Pectoral Girdle, Shoulder, Arm & Elbow Flashcards
(46 cards)
What are the 2 main palpable bony features on the anterior clavicle?
- Acromion: palpable bony shelf above shoulder
- Coracoid process: palpable below the lateral clavicle - shoulder joint space can accessed with a needle via a point 2cm inferior to this directly supero-laterally
What is the attachment point for rotator cuff muscles?
Lesser tubercle of humerus
What runs through the intertubercular (bicipital) groove?
Tendon of the long head of the biceps muscle
What are the surface anatomy landmarks of the superior and inferior angles of the scapula inferiorly?
T2-T7 spinous processes with the medial spine sitting at T3 spinous process
The medial scapula border of an abducted upper limb posteriorly marks the _________.
Oblique lung fissure
What is the function of the clavicle? When is it at risk of fracture?
Acts a strut supporting the upper limb and transmitting forces to axial skeleton - risk of fracture when a patient falls onto outstretched limb or onto lateral shoulder
What are the joints of the shoulder?
- Acromioclavicular: synovial plane joint passing anterior-posterior - dislocation (shoulder separation possible) and a visible deformity shows
- Sternoclavicular: ONLY bone-bone joint between upper limb and axial skeleton functioning as a synovial B&S joint - dislocation rare due to good joint support
- Glenohumeral (shoulder): lax B&S joint allowing wide range of movement (high risk of dislocation) made up of 3x glenohumoral ligaments that pass from margin of glenoid fossa of scapula to humeral head and support shoulder anteriorly
Why must joint injection/aspiration of the sternoclavicular joint take place under ultrasound guidance?
Because the apex of the lungs sits here putting the patient at high risk of pneumothorax and also, the jugular and brachiocephalic veins sit here so its important to see what you are doing
What supports the acromioclavicular joint?
- Coracoclavicular ligaments: made up of trapezoid (posterior) and conoid (anterior) ligaments but can be torn by AC joint dislocation (once a patient does it 1x, there likely to do it again)
- Coracoacromial ligament: supports shoulder joint superiorly so it cannot dislocate this way but can be ruptured by superiorly directed forces and can impinge on supraspinatus/subacromial bursa
What will joints made of hyaline look like on an X-ray?
Like space as hyaline is less dense
In order or frequency, where do fractures of the clavicle take place?
Weakest point of clavicle is the junction between the middle and lateral 1/3 > Middle 1/3 > lateral 1/3 > medial 1/3
What will a fractured clavicle look like?
The separated parts of a fractured clavicle move in opposite direction due to muscle contraction of SCM and gravity so there will be a big step between the shoulder and neck
What nerve is at risk of damage from a fracture of the surgical neck of the humerus? What symptoms would the patient have? Have examination findings would be present?
Axillary nerve - paraesthesia/LOS of skin over lower deltoid of upper lateral arm (regimental badge area) and weakness/paralysis of teres minor and deltoid muscles so the patient will not be able to abduct the affected limb and over long-term, the muscles of deltoid will atrophy giving the shoulder a flattened appearance
What structures can be damaged by a mid-shaft humeral fracture through the spiral groove posteriorly?
Radial n.
Profunda brachii artery
Why is the lower part of the shoulder joint capsule lax and folded?
To permit free movement especially ABDUCTION of the arm - this is why downward force applied to an abducted arm can dislocate the shoulder (can damage axillary n. too)
What is the glenoid labrum? What happens if its damaged?
A fibrocartilage rim deepening the glenoid fossa shallow socket and stabilising the shoulder joint - tear can result from trauma/overuse and can produce a snapping sensation or pain on abduction or lateral rotation
What is the bursa called in the shoulder? How can it become irritated? How can you inject it?
Subacromial bursa can become irritated and inflamed if a tendon of one of the rotator cuff muscles rubs on the acronium sat above due to wear or impingement - injection takes place via the acromio-deltoid groove
What are the superficial muscles of the pectoral girdle, their function and innervation?
- Trapezius: elevates, retracts and depresses the scapula (CNXI)
- Latissimus dorsi: extends, adducts and medially rotates humerus and raises the trunk to arm e.g. climbing (thoracodorsal n.)
What are the deeper muscles of the pectoral girdle, their function and innervation?
- Levator scapulae: elevates and rotates scapula (dorsal scapula n. C3-4)
- Rhomboid major and minor: retract and fix position of scapula (dorsal scapula n.)
- Teres major: adduction and medial rotation of humerus (lower subscapsular n.)
What are the borders of auscultation? Why it used?
- Trapezius (runs from base of skull to T12 vertebrae with fibres running to acromium of scapula)
- Rhomboid major
- Latissimus dorsi
The skin here is thin so you can hear breath sounds very clearly in this area from the lower lobe
What are the pectoralis muscles of the pectoral girdle, attachment points, their function and innervation?
- Pectoralis major: attaches to clavicle, sternum and adjacent costal cartilages and lateral side of intertubercular groove of humerus - adducts and medially rotates the shoulder acting as an accessory breathing muscle (medial and lateral pectoral n.)
- Pectoralis minor: attaches to ribs 3-5 and coracoid process - depresses and protracts the scapula dividing axillary artery into 3 parts (medial pectoral n.)
What is the attachment points of the deltoid pectoral girdle muscles and their action? What is their innervation?
Attaches to lateral clavicle, acromion, scapula spine and humerus - brings about all shoulder movements EXCEPT adduction (axillary n.)
Where is the axillary nerve? How can it become damaged? What would be the consequence of damage?
Passes around surgical neck of humerus ~ 5cm below acromion with circumflex humoral vessels so it can be damaged by shoulder dislocation, surgical neck of humerus # or IM injection (e.g. vaccines) and this would cause:
- Paralysis and wasting of deltoid and teres minor so patient would not be able to move shoulder much
- Limb hangs limb by side
- Loss of shoulder contour
- LOS over lateral shoulder (regimental badge region)
What does a shoulder dislocation most often look like?
Anteriorly (but can also get posterior or inferior but NOT superior) where the humeral head comes out of glenoid fossa/infraglenoid tubercle anteriorly causing a loss of contour
