Neck Muscles Anatomy

As you know, the neck is the part of the body that sits between the head and torso. The neck has no external bony protective structures, so it is quite mobile.

Neck mobility is necessary primarily to rotate the head and keep the head upright. This is a rather important task that is performed not only by the bones but also by the muscles of the neck. We will talk about them.

The neck muscles are divided into three large groups, which correspond to the depth of their location:

• Neck muscles of the superficial layer;
• Neck muscles of the middle layer;
• Deep neck muscles.

For plastic anatomy, the muscles of the neck that shape the appearance of this part of the body and become noticeable during contraction are of particular importance. These are, first of all, the superficial muscles and some muscles of the middle layer. In this article, we are going to study these muscles.

The Muscles of the Superficial Layer

Platysma Muscle

It is a very wide, flat muscle of the neck that covers much of the front and sides of the neck like a collar. The platysma extends from the upper chest and shoulder region to the lower part of the face.

Many anatomists classify this muscle among the muscles of facial expression because some of its fibers blend with the muscles and skin around the lower part of the face. Therefore, under tension, the platysma can create a characteristic facial expression with tense skin and downward-pulled corners of the mouth.

The muscle begins from the superficial fascia covering the upper parts of the pectoralis major and deltoid muscles.

The Sternocleidomastoid Muscle

This muscle also belongs to the superficial layer, although it is very different from the thin and wide platysma.

The sternocleidomastoid is a large, powerful paired muscle that starts from the manubrium of the sternum and the medial part of the clavicle and attaches to the mastoid process of the temporal bone and the superior nuchal line. This muscle lies deep to the platysma.

In a person without excess body weight or conditions that alter the contour of the neck, this muscle is clearly visible through the skin when the head is turned.

The Muscles of the Middle Layer

The muscles of the middle layer are also divided into two groups according to their location. The first group is located above the hyoid bone, and the second is below the hyoid bone. We will dwell in detail only on some of the muscles of this group, which are important for plastic anatomy.

Digastric Muscle

It is a rather unusual muscle that consists of two bellies connected by an intermediate tendon. The anterior belly starts from the digastric fossa of the mandible, while the posterior belly starts from the mastoid notch of the temporal bone. The intermediate tendon is connected to the hyoid bone by a fibrous sling.

Mylohyoid Muscle

The mylohyoid muscle looks like a wide plate and is located deep to the anterior belly of the digastric muscle. This muscle starts from the mylohyoid line of the mandible and attaches to the median raphe and the hyoid bone.

Like the other suprahyoid muscles, the mylohyoid helps raise the hyoid bone. It can also assist in lowering the mandible when the hyoid bone is fixed.

Muscles Located Below the Hyoid Bone

These muscles are generally longer and more elongated than the muscles located above the hyoid bone. The muscles located below the hyoid bone include the omohyoid, sternohyoid, sternothyroid, and thyrohyoid muscles.

We will analyze two muscles that are most important for topography and plastic anatomy.

Omohyoid Muscle

It is a long muscle consisting of two bellies connected by an intermediate tendon. It runs from the upper edge of the scapula to the hyoid bone. The omohyoid helps divide the neck into several triangular regions. This makes it a useful landmark for studying other anatomical structures of the neck.

Sternohyoid Muscle

It is one of the most superficial infrahyoid muscles. The sternohyoid muscle runs vertically along the front of the neck and connects the manubrium of the sternum and the medial end of the clavicle to the hyoid bone. Its main function is to lower the hyoid bone.

Neck Borders

The upper border of the neck is a line drawn from the lower edge of the mandible to the mastoid process, then along the superior nuchal line of the occipital bone to the external occipital protuberance.

The lower border of the neck is drawn from the manubrium of the sternum along the upper edges of the clavicles, then toward the acromions and the spinous process of the 7th cervical vertebra.

Neck Regions

The anterior region of the neck is bordered above by the lower edge of the mandible, below by the manubrium of the sternum, and laterally by the anterior edges of the sternocleidomastoid muscles. The anterior region is an unpaired region.

The lateral region of the neck is paired. Each area is bordered in front by the posterior margin of the sternocleidomastoid muscle, behind by the anterior edge of the trapezius muscle, and below by the clavicle. Superiorly, the sternocleidomastoid and trapezius muscles meet near the superior nuchal line.

The sternocleidomastoid region corresponds to the sternocleidomastoid muscle.

The posterior region is bounded above by the superior nuchal line of the occipital bone, below by a line drawn through the spinous process of the 7th cervical vertebra, and laterally by the anterior borders of the trapezius muscles. The back of the neck is an unpaired area.

Triangles of the Neck

The submandibular triangle is bounded by the anterior and posterior bellies of the digastric muscle and the lower edge of the mandible.

The anterior triangle of the neck is bounded by the midline of the neck, the anterior edge of the sternocleidomastoid muscle, and the lower edge of the mandible.

The posterior triangle is bounded by the posterior margin of the sternocleidomastoid muscle, the anterior edge of the trapezius muscle, and the middle part of the clavicle.

The carotid triangle is bounded by the anterior edge of the sternocleidomastoid muscle, the posterior belly of the digastric muscle, and the superior belly of the omohyoid muscle.

The omoclavicular triangle is bounded by the clavicle, the inferior belly of the omohyoid muscle, and the posterior edge of the sternocleidomastoid muscle.

The omotrapezoid triangle is bounded by the anterior edge of the trapezius muscle, the posterior edge of the sternocleidomastoid muscle, and the inferior belly of the omohyoid muscle.