15 - Shoulder Joint Flashcards
Label the following diagram.
What are the three different joints of the scapula?
- Glenohumeral (shoulder)
- Acromioclavicular
- Scapulothoracic
What muscles insert and originate from the scapula coracoid process?
Insert: Pec minor and coracobrachialis
Origin: Short head biceps brachii
What are the important bony landmarks of the lateral surface of the scapula?
- Glenoid fossa: head of humerus articulates here with glenoid lavbrum
- Supraglenoid tubercle: site of origin of long head of biceps
- Infraglenoid tubercle: site of origin of long head triceps
Where is the anatomical neck of the humerus?
Between the head of the humerus and the tubercles
Label the different bony landmarks of the humerus.
How do fractured scapulas occur and what is the best way to treat them?
- Rare
- Severe chest trauma, e.g high speed road collisions, crushing injuries
- Tone of muscles surrounding holds fragments in place whilst healing occurs so no fixation needed
Label this AP x-ray of the shoulder joint.
What factors are responsible for the mobility and stability of the shoulder joint?
Mobility: (makes unstable)
- Shallow glenoid fossa
- Lax capsule
- Disproportion of articular surfaces
Stability:
- Muscles of rotator and others
- Ligaments
- Capsule
What is the function of the clavicle and where does it attach to?
- Attach upper limb to trunk as part of shoulder girdle
- Protect underlying neurovascular to upper limb
- Transmit force from upper limb to axial skeleton
Label the important bony landmarks of the clavicle and state what each end articulates with.
- Long S bone
- Medial aspect convex anteriorly, lateral is concave
What is the coracoclavicular ligament?
TWO PARTS - suspending weight of upper limb from clavicle
- Conoid tubercle: conoid ligament, medial coracoclavicular ligament
- Trapezoid line: trapezoid ligament, lateral coracoclavicular ligament
What muscles and ligaments originate or insert onto the clavicle?
- Deltoid
- Trapezius
- Subclavis
- Pec maior
- Sternocleidomastoid
- Sternohyoid
What type of joint is the acromioclavicular joint and what makes it atypical?
- Plane type synovial
- Palpated 2-3cm medially from tip of shoulder
- Articular surface lined with fibrocartilage not hyaline
- Joint cavity partially divided by articular fibrocartilage disc
Where is the joint capsule of the acromioclavicular joint?
- Loose fibrous layer that gives rise to articular disc
- Lined internally by synovial membrane
- Posterior aspect of joint reinforced by trapezius fibres
What are the ligaments of the acromioclavicular joint?
Intrinsic: Acromioclavicular ligament superiorly
Extrinsic: Conoid and trapezoid ligament
What movement occurs at the acromioclavicular joint?
- Small degree of axial rotation and anteroposterior movement
- Passive movement as no muscles cross it
What type of joint is the sternoclavicular joint?
- Saddle type synovial
- Manubrium of sternum, clavicle and upper medial first costal cartilage
- Only attachment of upper limb to skeleton so strong
- Fibrocartilage lining not hyaline and articular disc*
Why is there an articular disc in the sternoclavicular joint?
Allows clavicle and manubrium to slide over each other more freeling allowing rotation in 3 axes rather than 2 like a normal saddle
What are the possible movements of the shoulder that require the sternoclavicular joint to move too?
- Elevation of shoulder joint (e.g shrugging shoulders or abducting arm over 90)
- Depression of shoulders
- Protraction/Retraction of shoulder
- Rotation (e.g arm over head)
Label this diagram of the proximal humerus and state what passes through the intertubercular sulcus?
- Tendon of the long head of biceps brachii
- Edges of the groove are know as the lips and different muscles insert onto them, see on diagram
A LADY BETWEEN TWO MAJORS
What is the danger of fracturing the surgical neck of the humerus?
- Blund trauma to shoulder from falling on outstretched hand
- Axillary nerve and circumflex humeral vessels in close proximity
- Nerve damage results in paralysis of deltoid and teres minor so hard to abduct limb. Will also have loss of sensation of regimental badge area over deltoid
What is being pointed to here on the humerus and what is it the landmark for?
- Radial groove
- Radial nerve and profunda brachii artery lie in this groove
What muscles attach to the humeral shaft and where?
Posteriorly: Lateral and medial head of triceps, with spiral groove between
Anteriorly: Corachobrachialis, deltoid, brachioradialis, brachialis
What defines whether a muscle is intrinsic or extrinsic in the shoulder?
Extrinsic: Originate from torso and insert onto bones of shoulder (humerus, clavicle, scapula)
Intrinsic: Originate from scapula and/or clavicle and insert onto the humerus
What are the extrinsic muscles of the shoulder?
All on back of the trunk and organised into two layers
What are the superficial extrinsic muscles of the shoulder, their innervation, their origin/insertion and their actions?
What are the deep extrinsic muscles of the shoulder, their innervation, their origin/insertion and their actions?
How do you test the trapezius muscle?
Ask patient to shrug shoulders whilst you push down on them
What are the intrinsic muscles of the shoulder? (scapulohumeral group)
- 4 rotator cuff muscles
- Deltoid
- Teres Major
What are the intrinsic muscles of the shoulder (apart from the rotator cuff) , their innervation, their origin/insertion and their actions?
What are the rotator cuff muscles of the shoulder, their innervation, their origin/insertion and their actions?
Give glenohumeral joint extra stability
What are the muscles of the anterior arm, their innervation, their origin/insertion and their actions?
- BBC
- Musculocutaneous nerve penetrates C and passes between bb in lateral side of the arm
- Continues into the forearm and becomes the lateral cutaneous nerve
What is the bicipital aponeurosis?
Thick fadica close to musculotendinous junction of the biceps, forms roof of the cubital fossa and blends with deep fascia of ulnar border and anterior forearm
What does the biceps tendon reflex test?
- C6 because this is predominant for supination and elbow flexion
Where are the different places the biceps tendon can rupture, what is the signs, and what is the treatment?
- Over 50 long head may rupture near scapular origin after minimal trauma, but in weightlifters distal tendon can snap near insertion
- Patient says heard something snap in shoulder whilst lifting
- During flexion popeye’s sign due to unopposed contracted muscle bell of biceps
- Usually not much weakness due to supinator muscles and brachialis
- Conservative management
What are the posterior muscles of the arm, their innervation, their origin/insertion and their actions?
What are the the paths of the three nerve branches in the upper arm in the anterior brachial plexus?
What does the triceps reflex test?
- C7 as responsible for elbow extension
What is the significance of the quadrangular space and what is it bordered by?
Route where axillary nerve and posterior circumflex humeral artery and vein enter the posterior compartment of the arm
Superior: inferior teres minor
Inferior: superior teres major
Medial: Long tri brachii
Lateral: surgical neck of humerus
Anteriorly: subscapularis
What is the significance of the triangular space and what are its borders?
Circumflex scapular vessels enter infraspinous fossa, NO NERVES
Superior: inferior teres minor
Medial: superior teres major
Lateral: long tri brachii
What is the significance of the triangular interval and its borders?
Radial nerve and profunda brachii artery in base of interval as they wind around humerus in the radial groove
Superior: inferior border of teres major
Medial: long tri brachii
Lateral: shaft of humerus or lateral tri brachii
What are the main arteries of the upper arm?
- Brachial when axillary past inferior border or teres major
- Profunda brachii travels with radial nerve to posterior compartment of arm and terminates in anastomoses in elbow
- Brachial travels in anterior compartment and goes under brachialis where it bifurcates in cubital fossa. Travels with median nerve lateral to medial
What are the veins of the anterior arm?
Where is the capsule of the glenohumoral joint?
- Glenoid labrum and fossa to anatomical neck of humerus
- Dips down medially to surfical neck
- Laxity for full abduction
What does the anatomical neck mark the site of?
- Articular capsule
- Epiphyseal growth plate in children
What is the issue with a fracture of the surgical neck of the humerus?
- Axillary nerve damage
- Posterior circumflex humeral artery damage
What is the weakest point of the glenohumoral joint and why?
- Inferior, no reenforcement
- Only depth of glenoid labrum reducing risk of dislocation
What are the intracapsular ligaments of the glenohumoral joint?
- Superior
- Middle
- Inferior
From glenoid labrum to humerus to reinforce capsule anteriorly and prevent anterior dislocation
What are the extracapsular ligaments of the glenohumoral joint?
- Coracoacromial (allows supraspinatous tendon to run through)
- Coracohumoral (base of coracoid)
- Transverse humoral
What are the main dynamic stabilisers of the shoulder joint and their actions?
Insertions of the rotator cuff muscles blend to form cuff which fuses with joint cavity strengthening it
What are the two bursa in the shoulder joint?
- Subacromial bursa: under acromion to reduce friction as supraspinatus tendon passes under structures
- Subscapular bursa: between tendon of subscapularis and neck of scapula to protect tendon as it passes inferior to root of coracoid
What structures pass through the coraco-acromial arch and what does it prevent from happening?
- Subacromial bursa, long head of biceps, supraspinatus tendon, joint capsule
- Prevents upward displacement of the humerus
- Impingement can occur leading to irritation
What are all the stabilisers, dynamic and static, of the shoulder joint?
What muscles cause abduction of the shoulder joint?
What muscles cause adduction of the shoulder?
What muscles cause flexion of the shoulder?
What causes extension of the shoulder joint?
What causes medial and lateral rotation of the shoulder joint?
What is the nerve supply to the shoulder?
ALL BRANCHES OF PLEXUS WITH C5 AND C6
C5 dermatome overlies shoulder
What is the blood supply to the shoulder?
- Axillary passes behind pec minor at at surgical neck gives off anterior and posterior circumflex humeral arteries
- Arterial anastomosis around margin of scapula. Subscapular artery (3rd branch of axillary) with suprascapular and transverse cervical
When does the subclavian artery become the axillary artery and the axillary artery become the brachial artery?
