Shoulder & Pectoral Regions,

Muscles OF

Objectives

• Identify the bony components of the shoulder girdle including the clavicle, scapula and humerus

• Describe how primary muscles are responsible for the following shoulder motion: adduction, abduction, flexion, extension

Surface Anatomy

Surface Anatomy

Bony Skeleton

• Axial?• Appendicular

• Can you name some?

• Shoulder Girdle..

Bony Skeleton

Shoulder Girdle

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.

Pectoral Girdle

• Direct : Clavicle , scapula from the trunk Pectoralis minor, trapezius, rhomboids… Most will be discussed in the scapular region lecture

• Indirect : muscles of the great axillary folds as Pectoralis Major, and Latismus dorsi

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”

Will make our life easier memorizing all the names..Nerve supply of the muscles tells us the story about it’s embryological origin..please pay attention in the embryology classes and enjoy the

integration

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 pec. major - protraction of scapula - guide to axilla

Poland Syndrome

CongenitalAbsence of Pectoralis MajorPartial or complete absence

Trapezius: 3 parts-Superior fibres elevate (insert lateral 1/3 of clavicle)

-Middle fibres retract (insert acromion)

-Inferior fibres depress (insert spine of scapula)

- Acting together, thesuperior and inferiorfibres will rotate scapula.

Superior

Middle

Inferior

Latissimus Dorsi:-(inserts floor of intertubercular groove)

-Extends, adducts and medially rotates humerus.

Butterfly swimming, CrutchClimbing a tree

Anterior

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

Posterior

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

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.

Dermatomes

Case

• 9 Years old boy fell on his shoulder while playing on the monkey bars, he is experiencing pain, and inability to

Lift his left arm this is his X-ray

What’s your diagnosis?

Clavicle Fractures

Fracture Clavicle

Glossary

• Pectoral: Worn on the chest or breast• Girdle: Something that encircles like a belt

References

• www.medicalstudents.com• www.google.com• www.dcfirst.com/

surface_arm_muscle_anatomy_posters.html• http://

etl2.library.musc.edu/surface_anatomy/core/structures/003.html

• http://www.shoulderdoc.co.uk/article.asp?section=902

• http://depts.washington.edu/msatlas/105.html