Myology of the shoulder complex Flashcards
Muscles of the Proximal Arm
- Biceps brachii
- Coracobrachialis
- Triceps brachii
- Deltoid
Biceps Brachii
Origin – 2 heads, 2 origins
Long head - supraglenoid tubercle of the scapula
Short head - apex of coracoid process
Insertion
Tuberosity of radius
Actions
Flexion of shoulder joint
Flexion of elbow joint
Forearm supination
Coracobrachialis
Origin
Coracoid process of scapula
Insertion
Medial surface of mid-humeral shaft
Action
Flexion and adduction of shoulder joint
Triceps Brachii
Origin
* Long head - infraglenoid tubercle of
scapula
* Medial head - distal 2/3 of medial and
posterior surfaces of humerus below the
radial groove and from medial
intermuscular septum
* Lateral head - lateral and posterior
surfaces of humerus of proximal 1/2 of
body of humerus and lateral
intermuscular septum
Insertion
▪ Form a single tendon distally, inserting
into proximal posterior surface of
olecranon process of ulna
Action
▪ Primary action - Extends the elbow joint
▪ Long head assists extension and
adduction of shoulder join
Deltoid
Origin:
* Anterior fibres (clavicular part) - anterior
border, superior surface lateral 1/3 clavicle);
* Middle fibres (acromial part) - lateral margin
and superior margin of acromion;
* Posterior fibres (spinal part) inferior lip of
scapular spine
Insertion:
Deltoid tuberosity of humerus
Action:
Abduction of shoulder joint (middle fibres with stabilisation by anterior and posterior fibres)
Flexion and medial rotation of shoulder by
anterior fibres
Extension and lateral rotation of shoulder by posterior fibres
Shoulder Muscles with no
direct attachment to scapula
- Pectoralis Major, Latissimus Dorsi, and
Teres Major have no direct attachment to
the scapula… - Therefore, do not directly influence
scapular movements.
Pectoralis Major
Origin:
* Clavicular part - anterior surface of sternal
half of clavicle
* Sternocostal part - anterior surface of
sternum and 1st-7th costal cartilages
* Abdominal part - aponeurosis of external
abdominal oblique
Insertion:
Lateral lip of intertubercular sulcus
Action:
* Upper fibres - flexion, medial rotation and
horizontal adduction of shoulder joint
* Lower fibres - depress the shoulder by
pulling on humeral attachment and
obliquely adduct the humerus
Latissimus Dorsi
Origin
* Spinous processes of T7-T12, surface
of ribs 9-12, the thoracolumbar fascia
(from the lumbar and sacral
vertebrae) posterior 1/3 of external lip
of iliac crest, occasionally: inferior
angle of the scapula
Insertion:
* Floor of the intertubercular sulcus
(bicipital groove)
Action:
* Medial rotation, adduction &
extension of the shoulder joint
depresses the shoulder girdle;
ipsilateral trunk flexion; tilts pelvis
anteriorly and laterally
Teres Major
Origin
* Lower 1/3 dorsal surface lateral
border and inferior angle of
scapula
Insertion
* Medial lip of intertubercular
sulcus, crest of lesser
tuberosity
Action
* Medially rotates, adducts and
extends the shoulder joint
Bicipital Groove
A way to remember insertions
A lady between two majors
- Pectoralis Major
- Latissimus Dorsi
- Teres Major
All adduct and medially rotate
Shoulder Flexion
CLAP
Coracobrachialis
Long Head Biceps
Anterior Deltoid
Pectoralis Major
Shoulder Extension
- Posterior Deltoid
- Latissimus Dorsi
- Long Head Triceps
- Teres Major
Rotator cuff muscle function
CUFF = wrapped around tightly
All rotator cuff muscles wrap around the head of humerus to stabilize it in the glenoid fossa.
If the ligaments passively stabilise, the RC actively stabilises the glenohumeral joint
by contraction of their musculature.
If they did not actively stabilise, the head of humerus would collide with bony
structures.
SITS muscles
Supraspinatus
Infraspinatus
Teres Minor
Subscapularis
Supraspinatus
1/4 rotator cuff muscles
Origin
* Supraspinous fossa
Insertion
* Superior facet of greater tuberosity and shoulder joint capsule
Action
* Abducts the shoulder joint and stabilises the humeral head during movements of
the joint
Infraspinatus
1/4 rotator cuff muscles
Origin
* Medial 2/3 of Infraspinous fossa
Insertion
* Middle facet of greater tuberosity
and shoulder joint capsule
Action
* Laterally rotates the shoulder joint
and stabilises the humeral head during movements of the joint
Teres Minor
1/4 rotator cuff muscles
Origin
* Upper 2/3 dorsal surface lateral
border of scapula
Insertion
* Inferior facet of greater tuberosity
and shoulder joint capsule
Action
* Laterally rotates the shoulder joint
and stabilises the humeral head
during movements of the joint
Subscapularis
1/4 rotator cuff muscles
Origin
* Subscapular fossa of scapula
Insertion
* Lesser tubercle of humerus
(and joint capsule)
Action
* Medially rotates (and adducts)
the shoulder joint and stabilises the humeral head during movements of the joint
Shoulder Abduction
- Middle Deltoid
- Supraspinatus
Shoulder Adduction
- Latissimus dorsi
- Teres major
- Teres minor
- Infraspinatus
- Triceps brachii (long head)
- Pectoralis major
- Coracobrachialis
Medial Rotation
Anterior and Posterior Origin
Anterior origin
* Anterior Deltoid
* Pectoralis Major
Posterior origin
* Latissimus Dorsi
* Teres Major
* Subscapularis
Lateral Rotation
- Infraspinatus
- Teres Minor
Physiological movements at Shoulder Girdle
Elevation
Depression
Protraction
Retraction
Upwards rotation
Downwards rotation
Protractors
- Serratus Anterior
- Pectoralis Minor
