Explore the Neck Anatomy in a free and downloadable 3D Model

The "neck"—colloquially speaking—is the section of human anatomy between the head and the rest of the body. The word "cervical" is derived from Latin and simply translates to "of the neck." The neck has a huge responsibility in supporting the head, while also allowing enough flexibility to change the position of the head—a full 60 to 80 degrees of rotation in most healthy adults. Because of its versatility and utility, the neck is simply one of the most fascinating parts of the human form.

One of the best ways to explore neck anatomy is in a 3D model. In this week's post, the staff at embodi3D® have put together a number of exciting examples demonstrating the usefulness of 3D printing in modeling the head, neck, and upper torso. 

These days, physicians, radiologists, and those within the medical community are using DICOM CT scans converted into STL files in order to create 3D-printed models of this fascinating region of the human body. These 3D-printed models are then used in medical training, as references during patient consultations, as well as guides during complicated surgeries. In a recent issues of the Journal of Spine Surgery, they explored 3D-printed models' use in complex neck and spine surgeries, with a particular emphasis on how neurosurgeons are using the technology. 

The embodi3D® website hosts a section dedicated to CT scans of the head, neck, and spine, but this is the first blog post devoted to the neck. In this week's embodi3D® blog post, we will take a look at some of the most compelling files uploaded to the embodi3D® website. All of these can be used to explore the anatomy of the neck in a 3D model. Before you can begin printing your own 3D models, you must first become a registered member. It is absolutely free to join embodi3D® and take advantage of our many industry-leading tools and conversion algorithms. Register with embodi3D® today!

#1. A CTA Scan of the Neck in NRRD Format

Dr. Mike uploaded this excellent CT scan showing all the intricate structures of the neck in beautiful detail, including spaces of the infrahyoid neck.

Spaces of the infrahyoid neck

The infrahyoid neck is divided into 5 major anatomical compartments or spaces by the various layers of the cervical fascia.
These spaces are well recognized in the axial plane and therefore suited for analysis on axial CT or MR. 

- Visceral space
Central compartment containing several viscera like the larynx, thyroid, hypopharynx and cervical esophagus.

- Carotid space
Paired space just lateral to the visceral compartment which contains the internal carotid artery, internal jugular vein and several neural structures.

- Retropharyngeal space 
A small virtual space containing only fat continuous with the suprahyoid space and the middle mediastinum.

- Posterior Cervical Space 
Paired space posterolateral to the carotid space. 
It contains fat, lymph nodes and neural elements.

- Perivertebral space 
This large space completely encircles the vertebral body including the pre- and paravertebral muscles.

#2. A 3D Model Showing Skin of the Neck (in 3D-Printable STL Format)

This awesome 3d model of the neck shows the surgical triangles. The infrahyoid neck is the region of the neck extending from the hyoid bone to the thoracic inlet.  Traditionally the anatomy of the infrahyoid neck has been subdivided into a group of surgical triangles whose borders are readily palpable bones and muscles. These triangles have a cranial-caudal orientation and therefore are difficult to correlate with cross-sectional imaging. Another approach to the anatomy of the neck is the so-called 'spatial approach', which we shall use in this review.

#3. MRI of the neck

This dicom image shows the neck and head without contrast. T1 sequence allows evaluate the normal anatomy.

#4. CT of the Neck in a Coronal View

This model shows the muscles in the front of the neck are the suprahyoid and infrahyoid muscles and the anterior vertebral muscles (see the images below). The suprahyoid muscles are the digastrics, stylohyoid, mylohyoid, and geniohyoid. The infrahyoid muscles are the sternohyoid, sternothyroid, thyrohyoid, and omohyoid.

#5. CT Scan of the Neck in a Patient with Craniotomy

This ct scan shows the neck muscles and spaces.

#6. 3D Model of the Cervical Spine from an STL File

This 3d model shows all the bony structures of the neck with some important vessels. The cervical spine is made of 7 cervical vertebrae deemed C1 to C7. The cervical portion of the spine has a gentle forward curve called the cervical lordosis. Certain cervical vertebrae have atypical features and differ from the general form of a typical vertebra. C1 is also called the atlas because it bears the head, "the globe." It has 2 concave superior facets that articulate with the occipital condyles of the skull. This important articulation provides 50% of the flexion and extension of the neck. C1 has no vertebral body and no spinous process.

#7. CT of the Neck in a Sagittal View

In this ct scan we can evaluate all the lateral vertebral muscles, which are the scalenus anterior, scalenus medius, and scalenus posterior.

Scalenus anterior lies at the side of the neck, behind the sternocleidomastoid. It arises from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebrae, and descending, almost vertically, is inserted by a narrow, flat tendon into the scalene tubercle on the inner border of the first rib and into the ridge on the upper surface of the rib in front of the subclavian groove.

Scalenus medius the largest and longest of the three scaleni, arises from the posterior tubercles of the transverse processes of the lower 6 cervical vertebrae, and descending along the side of the vertebral column, is inserted by a broad attachment into the upper surface of the first rib, between the tubercle and the subclavian groove.

Scalenus posterior, the smallest and most deeply seated of the 3 scaleni, arises, by 2 or 3 separate tendons, from the posterior tubercles of the transverse processes of the lower 2 or 3 cervical vertebrae and is inserted by a thin tendon into the outer surface of the second rib, behind the attachment of the serratus anterior. It is occasionally blended with the scalenus medius.

The scaleni are supplied by branches from the second to the seventh cervical nerves.

When the scaleni act from above, they elevate the first and second ribs, and are, therefore, inspiratory muscles. Acting from below, they bend the vertebral column to one or other side; if the muscles of both sides act, the vertebral column is slightly flexed.

#8. 3D model of the neck´s muscles

This incredible 3d model shows all the muscles groups with detail.

The muscles of the neck can be grouped according to their location. Those immediately in front and behind the spine are the prevertebral, postvertebral, and lateral vertebral muscles and on the side the neck are the lateral cervical muscles. In addition, a unique superficial muscle, the platysma, exists.

The platysma muscles are paired broad muscles located on either side of the neck. The platysma arises from a subcutaneous layer and fascia covering the pectoralis major and deltoid at the level of the first or second rib and is inserted into the lower border of the mandible, the risorius, and the platysma of the opposite side. It is supplied by the cervical branch of the facial nerve. The platysma depresses the lower lip and forms ridges in the skin of the neck and upper chest when the jaws are "clenched" denoting stress or anger. It also serves to draw down the lower lip and angle of the mouth in the expression of melancholy.

The sternocleidomastoid is the prominent muscle on the side of the neck. It arises from the sternum and clavicle by 2 heads. The medial or sternal head arises from the upper part of the anterior surface of the manubrium sterni and is directed upward, lateralward, and backward.

#9. 3D model of the neck´s muscles

You can see the supravicular fossa in this example and its relations.  It´s limited anteromedially by the sternocleidomastoid muscle, posteromedially by the trapezius muscle and superiorly by the omohyoid muscle. Its pavement is formed by the middle scalene muscle and the first fasciculation of the anterior serratus muscle, involved
by the deep layer of the deep cervical fascia. Its roof is formed by skin, superficial fascia and platysma muscle.
Its content includes a series of structures that intersect this region, separated from each other by connective and adipose tissue, such as: the subclavian, suprascapular and transverse cervical arteries and veins; the terminal portions of internal and external jugular veins; lymph nodes; the thoracic duct on the left side; the lymphatic duct on the right side; the brachial plexus trunk; the phrenic nerve; and scalene muscles!

#10. MRI of the skull and neck

In this last example uploaded by Axel Foley you can evaluate with more detail the neck muscles. 

Tip: Nodes less than 1 cm in size can still be malignant and should be carefully evaluated for other abnormal features, particularly if in expected drainage sites of the primary tumor.

References

1.      The Radiology Assistant : Infrahyoid neck. (2009). Radiologyassistant.nl. Retrieved 23 September 2018, from http://www.radiologyassistant.nl/en/p49c603213caff/infrahyoid-neck.html

2. Li, H., Chen, R. K., Tang, Y., Meurer, W., & Shih, A. J. (2018). An experimental study and finite element modeling of head and neck cooling for brain hypothermia. Journal of thermal biology, 71, 99-111.

3. Kaye, R., Goldstein, T., Zeltsman, D., Grande, D. A., & Smith, L. P. (2016). Three dimensional printing: A review on the utility within medicine and otolaryngology. International Journal of Pediatric Otorhinolaryngology, 89, 145-148.

4. Neck Anatomy: Overview, Quadrangular Area, Osteology: The Cervical Spine. (2018). Reference.medscape.com. Retrieved 23 September 2018, from https://reference.medscape.com/article/1968303-overview#a5

5. Hoang JK, Vanka J, Ludwig BJ, Glastonbury CM. Evaluation of cervical lymph nodes in head and neck cancer with CT and MRI: tips, traps, and a systematic approach. American Journal of Roentgenology. 2013 Jan;200(1):W17-25.