerus?
axillary nerve
what structures are at risk in a surgical neck fracture of the humerus?
axillary nerve
posterior circumflex humeral arteries
sensory and motor consequences of damage to the axillary nerve?
motor damage - weakness/ paralysis of the deltoid muscle, causes difficulty with arm abduction
sensory damage - reduced sensation in the regimental badge area (superolateral aspect of the arm)
what structures are at risk in a mid-shaft humerus fracture?
radial nerve
profunda brachii artery
sensory and motor consequences of damage to the radial nerve?
sensory damage - reduced sensation in the posterior arm, forearm, and hand
motor damage - wrist drop due to paralysis of wrist extensors
why may wrist drop occur following a mid-shaft humerus fracture?
damage to the radial nerve can cause paralysis of wrist extensors - leads to wrist drop
in what type of humerus fracture may reduced sensation in the regimental badge area occur?
surgical neck fracture of the humerus
what nerve is at risk in a distal humeral fracture?
median nerve
what nerve is at risk with an avulsion fracture of the medial epicondyle?
ulnar nerve
clinical (sensory & motor) consequences of an avulsion fracture of the medial epicondyle?
motor damage - weakness in muscles innervated by the ulnar nerve (e.g. intrinsic hand muscles)
sensory damage - reduced sensation along the ulnar aspect of the hand and forearm
what is the characteristic motor deficit of a radial nerve injury in a mid-shaft humerus fracture?
wrist drop due to paralysis of wrist extensors
(!!) describe the motor functional implications of an avulsion fracture of the medial epicondyle, and why
weakness or paralysis in intrinsic hand muscles as they’re innervated by the ulnar nerve - can reduce grip strength
(!!) how does the anatomical location of the radial nerve in the radial groove contribute to the specific deficits seen in a mid-shaft humerus fracture?
the radial nerve spirals along the radial groove of the humerus - it’s vulnerable to damage in fractures of the mid-shaft
this can lead to:
- wrist drop due to paralysed/damaged wrist extensors
- reduced sensation in the posterior arm, forearm and hand
where is sensation often reduced/ affected with mid-shaft humeral fractures?
posterior arm, forearm and hand
An 84-year-old man injures his arm while skiing. An x-ray film taken in the emergency department indicates a fracture that has displaced the greater tubercle of the humerus. Movements of the humerus most likely affected by this injury would include which of the following?
abduction & lateral rotation
A 32-year-old woman undergoes a right mastectomy for cancer. After her operation, she complains to her physician that when she pushes her arms against the wall her right scapula protrudes posteriorly away from the thoracic wall. Injury to which of the following nerves would most likely cause this problem?
long thoracic nerve
anteroinferior dislocations are the most common type of shoulder dislocation - how do they happen? what structures are at risk?
mechanism: excessive extension/ lateral rotation - e.g. falling on an outstretched arm
structures at risk:
- axillary & musculocutaneous nerves of brachial plexus
Erb’s palsy is most commonly due to injury of which part of the brachial plexus?
A. Roots C8–T1
B. Upper trunk (C5–C6)
C. Posterior cord
D. Lateral cord
B. Upper trunk (C5–C6)
Which nerve is not typically affected in Erb’s palsy?
A. Suprascapular
B. Axillary
C. Musculocutaneous
D. Ulnar
D. Ulnar (Ulnar is C8–T1 - lower trunk injury (like in Klumpke’s palsy))
The characteristic “waiter’s tip” posture in Erb’s palsy is due to:
A. Flexed elbow and supinated forearm
B. Extended elbow, pronated forearm, adducted and medially rotated arm
C. Extended wrist and hyperflexed fingers
D. Claw hand deformity
B. Extended elbow, pronated forearm, adducted and medially rotated arm
A new-born presents with loss of shoulder abduction and elbow flexion on one side after a difficult delivery. Which of the following muscles is most likely still functioning normally?
A. Supraspinatus
B. Deltoid
C. Triceps brachii
D. Biceps brachii
C. Triceps brachii - innervated by the radial nerve (C6–T1), and usually spared in upper trunk injuries (also has an extensor function)
which nerve roots are affected in Erb’s palsy?
C5-6
what is the characteristic sign of Erb’s palsy?
‘waiter’s tip’ = arm adducted, medially rotated, elbow extended, forearm pronated
Characteristic sign of Klumpke’s palsy?
claw hand - hyperflexed medial fingers, impaired MCP and IP control (lumbrical weakness)
