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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
(Moore, Dalley & Agur, 2010)
Deep cervical fascia
• Investing layer
• Prevertebral layer
• Pretracheal layer
• Carotid sheath
(Moore, Dalley & Agur, 2010)
Fascial spaces
• “Potential spaces” within neck
• Pretracheal space• Retropharyngeal
space• Prevertebral space
(Moore, Dalley & Agur, 2010)
Fascial spaces• “Potential spaces” within neck• Pretracheal space• Retropharyngeal space• Prevertebral space
(Drake, Wayne & Mitchell, 2005)
Anterior triangle of neck
• Area anterior to sternocleidomastoid muscle• Sub-triangles :▫ Submental▫ Submandibular▫Carotid▫Muscular
(Moore, Dalley & Agur, 2010)
Skeletal landmarks• Hyoid bone• Thyroid cartilage▫ Thyroid prominence▫Oblique line▫ Thyrohyoid membrane
• Cricoid cartilage
(Drake, Wayne & Mitchell, 2005)
Muscles of anterior triangle
• Suprahyoid muscles▫Digastric m.▫ Stylohyoid m. ▫Mylohyoid m.
(Moore, Dalley & Agur, 2010)
(Drake, Wayne & Mitchell, 2005)
Muscles of anterior triangle
• Infrahyoid muscles▫ Sternohyoid m.▫Omohyoid m.▫ Sternothyroid m.▫ Thyrohyoid m.
(Moore, Dalley & Agur, 2010)
(Drake, Wayne & Mitchell, 2005)
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
(Drake, Wayne & Mitchell, 2005)
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
(Moore, Dalley & Agur, 2010)
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
(Moore, Dalley & Agur, 2010)
External carotid artery : branches
• Superior thyroid artery▫ Superior laryngeal a. : pierces thyrohyoid membrane to
supply larynx▫Glandular branch : supply thyroid gland
(Drake, Wayne & Mitchell, 2005)
External carotid artery : branches
• Lingual artery▫ Passes anteriorly and deep to hyoglossus muscle to supply
tongue
(Drake, Wayne & Mitchell, 2005)
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
(Drake, Wayne & Mitchell, 2005)
External carotid artery : branches• Occipital artery▫ Passes posteriorly and medial to posterior belly of digastric
muscle▫ Supplies sternocleidomastoid muscle and posterior part of
scalp
(Drake, Wayne & Mitchell, 2005)
Carotid pulse
(Drake, Wayne & Mitchell, 2005)
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
(Moore, Dalley & Agur, 2010)
Lymphatics of the neck
• Superficial lymph nodes
▫Occipital nodes
▫Mastoid nodes
▫ Parotid nodes
▫ Submental nodes
▫ Submandibular nodes
▫ Superficial cervical nodes
(Drake, Wayne & Mitchell, 2005)
Lymphatics of the neck
• Deep cervical lymph nodes▫ Superior deep cervical nodes▫ Inferior deep cervical nodes▫ Pretracheal and Paratrachel
nodes
(Moore, Dalley & Agur, 2010)
Posterior triangle of neck
• Area posterior to sternocleidomastoid muscle• Sub-triangles :▫Occipital▫Omoclavicular
(Moore, Dalley & Agur, 2010)
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)
(Drake, Wayne & Mitchell, 2005)
Muscles of posterior triangle
• Sternocleidomastoid muscle : Actions▫ Extends neck (when in anatomical position)▫ Flexes neck (when neck is initially flexes)▫Rotates neck to opposite side (unilateral)
(Moore, Dalley & Agur, 2010)
Muscles of posterior triangle
• Scalene muscles▫ Scalenus anterior▫ Scalenus medius▫ Scalenus posterior
• Main action : Flex neck and elevate ribs 1-2
(Drake, Wayne & Mitchell, 2005)
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
(Moore, Dalley & Agur, 2010)
Nerves of posterior triangle
• 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)
Nerves of posterior triangle
• 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)
Nerves of posterior triangle
• Supraclavicular part of brachial plexus (root + trunk level)▫ Passes between scalenus
anterior and medius muscles
(Drake, Wayne & Mitchell, 2005)
Nerves of posterior triangle
• Terminal branches▫Dorsal scapular n. (C5)▫ Long thoracic n.(C5 – C7)▫ Suprascapular n. (C5, C6)▫Nerve to subclavius (C5, C6)
(Drake, Wayne & Mitchell, 2005)
Arteries of posterior triangle
• Branches from Subclavian artery▫ Suprascapular artery▫ Transverse cervical artery
(Drake, Wayne & Mitchell, 2005)
Root of the neck
• Deep part of neck that connects with thorax (via superior thoracic aperture)▫ Floor : Apex of lung
(Drake, Wayne & Mitchell, 2005)
Root of the neck• Major contents : Subclavian vessels, Nerves, Lymph
trunks, Visceral structures
(Moore, Dalley & Agur, 2010)
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
(Drake, Wayne & Mitchell, 2005)
Subclavian artery : branches
• 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.
(Moore, Dalley & Agur, 2010)
Subclavian artery : branches
• Second part : Costocervical trunk▫Give rises to Deep cervical artery and Superior thoracic
artery
Subclavian artery : branches
• 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
(Drake, Wayne & Mitchell, 2005)
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
(Moore, Dalley & Agur, 2010)
Nerves of root of the neck
• Vagus nerve▫Recurrent laryngeal nerve : passes in tracheo-esophageal
groove to supply internal laryngeal muscles
(Drake, Wayne & Mitchell, 2005)
Nerves of root of the neck
• Phrenic nerve (C3-C5)▫ Passes anterior to scalenus anterior muscle and descends into
thorax to supplies diaphragm
(Drake, Wayne & Mitchell, 2005)
Nerves of root of the neck
• 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
(Drake, Wayne & Mitchell, 2005)
Nerves of root of the neck
• 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
(Drake, Wayne & Mitchell, 2005)
Thyroid and Parathyroid glands
(Drake, Wayne & Mitchell, 2005)
Trachea and Esophagus
(Drake, Wayne & Mitchell, 2005)