Triangles & Root of the Neck

Triangles and Root of the Neck

BMES208 Human Musculoskeletal System

Kittikun Viwatpinyo, Ph.D.

Neck : Introduction

• Neck (Cervical region)▫ Area in between base of

skull to T1 vertebra, clavicle and acromion

• Transitional area between head, thorax and upper limb

(Drake, Wayne & Mitchell, 2005)

Superficial structures of neck

• Skin• Superficial fascia • Platysma muscle

(Tank, 2005)

Superficial structures of neck• Cutaneous nerves▫Great auricular n.▫ Lesser occipital n.▫ Transverse cervical n.▫ Supraclavicular n.

(Tank, 2005)

(Moore, Dalley & Agur, 2010)

Superficial structures of neck• Superficial veins : ▫ External jugular & Anterior jugular veins


Deep cervical fascia

• Investing layer

• Prevertebral layer

• Pretracheal layer

• Carotid sheath


Fascial spaces

• “Potential spaces” within neck

• Pretracheal space• Retropharyngeal

space• Prevertebral space


Fascial spaces• “Potential spaces” within neck• Pretracheal space• Retropharyngeal space• Prevertebral space


Anterior triangle of neck

• Area anterior to sternocleidomastoid muscle• Sub-triangles :▫ Submental▫ Submandibular▫Carotid▫Muscular


Skeletal landmarks• Hyoid bone• Thyroid cartilage▫ Thyroid prominence▫Oblique line▫ Thyrohyoid membrane

• Cricoid cartilage


Muscles of anterior triangle

• Suprahyoid muscles▫Digastric m.▫ Stylohyoid m. ▫Mylohyoid m.



Muscles of anterior triangle

• Infrahyoid muscles▫ Sternohyoid m.▫Omohyoid m.▫ Sternothyroid m.▫ Thyrohyoid m.



Nerves of anterior triangle

• Vagus nerve (CN. X)

▫ Located within carotid sheath posterior to vessels

▫Major branch : Superior laryngeal n. Internal and External laryngeal nerves


Nerves of anterior triangle • Hypoglossal nerve (CN. XII)▫ Located anterior to vessels and medial to digastric and

stylohyoid muscles▫ In submandibular triangle : located lateral to hyoglossus

muscle


Nerves of anterior triangle • Transverse cervical nerve (C2, C3)▫Receives sensation from skin of

anterior triangle

(Tank, 2005)(Drake, Wayne & Mitchell, 2005)

Nerves of anterior triangle

• Ansa cervicalis▫ Loop of motor branches of

cervical plexus (C1-C3)▫ Located anterior to carotid

sheath▫ Superior and inferior roots▫ Supplies infrahyoid muscles

(except thyrohyoid m.)

(Tank, 2005)

Carotid arterial system

• Common carotid artery

▫ Bifurcates at level of upper border of thyroid cartilage

• Internal carotid artery

▫ Directs into skull

▫ No branches in neck

• External carotid artery

▫ Gives many branches to neck and facial structures


External carotid artery : branches

• Superior thyroid artery▫ Superior laryngeal a. : pierces thyrohyoid membrane to

supply larynx▫Glandular branch : supply thyroid gland


External carotid artery : branches

• Lingual artery▫ Passes anteriorly and deep to hyoglossus muscle to supply

tongue


External carotid artery : branches• Facial artery▫ Passes anteriorly and medial to posterior belly of digastric

muscle and travels along inf border of mandible▫ Supplies submandibular salivary gland, submental region and

face


External carotid artery : branches• Occipital artery▫ Passes posteriorly and medial to posterior belly of digastric

muscle▫ Supplies sternocleidomastoid muscle and posterior part of

scalp


Carotid pulse


Internal jugular vein

• IJV : located lateral to common carotid a.

• Joins subclavian vein at venous angle

• Major tributaries▫ Facial vein▫ Lingual vein▫ Superior and middle

thyroid veins▫Occipital vein


Lymphatics of the neck

• Superficial lymph nodes

▫Occipital nodes

▫Mastoid nodes

▫ Parotid nodes

▫ Submental nodes

▫ Submandibular nodes

▫ Superficial cervical nodes


Lymphatics of the neck

• Deep cervical lymph nodes▫ Superior deep cervical nodes▫ Inferior deep cervical nodes▫ Pretracheal and Paratrachel

nodes


Posterior triangle of neck

• Area posterior to sternocleidomastoid muscle• Sub-triangles :▫Occipital▫Omoclavicular


Muscles of posterior triangle

• Sternocleidomastoid muscle (SCM)▫Origin : Mastoid process

and lateral ½ of sup nuchal line

▫ Insertion : medial 1/3 of clavicle and upper manubrium

▫Nerve : Spinal accessory nerve (CN. XI)



• Sternocleidomastoid muscle : Actions▫ Extends neck (when in anatomical position)▫ Flexes neck (when neck is initially flexes)▫Rotates neck to opposite side (unilateral)



• Scalene muscles▫ Scalenus anterior▫ Scalenus medius▫ Scalenus posterior

• Main action : Flex neck and elevate ribs 1-2


Nerves of posterior triangle

• Accessory nerve (CN. XI)▫ Passes downward and

posteriorly to supplies SCM and Trapezius muscles

(Tank, 2005)

Nerves of posterior triangle• Cervical plexus : from ventral rami of C1-C4▫Muscular branches : Ansa cervicalis and Phrenic n.▫Cutaneous branches



• Cutaneous branches of cervical plexus▫ Lesser occipital n. (C2) : passes

toward apex of post. triangle and supplies skin of posterior neck and scalp

▫Great auricular n. (C2-C3) : parallels with EJV and supplies skin of parotid region and anterior ear

(Tank, 2005)


• Cutaneous branches of cervical plexus▫ Transverse cervical n. (C2-

C3)

▫ Supraclavicular n. (C3-C4) : passes downward and laterally to supply skin of lower neck

(Tank, 2005)


• Supraclavicular part of brachial plexus (root + trunk level)▫ Passes between scalenus

anterior and medius muscles



• Terminal branches▫Dorsal scapular n. (C5)▫ Long thoracic n.(C5 – C7)▫ Suprascapular n. (C5, C6)▫Nerve to subclavius (C5, C6)


Arteries of posterior triangle

• Branches from Subclavian artery▫ Suprascapular artery▫ Transverse cervical artery


Root of the neck

• Deep part of neck that connects with thorax (via superior thoracic aperture)▫ Floor : Apex of lung


Root of the neck• Major contents : Subclavian vessels, Nerves, Lymph

trunks, Visceral structures


Subclavian artery

• From Brachiocephalic trunk (right) and aortic arch (left)▫Curves laterally in between

Scalenus anterior and medius muscles

▫Continues as Axillary artery▫ Three parts (related with

scalenus anterior muscle)

(Tank, 2005)

Subclavian artery : branches

• First part : Vertebral a., Internal thoracic a. & Thyrocervical trunk

• Vertebral artery▫ Passes upward and medial to

scalenus anterior m.▫ Penetrates foramen

transversarium (mostly C6)▫ Supplies brainstem,

cerebellum and posterior part of cerebrum



• Internal thoracic artery▫ Pass downward to supply anterior

thoracic wall

• Thyrocervical trunk▫ Suprascapular a. ▫ Transverse cervical a. gives

superficial and deep branches▫ Inferior thyroid a.



• Second part : Costocervical trunk▫Give rises to Deep cervical artery and Superior thoracic

artery


• Third part : ▫ In 1/3 give rises to Dorsal scapular artery (replace deep

branch of transverse cervical artery)

Subclavian vein

• Subclavian vein ▫Continues from Axillary vein ▫ Passes anterior to scalenus

anterior muscle and join IJV at venous angle

▫Drained into Brachiocephalic vein


Lymph trunks and nodes• At venous angle, lymph trunks join

venous system:▫ Left side : Thoracic duct▫Right side : Rt lymphatic duct

• Supraclavicular lymph nodes can be found along subclavian vein


Nerves of root of the neck

• Vagus nerve▫Recurrent laryngeal nerve : passes in tracheo-esophageal

groove to supply internal laryngeal muscles



• Phrenic nerve (C3-C5)▫ Passes anterior to scalenus anterior muscle and descends into

thorax to supplies diaphragm



• Cervical part of sympathetic trunk▫ A bundle of sympathetic fibers

posterior to carotid sheath▫ Three ganglions (location of

postganglionic sympathetic neurons)

• Lesion : Horner’s syndrome ▫ loss of sympathetic control in

head



• Cervical sympathetic ganglions▫ Superior cervical ganglion :

sends symp fibers into head and neck along internal carotid artery

▫ Middle cervical ganglion sends symp fibers to heart

▫ Inferior cervical ganglion sends symp fibers to heart


Thyroid and Parathyroid glands


Trachea and Esophagus


Triangles & Root of the Neck

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