a question about movements of the cervical spine via muscles.?

Question

in a unilateral contraction of the cervical spine, is the lateral flexion the same as ipsilateral flexion.
and the rotation of the head the same as the contralateral rotation of the head.?
sorry i got stuck with some uni revision.

Answer 1

Yes, those are correct. The lateral-flexion / ipsiplateral-muscles concept should be intuitive -- but the rotation of the head is indeed caused by contraction of the contralateral sternocleidomastoid because the movement is produced by a pulling action exerted at a point on the far, distal portion of the mandible, the effect of which rotates the head in the contralateral direction.

It is somewhat similar to contraction of the pectoralis muscles, which pull the outstretched arms toward midline in the CONTRALATERAL direction -- i.e. like doing the "butterfly" exercise for the chest. The main difference is that the head is able to rotate far beyond midline, whereas the proximal arm is restricted from doing so.

Answer 2

MUSCLES:
FLEXORS: longus colli & capitis, infra hyoids

EXTENSORS: splenius capitis, semispinalis capitis, suboccipitals, trapezius

ROTATORS: splenius capitis, sternocleidomastoid, levator scapula, suboccipitals

LATERAL FLEXORS: scalenes

COMMENTS: The motion of the neck can be divided into rotation (looking side to side), lateral flexion (ear to shoulder) .
Unilateral flexion of neck is ipsilateral flexion because suboccipital muscles are always involved.
Rotation of head is technically a motion of Atlas over Axis but practically involves sterncleidoomastoids causing mild rotation of cervical spine. So it is contralateral rotation