Shoulder girldle
Upper Trap
O: occiput, nuchal ligament on cervical
spinous processes
I: lateral clavicle, acromion process
A: Scapular elevation
and upward rotation
N: Spinal accessory
Middle Trap
O: spinous processes of C7-T3
I: scapular spine
A: scapular retraction
N: Spinal accessory
Lower Trap
O: spinous processes of middle and lower
thoracic
I: base of scapular spine
A: Scapular depression and upward rotation
N: Spinal accessory
Levator Scapulae
O: C1-C4 transverse process
I: superior angle of scapula
A: scapular elevation and downward rotation
N: dorsal scapular and C3-C4
Rhomboids Major and minor
O
- nuchal ligament and spinous process
of C7-T5
I
- medial border of scapula
N
- dorsal scapular nerve
A
- scapular retraction, elevation and
downward rotation
Serratus Anterior
O: first 8 ribs
I: medial border of scapula
N: long thoracic nerve (C5, C6, C7)
A: scapular protraction and upward rotation
PEC minor
O: ribs 3-5
I: coracoid process
A: scapular depression, protraction,
downward rotation and tilt
N: Medial pectoral (C8-T1)
Force couples
Muscles pulling in different directions to
accomplish the same motion
UT + LT + SA → upward rotation
Levator + Pec minor + Rhomboids→
downward rotation
Shoulder part 2
Rotator Cuff
- Supraspinatus
- Infraspinatus
- Teres Minor
- Subscapularis
Force couple acts to hold the humeral head
into the glenoid fossa
Anterior Deltoid
O: lateral 1/3 of clavicle
I: deltoid tuberosity
A: shoulder abduction, flexion, medial rotation
and horizontal adduction (when shoulder
flexed to 90)
N: Axillary (C5-C6)
Rotator Cuff
- Supraspinatus
- Infraspinatus
- Teres Minor
- Subscapularis
Force couple acts to hold the humeral head
into the glenoid fossa
Supraspinatus
O: supraspinous fossa
I: greater tubercle of humerus
A: shoulder abduction
N: suprascapular n. (C5-C6)
Infraspinatus
O: infraspinous fossa
I: greater tubercle of the humerus
A: shoulder lateral rotation, horizontal
abduction
N: suprascapular n. (C5-C6
Teres Minor
O: axillary border of scapula
I: greater tubercle of humerus
A: shoulder lateral rotation, horizontal
abduction
N: axillary n. (C5-C6)
Subscapularis
O: subscapular fossa of the scapula
I: lesser tubercle of the humerus
A: shoulder medial rotation
N: subscapular n. (C5-C6)
Pec Major
O: (clavicular portion) medial clavicle (sternal
portion) sternum, ribs 1-6
I: lateral lip of bicipital groove of humerus
A: (claviular portion) shoulder flexion- first 60°
(sternal portion) shoulder extensionfirst 60° (from 180°-120°)
N: lateral and medial pectoral nn. (C5-T1)
Latissimus Dorsi
O: spinous processes T7-L5, posterior
sacrum, iliac crest and lower 3 ribs
I: medial lip of bicipital groove of humerus
A: shoulder extension, adduction, medial
rotation, hyperextension
N: thoracodorsal n. (C6-C8
Teres Major (lats little helper)
O: axillary border of scapula
I: medial lip of bicipital groove of humerus
A: shoulder extension, adduction, medial
rotation
N: subscapular n. (C5-C6)
Coracobrachialis
O: coracoid process
I: mid-humerus (medial portion)
A: stabilizes the shoulder joint
N: musculocutaneous n. (C6-C7)
Force Couples -Glenohuneral Jt
Arthrokinematic motions of roll, spin and glide
help to keep the humeral head articulating
with the glenoid fossa
Abduction begins (deltoid and
supraspinatus)→ HH rolls along glenoid→ HH
glides inferiorly (rot cuff) to allow abd to
continue
Note that full abd cannot take place without
ER of the humerus….why??
“empty can” vs “full can”