PBL questions Flashcards
- Define abduction of the shoulder? (You should also know what the other movements of the shoulder are as well).
Abduction is the movement that takes the limb away from the midline, so for the shoulder it takes the arm out to the side of the body.
What structures would you want to check had not been damaged by Barry dislocating his shoulder? (one nerve, and one structure associated with the shoulder that if damaged may weaken the joint and mean that dislocations of the same joint in the future are more common)
Glenoid labrum, axillary nerve, possibly also the axillary artery.
Martin is a 33 year old man who undergoes a deep cervical lymph node biopsy on the right side of his neck. Immediately after the surgery, Martin complains of right sided shoulder droop and he is unable to lift the point of the shoulder, and he is unable to elevate the scapula. There is no sensory loss over the shoulder, back and neck. (Clue: this is not a nerve from the brachial plexus, the other main muscle innervated by this nerve is in the anterior neck, with a superior attachment to the mastoid process, and inferior attachments to the sternum and clavicle)
- What nerve has been damaged in Martin and what muscle has become paralysed?
- Explain why there is no sensory loss in this scenario. (hint there is something special about the nerve that is injured in this case)
1 The trapezius muscle has become paralysed this is innervated by the spinal accessory nerve (CN XI) for motor, while the C3, 4 spinal nerves give the sensory supply to the muscle.
2 There is no sensory loss at spinal accessory is a pure motor nerve and has no sensory supply to the skin.
1 What are the actions of latissimus dorsi for both the upper and lower limbs (look at its insertions on both the humerus and pelvis)?
1 Latissimus dorsi extends, adducts, and medially rotates the humerus; raises body (and therefore legs) towards the arms during climbing.
What does serratus anterior do? Therefore, explain sign “winging of the scapula” and the lack of abduction above the horizontal plane (note the deltoid and the supraspinatus are not affected in this case, look at the picture of Elizabeth on the next page to help you).
2 Serratus anterior; protracts scapula and holds it against the thoracic wall; rotates scapula. When paralysed (injury to long thoracic nerve) the medial border of scapula moves laterally and posteriorly away from thoracic wall giving the scapula the appearance of a wing. When the arm is raised the scapulothoracic joint does not work. Serratus anterior is unable to rotate the glenoid cavity superiorly to allow complete abduction.
What condition might arise from interference of the lymphatic drainage?
lympodema
4 In some forms of radical mastectomy, the pectoralis major and minor muscles are also removed what would the affect be on the function of the upper limb?
4 Pectoralis major adducts and medially rotates humerus, the clavicular head flexes arm, pectoralis minor stabilises scapula by drawing it inferiorly and anteriorly against thoracic wall. Therefore flexion of the arm and controlled adduction of the arm is affected.
Sharon is a 21-year-old international butterfly swimmer, who goes to her doctor complaining of shoulder pain and a reduced range of motion in the shoulder joint. On examination, Sharon was able to achieve about 165° of shoulder flexion/elevation, with pain near the end of that range. During abduction, pain was demonstrated between about 70° and 120°, after which Sharon no longer felt pain. Shoulder abduction against resistance yielded pain only during the first 35° of movement. All other resisted movements were pain-free. Palpation of the shoulder only produced pain on the superior surface of the greater tubercle of the humerus. Pressure at this location also produced pain that radiated down the lateral side of Sharon’s arm. The doctor told Sharon that she had tendonitis in her rotator cuff and prescribed anti-inflammatory medication, ultrasound therapy, and rest.
- Based on the information above, which tendon specifically was inflamed?
- Why did the pain radiate down the patient’s arm (clue the nerve to the muscle involved is composed of nerve fibres from C5)? This clinical feature is an important concept in other areas of medicine as well such as in MIs and appendicitis.
- When the arm was abducted without resistance, pain was felt between 70° and 120° of abduction; however, abduction against resistance produced pain only during the first 35°. How would you explain this (clue the muscle involved is part of the rotator cuff but its main function is in abduction of the shoulder, and look at the relationship of its tendon to the bony elements of the shoulder)?
- When abducting the arm fully through 180°, how much of the elevation is due to movement of the glenohumeral (shoulder) joint, and how much is due to rotation of the scapula?
- supraspinatus because it passes under the acromion
- supraspinatus is innervated by suprascapular nerve also composed from C5 so the pain in the arm is referred pain.
- Supraspinatus initiates abduction for first 10 degrees then deltoid takes over, with active unresisted movement the supraspinatus tendon does not get impinged until around 90 degrees maximally. With resistance the muscle works harder sooner and the scapula rotates earlier, so pain is felt earlier.
- 90 degrees is at the glenohumeral joint with 60 degrees from rotation of the scapula and 30 rotation of the humerus.
- Describe the course of the radial nerve in the arm. Which group of muscles in the arm will be affected in radial nerve palsy?
1 Radial nerve exits the axillary fossa posterior to axillary artery, passes posterior to humerus in radial/spiral groove enters cubital fossa travels down posterior/radial side of forearm. All the extensor muscles
- Why would a patient with wrist-drop resulting from radial nerve injury be unable to perform a power grip (the type of grip used to hold items firmly, try it yourself flex the wrist fully and try and make a fist)?
2 The tendons of the long flexors will be slack and unable to make a powerful fist as they are not a good working length.
SELF TEST PBL SCENARIO 6
Mrs Addison goes to give a blood sample, the blood is taken by a trainee technician. The blood that is taken is bright red and there are spurts of blood as well when the needle is removed. She also complains of pins and needles in her hand.
1. What is the source of the red spurting blood, and what structure was the technician aiming for?
2. Explain why there are sensory problems with Mrs Addison hand?
1 brachial artery, was aiming for the median cubital vein
2 median nerve also runs in close relationship to the brachial artery
- What artery may be palpated in the anatomical snuffbox and which of the palmar arches does contribute most to?
1 radial artery it contributes most to the deep palmar arch
During a pony trekking holiday Mark Philips a 28-year-old man, fell from his horse Trigger. In order to break his fall, Mark stretched out his right hand, and injured his right wrist. Mark was able to remounted Trigger and is able to ride him back to the stables, however, his right wrist continued to hurt, with the greatest pain located in the region of the anatomical snuffbox. When the riders got back to the stables Mark went to the local hospital to have his wrist examined. The doctor gave Mark a quick examination, and decided that the wrist was sprained, wrapped it in an elastic bandage and gave Mark a prescription for a painkiller. Two weeks after the accident Mark was still in pain and he began to experience a loss of movement in the injured wrist. Mark went to see his own doctor, who ordered x-rays of the wrist. The radiologist who examined the x-rays determined that Mark had suffered a fracture of one of the bones of the wrist. The fracture did not appear to be healing, so Mark was referred to an orthopaedic surgeon.
- What bone did Mark break? (Hint: It is palpable in the floor of the anatomical snuff box.)
- What are some of the possible anatomic reasons that this bone failed to heal? (bone is a living tissue!)
- Why might the clinician have missed the diagnosis initially? (x-rays of fractures like those of Mark will be put up in the LL have a look and try and see the fracture)
2 scaphoid
3 disruption to the blood supply to the bone resulting in avascular necrosis, because of its retrograde blood supply
4 as bone is entirely within the joint leaking synovial fluid can inhibit the bone healing process and its might also not have a blood supply.
5 The ligaments that surround the carpal bones may mean there is no displacement of the fracture pieces and therefore they do not show on the x-ray.
- What is the carpal tunnel? What is contained within it? (you’re looking for 10 items you might want to draw a simple diagram to help)
1 The carpal tunnel runs between the flexor retinaculum and the carpal bones. It contains the tendons for FDS, FDP and FPL (9 tendons in their synovial tendon sheaths) plus the median nerve.
- What causes the symptoms of carpal tunnel syndrome?
2 Compression of the median nerve.
