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Portrait of Scapula

Anatomy · Bones

Scapula

The shoulder blade

Pectoral girdle · back of the shoulder

The scapula, or shoulder blade, is a flat triangular bone on the back of the ribcage. A long ridge, the spine, runs across its back and ends in the flattened acromion at the tip of the shoulder, while a hook-shaped coracoid process projects forwards. Its shallow glenoid cavity forms the socket of the shoulder joint.

How to spot them

  • ▸Flat, triangular bone sitting on the back of the upper ribcage, with a prominent ridge (the spine) across its rear surface
  • ▸The spine ends laterally in the acromion, which meets the outer end of the collarbone
  • ▸A beak-like coracoid process curves forward from the upper border, below the collarbone
  • ▸A shallow socket, the glenoid cavity, at the upper outer corner receives the head of the arm bone

What to know

A flat triangular bone on the back of the chest wall, with a ridge across its upper back that ends in a flattened projection forming the point of the shoulder

Scapula — the shoulder blade, with its spine and acromion.

A hook-like process, named for a crow's beak, curves forward from its upper border, below the outer end of the collarbone

Scapula — the coracoid process.

Its shallow socket receives the rounded head of the arm bone to make the shoulder joint

Scapula — the glenoid cavity.

Paralysis of the long thoracic nerve, which supplies serratus anterior, makes its inner border stand out from the back like a wing

Scapula — 'winging'.

Its lowest tip is a surface landmark lying at about the level of the seventh thoracic vertebra

Scapula — the inferior angle.

It is held on the back of the ribs entirely by muscle and glides over the chest wall without articulating with any rib

Scapula — the scapulothoracic 'joint' is muscular, not bony.

A nerve passes beneath the ligament bridging a notch on its upper border, while the artery passes above it

Scapula — the suprascapular notch.

Key ideas

  • The scapula is supported only by the clavicle at the acromioclavicular joint and by muscle; that freedom is what gives the shoulder its wide range of motion.
  • Clavicle, acromion and the spine of the scapula together form a V-shaped bony line on which the neck and back muscles that move the shoulder attach.

Quick-fire facts

  • •It is a flat bone lying over roughly the second to seventh ribs; it has three borders (superior, medial, lateral) and three angles.
  • •The glenoid cavity is small and shallow, which makes the shoulder the most mobile, and most easily dislocated, major joint.
  • •The coracoid process is named for a crow's beak (Greek korax, crow); the acromion is the outer end of the spine and forms the bony tip of the shoulder.
  • •The spine divides the back of the bone into the supraspinous fossa above and the infraspinous fossa below; the front (deep) surface is the subscapular fossa.
  • •It does not articulate with the ribs; it is surrounded by muscle on both its front and back surfaces.
  • •The inferior angle is where powerful muscles such as teres major attach and is a classic landmark for counting levels on the back.
  • •The suprascapular notch carries the suprascapular nerve beneath the superior transverse scapular ligament; the mnemonic is that the Army (artery) goes over the bridge and the Navy (nerve) goes under.
  • •Latin scapula means 'shoulder blade'.

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