ATLAS OF HUMAN ANATOMY - G.L. Bilich - 2014

Muscular System

MUSCLES AND FASCIAE OF THE NECK

Topography of the Fasciae and Fascial Spaces of the Neck

Corresponding to the three groups of Neck Muscles (superficial, supra- and infrahyoid, and deep), which differ in origin and anatomical position, three layers of the Cervical fascia (three cervical fasciae) are distinguished (Figs. 243, 244, 245). The platysma, much like the Muscles of facial expression, lies subcutaneously and possesses only its own proper fascia.

The cervical fascia (fascia cervicis), located primarily in the anterior Regions of the neck, consists of three layers (sheets): the superficial, the pretracheal (middle), and the deep (prevertebral).

The Superficial layer of the cervical fascia (lamina superficialis fasciae cervicis) encircles the neck on all sides, attaches inferiorly to the anterior border of the clavicle and the manubrium of the Sternum, and continues into the pectoral fascia. Superiorly, the superficial layer ascends to attach to the Hyoid bone and extends upward anterior to the Suprahyoid muscles. This layer fuses with the Connective Tissue capsule of the Cytology/practical/98.html">Submandibular salivary gland, and in the region of the body of the Mandible, with the masseteric fascia and the capsule of the Parotid salivary gland. Within the splits of the superficial layer on the right and left sides lie the sternocleidomastoid and trapezius muscles, for which this fascia forms fascial sheaths. In the posterior regions of the neck, the superficial layer fuses with the nuchal ligament and the leaves of the nuchal fascia; superiorly, it attaches to the external occipital protuberance and the superior nuchal line, while inferiorly it transitions into the thoracolumbar fascia. In the region of the opening where the External Jugular Vein—situated posterior to the sternocleidomastoid Muscle—pierces the fascia and empties into the venous angle, There is a thickening of the superficial cervical fascia known as Gruber's falciform fold (Leopold von Dittell, 1815–1898, Austrian surgeon and anatomist).

The pretracheal layer (lamina pretrachealis, s. fascia media), also known as Porter's fascia, is located in the anterolateral regions of the neck (William Henry Porter, 1790–1861, Irish anatomist and surgeon). Inferiorly, it attaches to the posterior surface of the clavicles and the manubrium of the sternum; superiorly, it fuses with the hyoid bone and the superficial layer of the cervical fascia. The pretracheal layer forms fascial sheaths for the muscles situated inferior to the hyoid bone (sternohyoid, sternothyroid, thyrohyoid, and omohyoid muscles). Along its borders on the right and left, the pretracheal layer fuses with the connective tissue Sheath of the cervical neurovascular bundle (common carotid artery, Internal jugular vein, and Vagus nerve) and with the superficial layer of the cervical fascia. Posterior to the pretracheal layer lie the Larynx, The Thyroid Gland, and the upper part of the Trachea. Anterior to the pretracheal layer are only the superficial layer of the cervical fascia and the Skin. The pretracheal layer of the cervical fascia, together with the muscles enclosed within it, has the shape of a trapezoid whose boundaries correspond to its attachment sites: superiorly to the hyoid bone, inferiorly to the sternum and clavicle, and laterally to the superficial layer of the cervical fascia lateral to the omohyoid muscles. Due to the topographical and Anatomical Features of the pretracheal layer, it is referred to as the vertebroclavicular aponeurosis or Richet's sail (aponeurosis) (Louis Alfred Richet, 1816–1891, French surgeon), as it resembles a sail, particularly when the layer is taut during the contraction of the omohyoid muscles, which facilitates venous Blood drainage from the HEAD via the cervical Veins.

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Fig. 243. Layers of the cervical fascia, anterior view:

1 — Sternohyoid; 2 — Investing layer; 3 — Parotid gland; 4 — Mandible; 5 — Sternocleidomastoid; 6 — Carotid sheath; 7 — Trapezius;

8 — Prevertebral layer; 9 — Clavicle

Between the superficial and pretracheal layers, just above the jugular notch of the sternum, lies the suprasternal interfascial space, known as Burns' space (syn.: suprasternal interaponeurotic space, spatium interaponeuroticum suprasternale), which contains the jugular venous arch connecting the superficial VEINS OF THE right and left sides of the neck (Allan Burns, 1781–1813, British physician and anatomist). Posterior to the inferior part of the sternocleidomastoid muscle on the right and left, this fascial space forms a blindly ending pouch (Gruber's suprasternal-sternocleidomastoid blind pouch) that extends to the lateral border of these muscles.

Between the Internal Organs of the neck (thyroid gland, larynx, and trachea) posteriorly and the pretracheal layer anteriorly lies the pretracheal space, which communicates along the anterior surface of the trachea with the superior Mediastinum.

Fig. 244. Fasciae of the neck, anterior view:

1 — Sternocleidomastoid; 2 — Clavipectoral triangle; Deltopectoral triangle; 3 — Pectoral fascia; 4 — Nuchal fascia; 5 — Cervical fascia, investing layer; superficial layer; 6 — Submandibular gland; 7 — Platysma; 8 — Hyoid bone; 9 — Internal jugular vein; 10 — External Carotid Artery; 11 — Carotid sheath; 12 — Laryngeal prominence; 13 — Omohyoid; 14 — Cervical fascia, pretracheal layer; 15 — Cervical fascia, prevertebral layer

The prevertebral layer (lamina prevertebralis, s. fascia prevertebralis, s. fascia profunda) is situated posterior to the Pharynx and Esophagus and anteriorly covers the deep prevertebral neck muscles (scalene muscles, longus capitis, longus colli, and the anterior and lateral rectus capitis muscles). Superiorly, this layer attaches to the external Skull base posterior to the pharyngeal tubercle; laterally, it attaches to the transverse processes of the cervical vertebrae, forming fascial sheaths for the scalene muscles arising from these processes. Inferiorly, the prevertebral layer attaches, along with the scalene muscles, to the 1st and 2nd Ribs and continues into the endothoracic fascia. Between the prevertebral layer posteriorly and the pharynx and esophagus anteriorly lies the retropharyngeal (retrovisceral) space, which extends downward along the esophagus into the posterior mediastinum. The space situated between the prevertebral layer anteriorly and THE Vertebral Column posteriorly, filled with the aforementioned deep neck muscles, is termed the prevertebral space (see Fig. 245).

Interfascial spaces filled with loose Fibrous connective tissue can serve as pathways for the spread of inflammatory processes extending beyond the confines of the neck, potentially involving both the anterior and posterior mediastina.

In the posterior regions of the neck, between the Muscles of the occipital group, lie the leaves of the nuchal fascia (fascia nuchae), which forms fascial sheaths for these muscles and inferiorly transitions into the thoracolumbar fascia.

The distinguished Ukrainian and Russian topographic anatomist V.N. Shevkunenko distinguished five leaves of the cervical fascia, which is more practical from the perspective of operative surgery (Figs. 246, 247, Table 40) (Viktor Nikolayevich Shevkunenko, 1872–1952, prominent topographic anatomist and surgeon, Academician of the USSR Academy of Medical Sciences). The first of these is the superficial Fascia of the neck (fascia superficialis), which represents a continuation of the general subcutaneous fascia of the body, passing uninterrupted onto the neck region. This fascia encloses the platysma, functioning as its perimysium.

Fig. 245. MUSCLES AND FASCIAE of the neck in transverse section. The section is taken at the level of the 7th cervical vertebra and the thyroid

gland:

1 — Sternohyoid; 2 — Previsceral space; 3 — Trachea; 4 — Omohyoid; 5 — Sternocleidomastoid; 6 — Common carotid artery; 7 — Vertebra prominens [CVII]; 8 — Semispinalis cervicis; 9 — Semispinalis capitis; 10 — Trapezius; 11 — Levator scapulae; 12 — Scalenus; 13 — Cervical fascia, prevertebral layer; 14 — Cervical fascia, pretracheal layer; 15 — Cervical fascia, investing layer; superficial layer; 16 — Platysma; 17 — Sternothyroid

Fig. 246. Fasciae of the neck, horizontal section (diagram);

1 — Superficial fascia of neck; 2 — Superficial layer of cervical fascia; 3 — Deep Layer of cervical fascia; 4 — Visceral layer of endocervical fascia; 5 — Parietal layer of endocervical fascia; 6 — Prevertebral fascia; 7 — Trapezius; 8 — Deep Muscles of neck; 9 — Oesophagus; 10 — Scalenus; 11 — Common carotid artery, Internal jugular vein: Vagus nerve [X]; 12 — Omohyoid; 13 — Thyroid gland; 14 — Trachea;

15 — Sternocleidomastoid; 16 — Previsceral space (after Shevkunenko)

Fig. 247. Fasciae and fascial spaces of the neck, sagittal section (diagram):

1 — Manubrium of sternum; 2 — Suprasternal space; 3 — Interaponeurotic space; 4 — Jugular venous arch; 5 — Visceral layer of endocervical fascia; 6 — Parietal layer of endocervical fascia; 7 — Deep layer of cervical fascia; 8 — Superficial fascia of neck; 9 — Superficial layer of cervical fascia: 10 — Hyoid bone; 11— Prevertebral fascia; 12— Epiglottis; 13 — Rima glottidis; 14 — Cricoid Cartilage; 15— Oesophagus; 16 — Trachea; 17 — Previsceral space; 18 — Retrovisceral space; 19— Prevertebral space; 20 — Brachiocephalic vein; 21 — Brachiocephalic trunk (after Shevkunenko)

Table 40. Fasciae of the neck

The second fascia — the superficial lamina of the proper cervical fascia (lamina superficialis fasciae colli propriae) — forms a collar-like covering over the suprahyoid and Infrahyoid muscles of the neck, Blood Vessels, nerves, and Salivary Glands, attaching superiorly to the mandible and mastoid process, and extending into the masseteric and parotid fasciae. Inferiorly, the superficial lamina attaches to the clavicle and the anterior border of the manubrium of the sternum, while in the midline it fuses with the deep lamina of the proper cervical fascia, forming a narrow (2–3 mm) Linea Alba of the neck. From this white line, the superficial lamina extends posteriorly toward the spinous processes of the cervical vertebrae and attaches to them. Along its course, the lamina splits to form distinct fascial sheaths for the sternocleidomastoid and trapezius muscles. N.I. Pirogov described a frontal process of the superficial lamina that extends to the right and left from the spinous processes, dividing the neck into anterior and posterior fascial spaces — known as Pirogov's fascia (Pirogov's aponeurosis, syn. aponeurosis of the biceps brachii, aponeurosis musculi bicipitis brachii). Due to this anatomical feature, inflammatory processes in the anterior and posterior spaces remain separated and progress independently of one another (Nikolay Ivanovich Pirogov (1810–1881) — Russian surgeon, anatomist, and public figure).

The third fascia — the deep lamina of the proper cervical fascia (lamina profunda fasciae colli propriae) — appears as a trapezoidal plate passing posterior to the sternocleidomastoid muscles and attaching to the hyoid bone, omohyoid muscles, clavicles, and sternum. Situated between the superficial and deep lamminae of the proper cervical fascia is the narrow, slit-like suprasternal interaponeurotic space, which contains loose areolar tissue, the jugular venous arch, and superficial neck veins. Laterally, this space communicates on each side with a blind lateral pocket located posterior to the sternocleidomastoid muscle, which can be a site for inflammatory processes. The deep lamina of the proper cervical fascia splits to form fascial sheaths for the infrahyoid muscles (sternohyoid, sternothyroid, and thyrohyoid). Together with the enclosed muscles, the deep lamina forms a dense musculo-fascial Structure (the cervical sail) that, upon contraction of the omohyoid muscles, facilitates venous blood outflow through the cervical veins passing through it.

The fourth fascia — the internal cervical fascia (fascia endocervicalis), consisting of visceral and parietal layers — encloses the Organs of the neck. The visceral layer forms capsules for each individual organ (the larynx, trachea, thyroid gland, pharynx, oesophagus, and large vessels), whereas the parietal layer, located posterior to the hyoid muscles, surrounds all these organs collectively and also forms the sheath for the common carotid artery and internal jugular vein. Located between the two layers of the internal cervical fascia anterior to the organs (the pre-organ space) is loose areolar tissue, Lymph Nodes, the ISTHMUS OF THE thyroid gland, the inferior thyroid artery, and the unpaired thyroid venous plexus. This anatomical feature is of great clinical significance, as these vessels may be injured during a tracheotomy.

Inferiorly, a portion of the pre-organ pretracheal space extends into the anterior mediastinum, thereby allowing inflammatory processes to track downward into the mediastinum.

The fifth fascia — the prevertebral fascia (fascia prevertebral is) — originates at the BONES OF THE external cranial base posterior to the pharynx, extends inferiorly through the neck into the posterior mediastinum, where it fuses with the endothoracic fascia. Fusing with the transverse processes of the cervical vertebrae, the fifth fascia lies anterior to the scalene and prevertebral muscles, forming fascial sheaths for them. Situated between the internal and prevertebral fasciae is a narrow, slit-like, tissue-filled retrovisceral space that continues into the posterior mediastinum.

Taking into account the surface relief of the neck caused by the underlying muscles and internal organs, the anterior neck is divided into three regions: an unpaired region (the anterior region proper), a paired sternocleidomastoid region (right and left) corresponding to the PROJECTION OF THE muscle of the same name, and a paired lateral region (right and left) bounded anteriorly by the posterior border of the aforementioned muscle, posteriorly by the lateral border of the trapezius muscle, and inferiorly by the clavicle.

The anterior region of the neck, or the anterior cervical triangle (regio cervicalis anterior, s. trigonum cervicale anterius), is bounded laterally by the sternocleidomastoid muscles. Superiorly, the Base of the triangle is formed by the mandible, while its apex reaches the jugular notch of the manubrium of the sternum.

Within the anterior neck region, a medial cervical triangle is distinguished on each side, bounded anteriorly by the midline, superiorly by the mandible, and posteriorly by the anterior border of the sternocleidomastoid muscle. An imaginary horizontal plane passing through the body and greater horns of the hyoid bone divides the median region of the neck (the anterior triangle) into two zones: the superior suprahyoid region (regio suprahyoidea) and the inferior infrahyoid region (regio infrahyoidea). In the infrahyoid region of the neck, two triangles are distinguished on each side: the carotid and muscular (omotracheal) triangles.

The triangle formed by the posterior belly of the digastric muscle, the posterior border of the hyoglossus muscle, and the greater horn of the hyoid bone is known as Béclard's triangle; within it, deep to the hyoglossus muscle, lies the lingual artery (Pierre Béclard (1785–1825) — French physician and anatomist).

The carotid triangle (trigonum caroticum) — also known as Gerdy's hyoid fossa, Malgaigne's triangle, or Rüdinger's triangle — is bounded superiorly by the posterior belly of the digastric muscle, posteriorly by the anterior border of the sternocleidomastoid muscle, and anteroinferiorly by the superior belly of the omohyoid muscle (Joseph-François Malgaigne (1806–1865) — French surgeon and anatomist; Nicolaus Rüdinger (1832–1896) — German anatomist). Within this triangle, superficial to the superficial lamina of the cervical fascia, lie the cervical branch of the Facial Nerve, the superior branch of the transverse cervical nerve, and the Anterior jugular vein. Deeper, within the connective tissue sheath, lie the common carotid artery, the internal jugular vein, and, posterior to them, the vagus nerve. Deep lateral cervical lymph nodes are also located here.

At the level of the hyoid bone, the common carotid artery divides into the internal and external carotid Arteries. The external carotid gives off several branches: the superior thyroid, lingual, facial, occipital, posterior auricular, ascending pharyngeal, and sternocleidomastoid arteries, which supply the respective organs. Anterior to the sheath of the neurovascular bundle lies the superior ROOT of the ansa hypoglossi, deeper and inferiorly is the laryngeal nerve (a branch of the vagus nerve), and even deeper, upon the prevertebral lamina of the cervical fascia, lies the Sympathetic trunk. The part of the carotid triangle bounded by the internal jugular vein, the facial vein draining into it, and superiorly by the Hypoglossal nerve, is known as Farabeuf's triangle (Louis Hubert Farabeuf (1841–1910) — French anatomist and surgeon).

The muscular (omotracheal) triangle (trigonum musculare, s. omotracheale) is bounded posteroinferiorly by the anterior border of the sternocleidomastoid muscle, superolaterally by the superior belly of the omohyoid muscle, and medially by the anterior median line. Within this triangle, immediately superior to the jugular notch of the manubrium, the trachea is covered only by skin and the fused superficial and pretracheal laminae of the cervical fascia. Approximately 1 cm lateral to the midline lies the anterior jugular vein, which descends into the sternal interfascial cellular space.

In the suprahyoid region, three triangles are distinguished: the submental triangle (unpaired) and the paired submandibular and lingual triangles. The submental triangle (trigonum submentale) is bounded laterally by the anterior bellies of the digastric muscles; its base is formed by the hyoid bone, its apex points toward the mental spine, and its floor is formed by the right and left mylohyoid muscles joined by a raphe. The submental lymph nodes are located within this triangle.

The submandibular triangle (trigonum submandibulare) is bounded superiorly by the body of the mandible and inferiorly by the anterior and posterior bellies of the digastric muscle. It contains the submandibular salivary gland. Piercing the platysma, the cervical branch of the facial nerve and the branch of the transverse cervical nerve enter this triangle. The facial artery and vein lie superficially here, while the retromandibular vein is situated posterior to the submandibular gland. Lymph nodes of the same name are located beneath the mandible within the submandibular triangle.

The lingual triangle, or Pirogov's triangle, is small but clinically very important, and is located within the submandibular triangle. The lingual artery is situated within the lingual triangle and can be accessed surgically at this site. Anteriorly, the lingual triangle is bounded by the posterior border of the mylohyoid muscle, posteroinferiorly by the posterior belly of the digastric muscle, and superiorly by the hypoglossal nerve.

In the lateral region of the neck, the omoclavicular and omotrapezoid triangles are distinguished. The omoclavicular triangle (trigonum omoclaviculare), located above the middle third of the clavicle, is bounded inferiorly by the clavicle, superiorly by the inferior belly of the omohyoid muscle, and anteriorly by the posterior border of the sternocleidomastoid muscle. This triangle contains the Subclavian Artery as it emerges from the interscalene space; the supraclavicular part of the Brachial Plexus, between the trunks of which the transverse cervical artery passes; and, superior to the plexus, the suprascapular and superficial cervical arteries. Anterior to the subclavian artery (anterior to the anterior scalene muscle, within the prescalene space) lies the subclavian vein, which is firmly fused with the fascia of the subclavius muscle and the laminae of the cervical fascia.

The omotrapezoid triangle (trigonum omotrapezoideum) is bounded by the anterior border of the trapezius muscle, the inferior belly of the omohyoid muscle, and the posterior border of the sternocleidomastoid muscle. The Accessory nerve runs through this region. The cervical and brachial plexuses are formed between the scalene muscles, with the lesser occipital, great auricular, and other nerves arising from the Cervical plexus.

The depression between the sternal and clavicular heads of the sternocleidomastoid muscle is called Zang's fossa (syn. lesser supraclavicular fossa, fossa supraclavicularis minor) (Christoph Bonifacius Zang, 1772–1835, an Austrian surgeon and anatomist).