Scapula Osteology Explained | First MBBS Anatomy|CRACK THE BONE

Scapula (Shoulder Blade)
Flat, triangular bone on the posterolateral aspect of the thorax (ribs 2–7).
Connects the upper limb to the trunk.

Parts:
Body
3 Processes: Spine, Acromion, Coracoid process

Surfaces
1. Costal (Anterior) Surface
Concave and forms the subscapular fossa.
Muscle attachment:
Subscapularis muscle (entire surface).
2. Dorsal (Posterior) Surface
Divided by the spine of scapula into:
Supraspinous fossa → Supraspinatus muscle
Infraspinous fossa → Infraspinatus muscle
The fossae communicate via spinoglenoid notch.

Borders
1. Superior Border
Contains suprascapular notch, converted into foramen by the superior transverse ligament.
Suprascapular artery passes through.
2. Medial (Vertebral) Border
Attachments:
Levator scapulae (upper part)
Rhomboid minor (middle)
Rhomboid major (lower part)
Serratus anterior (costal surface along the border)
3. Lateral (Axillary) Border
Thickest border.
Attachments:
Teres minor (upper part)
Teres major (lower part)
Long head of triceps brachii (infraglenoid tubercle)

Angles
Superior angle → Levator scapulae
Inferior angle → Latissimus dorsi
Lateral angle → bears glenoid cavity (articulates with head of humerus to form shoulder joint)

Processes
1. Spine of Scapula
Divides dorsal surface into two fossae.
Attachments:
Trapezius (upper lip of spine)
Deltoid (lower lip of spine)
2. Acromion Process
Articulates with clavicle at the acromioclavicular joint.
Attachments:
Trapezius (posterior border)
Deltoid (lateral border)
3. Coracoid Process
Projects forward.
Attachments:
Pectoralis minor (medial border & upper surface)
Coracobrachialis (tip)
Short head of biceps brachii (tip)
Coracoacromial ligament, coracoclavicular ligament (to clavicle)

Arterial Supply (Scapular Anastomosis)
Clinical importance: Provides collateral circulation between first part of subclavian artery and third part of axillary artery if one is blocked.
Arteries involved:
From 1st part of subclavian artery:
Transverse cervical artery (or superficial cervical)
Suprascapular artery
From 3rd part of axillary artery:
Subscapular artery → Circumflex scapular branch
Descending branch of dorsal scapular artery
Sites of anastomosis:
Over infraspinous, supraspinous, and subscapular fossae.

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