UL -- Injuries at joints + nerve injuries Flashcards
Acromioclavicular joint - injury?
Type: Plane synovial jt.
Injury: Dislocation - due to hard fall on shldr or on an outstretched UL during contact sports
Imp. Feature: Acromion more prominent in the patient
Sternoclavicular jt.
Saddle-shaped synovial jt.
- rarely gets disolcated
** Only joint where the UL girdle articulates with the trunk.
Fracture of the Clavicle
- Occurs commonly in children
- Due to fall on outstretched hand
- Middle 1/3rd of clavicle usually fractured
- SCM elevates the medial fragment of the clavicle – this broken surface can be often felt under the skin
- Patient usually holds their UL with their opposite arm due to weight of the UL – patients shoulder also drops
Accessory nerve (CN XI)
Supplies: Trapezius (and also SCM but injury in relation to traps)
Pathway: passes deep to SCM and supplies it then crosses posterior triangle of the neck superficially to supply the traps.
Causes of injury:
- traumatic injury
- neck lacerations due to its superficial location
Injury: Traps lose their nerve supply
–Drooping of shoulder – cant elevate the shoulder
– cant lift arm above the head (like in brushing your hair)
Test for damage:
- ask patient to shrug their shoulders while you push down on them
- ask patient to push their head against your hand
—- tests for functioning/weakness of SCM and traps.
(** traps used to test functioning of accessory n.)
Long thoracic nerve
Supplies: serratus anterior musc.
Susceptible to injury at :
– When the nerve travels superficial to the thoracic wall muscles especially when UL is outstreched
– also during mastectomy
Results in:
–winging of scap.
– medial border of scap projects posteriorly
– Normal elevation of arm not possible (as rotation of scap. affected)
Thoracodorsal nerve
Supplies: Lats
Susceptible at:
– injury to axilla
–surgery to axilla (removal of lymph nodes)
– mastectomy
Can cause issues with extension of flexed arm,
adduction of arm,
extension of arm
and medial rot. of arm
Accessory musc. for inspiration?
Pec major musc. – supplied by medial and lateral pectoral nerves
– used in ppl with asthma to assist with inspiration
– when used for inspiration origin (medial clavicle, sternum, upper ribs, aponeurosis of external oblique music. of abdomen) and insertion (bicipital groove/intertubercular sulcus) swap.
– thus contraction results in elevation of thoracic cage
venous access in UL - most commonly where?
The ceph. vein - just proximal to the wrist
For replacement of fluids and blood transfusions
venepuncture in the arm - most commonly where?
Median cubital vein
lies above bicipital aponeurosis thus the brachial A. and median n. are protected from injury
which is the only UL muscle that isn’t supplied by the brachial plexus
Trapezius (accessory nerve - Cranial N. XI)
what happens in a brachial plexus nerve block
A local anaesthetic is inserted close to the brachial plexus within the axillary sheath (a sheet of connective tissue enclosing the axillary nerve, axillary vein and the brachial plexus cords) so as to block any sensation to the UL.
Useful when performing surgery on the UL
The easily palpable axillary artery can be located and serves as a reliable anatomical landmark for this block. The local anaesthetic is injected near the artery within the axillary sheath.
Where may pus travel in the UL
in the axillary sheath
What does and enlarged node above the medial epicondyle of the humerus indicate?
Indicates infection in the medial aspect of the palm
which muscles indicate a physical sign of respiratory distress/used for forced inspiration?
The SCM and the scalene muscles (anterior, posterior and middle)
Muscles used to test for accessory nerve?
The traps and the SCM
axillary nerve
Motor innervation: the deltoid and teres minor
Sensory innervation: the skin over the upper part of the lateral side of the arm.
Pathway:
It exits the axilla –> passes thru the quad. space –> enters the posterior aspect of the shoulder –> winds around surgical neck of the humerus (accompanied by the post. circumflex humeral A.) –> deep to deltoid.
Injury to axillary n. due to:
– Inferior dislocation of the head of the humerus
– Fracture of the surgical neck of the humerus
– Can also be damaged due to quad. space syndrome (compression of the axillary nerve as it passes thru the quad space – if enlargement of muscles in the space)
Injury results in:
– Paralysis/weakness of the deltoid
– Weakness of teres minor as well if injured in quad. space.
– Inability/ difficulty in abducting the UL
– Difficulty in extension and flexion at the shoulder joint
– loss of sensation over the “badge area” of the skin covering the deltoid muscle.
what nerve can shoulder dislocation damage?
Axillary nerve
Intramuscular injection site in UL
the deltoid musc.
how do you test for accessory nerve damage?
- Ask the patient to shrug their shoulders while you push down on their shoulders
- Ask the patient to push their head against your hand
– tests for weakness of traps and SCM
How is the subclavian artery protected from injury during subclavian v catheterization?
The subclavian artery is separated from the subclavian Vein by the anterior scalene muscle
thus protection :)
Subclavian V. catheterisation mechanism
The subclavian vein is usually used to gain venous access by inserting a long and thin catheter into a large vein.
Done in order to administer drugs or provide intravenous nutrition
The catheter is inserted below the middle part of the clavicle and is directed towards the sternoclavicular joint.
The subclavian A. is protected from injury during catheterisation as it’s separated from the Subclavian V by the anterior scalene muscle.
where can the pulse of the subclavian A be felt?
In the posterior triangle of the neck - Where the subclavian artery lies most superficially.
– It passes thru the inferior part of the posterior triangle of the neck – also it lies posterior to the anterior scalene muscle.
how can bleeding of the UL be controlled in a haemorrhage?
-The subclavian artery passes over the 1st rib
- If pressure is applied to the artery over the rib it can be occluded.
- During haemorrhage of the UL pressure applied - occludes it - control bleeding
Features of the subacromial bursa and mechanism of injury.
– The subacromial brursa doesn’t communicate with the synovial glenohumeral cavity of the shoulder joint.
– Located between the acromion and the deltoid music (superiorly) and the supraspinatus tendon and the capsule of the glenohum. joint (inferiorly)
– Subacromial bursa allows for friction-free movement between the supraspinatus tendon and the acromion and also between the deltoid and the capsule of the shoulder jt.
– Injury to shoulder or the supraspinatus tendon can result in an inflammation of the subacromial bursa
– results in painful movements of the joint
– Abduction of the joint become painful
What prevents superior dislocation of the humeral head
The coraco-acromial arch ( coracoid process, acromion and coraco-acromial ligament)
what provides stability of the shoulder joint?
rotator cuff muscles and the coraco-acromial arch
what prevents upward movement of the humerus?
the tendon of the long head of the biceps muscle passes thru the joint into its insertion on the suprglenoid tubercle.
which direction is shoulder dislocation most likely to occur in and why?
Anterior + inferior
– As the joint deficient in support inferiorly
– muscles support anterior, posterior and superior surfaces
Rotator cuff syndrome - mechanism of injury
Rotator cuff muscles (SITS)
– Most commonly involved musc. - supraspinatus musc.
– As it passes thru a narrow space under the acromion
– Repetitive injury to this area may occur in sports (like due to strong throwing action)
– Can result in inflammation of the supraspinatus tendon and the subacromial tendon
– Painful abduction
What is the quad. space syndrome?
Quad. space boundaries:
- Teres minor + major, triceps brachii and humerus
– The axillary nerve passes thru this space
– If there’s enlargement of these muscles then they can compress the axillary nerve and damage it
– leads to weakness in the teres minor and deltoid muscles
– thus makes the rotator cuff less effective
most common type of dislocation of the shoulder joint
anterior+inferior
what compartments is the arm divided into and by what?
posterior and anterior by intermuscular septum
compartment syndrome?
– Pressure build up within these compartments can cause compression within the compartment.
– Reduces the blood supply to the muscles in the compartment
– can cause ischaemia and thus damage the muscles
ACUTE COMPARTMENT SYND. – if bleeding occurs due to trauma– pressure can be relieved by performing surgery to cut the deep fascia.
CHRONIC COMPARTMENT SYND. –
- induced by exercise esp. repetitive exercises like running
- compression in compartment over long sustained periods of time
- results in pain, swelling and sometimes weakness of the muscles
- can be corrected by modifying exercise pattern but surgery can be required.
Reflexes at the elbow region?
Tapping on biceps tendon – C6
Tapping on triceps tendon – C7
supracondylar fracture?
- Fracture common in children as relatively weak spot
- TRANSVERSE fracture of distal part of humerus above the level of the two epicondyles
- Distal fragment of bone can be displaced posteriorly
- Can result in occlusion of the brachial artery and damage to the contents within the cubital fossa
- Blood supply to forearm is thus occluded – requires immediate surgery
– causes ischaemia to forearm muscles
– If not treated – leads to VOLKMANNS ischaemic contracture
– characterised by uncontrolled flexion as flexor muscles are shortened and damages
What are two types of lesions to the brachial plexus?
Upper -
Lower -
Upper lesion to the brachial plexus – Explain what happens - name, how? motor and sensory loss?
Lower lesion to the brachial plexus – Explain what happens - name, how? motor and sensory loss?
Mechanism of tenosynovitis spread?
Injury in guyon canal/ wrist laceration - how is it caused? and what are its effects?
Arterial blood sampling from radial artery – describe the mechanism of doing so
