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Anatomy of the neck
By Dr. Rasha Sabry
الرحمن الله بسمالرحيم
”” تبصرون أفال أنفسكم تبصرون وفي أفال أنفسكم ““وفي
• The anterolateral part of the neck is quadrilateral area which is divided by sternomastoid muscle into 2 large triangular areas ( anterior and posterior ) .
• The investing layer of deep fascia roofs both triangles .
• Sternomastoid muscle :• 1- action :when one muscle acts alone , it bends the
head to its same side and rotates it to the opposite side ( the face looks to the opposite side
• As you want to approximate the mastoid process to the manubrium of the sternum ).
• When the two muscles act together , they flex the head .
• 2-Nerve supply : 1- the spinal root of the accessory nerve (motor )
• 2- the cervical nerves C2&C3 (proprioceptive )
Omohyoidmuscle Sternomastoid
muscle
Relations of the sternomastoid
• 1- superficial relations :• 1- the lower end of the parotid gland .• 2- the great auricular nerve .• 3- anterior cutaneous nerve of the neck .• 4- external jugular vein .
Great auricular nerve
Transverse cutaneous nerve of the neck
External jugular vein
Parotid gland
• Deep relations :• A- Deep relations to its upper half : • 1- posterior belly of digastric muscle .• 2- spinal accessory nerve .• 3- splenius capitis • 4- occipital artery
• B- Deep relations to its lower half :• 1- intermediate tendon of omohyoid muscle .• 2- transverse cervical artery .• 3- suprascapular artery • 4- anterior jugular vein• 5- scalenous anterior • 6- phrenic nerve • 7- carotid sheath and its contents
• Stucture emerging from its posterior border (they appear in the posterior triangle )
• 1- branches of the cervical plexus • 2- trunks of brachial plexus • 3- spinal accessory nerve • 4- transverse cervical artery &suprascapular
arteries • 5- the 3rd part of subclavian artery • 6- deep cervical lymph nodes
• Clinical importance of the sternomastoid muscle :
• 1- congenital torticollis : (wry neck ), it is a fibrous tissue tumour or injuiry of the muscle during birth .
• 2- spasmodic torticollis : abnormal tonicity in the muscle .
apex
trapeziusmuscle
Investing layer of deep fascia roof
Sternomastoid muscle
Middle 1/3 of clavicle – base
The posterior triangle
• the posterior triangle lies behind the sternomastoid muscle , it has an apex , base and 2 borders .
• The outlines of the posterior triangle :• 1- the posterior border of the sternomastoid muscle .
(infront )• 2- the anterior border of trapezius muscle(behind )• 3- the middle one third of the clavicle forms the base
of the triangle .• 4- the meeting of the sternomastoid muscle and
trapezius muscle forms the apex of the triangle .
• Roof :• It consists of the following layers (from outwards
inwards )• 1-the skin • 2- the superficial fascia containing :• 1- the platysma muscle (very thin sheet of muscle
layer )• 2- the external jugular vein • 3- the deep fascia of the roof ( part of the general
investing layerof the deep fascia of the neck ) .
• Floor :• The deep fascia of the floor ( prevertebral fascia )
which cover the muscles of the floor .• The muscles of the floor ( arranged from below
upwards ) • 1- scalenus medius • 2- levator scapulae • 3- splenius capitis • 4- semi- spinalis capitis ( at the apex of the
triangle )
• The posterior triangle is subdivided by the inferior belly of omohyoid into 2 smaller triangles :
• 1- the occipital triangle ( above )• 2- the subclavian triangle ( below )
Contents of the posterior triangle
• 1- nerves, remember that the main contents of the posterior triangle are nerves .
• 2- vessels ( arteries and veins )• 3- the inferior belly of the omohyoid muscle
Nerves in posterior triangle
1-Cervical plexus 2-Brachial plexus 3- spinal root of accessory nerve (11th cranial nerve )
1- four muscular branches
2- four cutaneous branches
Roots , trunks and their branches1- dorsal scapular nerve –c5(nerve to rhomboids )2- nerve to subclavius – c5 &c63- nerve to serratus anterior –c5,6 &7Suprascapular nerve –c5&6
It is the most important structure in the occipital triangle
Spinal part of accessory nerve
• Cervical plexus :• It is formed by the anterior 1ry rami of the upper
4 cervical nerves .• It gives off 4 muscular branches :• 1- nerve to sternomastoid muscle ( C2&C3
proprioceptive)• 2- nerve to trapezius muscle ( C3&C4
proprioceptive)• 3- nerve to levator scapulae muscle ( C3&C4)• 4- roots to the phrenic nerve . (C3&C4 & C5)
• Cutaneous branches of the cervical plexus :• 1- lesser occipital nerve (C2)• 2- great auricular nerve (C2&C3).• 3- transverse cervical nerve (C2&C3)• 4- supraclavicular nerves (C3&C4)
• Arteries :• 1- 3rd part of subclavian artery .• 2- two branches which come from the 1st part of
the subclavian artery ( transverse cervical artery and suprascapular artery )
• Veins :• 1- subclavian vein • 2- transverse cervical vein • 3- suprascapular vein
The anterior triangle of the neck • It lies in front of the sternomastoid muscle .• It is bounded by :• 1- anterior border of sternomastoid muscle .
(behind)• 2- anterior midline of the neck ( in front )• 3- lower border of the mandible (base )• It is subdivided into 4 triangles by means of the
superior belly of omohyoid muscle , the anterior and posterior bellies of digastric muscle as follows :
• 1- Digastric triangle • 2- carotid triangle • 3- Muscular triangle • 4- Submental triangle
Anterior belly of digastric muscle
Posterior belly of digastric
Stylohyoid
Sternohyoid muscle
Digastric triangle
• Outlines :• Above : the lower border of the mandible • Below & infront : the anterior belly of Digastric
muscle • Below & behind : the posterior belly of Digastric
and stylohyoid muscles . • Floor : • Anteriorly : the mylohyoid muscle • Posteriorly : part of hyoglossus muscle
Contents of the Digastric triangle
• 1- submandibular salivary gland • 2- the submandibular lymph nodes lie on the
surface of the gland • 3- facial artery deep to posterior end of
submandibular salivary gland • 4- facial vein lies superficial to submandibular
salivary gland • 5- hypoglossal nerve • 6- nerve to mylohyoid muscle
• dDigastric triangle
Carotid triangle
Muscular triangle
Anterior belly of digastric
Posterior belly of digastric
Mylohyoid muscle forms the floor of the mouth
Carotid triangle • Outlines :• Behind : the sternomastoid muscle • Infront and above : the posterior belly of digastric
muscle • Infront and below : the superior belly of omohyoid
muscle • Floor : infont : the hyoglossus muscle ( above ) and the
thyrohyoid muscle (below) • Behind: the middle constrictor muscle of the pharynx
(above ) and the inferior constrictor muscle of the pharynx (below )
External carotid artery
Common carotid artery
Internal carotid artery
Contents of the Carotid triangle
• 1- The carotid sheath and its contents : • - common carotid artery : in the lower part of
the triangle .• - internal carotid artery : in the upper part of
the triangle .• Internal jugular vein : lateral • Vagus nerve : between the artery and the vein
but in a more posterior plane .
• 2- the external carotid artery : gives most of its branches in the carotid triangle ( superior thyroid artery ,lingual artery ,facial artery , ascending pharyngeal artery and occipital artery )
• 3- hypoglossal nerve • 4- Descendes cervicalis (C2,3) anterior to carotid
sheath.• 5- sympathetic trunk adherent to the posterior
wall of carotid sheath
Muscular triangle
• Outlines :• Infront : midline of the neck • Behind and above :superior belly of omohyoid
muscle • Behind and below : the sternomastoid muscle
Contents of the Muscular triangle
• It contains the infrahyoid muscle
Submental triangle
• Outlines : • Infront : symphysis menti of the mandible • On each side : the anterior belly of digastric
muscle • Behind ( base ) : the hyoid bone • Floor : parts of the mylohyoid muscles as they
meet each other in the median plane
Contents of the Submental triangle
• 1- submental lymph nodes • 2- beginning of the anterior jugular vein
The infrahyoid muscles
• They are strap like muscles occupy each side of the midline of the neck , from the hyoid bone to the manubrium sterni .
• They consist of 4 muscles arranged into 2 layers : • 1- superficial layer : a- sternohyoid • B- omohyoid • 2- deep layer: a- sternothyroid • B- thyrohyoid
The Hyoid Bone
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The only bone that does not articulate with another bone
• Serves as a moveable base for the tongue
The infrahyoid muscles
• Nerve supply : • All The infrahyoid muscles are supplied by
• Ansa cervicalis except thyrohyoid muscle supplied by fibres from C1 through hypoglossal nerve .
Ansa cervicalis
• Ansa = loop • It is a loop of cervical nerve fibres derived from
C1,2,3 which lies below the carotid sheath below the middle of the neck .
• It consists of 2 roots :• 1- descendes hypoglossi C1: derived from
hypoglossal nerve • 2- descendes cervicalis : C2,3 : from the cervical
plexus
Action of the infrahyoid muscles
• 1- superficial layer : a- sternohyoid : depress the hyoid bone after it has been elevated during swallowing .
• B- omohyoid : depresses , retracts and steadies the hyoid bone .
• 2- deep layer: a- sternothyroid : depress the hyoid bone and the larynx
• B- thyrohyoid : depress the hyoid bone and elevate the larynx
Suprahyoid muscles
• 1- digastric muscle • 2- mylohyoid muscle • 3- hyoglossus muscle • 4- geniohyoid muscle • 5- stylohyoid muscle
Geniohyoid muscle
Hyoglossus
Digastric muscle • It consists of 2 bellies anterior and posterior , that
connected together by an intermediate tendon .• Nerve supply :• 1- anterior belly : from nerve to mylohyoid which is a
branch of mandibular nerve .• 2- posterior belly : the facial nerve • Action : • When the mandible is fixed , it raises the hyoid bone
during swallowing .• When the hyoid bone is fixed , the anterior belly can
depress the mandible
• mylohyoid muscle :• Formed of superoir and inferior bellies .• Nerve supply : nerve to mylohyoid , which is a
branch of the mandibular nerve .• Action :• When the 2 bellies contract they elevate the
hyoid bone and the floor of the mouth as well as the root of the tongue during swallowing .
• If the hyoid bone is fixed , the 2 bellies depress the mandible and open the mouth .
Hyoglossus muscle
• Nerve supply :• Hypoglossal nerve ( 12th cranial nerve )• Action :• It draws the tongue downwards and thus help
suckling .
• Geniohyoid muscle :• Nerve supply :• Hypoglossal nerve ( via fibres from C1 )• Action : • It pulls the hyoid bone upwards and forwards ,
if the hyoid bone is fixed , it depresses the mandible .
• Stylohyoid muscle • Nerve supply :• Facial nerve • Action :• Raises the hyoid bone upwards