Subclavius posticus muscle - an accessory muscle

Case contributed by Dr Matt Skalski

Patient Data

Age: 55
Gender: Male

There is a curvilinear structure that is isointense to muscle on all sequences (however only T1-weighted images are show here), traveling from the superior angle of the scapula to the sternocleidomastoid (SCM) muscle through the posterior cervical space.  This finding is bilateral. 

Modality: Annotated image

The accessory muscle is indicated by the blue asterisks.

Case Discussion

The subclavius posticus muscle is a somewhat rare accessory muscle (although on dissection is found in up to 9% - so maybe not so rare), and may occasionally be associated with thoracic outlet syndrome (TOS); however, there is no evidence of TOS in this case. 

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Case Information

rID: 30797
Case created: 4th Sep 2014
Last edited: 27th Apr 2017
Inclusion in quiz mode: Included

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