Acromial types （肩峰分型）

多数文献根据Bigliani提出肩峰分型分为3型：扁平肩峰、弯曲肩峰、钩状肩峰。

I型(扁平型)占18.4%，

II型(弯曲型)占52.6%，

III型(钩型)占29.0%。

Ⅳ型：反弧型或上翘型(convex or upturned)。

斜矢状位T1WI像4种肩峰示意图:

The shape of the acromion has been initially divided into 3 types (which was known as the Bigliani classification), to which a fourth has been added:

1.  flat inferiorly

2.  curved - parallel to the humeral head with convex undersurface - considered commonest type 

3. hooked - the most anterior portion of the acromion has a hooked shape ,associated with increase incidence of shoulder impingement

4. convex (upturned )

• this is the most recent classification of acromion process
• in this type of acromion, the undersurface is convex near the distal end
• no convincing correlation between a type 4 acromion and impingement syndrome exists

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冈上肌出口位X线片的肩峰分型:

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肩峰下撞击及肩袖撕裂示意图：

   Anatomical abnormality in the shape of the acromion or degeneration with formation of spurs on the underside of the ACJ can lead to the tendon rubbing painfully against these structures, leading to inflammation within the bursa and tendon and possibly to eventual tendon damage and rupture.

      肩峰解剖异常或肩锁关节（ACJ）下方骨刺形成，可导致肌腱痛性摩擦这些结构，导致滑囊和肌腱内发炎，并可能最终导致肌腱损伤和撕裂。