Shoulder & Pectoral Region

Muscles OF

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

AnteriorScapula.-angles, borders-glenoid cavity, -acromion, -coracoid process, -Subscapular fossa

Humerus.-Head,-Surgical neck-Anatomical neck-Greater tubercle-Lesser tubercle-Intertubercular (bicipital) groove

PosteriorClavicle.Acromioclavicular joint

Scapula.- Spine - Acromion- Supraspinous fossa- Infraspinous fossa

Humerus. - Head - Anatomical neck, - Surgical neck, - Deltoid tuberosity- Spiral (radial) groove.

Movements of the shoulder joint (Scapulohumeral):

Abduction / adductionFlexion / extension

Rotation – internal (medial)- external (lateral)

Movements of the scapula (Thoracoappendicular):(increase range of movement of upper limb)Protraction / RetractionElevation / DepressionRotation: 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.

Clavicular

Sternocostal

Pectoralis Major: 2 parts- Together (adduction, medial rotation)- Clavicular head (flexion)- Sternocostal head (extension)- (common insertion: lateral lip of intertubercular groove)

Pectoralis minor - deep to pectoralis major - protraction of scapula - guide to axilla

Trapezius: 3 parts-Superior fibers elevate (insert lateral 1/3 of clavicle)-Middle fibers retract (insert acromion)-Inferior fibers depress (insert spine of scapula)

- Acting together, thesuperior and inferiorfibers will rotate scapula.

SuperiorMiddle

Inferior

Latissimus Dorsi:-(inserts floor of intertubercular groove)-Extends, adducts and medially rotates Humerus.

Swimming, And

Climbing a tree

Posterior view:- Trapezius- Latissimus Dorsi- Deltoid

Rhomboids:- minor and major- retract / inferior rotate scapula

Teres major:- inserts near Latissimus dorsi- adduct / medially rotate arm

Anterior Arm.– Biceps brachi– Coracobrachialis

Actions: Biceps – supination + flexion (shoulder, elbow)Coracobrachialis – weak flexion / adduction (shoulder)

Shoulder Flexion

Anterior

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

Posterior

Posterior Arm.-Triceps (3 heads)-long head extends shoulder.

Action: Extension

Shoulder Extension

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).

Key Muscles that act across the Shoulder Joint.

Thank you