Question

Мышцы, наклоняющие голову вперёд, когда сокращаются вместе, и наклоняющие голову в стороны, когда сокращаются поодиночке

Answer 1

Кивательные (Грудино-ключично-сосцевидные). 

Answer 2

Кивательные мышцы. 

Answer 3

Muscles that Flex the Head Forward and Sideways

When it comes to flexing the head forward, there are several muscles that work together to achieve this movement. One of the main muscles involved is the sternocleidomastoid muscle, which is located on the sides of the neck. When the sternocleidomastoid muscle contracts, it tilts the head forward and also rotates it to the opposite side. This muscle is responsible for movements such as nodding the head and looking down.

Another muscle that contributes to flexing the head forward is the scalene muscle group. The scalene muscles are located on the sides of the neck, and when they contract, they assist in tilting the head forward. These muscles also play a role in elevating the ribs during breathing.

Source

In addition to flexing the head forward, there are also muscles that are responsible for tilting the head sideways. One of these muscles is the sternocleidomastoid muscle, which we mentioned earlier. When only one side of the sternocleidomastoid muscle contracts, it tilts the head to the same side.

Another muscle involved in tilting the head sideways is the splenius capitis muscle. This muscle is located at the back of the neck and upper back. When it contracts on one side, it tilts the head to the same side.

Source

To summarize, the muscles that flex the head forward when they contract together include the sternocleidomastoid muscle and the scalene muscle group. When these muscles contract, they tilt the head forward. On the other hand, when these muscles contract individually, they tilt the head sideways.

I hope this information helps! Let me know if you have any further questions.