Muscles of Lateral Cervical Region Flashcards
What are the contents of the posterior cervical triangle?
Splenius capitis, scalenes (anterior, middle, posterior), levator scapulae
What are the boundaries of the posterior cervical triangle?
SCM, clavicle, and trapezius.
Where is the insertion of the SCM?
It originates on the lateral surface of mastoid process and lateral half of superior nuchal line.
Where does the SCM originate?
The clavicular head inserts on the superior surface of the medial third of the clavicle.
The sternal head inserts on anterior surface of manubrium on sternum.
What is the innervation of the SCM?
Spinal accessory nerve (CN XI for motor), C2 and C3 nerves for sensory (pain and propioception)
What is the action of the SCM during unilateral contraction?
During unilateral contraction, the SCM performs lateral flexion of the neck and rotation of the face superiorly to opposite side.
What is the action of the SCM during bilateral contraction?
During bilateral contraction, the SCM extends the neck at atlanto-occipital joints, flexes cervical vertebrae (chin toward manubrium), extends superior cervical vertebrae while flexing inferior vertebrae (protrusion)
What is the origin of the anterior scalene?
The anterior tubercles of transverse processes C3-C6
Where does the anterior scalene insert?
First rib
What is the innervation of the anterior scalene?
Cervical spinal nerves C4-C6
What action does the anterior scakene perform?
Lateral flexion of the neck, also elevates first rib during forced respiration
What is the origin of the middle scalene?
The posterior tubercles of transverse processes C4-C7
Where does the middle scalene insert?
It inserts on the superior surface of the first rib; posterior to groove of subclavian artery
What is the innervation of the middle scalene?
Anterior rami of cervical spinal nerves
What action does the middle scalene perform?
Lateral flexion of the neck, also elevates first rib during forced respiration
