Gross B 2.20. Superficial Structures and Posterior Triangle of The Neck [PDF]

Zitiervorschau

Far Eastern University – Nicanor Reyes Medical Foundation

Gross B – Superficial Structures & Post. Cervical Triangle of the Neck Clester Bea, M.D. (add. notes from James Taclin Banez, M.D.) NECK  Connects the head and the thorax, made up of skeletal muscles  At the back, it is represented at the midline by the cervical vertebra which is covered on both sides by the trapezius muscle

B. POSTERIOR (LATERAL) TRIANGLE  Contains the neuromuscular structures  Accessory spinal nerve  Lateral muscles of the neck  Boundaries  Anteriorly: Sternocleidomastoid  Posterolaterally: Trapezius  Inferiorly: Clavicle

The natural lines of cleavage of the skin are constant and run almost horizontally around the neck. This is important clinically because an incision along a cleavage line will heal as a narrow scar, whereas one that crosses the lines will heal as a wide or heaped-up scar.

Trauma to the central triangle is more fatal compared to trauma in the lateral triangle of the neck. Trauma to the central triangle can block the blood supply to the head and block the airway for breathing. Trauma to the lateral triangle can paralyze the muscles of the neck.

Boundaries of the Neck:  Superior (anterior):  Lower margin of the mandible and Superior nuchal line of the cranium  Inferior:  Suprasternal notch and the upper border of the clavicle  Anterior:  Anterior midline of the neck  Posterior:  Trapezius

Surface Landmark:  Laryngeal Prominence  Known as the Adam’s Apple in males  Formed by the thyroid (tracheal) cartilage  Sternocleidomastoid  Two points of origin: manubrium (head of the sternum) and the clavicle  Inserted to the mastoid process of the temporal bone

In surgery, the clavicle and the manubrial notch are used to divide the thoracic cavity and the cervical region. Anything below is the thoracic region, anything above is the cervical region

Triangles of the Neck:  The two triangles are separated by the sternocleidomastoid

A. ANTERIOR (CENTRAL) TRIANGLE  Contains the visceral structures  Trachea  Larynx  Esophagus  Carotid Sheath and contents  Boundaries  Superiorly: Inferior border of the mandible  Laterally: Medial border of the sternocleidomastoid  Medially: Imaginary sagittal line, midline

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COMPARTMENTS OF THE NECK  The subcutaneous tissue and superficial fascia is found immediately beneath the skin of the neck supporting the platysma muscle, neurovascular structures and lymph nodes  Deep the superficial fascia is formed by the deep cervical fascia which makes the area of the neck limited A. DEEP CERVICAL FASCIA  Embraces muscles and visceral structures anteriorly  Condensed to form well defined, fibrous sheets

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Superficial (Investing) Fascia  Most superficial of the deep cervical fascia and goes all the way around the neck  Splits into two to cover the the sternocleidomastoid and trapezius  Suprasternal Space of Burns – space formed by the superficial fascia near the manubrium. This is where the

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 Vagus nerve – most posterior, located between the carotids and internal jugular vein  Deep cervical lymph nodes  Root of ansa cervicalis - supplies the strap muscles (deep muscles of the neck)

jugular arch, a branch of the anterior jugular vein passes through Serves as the roof of the posterior triangle of the neck Superior attachment: hyoid bone, lower border of the mandible, zygomatic arch and occipital bone Inferior (anterior) attachment: acromion, clavicle, manubrium Posterior attachment: spinous process of cervical vertebrae and ligamentum nuchae. Holds the omohyoid to the clavicle

Pretracheal Fascia  Middle fibrous sheet from the deep cervical fascia  Attachment: superiorly to the oblique line of thyroid cartilage and cricoid cartilage, inferiorly to the sternum  Continues to the mediastinum to blend with the pericardium  Muscular part ensheaths the strap muscles (sternohyoid, sternothyroid, omohyoid)  Visceral part ensheaths the side of esophagus, larynx, trachea, thyroid and parathyroid  Acts as pseudocapsule of the thyroid Prevertebral Fascia  Deepest layer and starts at the posterior midline  Attachment: Base of skull. Enters the thorax and blends with the anterior longitudinal spinous process and ligamentum nuchae  Encloses lateral vertebral muscles and prevertebral muscles  Muscles of the back: splenius capitis, semispinalis capitis and iliocostalis capitis  Suboccipital muscles: rectus capitis posterior major and minor, oblique capitis superior and inferior  Forms the floor of the posterior triangle of the neck and covers the body of the vertebra  Extends laterally to the first rib, into the axilla to form the axillary sheath

The common carotid has no branch except at the level of the superior horn of the tracheal cartilage. This is where it will divide into the external and internal carotid artery. The internal carotid artery is within the carotid sheath, but does not give off any branch until it reaches the cranial nerve

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Retropharyngeal Sheath / Space  Potential space between the pharynx and the prevertebral fascia  Danger space of the neck because this may serve as a possible route for spread of infection from head to mediastinum  Alar fascia  Subdivision of the retropharyngeal space  Attached along the midline of Buccopharyngeal fascia from cranium to C7  Terminates to the carotid sheath  Anterior border: pretracheal fascia  Posterior border: prevertebral fascia When a patient has pharyngitis and left untreated the infection may go into the retropharyngeal space. The abscess may then continue to spread to the mediastinum thereby causing medisatinitis.

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Axillary Sheath  Extension of the prevertebral fascia, carried to the axilla by the subclavian artery and the brachial plexus  Formed as C5-T1 forms the brachial plexus  Encloses the axillary vessels and the brachial plexus

B. SUPERFICIAL CERVICAL FASCIA  Forms a thin layer that encloses the platysma muscle  Embedded on it are the cutaneous nerves, superficial veins (external and anterior jugular) and superficial lymph nodes 1.

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Carotid Sheath  Tubular condensation of the layers of the deep cervical fascia  Blends with the superficial, pretracheal fascia and prevertebral fascia (union of the three fasciae)  From the base of the skull to the root of the neck  Contents:  Common and internal carotid arteries – most medial  Internal Jugular Vein – most lateral

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Platysma – anterolateral structure, superficial muscle of the neck Origin: Fascia of the deltoid and pectoralis major Insertion: Skin and the superficial fascia of the lower face, angle of the mouth Action: Draws lower lip downward and back. Considered as muscle of facial expression Nerve: Cervical branch of the Facial Nerve

Platysma = superficial muscles of the neck Strap muscles = deep muscles of the neck

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Anterior Jugular Vein

Jugular Arch

In surgery, the platysma muscle serves as a marker in injuries regarding the neck. An injury penetrating the platysma is considered as a deep injury.

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External Jugular Vein

 Lies in the sternohyoid and begins below the chin, near the hyoid bone from the confluence of the superficial mandibular veins  Formed by superficial veins of the submental area and also a contribution from the external jugular vein through the transverse cervical vein  May terminate to the external jugular vein or the subclavian vein  Tributaries:  Laryngeal vein  Small thyroid vein  Jugular arch The right and left anterior jugular vein lies on the sternohyoid muscle. The two veins will be connected by one of its tributaries, the jugular arch. The jugular arch is particularly of importance to the thoracic surgeons, especially when performing a midline sternal incision.

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Superficial Lymph Nodes

Superficial Parotid Nodes

 Most superficial of the jugular veins, begins behind the angle of the mandible and lies in the SCM  Formed by the union of the posterior auricular vein and the posterior division of the retromandibular vein  Drains mainly into the subclavian vein, but may drain to the internal jugular vein  Tributaries:  Transverse Cervical  Suprascapular  Anterior Jugular  Posterior External Jugular – small vein that drains the posterior part of the scalp and neck and joins the external jugular vein about halfway along its course  Posterior Auricular  Posterior Division of the Retromandibular vein

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Submandibular Nodes Submental Nodes

Superficial Cervical Nodes Deep Cervical Nodes

 Lies along the external jugular vein superficial to the sternocleidomastoid  Based on anatomy, theses nodes are grouped based on location:  Parotid  Submental  Submandibular  Superficial cervical

 Deep cervical  Receives lymph vessels from the occipital and mastoid lymph nodes  Drains into deep cervical lymph nodes

Boundaries of the Posterior Triangle of the Neck:  Anteriorly: Sternocleidomastoid  Posterolaterally: Trapezius  Inferiorly: Clavicle

Cutaneous Branches of the Cervical Plexus  Purely sensory  These nerves are part of the cervical plexus (C1-C4, minimal from C5)  Lesser Occipital  Anterior rami of C2  Supplies the skin over the lateral part of the occipital region and the medial surface of the auricle  Great Auricular  Anterior rami of C2-C3  Supplies the skin over the angle of the mandible, the parotid gland and on both surfaces of the auricle  Transverse Cervical (transverse cutaneous)  Anterior rami of C2-C3  The skin on the anterior and lateral surfaces of the neck, from the body of the mandible to the sternum  Supraclavicular  Anterior rami of C3-C4  Medial part crosses the middle end of the clavicle and supplies the skin as far as the median plain  Intermediate part crosses the middle of the clavicle and supplies the skin of the chest wall  Lateral part crosses the lateral end of the clavicle and supplies the skin over the shoulder and upper half of the deltoid muscle  Supplies the posterior aspect of the shoulder down to the spine of the scapula  The lesser occipital nerve and great auricular nerve supply the back of the ear  First Cervical nerve  Has no cutaneous innervation  Greater Occipital nerve nd  Branch of the posterior rami of the 2 cervical nerve

Divisions of the Posterior Triangle of the Neck:  Occipital Triangle  Contains the lateral muscles of the neck  Apex contains portion of the occipital bone and occipital artery  Crossed by the accessory nerve  Supraclavicular or Subclavian Triangle  Contains brachial plexus and subclavian vessels  Crossed by the external jugular vein and subclavian artery

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The inferior belly of the omohyoid serves as boundary between the two triangles

Floor of the Posterior Triangle:  Semispinalis capitis  Splenius capitis  Levator scapula  Posterior scalene  Scalene medius  Scalene anterior

POSTERIOR TRIANGLE OF THE NECK

The brachial plexus will be seen emerging between the anterior and middle scalene to supply the upper extremities

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Semispinalis capitis Origin: Transverse process of T1-T6 Insertion: Occipital bone between superior and inferior nuchal line Action: Extend the head (both); rotate the head to the side (individually) Nerve: Dorsal rami of the cervical nerve

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Splenius capitis Origin: Ligamentum nuchae and spinous process of C7T4 Insertion: Lateral superior nuchal line near the mastoid process Action: Extend the head and neck (both); rotate head same side (individually) Nerve: Dorsal rami of the lower cervical nerve

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Levator scapula Origin: Transverse process of C1-C4 Insertion: Upper medial border of the scapula Action: Elevates the scapula Nerve: Dorsal scapular nerve (C3-C5)

Arteries in the Posterior Triangle of the Neck  Transverse cervical artery – branch of the thyrocervical trunk  Suprascapular artery – branch of the thyrocervical trunk  Third part of the subclavian artery – usual location of aneurysm because it is compressed by the clavicle and the first rib  Occipital artery – branch of the external carotid artery

Subclavian Artery – divided into three parts by the anterior scalene 1.

The accessory nerve has nuclei in the medulla oblongata and in the cervical region. It lies on the levator scapula 4.

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Scalene posterior Origin: Transverse process of C4-C6 Insertion: 2nd rib Action: Elevates the 2nd rib and assists in forceful inspiration Nerve: C6-C8 Scalene medius Origin: Transverse process of C1-C7 Insertion: 1st rib st Action: Elevates the 1 rib, flexes and rotates cervical vertebra Nerve: C3-C7 Scalene anterior Origin: Transverse process of C3-C6 st Insertion: 1 rib (scalene tubercle) st Action: Elevates 1 rib, slight rotation of neck Nerve: Lower cervical nerves (C4-C6)

Veins in the Posterior Triangle of the Neck  External Jugular vein and tributaries  Subclavian vein  Continuation of axillary vein and receives the external jugular vein  Receives thoracic duct and the right lymphatic duct  With the internal jugular vein, it forms the brachiocephalic vein

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First Part – medial border of anterior scalene a. Vertebral artery  Basilar artery b. Thyrocervical trunk  Inferior thyroid artery  Suprascapular artery  Transverse cervical artery c. Internal thoracic artery  Superior epigastric artery  Musculophrenic artery Second part – behind anterior scalene a. Costocervical trunk  Superior intercostals artery  Deep cervical artery Third part – lateral border of anterior scalene  No branch, but superficial cervical, dorsal scapular and suprascapular arteries may arise here

Nerves in the Posterior Triangle of the Neck 1. Accessory nerve

 Passes the levator scapula accompanied by the anterior rami of C3-C4  Innervates the trapezius and sternocleidomastoid

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Cervical plexus

 Found between the anterior and middle scalene, and deep to the sternocleidomastoid and goes to the axilla.  Roots of the lower cervical plexus joins the brachial plexus to supply the upper extremities  The superficial branches of the plexus that initially pass posteriorly are sensory branches. The deep branches passing anteromedially are motor branches.  Phrenic nerve  Motor nerve of the diaphragm  Anterior rami of C3-C5. Chiefly from C4  Lies on the lateral border of anterior scalene  Cutaneous branches  Lesser occipital nerve  Great auricular nerve  Transverse cervical nerve  Supraclavicular nerve 3.

 Roots emerge between the anterior and middle scalene  Supraclavicular part is found in the posterior triangle, infraclavicular part in the axilla  Branches from the roots:  Dorsal scapular nerve (C5) – supplies the levator scapula and rhomboid muscles  Long thoracic nerve (C5-C7) – supplies the serratus anterior  Nerve to longus coli and scalene muscles (C5-C8)  Branches from the upper trunk:  Suprascapular nerve – supplies the supraspinatus and infraspinatus muscles  Nerve to subclavius – supplies the subclavius The middle trunk, inferior trunk and the divisions of the brachial plexus are not seen on the posterior triangle of the neck.

Brachial plexus

 Anterior rami of C5-T1  As the plexus divides further, it is classified as: Roots, trunks, divisions and cords:  Roots and trunks are found in the cervical region  Divisions are found behind the clavicle  Cords are found below the clavicle, at the level of the axilla

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Sesir rhaenal kipagon moris! “And so, we begin the journey to the finals!”