Anterior Traingle Flashcards
What are the borders of the anterior triangle of the neck
Superiorly - inferior border of the mandible
Postioerly - anterior border of SCM
Anteriorly - midline of neck
What are the 4 subdivisions of the anterior triangle
Submental, Submandibular, carotid and muscular
What does the submandibular division of the anterior neck consist of
Submandibular gland, lymph nodes, parts of hypoglossal nerve, mylohyoid nerve and parts of facial artery and vein
What does the submental region of the anterior triangle contain
Submental lymph nodes and some small veins
What does the carotid part of the anterior triangle contain
Thyroid gland, larynx, pharnyx ; carotid sheath ( and its components), branches of the cervical plexuses, super root of asna cervical is and parts of CN11 and 12
What does the muscular region of the anterior triangle contain
Sternohyoid and sternothryoid muscles and thyroid and para thyroid glands
Name the 4 suprahyoid muscles
( connect to skull or mandible and hyoid )
Mylohyoid, Diagastric( anterior and posterior ) , stylohyoid and geniohyoid.
Name the 4 infrahyoid muscles
( connect to inferior structure and the hyoid bone - with one exempt)
Sternothyroid, omohyoid, sternohyoid and thryohyoid
What is the function of the suprahyoid muscles
They function to elevate the hyoid during swallowing and the larynx for tone production.
They constitute substance of the floor of mouth
Mylohyoid muscle origin
Originates at the mylohyoid line on the mandible
Where does the mylohyoid muscle insert
Into the body of the hyoid and the fibres of the opposite mylohyoid
Action of mylohyoid
Elevates the hyoid and the floor of the mouth and reinforces the floor of the oral cavity
Where are the origins of the anterior and posterior diagastric belly
Anterior - diagastric fossa on medial surface of the mandible
Posterior -mastoid notch on medial side of mastoid process
Where is the insertion of both the diagastric muscles
The intermediate tendon at the hyoid
What other function does the anterior belly have that the other suprahyoid muscles do not
Anterior belly functions to open the mouth by lowering the mandible
What is the innervation of the mylohyoid muscle
The nerve to mylohyoid which is a branch of IAN which is a branch of CNV3
Diagastric Muscles innervation
Anterior belly =nerve to mylohyoid
Posterior belly = diagastric branch of CN7
Origin, insertion, Action and innervation of stylohyoid
Originates at styloid process
Inserts - body of hyoid.
Action - pulls hyoid upwards
Innervation - CN7
Origin, insertion, action, innervation Geniohyoid
Origin - from mandible
Inserts - body of hyoid
Action - fixed mandible= elevates and pulls hyoid forward
- fixed hyoid =. Pulls mandible downwards and inwards
Innervation = via anterior ramus of C1 which travels with Hypoglossal Nerve
Origin, insertion and action of sternohyoid muscle
Origin - posterior surface of the sternoclavivular joint and manubrium
Inserts - into body of hyoid
Action- depresses hyoid after elevation during swallowing
What is the group function of the infra-hyoid muscles
They function as a group to depress the hyoid and larynx during swallowing and speech
Discuss the two planes of the infrahyoid muscles
Superficial = sternohyoid and omohyoid
Deep = thyrohyoid and sternothyroid
What are the two bellies of omohyoid connected by
The superior and inferior bellies of the omohyoid are connected by an intermediate tendon
Origins, instertion and action of omohyoid muscle
Origins; Superior belly -immediate tendon
inferior belly -superior border of the scapula
Inserts ; Superior belly - Hyoid bone
Inferior belly - intermidaite tendon in posterior triangle
Action - depresses and fixes the hyoid
How is the omohyoid anchored to its immediate tendon at the Clavicle
By a facial sling
Thyrohyoid orgin insertion and action
Origin- oblique line on thyroid cartilage
Inserts - greater horn and adjacent Body of hyoid
Action - depresses hyoid ; can raise larynx when hyoid is fixed
Sternothyroid origin, action and insertion
Origin - at posterior surface of manubrium
Inserts - into oblique line on thyroid cartilage
Action - draws Larnyx downward
What is the innvervation of sternohyoid, omohyoid and sternothyroid
Anterior rami of C1-C3 ( through the ansa cerviaclis )
Thryrohyoid innervation
Anterior rami of C1 but the fibres run with CN12
The two lateral lobes of the thyroid gland extend from?
Thyroid cartilage to 5th tracheal ring
What is the level of the isthmus
Level of 3rd tracheal ring
The pyramidal lobe is on the thyroid gland is present in 80% of people - what is this the remenants of ?
Thyroglossal duct
What is the arterial supply of the thyroid gland
Superior thyroid artery ( 1st branch of external carotid)
Inferior thyroid artery ( branch of thyrocervical trunk from subclavian )
Discuss venous drainage of the thyroid gland
Drained through the thyroid Venous plexus ;
Superior thyroid and middle thyroid vein into the internal jugular vein
The inferior thyroid vein into the brachiocephalic
In 10% of people there is an additional artery which supplies the thyroid , apart from the superior and inferior thyroid arteries, what is this
The thyroid IMA artery
Unpaired artery which usually arises from brachiocephalic trunk but can come from elsewhere
Why must the thyroid IMA artery be considered clinically
In midline neck procedures like an insertion of a surgical airway ( tracheostomy) as it is a potential bleeding risk
Where are the two pairs of parathyroid glands MOST COMMONLY present ( position can vary)
On posterior surface of the thyroid
What is the arterial supply of the parathyroid arteries
Inferior thyroid arteries
What is the nerve innervation of both the thyroid and parathyroid glands?
They are both innervated by the thyroid branches from the cervical ( sympathetic) ganglia
Vasomotor fibres - cause blood vessel constriction
What are some implications of neck surgery surrounding the recurrent laryngeal nerves
The right reccrurent laryngeal nerve has a close relationship to the inferior thyroid artery and therefore during surgery there is a risk of damage
Left one carries less risk
If there has been injury to the recurrent laryngeal nerve or potential post surgical blood/exudate accumulation , how would this present
Hoarseness, temporary aphonia ( disturbance of voice production)
What are the two types of emergency and surgical airway procedures
Cricothyrotomy and Tracheostomy
What is a cricothryotomy
It is an emergency procedure, when a large bore needle is passsed through the cricothyroid ligament; this may be replaced by a small tracheostomy tube
What is a tracheostomy
More complex of surgical airway procedures
Involves retraction of infrahyoid muslces and incision of isthmus of thyroid to insert tube between second and first or second and fourth tracheal rings to insert tracheostomy tube
Why is there more of a risk in children and neonates when carry out surgical airway procedures
In these groups the trachea is very soft and surgical procedures may carry a risk of damage to oesphagous which lies deep to trachea
What does the carotid sheath contain
The vagus nerve, the carotid arteries ( internal and part of external ) and the internal. Jugular vein
The Ansa cervicalis usually lies on ( or is embedded in) the anterolateral aspect of the sheath
Where does the carotid sheath run from
From foramen of carotid Canal to the aortic arch
Where do the left and right Common carotid arteries come from?
Right common carotid artery is a branch of the brachiocephalic trunk
Left common carotid artery is a DIRECT branch from the arch of the aorta
At what level do the Common carotid arteries branch
Branch at the level of C3/C4 into internal and external carotid
The internal carotid artery supplies what
THE BRAIN
The internal carotid artery has no branches in the neck and ascends to carotid canal to supply the brain
What is the carotid sinus
It is an enlargement at the bifurcation of the common carotid artery which contains baroreceptors and pressoreceptors in the wall of internal carotid artery
What is the carotid sinus function?
It is important for monitoring blood pressure.
The baroreceptors are sensitive to stretch when the bP increases and they note it and report to CN9
CN9 then carries it to the medulla and brain stem to return BP to normal homeostatic values
What is the carotid sinus inverted by
Innvervated by CN9 via carotid sinus nerve and CN10
Action potentials travel from the baroreptors through CN9 to the cardioregulatory system and vasometers in the medulla
What is the carotid body
Small organ which houses chemoreceptors location at bifurcation of CCA near the carotid sinus
What is the function of the carotid body
It has chemoreceptors and it is important in monitoring the blood 02,C02, ph and temperature.
Stimulated by low blood 02 levels and initiates a reflex
in emergency situations by increasing respiration, blood pressure and cardiac rate
What is the innervation of the carotid body
Innverated by CN9 via the carotid sinus nerve and CN10
Afferent fibres from the carotid body travel into the cardioregulatory and vasomotor centres in the medulla
What does the external carotid artery supply
Most structures external to the cranium
Which structures are the expection to being supplied by the ECA and what instead are they supplied by
The orbit and part of the forehead and the scalp and supplied by the supra-orbital artery
Where does the middle menigeal artery branch from and how does it enter the cranium
The middle meningeal artery is a branch of the maxillary artery which is a terminal branch of ECA
Where does the ECA terminate and what happens there
The ECA terminates and it is there that it gives off its last 2 branches the terminal branches - maxillary artery and superficial temporal artery
What are the 8 branches of the ECA
Some Anatomists Like Freaking Out Poor Medical Students
Superficial Thyroid
Ascending pharyngeal
Lingual
Facial
Occipital
Posterior auricular
Maxillary
Superficial temporal
ECA - superior thyroid supply
Thyroid , muslces of larnyx and muscles of neck
ECA - Ascending pharyngeal Supply
Pharynx, palatine tonsils, dura mater, CN12,9 and 10
ECA - lingual artery supply
Tongue, salivary glands, soft palate, palatine tonsils and muslces attached to hyoid bone
ECA. - facial artery supply
Muscle of the face, cervical lymph nodes, palatine tonsils, lips and part of nose
ECA - occipital artery supply
Dura matter, the auricle, the SCM and deep posterior muscles of the back
ECA - Posterior auricular artery
Facial nerve , tympanic membrane and external auditory measutus
ECA - maxillary artery
Tympanic membrane. External ear, the mandible,the maxilla,the cal aria the dura mater, the nasal septum and many muslces of face
ECA- superficial temporal artery
Muslces and skin of face and scalp
What does the internal jugular vein drain?
The brain, skull and part of face and neck
What is the internal jugular vein a continuation of?
Sigmoid sinus
Venous drainage in posterior cranial fossa
How does the internal jugular vein exit the skull and where does it enter
Exits skull via the jugular foramen and then enters the carotid sheath
Runs lateral to CCA
Which veins drain into the internal jugular vein?
Parallel to branches of ECA and thyroid vessels
What is the superior bulb of the internal jugular vein
The internal jugular vein is continuous with the sigmoid sinus however its ORIGIN is demarcated by the superior bulb.
At this superior bulb the inferior pectoral sinus enters
What is the small dilation before the internal jugular veins termination before joining subclavian vein called?
Inferior bulb and this bulb has bicuspid valves here to prevent backflow into the vein ( if say standing on head) whilst permitting blood flow to The heart
Which infrahyoid muscle runs across the internal jugular vein?
Omohyoid
What does the IJV vein merge with and what does this then become
The internal jugular vein joins with the subclavian vein to become the left and right brachiocephalic veins
Where does the external jugular vein begin?
At the angle of the mandible
How is the external jugular vein formed?
By the union of the posterior division of retromanidubular vein with posterior auricular vein
What are the 5 branches of the facial nerve
Temporal , zygomatic, buccal mandibular and cervical.
What nerve innervates the platysma muscle
Cervical branch of CN7 - facial nerve
What are the digastric muscle innervation
Digastric branch of CN7
Where does CN7 the facial nerve emerge
Stylomastiod foramen
Which cranial nerves emerge through the jugular foramen
Cranial nerves 9, 10 and 11 all emerge via the jugular foramen and travel downward between the IJC and the ICA
The recurrent laryngeal nerves are branches of the vagus nerve.
What arteries do the right and left loop around
The right recurrent laryngeal nerve loops around the subclavian artery and the left loops around the arch of the aorta and brachiocephalic trunk
What two muscles does the accessory nerve cn11 innervate
The SCM and the trapezius
Which cranial nerve gives off the superior root of ansa cervicalis
Hypolossal nerve CN12
What is the main innervation to the infra hyoid muscles
Ansa cervicalis ( anterior rami C1-C3)
Which nerve supplies cutaneous innervation over SCM and anterior triangle
Transverse cervical nerve ( anterior rami of C2 and C3)
Where does the phrenic nerve run across?
The anterior scalene muscle on the right
Crosses anterior to subclavian artery on left
What supplies the upper limb
Brachial plexus ( C5-T1)
