Overview
The most superficial muscle of the scapular region. Classic feline anatomy texts describe three trapezius muscles: clavotrapezius, acromiotrapezius and spinotrapezius. The clavotrapezius is the cleidocervicalis, which veterinary nomenclature places in the brachiocephalicus. The other two are the parts of the trapezius:
- Cervical part (pars cervicalis): the acromiotrapezius, a thin sheet from the dorsal neck and withers to the metacromion and spine of the scapula.
- Thoracic part (pars thoracica): the spinotrapezius, from the thoracic spinous processes to the spine of the scapula.
Origin
Median fibrous raphe of the neck and spinous processes of the thoracic vertebrae.
Insertion
Spine of the scapula (spina scapulae), including the metacromion.
Action
Elevates and abducts the thoracic limb. The cervical part draws the scapula craniodorsally, the thoracic part caudodorsally.
Innervation
Dorsal branch of the accessory nerve (n. accessorius, cranial nerve XI).
Clinical relevance
It lies under the skin of the interscapular region, for years the usual site for vaccines and injections in the cat. Injection-site sarcomas here are hard to remove with wide margins, so current guidelines recommend vaccinating in the distal limbs or the tail.