Nerves
How does the median nerve enter the hand?
Passes under the flexor retinaculum and through the carpal tunnel to enter the hand
Which anastomotic network does the ulnar artery contribute to?
It contributes to an anastomotic network surrounding the elbow joint.
What are the two major superficial veins of the upper limb?
The major superficial veins of the upper limb are the cephalic and basilic veins.
Which vein is the most ideal for venous access for bloods, IV fluids, and medication? 💉
The median cubital vein in the cubital fossa
What is the motor function of the radial nerve?
All muscles of the posterior compartments of the arm and forearm
Testing the radial nerve we ask the patient to perform the 'paper sign'. Why?
The "paper sign" is a clinical test used to assess the function of the radial nerve, specifically its ability to extend the wrist. The radial nerve is a major nerve that supplies muscles in the arm and hand, including those responsible for wrist extension. During the "paper sign" test, the patient is asked to hold a piece of paper between their fingers and attempt to extend their wrist against resistance. This action primarily involves the muscles controlled by the radial nerve. If there is weakness or impairment in the radial nerve function, the patient may have difficulty extending the wrist or maintaining a strong grip on the paper.
How are the radial and ulnar arteries formed?
The radial and ulnar arteries are formed by the bifurcation of the brachial artery within the cubital fossa
Give a brief overview of the venous blood flow from the hand to the heart 🫀
Dorsal venous network - basilic + cephalic vein - median cubital vein (runs medially to join basilic vein) - brachial vein - axillary vein - subclavian vein - brachiocephalic vein - Superior Vena Cava - Right Atrium
What could be a sensory consequence of injury to the musculocutaneous nerve?
Sensory functions – loss of sensation over the lateral side of the forearm.
How do we test the function of the median nerve?
Thumb abduction against resistance OR Ask the patient to form the rock sign
How do we test the function of the ulnar nerve?
Finger abduction against resistance
Which artery can be palpated in the anatomical snuffbox?
Radial artery
Which network of veins drains the dorsum of the hand?
The dorsal venous network
What is the Allen's test?
The Allen test is used to assess collateral blood flow to the hands, generally in preparation for a procedure that has the potential to disrupt blood flow in either the radial or the ulnar artery.
Which nerve can be found in the carpal tunnel?
Median nerve
What is the sensory function of the ulnar nerve? (show me where)
Palmar aspect of medial 1 and ½ digits & associated palm and wrist
Dorsal aspect of medial 1 and ½ digits
At the lower border of the teres major muscle, the axillary artery is renamed the brachial artery.
Between which two muscles does the cephalic vein travel between at the shoulder?
At the shoulder, the cephalic vein travels between the deltoid and pectoralis major muscles
What is Volkmann’s ischaemic contracture?
If the artery is completely occluded (or severed), the resulting ischaemia can cause necrosis of forearm muscles. Muscle fibres are replaced by scar tissue and shorten considerably – this can cause a characteristic flexion deformity, called Volkmann’s ischaemic contracture.
By which vein are the basilic and cephalic veins joined and where?
At the elbow by the median cubital vein
Which muscles are innervated for motor function by the median nerve?
All muscles anterior compartment forearm, except flexor carpi ulnaris and medial ½ of flexor digitorum profundus
Lateral lumbricals (hand)
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
Give a brief overview of the pathway of the arteries from the heart to the hand right upper limb 💪🏻
Left ventricle - Aortic arch - Brachiocephalic trunk - Subclavian artery - axillary artery - brachial artery - Radial + ulnar artery - deep + superficial palmar arches
A nurse inserts a PICC line into a superficial vein located anterolaterally in the arm. Which vein is most likely to have been cannulated?
The cephalic vein is the major superficial vein located on the anterolateral aspect of the arm.
What is carpal tunnel syndrome? and what is a possible cause?
Compression of the median nerve by adjacent structures.
Idiopathic/no known cause in most cases BUT associated with repetitive strain or mass occupying lesions or result of trauma
In what percentage of people does the scaphoid receive sole blood supply from a single branch of the radial artery? And why is this relevant in a scaphoid fracture?
(need both correct for full points)
10% of people.
The singular radial artery enters through the distal portion of the bone to supply the proximal portion. Should a fracture occur across the waist of the scaphoid, the proximal portion therefore undergoes avascular necrosis.
What about the 90%?
It primarily receives its blood supply from the radial artery (70-80%), which further bifurcates into the dorsal carpal branch and the superficial palmar/volar branch