From the sloping platform of the shoulders the neck rises, a cylindrical column, curving slightly forward even when the head is thrown well back.
It is canopied in front by the chin. It is buttressed on the sides by the trapezius (table) muscle. The table shape of this muscle appears only from the back, a diamond with lower apex well down the back. Its lateral corners arise from
the shoulder girdle opposite the deltoid. Rising diagonally upward it braces the back of the head.
The strength of the neck is therefore at the back, which is somewhat flat and overhung by the base of the skull.
From bony prominences back of the ears two muscles (sterno-mastoid), aptly called the bonnet-string muscles, descend to almost meet at the root of the neck, forming a triangle whose base is the canopy of the chin.
In this triangle below is the thyroid gland, larger in women; and above it the angular cartilage of the larynx, or Adam's apple, larger in men.
Crossing its upper corners outward and downward is a thready skin muscle (platysma myoides) which lifts the skin into high folds and draws down the corners of the mouth. It carries the imagination back to the time in evolution when bared teeth were important weapons of defense.
Muscles of the Neck:
2 Levator of the scapula.
Sterno-cleido-mastoideus: From top of sternum and sternal end of clavicle to mastoid process (back of ear). Action: Together, pull head forward; separately, rotates to opposite side, depresses head.
Levator of the Scapula: From upper cervical vertebrae to upper angle of shoulder blade. Action: Raises angle of shoulder blade.
Trapezius: From occipital bone, nape ligament and spine as far as twelfth dorsal, to clavicle, acromion and ridge of shoulder blade. Action: Extends head, elevates shoulder and rotates shoulder blade.
Tongue-Bone and Larynx
I Hyoid bone.
a Thyroid cartilage.
3 Thyroid gland muscles.
4 Digastric (has two portions).
Movements of the Neck
In the neck are seven vertebra?, each moving a little. When the neck is turned to one side, that side of each vertebra moves back as far as the perpendicular and then the opposite sides move forward, lengthening the neck as they do so. This motion is much freer at the second joint from the skull, which turns on a pivot. The joint of the skull
itself moves only in nodding, in which the rest of the neck may be quite stationary.
Muscles of Neck
Platysma Myoides: A sheathing from chest and shoulder to masseter and corner of mouth. Action: Wrinkles skin of neck, draws down corner of mouth.
Digastric (double-bellied muscle): Anterior belly, from maxilla, behind chin; posterior belly, from mastoid process; fastened by loop to hyoid bone. Action: Raises hyoid and tongue.
Mylo-hyoid: Forms floor of mouth and canopy of chin in front.
Stylo-hyoid: From hyoid to styloid process. Action: Draws back hyoid and tongue.
Sterno-hyoid: From sternum to hyoid bone. Action: Depresses hyoid and Adam's apple.
Omo-hyoid: From hyoid bone to shoulder, upper border of scapula. Action: Draws hyoid down and to one side.