 | Term | Definition |
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Hyoid Bone |
o Mobile element; when at rest, lies at C3 vertebral level o Muscles and ligaments connect the hyoid to the mandible, manubrium, scapulae, cranium, and thyroid cartilage of the larynx o Consists of a body (anterior), greater horns (posterior projections), and lesser horns (superior projections) |
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Thyroid and cricoid cartilages |
these cartilages help form the larynx, they are located inferior to the hyoid and superior to the trachea, and can be palpated on the anterior aspect of the neck |
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Origin of Sternocleidomastoid |
(SCM) manubrium (sternal head); clavicle (clavicular head) |
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Insertion of Sternocleidomastoid |
Heads fuse and insert on mastoid process (temporal bone) |
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Action of Sternocleidomastoid |
Unilateral contraction: ipsilateral lateral flexion of the neck and contralateral rotation of the head |
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Innervation of Sternocleidomastoid |
CN XI (spinal accessory nerve) |
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Muscles within the posterior triangle |
• Inferior belly of Omohyoid (more details below) • Splenius capitis • Levator scapulae • Scalenes (posterior, middle, anterior) |
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Action of Scalenes |
laterally flex neck or elevate ribs |
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Innervation of Scalenes |
cervical plexus |
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Anterior Triangle |
o Posterior border: SCM o Superior border: Mandible o Anterior border: midline of the neck |
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Action of Infrahyoid Muscles |
depress hyoid (e.g., during swallowing) |
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Innervation of Infrahyoid Muscles |
ansa cervicalis |
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Omohyoid |
superior belly in anterior triangle; inferior belly in posterior triangle |
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Sternothyroid |
also depresses larynx |
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Thyrohyoid |
can also elevate larynx |
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Action of Suprahyoid Muscles |
elevate hyoid (e.g., during swallowing) |
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Innervation of Suprahyoid Muscles |
Most innervated by cranial nerves |
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Innervation of Mylohyoid |
mandibular nerve (CN V3) |
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Digastric Anterior belly |
mandible to hyoid |
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Digastric Posterior belly |
mastoid region to hyoid |
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Posterior Triangle |
• Posterior border: Trapezius • Inferior border: Clavicle • Anterior border: Sternocleidomastoid (SCM) |
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Torticollis |
The etiology of congenital muscular torticollis is unclear. Birth trauma or intrauterine malposition is considered to cause damage to the sternocleidomastoid muscle in the neck |
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Anterior Triangle |
• Posterior border: SCM • Superior border: Mandible • Anterior border: midline of the neck |
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Submandibular Triangle |
Between anterior and posterior bellies of digastric and the mandible |
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Submental Triangle |
Between anterior belly of digastric, hyoid, and midline of neck |
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Muscular Triangle |
Between hyoid, SCM and midline of neck |
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Carotid Triangle |
Between posterior belly of digastric, SCM and omohyoid m. |
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Innervation of Digastric Anterior belly |
mandibular nerve (CN V3) |
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Innervation of Digastric Posterior belly |
facial nerve (CN VII) |
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Ansa cervicalis |
•loop formed by C1-C3 •Superficial to the carotid sheath • Innervates the infrahyoid muscles (details below) • Fibers hitch a ride with hypoglossal n. (CN XII) making it look like they are branches of CN XII (they are not!). |
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Anterior Jugular Veins |
o Arise from small veins inferior to chin o Superficial to sternohyoid o Near sternum, course laterally and deep to SCM o Empty into external jugular veins |
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External Jugular Veins |
o Superficial to SCM o Receive blood from the scalp and face o Formed by union of posterior auricular and retromandibular veins o Receive blood from neck and shoulder via the transverse cervical, suprascapular, and anterior jugular veins (just superior to clavicle) o Empty into subclavian veins |
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Internal Jugular Veins (IJV) |
o Receive blood from structures within the cranial cavity o Course inferiorly within the carotid sheath o Receive blood from the face and neck (e.g., facial vein, lingual vein, etc.; these vessels parallel the branches of the external carotid artery) o Join the subclavian veins (at venous angle) to form the brachiocephalic veins |
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Common carotid arteries |
o Right common carotid artery originates from the brachiocephalic trunk o Left common carotid artery originates from the arch of the aorta o Course superiorly within the carotid sheath; the artery lies medial to the internal jugular vein and anterior to the vagus nerve (can palpate carotid pulse here) o Divide into internal and external carotid arteries |
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Internal carotid arteries |
o Courses superiorly within the carotid sheath o No branches in the neck (supplies intracranial structures, e.g., brain, orbit) |
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External carotid arteries |
o Supply neck, face, scalp, and part of the orbit |
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External carotid artery branches in the neck |
• Superior thyroid artery (supplies thyroid gland and larynx) • Ascending pharyngeal artery (supplies pharynx) • Lingual artery (supplies tongue) • Facial artery (supplies face) • Occipital artery (supplies scalp) • Continues on to give rise to branches in temporal region (posterior auricular, maxillary and superficial temporal). |
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Deep Muscles of the Neck |
o Longus capitis, longus colli, rectus capitis anterior, rectus capitis lateralis o Action: flex neck and head o Innervation: cervical plexus |
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Vertebral artery |
Branch of the subclavian artery that enters the transverse foramen of C6 and courses superiorly, enters foramen magnum at base of skull, supplies brain |
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Phrenic nerves (C3-C5) |
o Descend on superficial surface of anterior scalene o Innervate diaphragm (motor and sensory); parietal pleura, fibrous pericardium, and parietal layer of the serous pericardium (sensory) |
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Superficial Cervical Lymph Nodes |
o Located along the external jugular vein and aggregations include submental and submandibular nodes o Deliver lymph to deep cervical lymph nodes |
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Deep Cervical Lymph Nodes |
Located along the internal jugular vein |
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Platysma |
Thin sheet of muscle that covers the anterolateral aspect of the neck; it is a muscle of facial expression |
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Deep cervical fascia |
o Forms compartments within the neck o These compartments can limit the spread of infection; however they can also promote the spread of infection when they are continuous with adjacent regions |
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Investing layer of deep cervical fascia |
• Surrounds entire neck • Attached superiorly to the occipital bone, mastoid processes, zygomatic arches (cheekbones), and mandible • Attached inferiorly to the manubrium, clavicles, acromion and spine of the scapulae • Invests (encloses) trapezius and sternocleidomastoid (SCM) • Invests the submandibular and parotid glands (salivary glands) |
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Pretracheal layer of deep cervical fascia |
• Surrounds structures in the anterior neck only • Attached superiorly to the hyoid • Muscular part invests the infrahyoid muscles • Visceral part invests the thyroid gland, trachea, and esophagus and continues superiorly as the buccopharyngeal fascia (surrounding the pharynx) • Visceral part is continuous inferiorly with the mediastinum (potential pathway for spread of infection) |
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Prevertebral layer of deep cervical fascia |
• Surrounds structures in the middle of the neck • Attached superiorly to the base of the cranium • Continues laterally as the axillary sheath • Invests the muscles related to the vertebral column (longus colli and longus capitis anteriorly, scalenes laterally, and the intrinsic back muscles posteriorly) |
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Carotid sheath |
• Vertical tube of fascia (present bilaterally) • Continuous superiorly with the cranial cavity and continuous inferiorly with the mediastinum (potential pathway for spread of infection) |
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Contents of the carotid sheath |
• Common carotid and internal carotid arteries (medial) • Internal jugular vein (lateral) • Vagus nerve (CN X) (deep) • Deep cervical lymph nodes |
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Retropharyngeal space |
• Potential space between the visceral part of pretracheal layer (including buccopharyngeal fascia) and the prevertebral layer • Facilitates movement/expansion of pharynx, esophagus, larynx, and trachea • Attached superiorly to the cranium • Continuous inferiorly with the mediastinum (potential pathway for spread of infection) • An infection in the retropharyngeal space may cause difficulty swallowing/speaking due to the proximity of this space to the pharynx/esophagus and larynx/trachea |
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