Scapula

Description

Anatomy of the scapula

Anterior view of scapula

Posterior view of the scapula

Shoulder PA radiograph with the scapula labeled

(A) Illustration of a posterior right scapula demonstrating the approximate locations of anatomic and adventitial bursae. (B) Illustration of an axial slice at approximately the level of the scapular spine. Note the orientation of bursal tissue relative to the scapula, posterior thorax, and periscapular musculature

Attachment of muscles on the scapula

Name

• Scapula
• Shoulder Blade

Etymology

• Coracoid process dervices from korakodes, meaning "like a crow's beak"

General

• Flat, triangular bone located on the posterior aspect of the thorax
• Places a crucial role in shoulder function

Attachments

• Anterior
  • Subscapularis (subscapular fossa)
  • Pectoralis Minor (coracoid process)
  • Coracobrachialis (coracoid process)
• Medial
  • Serratus Anterior (medial border)
  • Rhomboid Major (medial border)
  • Rhomboid Minor (medial border)
  • Levator Scapulae (medial border)
• Posterior
  • Trapezius (spine of scapula)
  • Deltoid (spine of scapula)
  • Supraspinatus (supraspinatus fossa)
  • Infraspinatus (infraspinatus fossa)
• Lateral
  • Triceps Brachii (long head: infraglenoid tubercle)
  • Biceps Brachii (short head: coracoid process, long head: supraglenoid tubercle)
  • Teres Minor (lateral border)
  • Teres Major (lateral border)
• Inferior
  • Latissimus Dorsi (inferior border)

Actions

• Role of scapula
  • Provides synchronous scapular rotation during humeral motion
  • Serves as a stable base for Rotator Cuff activation
  • Functions as a link in the kinetic chain
• Planes of motion
  • Upward/downward rotation around a horizontal axis perpendicular to the plane of the scapula
  • Internal/external rotation around a vertical axis through the plane of the scapula
  • Anterior/posterior tilt around a horizontal axis in the plane of the scapula
• Planes of translation
  • Upward/downward translation on the thoracic wall
  • Retraction (posterior, medial)/protraction (anterior, lateral) around the rounded thorax
• Action by muscle group
  • Elevation: upper Trapezius, Levator Scapulae
  • Depression: lower Trapezius
  • Retraction (adduction): Rhomboid Major, Rhomboid Minor, middle Trapezius
  • Protraction (abduction): Serratus Anterior
  • Upward rotation: upper, middle Trapezius
  • Downward rotation: Rhomboid Major, Rhomboid Minor

Articulations

• Glenohumeral Joint: formed by the glenoid cavity articulating with the head of the humerus
• Acromioclavicular Joint: formed by the medial clavicle articulating with the acromion process
• Scapulothoracic Joint: The scapula forms an articulation with the thoracic cavity

Anatomic Landmarks

• Spine of the scapula: prominent ridge running across the posterior surface, divides supraspinous and infraspinous fossae
• Acromion: lateral extension of the spine, forms highest point of the shoulder
• Coracoid process: hook-like anterior structure, attachment for muscles and ligaments
• Glenoid cavity: shallow depression articulates with the head of the humerus, forms the shoulder joint
• Suprascapular notch: superior border, medial to the coracoid process, bridged by the superior transverse scapular ligament
• Inferior angle: most inferior aspect, important for muscle attachment and movement
• Medial border: attachment for several muscles
• Lateral border: site for muscle attachment
• Superior angle: uppermost point of the scapula, near the medial border
• Infraglenoid tubercle: Located below the glenoid cavity, attachment point for the long head of the triceps brachii muscle

Bursae related to the Scapula

• Scapulothoracic Bursae
• Subscapular Bursa
• Subcoracoid Bursa
• Scapulothoracic Bursa

Anatomic Variants

• Os Acromiale

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Clinical Significance

• Scapular Dyskinesis
• Scapula Fracture
• Scapulothoracic Bursitis
• Snapping Scapula Syndrome

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See Also

• Shoulder Pain (Main)
• Shoulder Anatomy (Main)
• Physical Exam Shoulder

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