Question

for the most part, the neck muscles, which move the head and (1. ) girdle, are small and straplike. we consider only two neck muscles here (figure 6.16).
platysma
the platysma is a single sheetlike muscle that covers the anterolateral neck (see figure 6.16). it originates from the connective tissue covering of the chest muscles and inserts into the area around the mouth. its action is to pull the corners of the (2. ) inferiorly, producing a downward sag of the mouth (the \sad clown\ face).
sternocleidomastoid
the paired sternocleidomastoid (ster
o - kli\do - mastoid) muscles are two - headed muscles, one found on each side of the neck. of the two heads of each muscle, one arises from the (3. ), and the other arises from the clavicle (see figure 6.22, p. 214). the heads fuse before inserting into the mastoid process of the temporal bone. when both sternocleidomastoid muscles (4. ) together, they flex your neck. (it is this action of bowing the head that has led some people to call these muscles the \prayer\ muscles.) if just one muscle contracts, the face is rotated toward the shoulder on the opposite side and tilts the head to its own side.
homeostatic imbalance 6.3
in some difficult births, one of the sternocleidomastoid muscles may be injured and develop (5. ). a baby injured in this way has torticollis (tor\ti - kolis), or wryneck.

1. spasms 2. shoulder 3. mouth 4. sternum 5. contract

1. shoulder 2. mouth 3. sternum 4. contract 5. spasms

1. mouth 2. sternum 3. contract 4. spasms 5. shoulder

1. sternum 2. contract 3. spasms 4. shoulder 5. mouth

1. contract 2. spasms 3. shoulder 4. mouth 5. sternum

Explanation:

The neck muscles move the head and shoulder girdle. The platysma pulls the corners of the mouth. One head of the sternocleidomastoid arises from the sternum. When both contract, they flex the neck. Injured sternocleidomastoid can develop spasms.

Answer:

1. shoulder 2. mouth 3. sternum 4. contract 5. spasms