Download MUSCLES OF THE PECTORAL GIRDLE Objectives At the end of

MUSCLES OF THE PECTORAL GIRDLE
Objectives
At the end of this demo the student should be able to:
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Explain the different muscles attached to the pectoral girdle and to which group they belong.
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Explain the attachments , innervations and blood supply of the muscles.
COURSE OUTLINE:
INTRODUCTION:
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Muscles of the pectoral girdle broadly are divided into
1. Ant.axioappendicular group
2. Post.axioappendicular group
1. Ant.axioappendicular muscles
Also called thoracoappendicular or pectoral muscles
Four muscles
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Pectoralis major
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Pectoralis minor
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Subclavius
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Serratus anterior
Pectoralis major
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Large fan shaped
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Covers superior part of thorax
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Has clavicular and sternocostal heads
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Its inferior border forms Ant. Axillary fold
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Pectoralis major and adjacent deltoid forms the narrow deltopectoral groove in which cephalic
vein runs
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Pectoralis major along with clavicle forms clavipectoral or deltopectoral triangle
Pectoralis minor
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Lies beneath Pectoralis major
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An imp.landmark for structures in axilla
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With coracoid process makes a bridge beneath which vessels and nerves pass
Subclavius
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Lies almost horizontally when the arm is in anatomical position
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Located inferior to clavicle and affords some protection to the subclavian vessels and the
superior trunk of brachial plexus if clavicle fractures
Serratus anterior
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saw toothed appearance, also called boxer’s muscle
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Overlies lateral part of thorax and forms medial wall of axilla
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Holds scapula against thoracic wall while doing push-ups
Attachments of muscles of ant.axioappendicular group:
Post.axioappendicular muscles
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Also called scapulohumeral muscles
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Divided into 3 groups
1. Superficial post. Appendicular(extrinsic shoulder) muscles;trapezius and latissimus dorsi
2. Deep post. Appendicular(extrinsic shoulder) muscles;levator scapulae or rhomboids
3. Scapulohumeral(intrinsicshoulder)muscles; deltoid, teres major ,and the 4 rotator cuff
muscles(supraspinatus,infraspinatus,teres minor and subscapularis)
Trapezius
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Large, triangular muscle, covers the posterior aspect of neck and superior half of trunk
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Have 3 types of fibres
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Superior fibres; elevate scapula
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Middle fibres; retract scapula
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Inferior fibres; depress scapula
Latissimus Dorsi
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Widest muscle of the back
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Climbing muscle
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Large fan shaped muscle passes from trunk to humerus
Levator Scapulae
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Sup.third lies deep to sternocleidomastoid,while inf.third lies deep to trapezius
Rhomboids
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Major and minor
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Forms oblique equilateral parrallelogram
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Lies deep to trapezius
Scapulohumeral (intrinsic shoulder)muscles
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Deltoid
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Supraspinatus
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Infraspinatus
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Teres major and minor
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subscapularis
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Deltoid
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Thick ,powerful, coarse textured forming rounded contour of the shoulder
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Shaped like delta
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Has unipennate ant.and post.parts
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Multipennate middle part