Musculo-neuro-vascular systems of arm and glenohumeral joint Flashcards
Anterior axio-appendicular muscles
1) pectoralis major
2) pectoralis minor
3) subclavius
4) serratus anterior
Posterior axio-appendicular muscles
1) Trapezius
2) latissimus dorsi
3) levator scapulae
4) rhomboid minor and major
Scapulohumeral muscles
Rotator cuff
Deltoid
Teres major
Rotator cuff muscles are______ stabilizers of the glenohumeral joint
Active
Origin of supraspinatus
Supraspinous fossa of scapula
Insertion of supraspinatus
Greater tubercle of humerus (superior facet)
Innervation of supraspinatus
Suprascapular nerve (C5,6) from superior trunk
Actions of supraspinatus (2)
Abducts arm 0-15 degrees
Assists deltoid with abduction from 15-90 degrees
Rotator cuff tear typically affects____ muscle
Supraspinatus
Origin of infraspinatus
Infraspinous fossa of scapula
Insertion of infraspinatus
Greater tubercle of humerus (middle facet)
Innervation of infraspinatus
Suprascapular nerve (C5,6) from superior trunk
Actions of intraspinatus (1)
Externally rotates arm at GH joint
Origin of suprascapular nerve
C5, C6
Course of suprascapular nerve
Arises from superior trunk of brachial plexus
Passes inferiorly through the scapular notch into the supraspinous fossa
Curves around the spine of the scapula entering the infraspinous fossa
Structures innervated by suprascapular nerve
Supraspinatus
Infraspinatus
Glenohumeral joint
Origin of teres minor
Infraspinous fossa
Insertion of teres minor
Greater tubercle of humerus (inferior facet)
Innervation of teres minor
Axillary nerve C5
Actions of teres minor (2)
External rotation of humerus at GH joint
Adduction of the GH joint
Origin of axillary nerve
Terminal branch of posterior cord (C5, C6)
Course of axillary nerve
Passes laterally through quadrangular space reaching the posterior of the surgical neck
Quadrangular space borders
Teres minor
Teres major
Surgical neck of humerus
Long head of triceps
Structures innervated by axillary nerve
GH joint
Teres minor
Deltoid muscles
Skin of superolateralam
Origin of subscapularis
Subscapular fossa of scapula
Insertion of subscapularis
Lesser tubercle of humerus (anterior)
Innervation of subscapularis
Upper and lower subscapular nerves from posterior cord (C5,C6)
Actions of subscapularis (2)
Internal rotation of humerus at GH joint
Stabilizes GH joint
Subscapularis tendon tear results in…..
Weak internal rotation of the humerus
Origin of subscapular nerve
Posterior cord, upper: C5, lower: C6
Course of subscapular nerve
Upper: passes posteriorly to enter subscapularis directly
Lower: passes inferolaterally, deep to subscapular artery and vein
Structures innervated by subscapular nerve
Subscapularis (upper + lower)
Teres major (lower)
Acute tear
cause
Sudden powerful movement
Chronic tear cause
Tendon rubs against bone
Origin of deltoid (3)
Lateral 1/3 clavicle
Acromion
Lateral 1/3 spine of scapula
Insertion of deltoid
Deltoid tuberosity on humerus
Innervation of deltoid
Axillary nerve (C5,C6)
Actions of deltoid on glenohumeral joint
Anterior fibers: flexion
Middle fibers: abduction
Posterior fibers: extension
Origin of teres major
Inferior 1/3 of Medial border of scapula
Insertion of teres major
Medial lip of bicipital groove (intertuberclar sulcus)
Innervation of teres major
Lower subscapular nerve (C5,6)
Actions of teres major on glenohumeral joint
Internal rotation
Adduction
Extension
Causes of quadrangular space syndrome
Repeated injury and subsequent fibrosis can reduce the size of the quadrangular space
Leads to compression of the axillary nervev as it passes through the quadrangular space
Consequences of quadrangular space syndrome
Shoulder pain and paraesthesia in distribution of axillary nerve
Weakness of muscles innervated by axillary nerve
What is shoulder impingement?
During glenohumeral abduction, the supraspinatus tendon or its overlying subacromial bursa can be impinged between the head of the humerus and the inferior surface of the acromion.
Repeated shoulder impingement can lead to….
tendonitis or subacromial bursitis
What is painful arc syndrome?
Pain during shoulder abduction, within the 60-120° range. Usually follows shoulder impingement