L2 Pectoral Girdle and Shoulder Flashcards
Which two parts make up the pectoral girdle?
Scapula and clavicle
Which structure connects the axial skeleton to the upper limb?
Pectoral girdle
The shoulder is an articulation between with two structures?
Glenoid cavity of scapula and the head of humerus
Give the innervation and function of trapezius
Upper: Elevate scapula
Middle: Retract scapula
Lower: Depress scapula
Upper + lower fibres: Rotate scapula to direct glenoid cavity superiorly
Innervation: Spinal accessory nerve (CN XI)
Give the innervation and function of deltoid
Middle: Abduction of shoulder beyond 15 degrees
Anterior: Flexion of shoulder
Posterior: Extension of shoulder
Innervation: Axillary nerve (C5, C6)
Give the innervation and function of the rhomboids
Retract and rotate scapula to tilt glenoid cavity inferiorly
Innervation: Dorsal scapular nerve
Give the innervation and function of levator scapulae
Elevate scapula and rotate to tilt glenoid cavity inferiorly
Innervation: Dorsal scapular nerve
Give the innervation and function of teres major
Medial rotation and adduction of humerus
Innervation: Lower subscapular nerve
Give the innervation and function of latissimus dorsi
Medial rotation, extension and adduction of shoulder
Raises body while climbing.
Innervation: Thoracodorsal nerve
Give the innervation and function of serratus anterior
Protraction of scapula (reaching out/punching)
Holds scapula to chest wall
Rotation of scapula to tilt glenoid superiorly, allowing raising of arm
Innervation: Long thoracic nerve
Give the innervation and function of pectoralis major and minor
Major: medial rotation and adduction of humerus
Innervation: medial and lateral pectoral nerves
Minor: Stabilises scapula
Innervation: medial pectoral nerve only
Give the innervation and function of subscapularis
Medial rotation and adduction of humerus
Innervation: Upper and lower subscapular nerves
Give the innervation and function of supraspinatus
Initiates abduction of shoulder (first 15 degrees)
Innervation: Suprascapular nerve
Give the innervation and function of infraspinatus
Lateral rotation of humerus
Innervation: Suprascapular nerve
Give the innervation and function of teres minor
Lateral rotation and adduction of humerus
Innervation: Axillary nerve (C5, C6)
Which muscles of the pectoral girdle are innervated by the axillary nerve?
The axillary nerve (C5-C6) innervates the deltoid muscle and teres minor
Which muscles of the pectoral girdle are medial rotators and adductors of humerus?
Teres major
Latissimus dorsi
Pectoralis major
Subscapularis
Which muscles of the pectoral girdle abduct the humerus?
Supraspinatus
- initiates movement (first 15 degrees)
Deltoid
- abducts beyond 15 degrees
Which muscles of the pectoral girdle laterally rotate the humerus?
Infraspinatus
Teres minor
What is the origin and insertion of levator scapulae?
Origin: Occiput
Insertion: Superior angle of scapula
What is the origin and insertion of rhomboid major?
Origin: T2-T5 spinous processes
Insertion: Medial border of scapula
What is the origin and insertion of rhomboid minor?
Origin: C7-T1 spinous processes
Insertion: Medial border of scapula
What is the origin and insertion of supraspinatus?
Origin: Supraspinous fossa of scapula
Insertion: Greater tubercle of humerus (superior facet)
What is the origin and insertion of infraspinatus?
Origin: Infraspinous fossa of scapula
Insertion: Greater tubercle of humerus (middle facet)
What is the origin and insertion of teres minor?
Origin: Lateral border of scapula
Insertion: Greater tubercle of humerus (inferior facet)
What is the origin and insertion of subscapularis?
Origin: Subscapular fossa of scapula
Insertion: Lesser tubercle of humerus
What is the origin and insertion of teres major?
Origin: Lateral border/inferior angle of scapula
Insertion: Intertubercular sulcus of humerus (medial lip)
What is the origin and insertion of latissimus dorsi?
Origin: Iliac crest, thoracic lumbar fascia, lower thoracic vertebrae
Insertion: Intertubercular sulcus of humerus (floor)
Originates on the posterior side of the body; inserts on the anterior side of the humerus.
What is the origin and insertion of deltoid?
Origin: Spine of scapula, acromion, anterior side of clavicle (lateral one-third)
Insertion: Deltoid tuberosity of humerus
What is the origin and insertion of trapezius?
Origin: Occiput, nuchal line, spinous processes of C8-T12
Insertion: Lateral one-third of clavicle, acromion, spine of scapula
What is the origin and insertion of serratus anterior?
Origin: Lateral surfaces of ribs 1-9
Insertion: Medial border of scapula (costal surface)
What is the origin and insertion of pectoralis major?
Origin: Medial clavicle, sternum and upper costal cartilages
Insertion: Intertubercular sulcus of humerus (lateral lip)
What is the origin and insertion of pectoralis minor?
Origin: Ribs 3-5
Insertion: Coracoid process of scapula
Damage to which nerve results in winged scapula?
Long thoracic nerve
Damage usually caused by:
- Penetrating injury to lateral chest
- Iatrogenic (chest drain insertion, breast surgery)
- Neuritis
Which tendon is most commonly damaged in a rotator cuff injury?
Supraspinatus
How do you test the function of the four rotator cuff muscles?
Supraspinatus: Abduct arm against resistance
Infraspinatus: Laterally rotate arm against resistance
Teres minor: Laterally rotate arm against resistance
Subscapularis: Place dorsum of hand to mid-lumbar spine, then ask patient to lift hand off back (medial rotation)
What structure prevents superior displacement of the humerus?
Coracoacromial arch
Anterior dislocation of the shoulder joint is usually caused by excessive extension and lateral rotation of the humerus.
Which nerve is commonly injured by anterior shoulder dislocation?
Axillary nerve (C5, C6)
Which nerve is at risk from a surgical neck of humerus fracture?
Axillary nerve (C5, C6)
What components form the coracoacromial arch?
Acromion + coracoid process + coracoacromial ligament
What are the roots of the brachial plexus?
C5, C6, C7, C8 and T1
What are the trunks of the brachial plexus?
Superior trunk (C5 + C6)
Middle trunk (C7)
Inferior trunk (C8 + T1)
What are the divisions of the brachial plexus trunks?
Each trunk divides into an anterior and posterior division
What are the cords of the brachial plexus? Which divisions form each one?
Lateral cord (anterior division of superior trunk + anterior division of middle trunk)
Medial cord (anterior division of inferior trunk)
Posterior cord (posterior divisions of all trunks - superior, middle, inferior)
What are the 5 terminal branches of the brachial plexus?
Musculocutaneous (C5-C7)
Axillary (C5, C6)
Radial (C5-T1)
Median (C6-T1)
Ulnar (C8, T1)
