Shoulder Flashcards
What are the types of scapula motion
Around vertical axis – glenoid
turns anteriorly
- Around horizontal axis –
glenoid turns superiorly or
inferiorly - Motions possible because
scapula can slide over
posterior rib cage
Describe the glenohumeral joiunts
- Tradeoff – a highly mobile
but also unstable joint - Stability due to muscles and
ligaments: - Glenoid labrum
- Biceps tendon
- Arch of coracoid and acromion
- Synovial and fibrous joint
capsule membranes - Rotator cuff muscles
What are the 4 bursae of the shoulder
subacromial
subdeltoid
tendon sheath
subscapular
What muscles make up the rotator cuff
Supraspinatus (anterior superior)
Infraspinatus
subscapularis
teres minor (posterior inferior)
What is the origin, insertion, action and nerve supply of the trapezius
Origin – midline of back
(occipital protuberance and
spinous processes C7 – T12)
* Insertion – lateral 1/3 of
clavicle, acromion and spine of
scapula
* Innervation – Cranial nerve XI
(accessory nerve), C3, C4
* Action – rotates scapula to
elevate arm; also elevates,
depresses and retracts scapula;
extends and rotates head
What is the origin, insertion, innervation and action of the levator scapulae
- Origin – transverse processes of
CI - CIV - Insertion – upper medial
border of scapula - Innervation – C3, C4, and dorsal
scapular nerve (C4, C5) - Action – elevates scapula
What are myotomes and peripheral nerves
Myotome = a region of skeletal muscle largely supplied by a single spinal cord
level
* Peripheral nerve = contributions from multiple spinal levels that powers
multiple muscles
Most individual muscles are powered by MORE than one spinal cord level so
testing myotomes usually involves certain movements or muscle groups
Describe the origin, insertion, nerve supply and action of latissimus dorsi
Origin – spinous processes of
T6-L5, sacrum, iliac crest, ribs
10-12
* Insertion – floor of
intertubercular sulcus
* Innervation – thoracodorsal
nerve (C6, C7, C8)
* Action – powerful adduction,
medial rotation and extension
of the arm
What is the origin, insertion, nerve supply and action of pectoralis major
- Origin – 2 heads, medial half of
clavicle, anterior surface of
sternum and first 7 costal
cartilages - Insertion – lateral lip of
intertubercular sulcus - Innervation – medial and
lateral pectoral nerves (C5 – T1) - Action – powerful adduction,
flexion, extension and medial
rotation of the arm
What are fan shaped muscles
Two large, fan-shaped
muscles pull the humerus
posteriorly relative to body
and pulls body forward
relative to ground
* Evolved for bounding or
galloping locomotion
Describe the origin, insertion, innervation and action of pectoralis minor
Origin – anterior surfaces of
ribs III to V
* Insertion – coracoid process
* Innervation – medial pectoral
nerve (C5 – T1)
* Action – rotates and protracts
scapula
Describe the origin, insertion, innervation and action of the subclavius muscle
Origin – first rib (at costal
cartilage)
* Insertion – middle 1/3 of
clavicle
* Innervation – nerve to
subclavius (C5, C6)
* Action – depresses clavicle and
stabilizes joint
Describe the origin, insertion, innervation and action of coracobrachialis
Origin – corocoid process
* Insertion – medial aspect
of humerus
* Innervation –
musculocutaneous nerve
(C5-C7)
* Action – flexes arm
Describe the origin, insertion, innervation and action of serratus anterior
Origin – lateral surfaces of ribs
1 – 8/9
* Insertion – medial border of
scapula (costal surface)
* Innervation – long thoracic
nerve (C5-C7)
* Action – protracts and rotates
scapula, prevents ‘winging’
Origin, insertion, innervation and action of supraspinatus
Origin – supraspinous fossa of
scapula
* Insertion – superior facet of the
greater tubercle of humerus
* Innervation – suprascapular
nerve (C5,C6)
* Action – initiates abduction of
arm (first 15 degrees)
Origin, insertion, innervation and action of infraspinatus
- Origin – infraspinous fossa of
scapula - Insertion – middle facet of the
greater tubercle of humerus - Innervation – suprascapular
nerve (C5,C6) - Action – lateral rotation of arm
Origin, insertion, innervation and action of teres minor and major
Teres minor
* Origin – lateral infraspinous fossa
* Insertion – inferior facet of the
greater tubercle of humerus
* Innervation – axillary nerve (C5, C6)
* Action – lateral rotation of arm
Teres major (not rotator cuff)
* Origin – posterior surface of
scapula near inferior angle
* Insertion – medial lip of
intertubercular sulcus
* Innervation – inferior subscapular
nerve (C5, C6)
* Action – medially rotates and
extends arm
Origin, insertion, innervation and action of subscapularis
Subscapularis
* Origin – subscapular fossa
* Insertion – lesser tubercle of
humerus
* Innervation – superior and
inferior subscapular nerves (C5,
C6, C7)
* Action – medial rotation of arm
What are the posterior nerves of the shoulder?
Suprascapular nerve
from brachial plexus (superior trunk),
travels THROUGH the suprascapular
foramen between bone and
supraspinatus muscle, through
greater scapular notch to
infraspinatus
Axillary nerve
from brachial plexus (posterior cord),
passes posterior to surgical neck of
humerus – IN DANGER IF
FRACTURED! Innervates teres minor
and deltoid, and “regimental
badge
Describe the arterial anastomoses of the shoulder
Subclavian-Axillary anastomosis
from Subclavian:
Thyrocervical trunk >
suprascapular a. > circumflex
scapular a. > subscapular a. >
axillary a.
Thyrocervical trunk > transverse
cervical a. > deep branch/dorsal
scapular a. > circumflex scapular a.
> subscapular a. > axillary a.
from Axillary
humeral circumflex aa. (anterior
and posterior)
thoracoacromial trunk
Axillary-Axillary anastomosis
between humeral circumflex aa. and
with profunda brachii a.
