Week III Muscles BD Flashcards
Origin of Sternocleidomastoid
O: sternal head- anteromedial manumbium of the sternum
clavicular head- medial (one third of the) clavicle
Insertion of Sternocleidomastoid
I: mastoid process of the temporal bone and lateral superior nuchal line of the occipital bone
Action of Sternocleidomastoid
A: Unilaterally- laterally flexes the head and neck to the same side at the spinal joints, rotates the head and neck to the opposite side (contralaterally rotates) at the spinal joints
Bilaterally- flexes the head and neck at the spinal joints
Origin of Scalenes
O: as a group- transverse processes (TPs) of C2-C7
Insertion of Scalenes
I: anterior & middle- first rib (posterior to clavicle)
posterior- second rib (at or above trapezius)
Action of Scalenes
A: Unilaterally- with ribs fixed, laterally flexes the neck to the same side at the spinal joints, rotates the neck to the opposite side (contralaterally rotates) at the spinal joints
Bilaterally- flexes the neck at the spinal joints (anterior and middle scalenes) (elevates the ribs during inhalation at the sternocostal and costospinal joints)
Origin of Splenius Capitis
O: inferior (one half) ligamentum nuchae and spinous processes (SPs) of C7-T4
Insertion of Splenius Capitis
I: mastoid process of the temporal bone and lateral (one third of the) superior nuchal lines of the occipital bone
Action of Splenius Capitis
A: Unilaterally- laterally flexes the head and neck to the same side as the spinal joints, rotates the head and neck to the same side (ipsilaterally rotates) at the spinal joints
Bilaterally- extends the head and neck at the spinal joints
Origin of Splenius Cervicis
O: spinous processes (SPs) of T3-T6
Insertion of Splenius Cervicis
I: transverse processes (TPs) of C1-C3
Action of Splenius Cervicis
A: Unilaterally- laterally flexes the neck to the same side at the spinal joints, rotates the neck to the same side (ipsilaterally rotates) at the spinal joints
Bilaterally- extends the neck at the spinal joints
