3.3 Flashcards
5 areas of the shoulder
Sternoclavicular joint
Fibrous support from 3 ligaments:
1. anterior sternoclavicular ligament
2. costoclavicular ligament
3. internclavicular ligament
Articular disc
Saddle joint that functions like ball and socket
Movement at sternoclavicular joint
Clavicle movement
- 60º with full elevation
- 25-30º with anterior/posterior movement
Acromioclavicular joint
- conoid ligament
- trapezoid ligament
- AC ligament (acromioclavicular ligament)
- coracoacromial ligament - creates coracoacromial arch
* conoid and trapezoid ligaments make up coracoclavicular ligament
Primarily functions in stability:
- Prevents acromion from moving under clavicle
- Creates roof for the humerus
Glenohumeral joint
Ball and socket
- fairly unstable
Glenoid labrum - labrum- shallow socket (1/3 of head of humerus)
Reinforced by:
1. Coracohumeral l.
2. Glenohumeral l.
3. Rotator cuff mm
Often inferior and anterior dislocates
Scapulothoracic joint
Physiologic joint; no attachment
Glide and rotation
Movements:
- elevation/depression
- protraction/retraction
- upward/downward rotation
Subacromial space
Not a joint
Between acromion and humeral head
Supraspinatus m.
Long head of biceps
Subacromial bursa - protects from friction
Subacromial bursa
Superior transverse scapular ligament
Not part of a joint
Traverses suprascapular notch
Creates a foramen for suprascapular nerve and artery
The ligament is ossified, causing compression of the structures which traverse the foramen.
Clavicle fracture
Clavicle is common bone to fracture, especially in children
Fall onto outstretched arm (FOOSH)
Fall directly onto shoulder
Fractures
- Usually at junction between middle and lateral 1/3
- SCM pulls medial third upward
- Pec major pulls humerus and lateral third medially
- Fractured ends can overlap
- Can be accompanied by ligament injuries: AC and CC
Glenohumoral injury
Humoral head movement in relationship to glenoid cavity
Subluxation: contact persists
Dislocation: no contact
Adhesive capsulitis
Idiopathic inflammatory condition affecting glenohumeral joint capsule
Results in severe loss of ROM and chronic pain
May have an autoimmune component
Planes of movement of the shoulder
Medial and lateral rotation: transverse plane
Flexion/extension: sagittal plane
Abduction/adduction: coronal plane
Scapulohumeral rhythm
the upper extremity
Scapular movement (at scapulothoracic joint) & humeral movement (at glenohumeral joint) act in concert
2:1 Movement of glenohumoral vs scapular joint
Ex: at 90° abduction, 30° is scapular movement and 60° is glenohumeral
- for every amount of movement you have 1º at scapula and 2º at glenohumeral
the upper extremity
Begin elevation:
30°: scapular rotation
Middle elevation:
120°: scapular & glenohumeral joints
Final elevation:
30°: scapular rotation
Humerus is blocked further by acromion
Intrinsic muscles of the shoulder
6 muscles act on glenohumeral joint
Deltoid
Teres major
Rotator cuff:
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
Rotator cuff tears
Partial or complete tears of a SITS muscle/tendon
Causes:
- Acute injury like a fall
- Chronic wear and tear with repetitive motions
- Subacromial impingement
Supraspinatus tendon is most common tear
Extrinsic muscles of the shoulder
Superficial layer – associated with scapula and UE
- Trapezius
- Latissimus dorsi
Deep layer
- Levator scapulae
- Rhomboids
Testing accessory nerve of the trapezius
The accessory nerve is particularly vulnerable to injury as it passes across the posterior triangle of the neck between the SCM and trap.
Ask the patient to shrug their shoulders against resistance.
Monitor for strength of one side compared to the other.
A significant strength deficit is indicative of a positive finding, which would be exhibited by asymmetrical elevation of the shoulders.
What movements use our latissimus dorsi?
rowing, climbing
Pectoral nerves
Named for cord of brachial plexus from which they arise:
- Lateral pec nerve: lateral cord
- Medial pec nerve: medial cord
Lateral pectoral n.
- Innervates pec major
- Descends in plane between muscles
- Medial side of pec minor
Medial pectoral n.
- Innervates pec major and minor
- “Medial does more”
- Pierces pec minor
Winged scapula
Injury to the long thoracic nerve or serratus anterior muscle results in a “winging scapula”.
- Originates from roots of C5-C7
- Descends along superficial surface of serratus anterior
- Exposed nature makes it more easily injured
Loss of function for the serratus anterior prevents the scapula from being held against the thoracic wall.
This is especially evident when the patient presses against a wall with outstretched arms.
What nerve(s) comes from the upper cord of the brachial plexus?
Suprascapular n:
- Supraspinatus
- Infraspinatus
What nerve(s) comes from the posterior cord of the brachial plexus?
Axillary n:
- deltoid
- teres minor
Upper subscapular n:
- subscapularis
Lower subscapular n:
- subscapularis
- teres major
Quadrangular space
Boundaries:
- Superior: teres minor (green)
- Inferior: teres major (blue)
- Medial: triceps long head (purple)
- Lateral: humerus (yellow)
Nerve and artery pass from axilla to posterior shoulder.
Axillary n
motor to deltoid and teres major
sensory to skin over deltoid
brachial plexus (C5-C6)
Posterior circumflex humeral artery
blood to deltoid
anastomosis with anterior circumflex humeral artery
Glenohumeral dislocation
Dislocations of the shoulder joint usually result in inferior displacement of the humeral head.
Coracoacromial arch prevents upward displacement.
Axillary n. passing through quadrangular space is most endangered by inferior displacement.
Gall on outstretched arm or onto shoulder.
Humeral fracture
Fractures of the surgical neck of the humerus endangers the axillary n. and posterior circumflex humeral a. as they pass through quadrangular space.
Most common in elderly people with osteoporosis.
Axillary n. damage will weaken/ paralyze the deltoid leading to an inability to abduct the arm.
