Topographic regions of the neck
For convenience in studying anatomy and clinical practice, the neck is conventionally divided into four key regions (regiones cervicales). This helps to precisely navigate the location of superficial and deep structures.
- Anterior cervical region (regio cervicalis anterior)
This space is defined by strict anatomical landmarks:
- The medial boundary runs along the midline of the neck.
- The lateral boundary is formed by the anterior border of the sternocleidomastoid muscle.
- Superiorly, the region is bounded by the lower border of the mandible.
- Inferiorly, the boundary is formed by the jugular notch of the sternum.
- Sternocleidomastoid region (regio sternocleidomastoidea)
This zone strictly corresponds to the projection of the muscle of the same name. It is of paramount clinical significance, as the neurovascular bundle of the neck, including the carotid artery, internal jugular vein, and vagus nerve, runs precisely through this area.
- Lateral cervical region (regio cervicalis lateralis)
Located posterior to the sternocleidomastoid muscle and anterior to the trapezius. This region contains the subclavian artery and the trunks of the brachial plexus. An important landmark in its lower part is the greater supraclavicular fossa (fossa supraclavicularis major).
- Posterior cervical region (regio cervicalis posterior)
Its external borders are defined by the lateral margins of the trapezius muscle (m. trapezius). This region includes the suboccipital zone and the complex of posterior neck muscles.
Classification of neck muscles
The entire muscle mass of the neck (mm. colli) is traditionally classified into three major groups based on their depth:
- Superficial muscles (discussed in this article).
- Middle muscles (including the suprahyoid and infrahyoid groups).
- Deep muscles.
In addition, there is a functional division into lateral, anterior (median), and deep groups.
Platysma
The platysma muscle, or platysma, is a thin, broad muscular sheet tightly fused with the skin.
- Origin: The muscle fibers originate in the chest region at the level of the 2nd rib, blending into the fascia of the pectoralis major and deltoid muscles.
- Insertion: Ascending superiorly, the muscle attaches to the inferior border of the mandible and also blends into the skin of the angle of the mouth and the lower lip.
- Function: The main task of the muscle is to tense the skin of the neck, protecting superficial veins from compression. By contracting, it pulls the angle of the mouth downward, which in facial expression is associated with an expression of intense fear or rage.
- Innervation: Provided by the cervical branch of the facial nerve — ramus colli n. facialis.
- Blood supply: Supplied by the superficial cervical artery (a. cervicalis superficialis) and the facial artery (a. facialis).
Sternocleidomastoid muscle
The sternocleidomastoid muscle (m. sternocleidomastoideus) is the most massive and prominent muscle of the anterolateral surface of the neck.
Attachment points:
- Origin: It has two heads. The sternal head (caput sternalе) originates from the anterior surface of the manubrium sterni, while the clavicular head (caput claviculare) arises from the medial third of the clavicle.
- Insertion: The fibers of both heads unite and attach to the mastoid process of the temporal bone (processus mastoideus) and the superior nuchal line (linea nuchae superior) of the occipital bone.
Biomechanics and functions:
- Unilateral contraction: The muscle tilts the head to its own side while turning the face in the opposite direction.
- Bilateral contraction: Causes flexion of the cervical spine, tilts the head backward, and pulls it forward. With a fixed head, the muscle is capable of elevating the thorax, acting as an accessory respiratory muscle.
Innervation and blood supply:
- Innervation: Motor innervation is provided by the accessory nerve — n. accessorius (XI), as well as branches of the cervical plexus at the C2–C4 segments.
- Blood supply: Provided from three sources: the sternocleidomastoid artery (a. sternocleidomastoidea), the superior thyroid artery (a. thyroidea superior), and the occipital artery (a. occipitalis).
Briefly: answers to topical questions
What triangles are distinguished within the anterior cervical region?
Within the anterior surface of the neck (the medial triangle), the following triangles are identified:
- Submental triangle (trigonum submentale) — unpaired, located in the suprahyoid region.
- Submandibular triangle (trigonum submandibulare) — contains the salivary gland of the same name and includes Pirogov's triangle.
- Carotid triangle (trigonum caroticum) — located in the anterior region, completely covered by the platysma.
- Omotracheal triangle (trigonum omotracheale) — located in the infrahyoid region.
Which fascial layers cover the superficial muscles of the neck according to Shevkunenko's classification?
According to V.N. Shevkunenko's classification, the superficial muscles of the neck are covered by the first and second fascial layers.
- Superficial fascia (fascia superficialis, s. subcutanea) — is the first fascia and forms an isolated sheath for the platysma (m. platysma).
- Superficial layer of the deep cervical fascia (lamina superficialis fasciae colli propriae) — represents the second fascia, which forms sheaths for the sternocleidomastoid muscle (m. sternocleidomastoideus) and the trapezius muscle (m. trapezius).
To remember the function of the sternocleidomastoid muscle during unilateral contraction, recall the "look at the neighbor" rule: the muscle tilts the head toward itself, but turns the face in the opposite direction.
Class and exam questions
Which nerves innervate the sternocleidomastoid muscle?
It is innervated by the XI pair of cranial nerves (accessory nerve, n. accessorius) as well as spinal branches of the cervical plexus (C2–C4).
Where does the platysma originate?
The platysma originates from the fascia of the pectoral and deltoid muscles at the level of the 2nd rib.
What is located in the sternocleidomastoid region?
This region corresponds to the projection of the muscle of the same name and conceals an important neurovascular bundle underneath: the common carotid artery, the internal jugular vein, and the vagus nerve.
What else to study on this topic
- Middle muscles of the neck (suprahyoid group)
- Middle muscles of the neck (infrahyoid group)
- Deep muscles of the neck
- Topography of the neurovascular bundle of the neck
- Anatomy of the supraclavicular fossa and brachial plexus
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