Upper limb nerve injuries Flashcards
What is the corticospinal tract (CST), also known as the pyramidal tract?
- a collection of axons that carry movement-related information from the cerebral cortex to the spinal cord
- relate to voluntary movement
The corticospinal tract (CST), also known as the pyramidal tract is a collection of axons that carry movement-related information from the cerebral cortex to the spinal cord. Is this an ascending or descending tract?
- descending tract
- carries instructions from motor cortex to spinal cord
What is the definition of an upper and lower motor neuron?
- UMN = begin in the cerebral cortex and end in brain stem or spinal cord
- LMN = begin in spinal cord or brain stem and end at target tissue
The corticospinal tract (CST), also known as the pyramidal tract is a descending tract of a collection of axons that carry movement-related information from the cerebral cortex to the spinal cord. Where do these synapse in the spinal cord and is this efferent or afferent?
- synapse at ventral/anterior horn
- efferent as they are effector neurons
The upper motor neurons of all cranial nerve of the brain (except CN I and CN II) synapse where?
- brain stem
The upper motor neurons of all cranial nerve of the brain (except CN I and CN II) synapse at the brainstem. Where do CN I (olfactory) and II (optic nerve) come from?
- cerebrum
The brainstem is composed of 3 major parts, the midbrain, the pons and the medulla. Using football formation of 4-4-2, working inferior to superior, which upper motor neurons of which cranial nerves synapse at the medulla of the brainstem?
- 4 in total
- CN IX (9) glossopharyngeal
- CN X (10) vagus nerve
- CN XI (11) accessory nerve
- CN XII (12) hypoglossal nerve
The brainstem is composed of 3 major parts, the midbrain, the pins and the medulla. Using football formation of 4-4-2, working inferior to superior, which upper motor neurons of which cranial nerves synapse at the pons of the brainstem?
- 4 in total
- CN V (5) trigeminal nerve
- CN VI (6) abducens nerve
- CN VII (7) facial nerve
- CN VIII (8) vestibulocochlear nerve
The brainstem is composed of 3 major parts, the midbrain, the pins and the medulla. Using football formation of 4-4-2, working inferior to superior, which upper motor neurons of which cranial nerves synapse at the midbrain of the brainstem?
- 2 in total
- CN III (3) oculomotor nerve
- CN IV (4) trochlear nerve
Once an upper motor neuron (UMN) travels down the corticospinal tract (pyramidal, voluntary movement tract) it synapses at the ventral/anterior horn of the spinal cord or brain stem. What lower motor neuron will the UMN synapse with to elicit voluntary movement?
1 - gamma motor neuron
2 - beta motor neuron
3 - beta 1a motor neuron
4 - alpha motor neuron
4- alpha motor neurons
- allow us to contract skeletal muscle
Once an UMN synapses with the alpha motor neuron, a LMN in the spinal cord or brainstem receives information to initiate an action. What modulates this to ensure we don’t over contract?
- proprioceptors through gamma motor neurons
- feedback through muscle spindles and golgi tendon organs
- ensure the muscle is not damaged
How do UMN and LMN lesions affect the reflexes ?
- UMN = brisk reflexes
- LMN = reduced reflexes
How do UMN and LMN lesions affect the muscle strength?
- UMN = reduced strength (no message getting to muscles)
- LMN = proximal weakness
How do UMN and LMN lesions affect muscle tone ?
- UMN = increased tone
- LMN = reduced tone
In an UMN lesions there is pyramidal weakness. What is this?
1 - unaffected
2 - flexors become stronger than extensors
3 - extensors become stronger than flexors
4 - complete loss of flexion and extension
2 - flexors become stronger than extensors
- rubrospinal tract facilitates flexion and inhibits extension
- reticulospinal tract can inhibit alpha and gamma motor neurons, thus fine tuning the movements, including balancing between flexion and extension
- in UMN the reticulospinal tract is lost so rubrospinal tract takes over, hence weaker in extension compared to flexion
How do UMN and LMN lesions affect the sensations?
- UMN = cortical sensations are lost
- LMN = peripheral sensations are lost
In addition to the corticospinal tract (pyramidal) there is another tract that also synapses with at the ventral (anterior) horn of the spinal cord. This is really important for doing what with the alpha and gamma motor neurons?
1 - inhibit gamma neurons only
2 - inhibit alpha neurons only
3 - fine tuning alpha and gamma neurons to fine tune them
4 - inhibiting alpha and gamma neurons altogether
3 - fine tuning alpha and gamma neurons to fine tune them
- this inhibition is fine tuning to ensure control and balance, NOT stopping alpha and gamma motor units altogether
The Reticulospinal Tract works closely with the corticospinal tract (pyramidal), synapsing with the ventral (anterior) horn of the spinal cord. The reticulospinal tract inhibit alpha and gamma motor neurons, thus fine tuning movements and balance. If there is a UMN lesion this inhibition is lost. What can this do to muscle tone and reflexes?
1 - increased reflexes with loss of tone
2 - increased reflexes with increased tone
3 - loss of reflexes and tone
4 - loss of reflexes with increased muscle tone
2 - increased reflexes with increased tone
- increased muscle tone as no inhibition of alpha motor units
- increased reflexes as no inhibition of gamma motor units
What is the difference between spasticity and rigidity?
- spasticity = velocity dependent (increased speed = increased tone) and only in one direction (flexor)
- rigidity = not velocity dependent and the same in both directions (flexion and extension for example)
Which nerve roots innervate the upper limbs?
- C5-T1
In terms of nerves, what does a dermatome relate to?
- a specific nerve root supplying a region of the skin and its senses
In terms of nerves, what does a myotome relate to?
- 1 nerve root supplying motor function to a muscle
If a nerve root is damaged, is this classed as peripheral nerve damage?
- no
- the peripheral nerve has not formed yet
Match the nerve roots with the muscle group and movement:
- C5, C6, C7, C8, T1
- Deltoid, Biceps, Triceps, Forearm extensors, Deep forearm flexors, Intrinsic muscles of the hand
- Shoulder abduction, Elbow flexion, Elbow extension, Wrist extension, Wrist flexion
Finger extension, Finger flexion, Finger abduction
- C5 = deltoid muscles and shoulder abduction
- C6 = biceps, elbow flexion
- C7 = triceps, superficial forearm flexors and extensors, elbow extension
- C8 = forearm extensors and deep forearm flexors, finger extension and flexion
- T1 = intrinsic muscles of the hand, finger abduction
There are 3 key reflexes in the upper limb. Match the reflex with the nerve root below:
biceps reflex ((musculocutaneous nerve)) triceps reflex (radial nerve) supinator reflex (radial nerve)
C5, C6 or C7
- biceps reflex = C5 (musculocutaneous nerve)
- supinator reflex = C6 (radial nerve)
- triceps reflex = C7 (radial nerve)
When eliciting the supinator reflex, supplied by C6 (radial nerve), where should we be looking for the reflex?
- near the elbow as its really brachioradialis reflex
If there was a nerve root problem that damaged C7, what myotome and dermatome would be affected?
1 - bicep flexion and sensation in thumb will be lost
2 - tricep extension and sensation in middle finger on dorsal surface will be lost
3 - bicep flexion and sensation in middle finger will be lost
4 - tricep extension and sensation in thumb will be lost
2 - tricep extension and sensation in middle finger on dorsal surface will be lost
The axillary nerve originates from C5 and C6 nerve roots. Which cord of the brachial plexus does it originate from?
1 - anterior
2 - posterior
3 - middle
All are the brachial plexus position relative to the axillary artery
2 - posterior
- which means it is behind the axillary artery
Which muscles does the axillary nerve innervate?
1 - deltoid, teres major and long head of the triceps
2 - deltoid, teres minor and long head of the triceps
3 - deltoid, teres minor and biceps brachii
4 - trapezius, teres minor and biceps brachii
2 - deltoid, teres minor and long head of the triceps
What particular space does the axillary nerve pass through?
1 - quadrangular space
2 - triangular space
3 - hiatus space
4 - cuboidal space
1 - quadrangular space
- also contains the posterior circumflex artery
What is the most common injury associated with damaged to the axillary nerve?
1 - fractured clavicle
2 - fractures surgical neck of humerus
3 - fractured humeral head
4 - shoulder dislocation
4 - shoulder dislocation
What would damage to the axillary nerve cause to the motor and sensory function?
- motor = loss of shoulder abduction
- sensory = lateral upper arm, where badge of honour would be placed (NOT dermatome, but cutaneous)
If someone has a dislocated shoulder and you suspect the axillary nerve is damaged what must you do prior to putting the shoulder back in?
- CHECK MOTOR AND SENSORY BEFORE ANY TREATMENT
- motor = assess shoulder abduction and flexion
- sensory = assess sensations over regimental badge area (lateral aspect upper arm)
Damage to the musculateaneous nerve is rare and is most commonly caused during surgery. If this is damaged what motor and sensory tests can we perform?
- motor = flexion of elbow and supination of the forearm
- sensory = lateral cutaneous nerve of forearm (posterior and anterior)
The median nerve passes down the arm and crosses the elbow. It then passes through the 2 heads of the pronator teres and gives off a nerve called what?
1 - anterior interosseus nerve
2 - radial nerve
3 - lateral cutaneous nerve
4 - brachialis nerve
1 - anterior interosseus nerve
- anterior as its on the front and interosseus as its on interosseus membrane
What is the most common fracture of the elbow, which can affect the anterior interosseus nerve, a branch of the median nerve?
1 - lateral epicondyle fracture
2 - medial epicondyle fracture
3 - supracondylar fracture
4 - radial groove fracture
3 - supracondylar fracture
The median nerve passes down the arm and crosses the elbow. It then passes through the 2 heads of the pronator teres and gives off anterior interosseus nerve (AIN). The AIN then innervates what muscles?
1 - deep flexors
2 - superficial flexors
3 - deep extensors
4 - superficial extensors
1 - deep flexor muscles
- flexor pollicis longus, flexor digitorum profundus, pronator quadratus, middle finger and index finger
The median nerve passes down the arm and crosses the elbow. It then passes through the 2 heads of the pronator teres and gives off anterior interosseus nerve (AIN). The median nerve will eventually pass through the carpal tunnel, but before it does it is sandwiched between which 2 muscles?
1 - flexor digitorum superficialis and flexor pollicis longus
2 - flexor digitorum profundus and flexor pollicis longus
3 - flexor digitorum superficialis and abductor pollicis longus
4 -flexor digitorum profundus and pronator quadratus
1 - flexor digitorum superficialis and flexor pollicis longus
The radial nerve, along with the deep brachial artery, travels down the spinal groove of the humerus and then passes from the anterior to the posterior compartment of the forearm, which is where all the extensors of the wrist and fingers are located. It is located deep to the brachioradialis and then as it crosses the elbow it has a branch that breaks off it that innervates all the extensors of the wrist and hand. What is this nerve called?
1 - anterior interosseus nerve
2 - radial nerve
3 - lateral cutaneous nerve
4 - posterior interosseus nerve
4 - posterior interosseus nerve (motor nerve only)
- posterior as it is located on posterior surface and interosseus as it is located along the interosseus membrane
Once the posterior interosseus nerve breaks off from the radial nerve just below the elbow, the radial nerve continues to the hand. What sensory information does the posterior interosseus nerve provide there?
1 - whole dorsal aspect of hand
2 - half of dorsal surface
3 - 1st dorsal web space as seen in the image
4 - digits 4 and 5
3 - 1st dorsal web space as seen in the image
The ulnar nerve loops around the medial epicondyle, which gives the common sensation we have when we bang the ‘funny bone’. It then passes deep to the 2 heads of which muscle?
1 - Flexor carpi ulnaris muscle
2 - Extensor carpi ulnaris muscle
3 - Flexor carpi radialis muscle
4 - Pronator teres muscle
1 - Flexor carpi ulnaris muscle
- then passes through the wrist through guyons canal
The median nerve can be compressed and cause symptoms. What are the 2 most common places this can be compressed?
1 - carpal tunnel and elbow
2 - carpal tunnel and shoulder
3 - carpal tunnel and forearm
4 - carpal tunnel and arm
2 - carpal tunnel and shoulder
- causing pronator syndrome
If a patient is presenting with loss of the thenar muscles only, which are innervated by the median nerve. Is this likely to be a distal or proximal compression?
- distal
- if it was proximal muscles in the forearm and arm would also be affected