Shoulder Muscles Flashcards
Trapezius Descending part
O: Occipital bone and SP of C1-C7
I: Lateral third of clavicle
A: Upward rotation and elevation of scapula
Head and neck extension, ipsilateral inclination, and controlateral rotation
In: Motor: Accessory n. (CN XI)
Motor/Sensory: cervical plexus (C3-C4)
Trapezius transverse part
O: SP of T1-T4
I: Acromion and superior crest of spine of scapula
A: Retraction of the scapula
In: Motor: Accessory n. (CN XI)
Motor/Sensory: cervical plexus (C3-C4)
Trapezius ascending part
O: SP of T5-T12
I: Lateral apex of the medial end of scapular spine
A: Upward rotation of the scapula
In: Motor: Accessory n. (CN XI)
Motor/Sensory: cervical plexus (C3-C4)
Rhomboids major
O: SP of T1-T4
I: Medial border of scapula (from inferior angle to root of spine of scapula)
A: Downward rotation, retraction, (elevation), of scapula
Supports position of scapula
In: Dorsal scapular n. (C4, C5)
Rhomboids minor
O: SP of C6-C7 and nuchal lig.
I: Medial border of the scapula (above major)
A: Downward rotation, retraction, (elevation), of scapula
Supports position of scapula
In: Dorsal scapular n. (C4, C5)
Levator scapulae
O: TP of C1-C4
I: Superior angle of the scapula (medial border)
A: Entire muscle: steadies’ scapula on thorax
Proximal insertion fixed: downward rotation and elevation of scapula
Distal insertion fixed : extension and ipsilateral inclination of cervical spine
In: Cervical spine nn. (C3, C4), and dordal scapular n. (C5)
Serratus anterior
O:
Superior part: Ribs 1-2
Middle part: Ribs-3-6
Inferior part: Ribs 7-9
I:
Superior part: Superior angle (Anterior surface)
Middle part: Medial border (Anterior surface)
Inferior part: Inferior angle (Anterior surface and medial border)
A: Protraction and upward rotation of scapula
Elevate ribs when shoulder is fixed
In: Long thoracic n. (C5-C7)
Subclavius
O: 1st rib
I: Anteroinferior surface of middle third of clavicle
A: Stabilization of the sternoclavicular joint and resisting elevation of the lateral end (depression) of the clavicle
In: Subclavius n. (C5, C6)
Pectoralis minor
O: 3rd-5th ribs
I: Coracoid process
A:
Proximal insertion fixed : scapula depression, downward rotation (and protraction)
Distal insertion fixed : elevation of ribs –> accessory inspiration
In: Medial pectoral n. (C8, T1)
Supraspinatus
O: Supraspinous fossa
I: Greater tubercle of humerus
A: Initiate shoulder abduction
Stabilizes humeral head in glenoid cavity
In: Suprascapular n. (C5, C6)
Infraspinatus
O: Infraspinous fossa
I: Greater tubercle of humerus
A: Shoulder external rotation
Stabilizes humeral head in glenoid cavity
In: Suprascapular n. (C5, C6)
Teres minor
O: Superior 2/3 of lateral border of the scapula
I: Greater tubercle of humerus
A: Shoulder external rotation, and weak adduction
Stabilizes humeral head in glenoid cavity
In: Axillary n. (C5, C6)
Subscapularis
O: subscapular fossa
I: Lesser tubercle of the humerus
A: Shoulder internal rotation
Stabilizes humeral head in glenoid cavity
In: Upper and lower subscapular n. (C5, C6)
Teres major
O: Inferior angle of scapula
I: Medial lip of the intertubercular (bicipital) groove of the humerus
A: Shoulder internal rotation, adduction, and extension
In: Lower subscapular n. (C5, C6)
Deltoid anterior (clavicular) fibers
O: lateral one third of the clavicle
I: Deltoid tuberosity of humerus
A: Shoulder flexion, internal rotation, abduction (guide the arm), and horizontal ADD (90°)
Entire muscle: stabilization of the glenohumeral joint (especially carrying load)
In: Axillary n. (C5, C6)
Deltoid lateral (acromial) fibers
O: Acromion
I: Deltoid tuberosity of huemrus
A: Abduction (over 15°)
Entire muscle: stabilization of the glenohumeral joint (especially carrying load)
In: Axillary n. (C5, C6)
Deltoid posterior (spinal) fibers
O: Spine of scapula
I: Deltoid tuberosity of humerus
A: Shoulder extension, external rotation, abduction (guide the arm), and horizontal abduction (90°)
Entire muscle: stabilization of the glenohumeral joint (especially carrying load)
In: Axillary n. (C5, C6)
Latissimus dorsi
O: Vertebral part: SP of T7-T12 and Thoracolumbar fascia
Costal part: Ribs 9-12
Scapular part: Inferior angle of scapula
Iliac part: Posterior one third of illiac crest
I: Intertubercular sulcus of the humerus (between pectoralis major and teres major muscles)
A: Shoulder extension, adduction, and internal rotation
Accessory muscle of expiration (cough muscle)
In: Thoracodorsal n. (C6-C8)
Coracobrachialis
O: Coracoid process of scapula
I: Anteromedial surface of the midshaft of humerus
A: Shoulder flexion, adduction, and assist internal rotation
In: Musculocutaneous n. (C5-C7)
Pectoralis major
O: Clavicular part: Anterior surface of medial half of clavicle
Sternocostal part: Anterior surface of sternum and costal cartilages of ribs 1-6
Abdominal part: Anterior layer of rectus sheath
I: Crest of greater tubercle (lateral lip) of humerus
A: Shoulder adduction, internal rotation, horizontal adduction, and scapula depression (entire muscle)
Clavicular part: shoulder flexion
Sternocostal part: shoulder extension
Accessory muscle of inspiration (insertion fixed)
In: Medial pectoral n. (sternocostal part) and lateral pectoral n. (clavicular part) (C5-T1)
