muscles of the shoulder region

Question 1

Pectoralis major

Answer 1

2 heads:
- sternal head: sternum to the humerus = intertubercular groove (lat lip)
- clavicular: attaches clavicle to humerus
ACTIONS:
- flexion, adduction, medial rotation
TYPE:
- convergent

Question 2

latissimus dorsi

Answer 2

- attaches axial skeleton (T7-S5), iliac crest, ribs 9-12, inferior angle of scapula to humerus = intertubercular groove 
ACTIONS:
- extension, medial rotation, adduction 
TYPE:
- pennate

Question 3

deltoid

Answer 3

• 3 parts: anterior, middle, posterior
• attaches shoulder girdle to humerus (deltoid tuberosity)
  ACTIONS:
• anterior = flexion, internal rotation
• middle = abduction
• posterior = external rotation, extension
  TYPE:
• middle = multipennate
• other two = parallel?

Question 4

Teres Major

Answer 4

• attaches shoulder girdle (scapula near inferior angle) to humerus (intertubercular groove - med lip)
• runs w/ lats
  ACTIONS:
• adduction, medial rotation, extension

Question 5

coracobrachialis

Answer 5

• coracoid process to mid-shaft of humerus
  ACTIONS:
• shoulder adduction, flexion

Question 6

biceps brachii

Answer 6

• long head attaches to supraglenoid tubercle
• short head attaches at coracoid process
• distal attachment: radial tuberosity
• tri-articular muscle
  ACTIONS:
• shoulder + elbow flexion, supination
  TYPE:
• fusiform

Question 7

Triceps brachii

Answer 7

• long head: attaches to infraglenoid tubercle
• lateral head: superior to radial groover
• medial: inferior to radial groove
• insertion: olecranon of ulna
• bi-articular muscle
  ACTIONS:
• shoulder + elbow extension

Question 8

Axioscapular muscles: trapezius

Answer 8

• most superficial muscle of back
  ACTIONS:
• upper trap = elevation + lateral rotation of scap
• middle trap = retraction of scap
• lower trap = retraction + lateral rotation of scap
  TYPE:
• triangular

Question 9

Axioscapular muscles: levator scapulae

Answer 9

• Lie underneath trapezius but superficial to back muscles
• origin = vertebrae
• insertion = medial border of scap (superior angle to root of spine)
  ACTIONS:
• elevation, medial rot of scap

Question 10

Axioscapular muscles: rhomboid major + minor

Answer 10

- Lie underneath trapezius but superficial to back muscles
Rhomboid major:
- origin = spine 
- insertion = medial border of scap
Rhomboid minor:
- origin = spine 
- insertion = medial border of scap 
ACTIONS:
- retract scap
- stabilise

Question 11

Axioscapular muscles: pectoralis minor

Answer 11

• lies deep to pec major
• origin: ribs
• insertion: coracoid process
  ACTIONS:
• protraction, medial rotation

Question 12

Axioscapular muscles: serratus anterior

Answer 12

• origin = ribs
• insertion = medial border + inferior angle of scapula
  ACTIONS:
• lateral rotation, protraction of scap

Question 13

Rotator cuff muscles: supraspinatus

Answer 13

• Supraspinous fossa
• to greater tubercle
  ACTIONS:
• external rotation + abduction (does not initiate)

Question 14

Rotator cuff muscles: infraspinatus + teres minor

Answer 14

Infraspinatus:
- Lies in infraspinous fossa on the posterior surface of the scap
- insert = greater tubercle 
Teres minor:
- lateral border of scap 
- insert = greater tubercle 
ACTIONS:
- external rotation of humerus

Question 15

Rotator cuff muscles: subscapularis

Answer 15

• Anterior surface of the scap - subscap fossa
• to insert at lesser tubercle of humerus
  ACTIONS:
• internal rotation of humerus
  TYPES:
• multipennate (55% of rotator cuff)