LEC: Anatomy: Upper Extremity I (Revised) Muscles OF Shoulder & Pectoral Region

Objectives Know the landmarks of the bony structures of the shoulder and axillary regions. Discuss the muscles of pectoral and shoulder regions in terms of their origin, insertion, nerve supply and actions. Understand how muscles are responsible for the movements (adduction, abduction, flexion and extension) at the shoulder joint. Know the rotator cuff muscles, external and internal rotators.

Surface Anatomy

Surface Anatomy

Bony Skeleton Axial? Appendicular? Can you name some? Shoulder Girdle..

Bony Skeleton

Shoulder Girdle

Pectoral Girdle Direct: Clavicle, Scapula from the trunk Pectoralis minor, trapezius and rhomboids. Indirect : Muscles of the great axillary folds as Pectoralis Major, and Latissimus dorsi.

Clavicle

Anterior Scapula. -angles, borders -glenoid cavity, -acromion, -coracoid process, -Subscapular fossa Humerus. -Head, -Surgical neck -Anatomical neck -Greater tubercle -Lesser tubercle -Intertubercular (bicipital) groove acromion anatomical neck coracoid process Lesser tubercule Greater tubercule surgical neck bicipital groove glenoid cavity

Posterior Clavicle. Acromioclavicular joint Scapula. - Spine - Acromion - Supraspinous fossa - Infraspinous fossa Humerus. - Head - Anatomical neck, - Surgical neck, - Deltoid tuberosity - Spiral (radial) groove. Acromioclavicular joint Supraspinous Fossa anatomical neck surgical neck Spine Deltoid Tuberosity Infraspinous Fossa Radial Groove

Movements of the shoulder joint (Scapulohumeral): Abduction / adduction Flexion / extension Rotation – internal (medial) - external (lateral) Movements of the scapula (Thoracoappendicular): (increase range of movement of upper limb) Protraction / Retraction Elevation / Depression Rotation: Superior / Inferior Circumduction

Name the action

We need MUSCLES for all that!! Muscles are named by either their; Attachments ----- “Sternohyoid” Location ---- ”Pectoralis” Action ---- “Levator” Shape ---- ”Quadratus” Direction of fibers ---- “Rectus” Nerve supply of the muscles tells us the story about it’s embryological origin.

Pectoralis Major: 2 parts Pectoralis minor - deep to pectoralis major - protraction of scapula - guide to axilla Pectoralis Major: 2 parts - Together (adduction, medial rotation) Clavicular head (flexion) Sternocostal head (extension) (common insertion: lateral lip of intertubercular groove) Clavicular Sternocostal

Trapezius: 3 parts Superior fibers elevate Middle fibers retract (insert lateral 1/3 of clavicle) Middle fibers retract (insert acromion) Inferior fibers depress (insert spine of scapula) - Acting together, the superior and inferior fibers will rotate scapula. Superior Middle Inferior

Latissimus Dorsi: Extends, adducts and medially rotates Humerus. -(inserts floor of intertubercular groove) Extends, adducts and medially rotates Humerus. Swimming, And Climbing a tree

- retract / inferior rotate scapula Posterior view: - Trapezius - Latissimus Dorsi - Deltoid Trapezius Rhomboids Deltoid Rhomboids: - minor and major - retract / inferior rotate scapula Teres Major Latissimus Dorsi Teres major: - inserts near Latissimus dorsi - adduct / medially rotate arm

Shoulder Flexion Anterior Arm. – Biceps brachi – Coracobrachialis Actions: Biceps – supination + flexion (shoulder, elbow) Coracobrachialis – weak flexion / adduction (shoulder)

Anterior (flexion, med. rotation) Middle (abduction) Deltoid: 3 parts Anterior (flexion, med. rotation) Middle (abduction) Posterior (extension, lat. rotation) (common insertion: deltoid tuberosity) Posterior Anterior Deltoid

Shoulder Extension Posterior Arm. Triceps (3 heads) -long head extends Action: Extension Axillary Nerve Teres minor Deltoid Long Lateral Triceps Medial

Key Muscles that act across the Shoulder Joint. Adduction – pectoralis major, lattisimus dorsi. Abduction – deltoid, supraspinatus. Flexion – pectoralis major, deltoid (anterior), – coracobrachialis, biceps. Extension – latissimus dorsi, deltoid (posterior); – pectoralis major from flexed position - triceps (long head). Medial Rotation – subscapularis, pectoralis major, deltoid (anterior), – latissimus dorsi, teres major; Lateral Rotation – infraspinatus, teres minor, deltoid (posterior). This slide will be repeated through the first week lectures, will add up as we proceed with the axilla and scapular region

Thank you