Week 4 - Muscles that move the Scapula & Arm Flashcards
What is the function of the main action of the muscles that move the pectoral girdle?
Main action of the muscles that move the pectoral girdle is to stabilise the scapula so it can function as a steady origin for most of the muscles that move the humerus.
What are the 2 groups you can class muscles that move the pectoral girdle into?
Based on location:
Anterior thoracic muscles
Posterior thoracic muscles
List the anterior thoracic muscles
Subclavius
Pectoralis minor
Serratus anterior
Origin + insertion for the subclavius
0 = Rib 1
I = Clavicle
Action of the subcalvius
Depresses + moves clavicle anteriorly + helps stabilise pectoral girdle.
Origin + insertion for the pectoralis minor
O = Ribs 2-5,3-5 or 2-4.
I = Coracoid process of scapula.
Action of the pectoralis minor
Abducts scapula + rotates downwards.
Origin + insertion for the serratus anterior
O = Ribs 1-8 or 1-9
I = Vertebral border + inferior angle of scapula
Action of serratus anterior
Abducts scapula + rotates upward.
List the posterior thoracic muscles
Trapezius
Levator scapulae
Rhomboid major
Rhomboid minor
Origin + insertion for the trapezius
O = Superior nuchal line of occipital bone, ligament nuchae + spines of C7-T12.
I = Clavicle + acromion + spine of scapula.
Action of trapezius
Superior fibres upward rotate scapula.
Middle fibres adduct scapula.
Inferior fibres depress + upward rotate scapula
Superior + inferior fibres rotate scapula upward
Origin + insertion for the levator scapulae
O = Transverse processes of C1-C4.
I = Vertebral border of scapula inferior to spine.
Action of the levator scapulae
Elevates scapula + rotates it downward.
Origin + insertion for the rhomboid major
O = Spines of T2-T5
I = Vertebral border of scapula inferior to spine
Action of rhomboid major
Elevates + adducts scapula + rotates it downward
Origin + insertion for the rhomboid minor
O = Spines of C7-T1
I = Vertebral border of scapula superior to spine.
Action of rhomboid minor
Elevates + adducts scapula + rotates downward.
Define + provide an example for elevation of the scapula
Superior movement of the scapula
i.e shrugging the shoulders or lifting a weight over the head.
Define + provide an example for depression of the scapula
Inferior movement of scapula
i.e pulling down on a rope attached to a pulley.
Define + provide an example for abduction of the scapula
Movement of the scapula laterally + anteriorly i.e doing a push up or punching.
Define + provide an example for adduction of the scapula
Movement of scapula medially + posteriorly I.e pulling the oars in a rowboat.
Define + provide an example for upward rotation of the scapula
Movement of inferior angle of scapula laterally so the glenoid cavity is moved upward. — Req. to move the humerus past the horizontal, i.e raising the arms in a jumping jack.
Define + provide an example for downward rotation of the scapula
Movement of inferior angle of scapula medially so that the glenoid cavity is moved downward.
i.e when gymnast on parallel bars supports the weight of the body on hands.
What 2 categories of muscles move the humerus?
Axial muscles
Scapular muscles
List the axial muscles that move the humerus
Pectoralis major
Latissimus dorsi
Origin for the pectoralis major
Clavicle, sternum + cartilages of ribs 2-6 + sometimes ribs 1-7.
Insertion for the pectoralis major
Greater tubercle + lateral lip of intertubercular sulcus of humerus.
Action of the pectoralis major
Adducts + medially rotates arm at shoulder joint.
Origin for latissimus dorsi
Spines of T7-L5
Lumbar vertebrae
Crests of sacrum
Ilium
Ribs 9-12
Insertion for latissimus dorsi
Intertubercular sulcus of humerus.
Action for latissimus dorsi
Extends, adducts + medially rotates arm at shoulder joint
List the scapular muscles that move the humerus
Deltoid
Subcapularis
Supraspinatus
Infraspinatus
Teres major
Teres minor
Coracobrachialis
Origin + insertion point for deltoid
O = Acromial extremity of clavicle, acromion of scapula + spine of scapula.
I = Deltoid tuberosity of humerus.
Action of deltoid
Lateral fibres abduct arm at shoulder.
Anterior fibres flex + medially rotate arm at shoulder.
Posterior fibres extend + laterally rotate at shoulder.
Origin of subscapularis
Subscapular fossa of scapula.
Insertion of subscapularis
Lesser tubercle of humerus
Action of subscapularis
Medially rotates arm at shoulder
Origin of supraspinatus
Supraspinous fossa of scapula
Insertion of supraspinatus
Greater tubercle of humerus.
Action of supraspinatus
Assists deltoid muscle in abducting arm at shoulder.
Origin of infraspinatus
Infraspinous fossa of scapula
Insertion of infraspinatus
Greater tubercle of humerus.
Action of infraspinatus
Laterally rotates arm at shoulder
Origin + insertion of teres major
O = Inferior angle of scapula
I = Medial lip of intertubercular sulcus of humerus.
Action of teres major
Extends arm at shoulder + assists in adduction + medial rotation of arm at shoulder joint.
Origin + insertion of teres minor
O = Inferior lateral border of scapula
I = Greater tubercle of humerus.
Action of teres minor
Laterally rotates + extends arm at shoulder
Origin + insertion of coracobrachialis
O = Coracoid process of scapula
I = Middle of medial surface of shaft of humerus
Action of coracobrachialis
Flexes + adducts arm at shoulder
What muscles are active throughout the entire throwing motion?
Rotator cuff muscles.
W/ activity levels peaking during cocking phase = infraspinatus + teres minor provide external rotation + the subscapularis + supraspinatus assist in providing stability to the glenohumeral joint.
