Anatomy of the Neck Quiz

Posterior Triangle of the Neck & Pharynx

• The posterior triangle is a region of the neck.
• Boundaries include the Trapezius, SCM, and Clavicle.
• Structures within the posterior triangle include the SCM (sternocleidomastoid) and Trapezius muscles.
• Other structures such as nerves and vessels are also present here.

Fascial Planes of the Neck

• Neck fascia contains muscles and viscera.
• Fascia allows structures to slide smoothly over each other.
• Fascia serves as a pathway for neurovascular structures.
• Two major fascial compartments are separated by the retropharyngeal space: anterior (pretracheal) and posterior (prevertebral).
• Superficial layer of deep (investing) cervical fascia encloses and covers structures.
• It surrounds the SCM and Trapezius muscles.
• It is a single sheet of fascia, around both the anterior and posterior triangles.

Scalene Muscles

• Anterior Scalene: Originates from transverse processes (anterior tubercles) of cervical vertebrae and inserts into the first rib. Innervated by cervical spinal nerves C3-6. Action: unilaterally laterally flexes the neck to the same side; bilaterally elevates the first rib during inhalation, and flexes the neck.
• Middle Scalene: Originates from transverse processes (posterior tubercles) of cervical vertebrae and inserts into the first rib. Innervated by cervical spinal nerves C3-8. Action: unilaterally laterally flexes the neck to same side; bilaterally elevates the first rib during inhalation and flexes the neck.
• Posterior Scalene: Originates from transverse processes (posterior tubercles) of cervical vertebrae and inserts into the second rib. Innervated by cervical spinal nerves C7-8, but also C3-8 (other references state). Action: unilaterally laterally flexes the neck to same side; bilaterally elevates the second rib during inhalation and flexes the neck.

Roots of Brachial Plexus & Key Relationships

• The roots of the brachial plexus and subclavian artery travel between the anterior and middle scalene muscles.
• The brachial plexus passes under the clavicle and the pectoralis minor.

Thoracic Outlet

• Interscalene triangle, costoclavicular triangle, and subcoracoid space are clinical relevant areas for potential neurovascular compression.

Scalene Muscles & Key Relationships

• There are three scalene muscles: anterior, middle, and posterior.

Deep Muscles of the Neck (Prevertebral Muscles)

• Longus Colli: Spans from anterior vertebral bodies of C1-C6. Its action is lateral flexion (unilaterally) and flexion (bilaterally) of the head and neck. It is innervated by the anterior primary rami of C2-6 spinal nerves.
• Longus Capitis: Originates from the transverse processes of the cervical vertebrae and inserts into the occipital bone. Its action is lateral flexion (unilaterally) and flexion (bilaterally) of the head and neck. It is innervated by the anterior primary rami of C1-3 spinal nerves.
• Rectus Capitis Anterior: Originates from the base of the cranium and inserts into the transverse process of C1. Action: flexes the head.
• Rectus Capitis Lateralis: Originates from base of cranium and inserts into the transverse process of C1. Action: flexes the head and also stabilizes it.

Cervical Plexus - Nerves in the Posterior Triangle

• Nerves in posterior triangle include Great Auricular , Lesser Occipital, Transverse Cervical, and Supraclavicular nerves.
• These nerves provide sensory innervation in that region (and nearby).

Phrenic Nerve

• C3, 4, 5 keep the diaphragm alive.
• The phrenic nerve provides motor innervation to the diaphragm.

Occipital Nerves

• The greater, lesser, and third occipital nerves are sensory.
• Greater occipital nerve: arises from C2/C3 ventral rami.
• Lesser occipital nerve: arises from C2 ventral rami.
• Third occipital nerve: arises from C3 ventral rami.

Suboccipital Nerve

• Arise from posterior rami of C1.
• Innervate suboccipital muscles (used for postural control of the head).

Vasculature in the Deep Neck

• Common carotid arteries: supply organs outside the cranium.
• Internal carotid arteries: supply organs inside the cranium

Subclavian Artery

• Arises from the brachiocephalic trunk on the right and the arch of aorta on the left.
• Travels deep to the anterior scalene.
• 3 parts related to the anterior scalene.
• It branches into other vessels in the arm, etc.

Subclavian Vein

• Direct continuation of the axillary vein.
• Located laterally to the 1st rib.
• Separated from subclavian artery by the anterior scalene muscle.
• Joins with the internal jugular vein at the venous angle.

Lymph System

• Right lymphatic duct: drains upper right body quadrant. Enters right venous angle.
• Thoracic duct: drains rest of the body. Enters left venous angle.

Pharynx & Larynx

• Pharynx: a tube-like structure that is a part of both digestive and respiratory systems. It extends from the base of the skull to the lower border of the cricoid cartilage (upper portion of the trachea).
• Subsections to the pharynx include nasal, oral, and laryngeal pharynx.
• Larynx contains cartilages, muscles, and is involved in breathing, swallowing, and phonation.

Laryngeal Cartilages

• The larynx has various cartilages that provide structure and support for the larynx.
• These structures include thyroid, cricoid, epiglottis, and arytenoid cartilages among others.

Vagus Nerve & Recurrent Laryngeal Nerves

• The vagus nerve travels with the common carotid artery and internal jugular vein in the carotid sheath.
• Right/Left vagus nerve loops around the subclavian artery and continues to the larynx, branching into recurrent laryngeal nerves.

Laryngeal Nerves

• Superior laryngeal nerve (from vagus): Internal branch (sensory) and External branch (cricothyroid m.).
• Recurrent laryngeal nerve (from vagus): Motor to larynx muscles (except for cricothyroid innervated by external branch superior laryngeal n).

Muscles of the Larynx

• Cricothyroid, Posterior Cricoarytenoid, Transverse Arytenoid, Thyroarytenoid, Lateral Cricoarytenoid, and Oblique Arytenoid are among the muscles of the larynx.
• These muscles control vocalization and breathing.

Lab

• Dissect the deep structures of the neck.
• Remove the middle third of the clavicle.
• Observe the roots and trunks of the brachial plexus, Scalenes/phrenic n, and Subclavian a.
• Review the larynx.
• Review previous labs.