Sternocleidomastoid muscle (dave's notes) Flashcards
What do the two heads of SCM arise from?
The manubrium (a rounded tendon) and clavicle (thick fleshy mass)
What is found between the two heads of SCM?
A small triangle where the lower end of the internal jugular vein lies
Into what does SCM insert?
A curved line from the tip of the mastoid process to the superior nuchal line
What nerve supplies SCM?
The accessory nerve enters and supplies it
What fascia is associated with SCM?
SCM is enclosed within a sheath of the investing fascia which splits around it
What is found deep to SCM?
Deep to the upper part lies the cervical plexus
Deep to the lower part lies the carotid artery and the carotid sheath
Describe the nerve supply of SCM in detail
The nerve supply is by the spinal part of the accessory nerve (from the cerebral cortex of its own side) Ipsilateral supply for contralateral action.
What is the main action of SCM?
SCM is the main rotator of the lateral atlantoaxial joint
What muscles does SCM oppose?
SCM seldom acts alone. It is an antagonist to the extensor muscles behind the verterbrae
