Neck Anatomy

Knowing the anatomy of the neck will help you prevent neck injuries. You will also be able to quickly detect which muscle, bone or ligament is causing discomfort at the base of your head. So, if you want to learn in depth what this cervical area is, read on. We will explain the bones, ligaments and muscles in this region of the body and their biomechanics.

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Parts and anatomy of the neck

Bones and joints

• Cervical vertebrae: Support the cranial cavity, connect the head to the lumbar spine and provide articulatory movements. It is composed of 7 vertebrae, called C1 to C7 inclusive. C1 is also called Atlas and C2, Axis. Within each are the apophyses, tubercles and nerve grooves.
• Hyoid: Its function is to support the tongue and larynx. It has a symmetrical U-shape and is located below the mandible, between the third and fourth vertebrae. It is one of the few odd bones that have no articulation, as it is suspended between ligaments and muscles.
• Sternal shaft: This is the upper part of the sternum, bounded by the jugular notch, the clavicular incisure and the costal part of the first notch. The shaft of the sternum is variable in shape and articulates with the body of the sternum by means of a fibrocartilage disc.
• Clavicle: This bone may be found as an integral part of the shoulder, but is also considered to be part of the skeleton of the neck. It is a flat, elongated bone that joins the manubrium of the sternum to the scapula.
• Atlantooccipitals: They are located between the atlas and the apophyses, reaching the foramen magnum. Their main function is extension, lateral tilt (or abduction) and flexion of the head.
• Atlantoaxial: Taking the axis of the axis tooth as its axis, it rotates the atlas to perform head rotation movements. Characteristic is the lack of intervertebral discs between these bones.
• Uncovertebral: These are flat joints located in the unciform processes to give movement to the cervical vertebrae.
• Cygapophyseal: Their main function is to limit movement between two vertebrae, so they need to be located between them.
• Intervertebral: As their name indicates, these fibrocartilaginous discs are located between the cervical vertebrae, which allows a small torsional movement between them.

Muscles

• Stylohyoid: Its function is to support the hyoid bone, which supports the mandible. It arises from the styloid process of the temporal bone in the skull and is located above the posterior belly of the digastric groove.
• Hyoglossus: By means of the hypoglossal nerve, it compresses and retracts the tongue so that it becomes more or less convex. Its origin is the hyoid bone, at the top.
• Mylohyoid: The upper part is located in the mandible, above the anterior belly of the digastric and its course is generated below the geniohyoid muscle. Its work is related to maintaining the hyoid bone, the tongue and the base of the mouth.
• Omohyoid: It is responsible for controlling the activity of the cervical fascia and the hyoid. It arises from the upper part of the scapula and is related to the hypoglossal nerve.
• Scalene: It is divided into anterior, middle and posterior. It is triangular in shape and arises from the cervical vertebrae C3, C4, C5 and C6. Its main function is to rotate the neck and elevate the first and second ribs of the thorax. It is characterised by having a different size according to the development of the muscle performed by the person.
• Sternocleidomastoid: It can be seen externally from the lateral aspect of the neck, as it originates in the manubrium of the sternum and inserts in the mastoid process of the nape of the neck. It is responsible for moving the articular bodies of the skull and cervical vertebrae. It also acts in the extension and elevation of the head and chin and also of the shoulder.
• Splenius: This muscle, also known as splenius, arises from the ligament located at the nape of the neck and runs towards the base of the skull. Its mission is to rotate and tilt the head to the same side, although it is also capable of extending the neck and skull.
• Elevator of the thyroid: it is responsible for raising the isthmus of the thyroid towards the hyoid bone. The reason for this is currently not known with certainty.
• Angular of the scapula: This muscle is responsible for controlling the movements of the scapula, in its elevation and adduction, which is why it is also known as the levator scapulae. It arises from the transverse processes of the cervical vertebrae C1 to C4 and inserts on the medial border of the scapula.
• Thyrohyoid: This is one of the shortest muscles in the anatomy of the neck, as it inserts into the sternohyoid, arising - in an oblique line - from the thyroid cartilage. The mission of this tissue is to lower the hyoid or to raise the larynx if it is in contraction.
• Sternothyroid: Its origin is in the manubrium of the sternum and in the first rib and it inserts into the thyroid cartilage, in an oblique line. It also works to lower the larynx so that the larynx does the same for the hyoid.
• Cricothyroid: In charge of stretching and tensing the vocal cords, its origin is in the cartilage of the larynx - called the cricoid - and the thyroid cartilage.
• Arytenoepiglottis: The epiglottis works to prevent food from entering the trachea through this muscle. It is located between the larynx, the arytenoid cartilage and above the cartilaginous structure of the epiglottis.
• Transverse arytenoid: This is the muscle responsible for regulating the laryngeal lumen through the glottis. It is therefore a single muscle found in the posterior part of the larynx and in the arytenoid cartilages.
• Pharyngoglossus: This muscle works as a constrictor of the pharynx at the top. It also directs the movements of the tongue.
• Geniohyoid: Also known as geniohyoid, it is responsible for widening the pharynx, acting as a depressor of the floor of the mouth by immobilising the muscles of the hyoid bone and pushing on the hyoid bone. The lower spine of the chin sees its origin at the hyoid bone.
• Genioglossus: Its action is to move the tongue in the mouth, to pull it out and to push it in. It arises from the chin of the mandible and inserts into the upper part of the tongue and the hyoid bone.
• Superior lingual: It arises from the tongue and inserts on the hyoid and glossoepiglottic. Its function is to retract and raise the tip of the tongue.
• Longus capitis: This muscle is located between the transverse process of the C3 to C6 vertebrae and inserts into the occipital bone, and its function is to flex the neck.
• Oblique: It is divided into two sections, the greater and the lesser. From the axis process it inserts into the transverse process of the atlas vertebra and into the occipital bone to turn the head.
• Rectus: This muscle is responsible for flexing the head and neck. It arises between the C1 and C2 vertebrae (precisely in the transverse process of the atlas) and inserts into the occipital bone. It can be divided into anterior and lateral rectus.
• Posterior rectus: Unlike the anterior muscle, this tissue arises from the spinous process of the axis and inserts into the occipital bone in a nuchal line. The work it performs is also that of extending and rotating the neck. It can be divided into posterior major and posterior rectus minor, which arises from the tubercle of the posterior arch of the atlas.
• Digastric: It arises from the mandible and the mastoid process of the temporal bone and inserts, among other places, in the hyoid bone. The work it performs in the anatomy is to carry forward and backward the mandible and to elevate the hyoid.

Ligaments

• Anterior longitudinal: It is characterised by being continuous and joins the base of the cranial cavity, running along the entire spinal column until it reaches the surface of the sacrum. It is characterised by regulating the extension of the cervical spine to prevent inappropriate elongation of the neck.
• Posterior longitudinal: Unlike the ligament mentioned above, this band is not very elastic and is wider and thicker. It is responsible for preventing hyperflexion of the neck; in other words, it ensures that head movements are not abrupt and exceed the limits when the skull moves forward.
• Intertransverse: These are discontinuous ligaments that are responsible for joining the transverse processes of the vertebrae with the muscles and bones.
• Interspinous: These are also discontinuous and are formed from the spinous processes with the posterior supraspinous ligament and the anterior yellow ligament.
• Supraspinous: Extends from one spinous process to another to hold the cervical structure in the correct position. On the other hand, it joins the skull to the process of the C7 vertebra and to the tubercle of C1.
• Yellow: This class of fibrocartilages are considered discontinuous ligaments and are found between the spinal canal with the upper vertebra. Their mission is to help the extension and separation of the cervical vertebrae at the moment of flexion.
• Transversus atlas: The job of this ligament is to prevent the odontoid process from moving backwards so that the rotation of the head can perform the pivoting movement correctly.
• Nuchal: It arises from the spinous process of the C1 vertebra and extends to the first thoracic vertebra to prevent anterior flexion of the neck. It also attaches some muscles to this skeletal structure.
• Atlantooccipital and atlantoaxial: These two ligaments join the arches of the atlas and axis to the external part of the foramen magnum.
• Pharyngoepiglottic: This ligament is responsible for joining the epiglottis to the upper part of the pharynx.
• Glossoepiglottic: joins the glottis to the tongue.
• Thyroepiglottic: this is responsible for joining the thyroid cartilage to the epiglottis.
• Thyrohyoid: It runs from the hyoid bone to the thyroid cartilage. It is related to the medial and lateral thyrohyoid ligaments which attach to the thyroid on both sides.
• Vocal: Also known as the inferior thyroarytenoid ligament, it is responsible for covering the vocal cords and attaching them to the larynx.
• Vestibular: It is located in the vocal fold. It is also called Ventricular. Its mission is to join the thyroid to the arytenoid cartilage.
• Sesamoid: A set of small ligaments located on the lateral side of the arytenoid cartilage and the corniculate cartilages.
• Hyoepiglottic: connects the hyoid bone to the glottis.
• Cricothyroid: This is the ligament responsible for working with the cricothyroid joints.
• Cricoarytenoid: The cricoarytenoid joints maintain their position thanks to the work of this ligament.

Biomechanics of the neck and spinal column

• Flexion: This is produced when the chin touches the thorax, modifying the angle of the neck by 90 degrees towards the front of the body. It is produced by the sliding of the upper vertebrae over the lower vertebrae.
• Extension: This is the opposite movement to flexion, placing the neck in its natural position. In this case, the gelatinous substances of the discs move backwards to provoke the movement. The sternocleidomastoid muscles work together with the deep muscles of the back.
• Lateral tilt: This is also referred to as lateral flexion, which occurs when the pinna rests on the shoulder. The axis of the neck rotates 45° due to the contraction and flexion of the head muscles.
• Rotation: Thanks to the articulatory body of the atlas and axis (C1 and C2) it is possible to rotate the head 90° to the left and right, causing an alignment between the shoulder and the chin.
• Flexion: The amplitude generated by the vertebral body is 30° and is obtained by moving the shoulders and head forward, causing the intervertebral discs to increase in thickness in the posterior area.
• Extension: This movement tilts the overlying vertebra backwards, causing the anterior part of the disc to increase in thickness. In this way it is possible to achieve an amplitude of 40 degrees in relation to the spinal axis.
• Lateral tilt: The tilt generated is between 20° and 30° thanks to the work done by the overlying vertebrae and the discs bending to the concave and convex side, respectively.
• Rotation: It is possible to achieve rotation only in the cervical and dorsal part while in the lumbar spine its range does not exceed 2°, but if one considers the whole spine movement, in total the rotation is 10°.