Where does the right common carotid artery originate from?
Brachiocephalic trunk
-posterior to right sternoclavicular joint
Where does the left common carotid artery originate from?
Aortic arch in superior mediastinum
Where does common carotid ascend?
In neck within carotid sheath
Where does common carotid divide?
Upper border of thyroid cartilage
What does the common carotid divide into at the upper border of thyroid cartilage?
External and internal carotid arteries
What is within the carotid sheath?
Internal jugular vein
Common carotid
Vagus nerve
How are the contents of the carotid sheath organized?
Internal jugular vein lies lateral to common carotid artery, and vagus nerve lies between common carotid artery and internal jugular vein, posteriorly
What is the terminal part of common carotid/beginning of internal carotid artery?
Localized dilation called carotid sinus
What is the highly vascularized epithelial structure located at the carotid bifurcation?
Carotid body
What does the carotid body contain?
Special nerve endings, mainly derived from glossopharyngeal nerve, which respond to chemical changes in blood composition, chemoreceptors
What does the carotid sinus have?
Wall contains numerous nerve endings, mainly derived from glossopharyngeal nerve, which are sensitive to changes in blood pressure (baroreceptors/pressoreceptors)
What are the carotid body and sinus important for?
Reflex control of heart rate, blood pressure, and rspiratory rate and depth
Where does the external carotid begin?
Upper border of thyroid cartilage
Where does the external carotid ascend into?
Carotid triangle
Where does the external carotid artery leave the carotid triangle?
As it passes deep (medial) to posterior belly of digastric and stylohyoid
Where does the external carotid terminate?
Within substance of parotid gland, posterior to neck of mandible, dividing into superficial temporal and maxillary arteries
What does the external carotid divide into?
Superficial temporal and maxillary arteries
Anterior branches of the external carotid
- superior thyroid
- lingual
- facial
Posterior branches of the external carotid artery
- occipital
- posterior auricular
Medial branch of the external carotid artery
Ascending pharyngeal artery
Terminal branches of the external carotid artery
Superficial temporal and maxillary arteries
Where does the superior thyroid artery originate from?
Initial part of external carotid artery
Superior thyroid artery route
Descends almost vertically to reach upper pole of lobe of thyroid gland and contributes to its blood supply
What artery does the superior thyroid artery give off?
Superior laryngeal artery (pierces thyrohyoid membrane with internal laryngeal nerve)
Lingual artery originates from where?
External carotid artery opposite tip of greater horn of hyoid
Lingual artery route
Initial segment is crossed superficially (laterally) by hypoglossal nerve.
Passes deep to hypoglossus muscle
What branches does the lingual artery give off?
Branches that supply the tongue
Where does the facial artery originate?
Immediately above the lingual artery (sometimes by a common trunk with it)
Facial artery route
Ascends medial (deep) to posterior belly of digastric and stylohyoid muscles, arches over these two muscles an submandibular gland, curves around inferior border of mandible (anterior to masseter) to enter face
What branches do the facial nerve give off?
Before it enters the face, it gives off branches that contribute to supply pharynx, soft palate, palatine tonsil, submandibular gland, and neighboring muscles
Where does the occipital artery originate from?
Posterior aspect of external carotid artery, close to inferior border of posterior belly of digastric
What is the route of the occipital artery?
Passes posteriorly and superiorly, deep (medial) to posterior belly of digastric and mastoid process, reaches back of scalp, its terminal branches accompany branches of greater occipital nerve and supply posterior part of scalp
What branches come off of the occipital artery?
Supply auricle, middle ear, mastoid air cells, cranial dura mater, and neighboring muscles
Where does the posterior auricular artery originate?
Arises from posterior aspect of external carotid artery at upper border of posterior belly of digastric
What is the route of the posterior auricular artery?
Passes posteriorly and superiorly to reach notch between cartilage of external acoustic meatus and mastoid process
What does the posterior auricular artery supply
Auricle Middle ear Scalp above and behind ear Parotid gland Neighboring muscles
Origin of ascending pharyngeal artery
Smallest branch of external carotid artery, arises near its origin
Pathway of ascending pharyngeal artery
Ascends along pharyngeal wall toward cranial base, medial to internal carotid artery
What does the ascending pharyngeal artery supply?
Pharynx Soft palate Palatine tonsils Middle ear Cranial dura mater
Where does the superficial temporal artery originate?
Upward continuation of external carotid artery
-terminal branch
What is the route of the superficial temporal artery?
- Upward continuation of external carotid artery
- ascends anterior to ear with auriculotemporal nerve and superficial temporal vein, passes superficial (latera) to root of zygomatic process of temporal bone
What does the superficial temporal artery divide into?
Superior to zygomatic process of temporal bone, it divides into anterior (frontal) and posterior (parietal) branches
What does the superficial temporal artery supply
Frontal, temporal, and parietal regions of scalp
What does the superficial artery give branches to?
Parotid gland, external ear, face, and temporomandibular joint
What is the largest of the two terminal branches of external carotid artery?
Maxillary artery
How does the maxillary artery run?
- Passes anteriorly, deep to neck of mandible
- runs through infratemporal fossa, and terminates in pterygopalatine fossa
What do the branches of the maxillary artery supply?
- external and middle ear
- cranial dura mater
- upper and lower teeth and gingiva
- muscles of mastication
- face
- hard and soft palate
- palatine tonsil
- nasal cavity
What does the internal jugular vein do?
Collects most venous blood from head and neck
Where does the internal jugular vein being?
In jugular foramen, as a continuation of sigmoid sinus
Where does the internal jugular vein end?
Posterior to the sternoclavicular joint, where it joins subclavian vein to form brachiocephalic vein
Where does the internal jugular vein lie?
Within the carotid sheath, lateral to internal carotid artery (in upper neck), and lateral to common carotid artery (in lower neck)
WHat lies alongside the internal jugular vein?
Deep cervical lymph nodes
Internal jugular vein upper and lower ends
They are dilated, superior and inferior bulbs
Tributaries of the internal jugular vein
- inferior petrosal sinus and sigmoid sinus, leaves cranial cavity via jugular foramen and drains into superior bulb
- lingual vein(s)
- pharyngeal veins
- facial vein
- superior and middle thyroid veins
- occipital vein (sometimes)
Where does the right subclavian artery being?
It is a branch of brachiocephalic trunk (artery), begins posterior to right sternoclavicular joint
Where does the left subclavian artery start?
Its a branch of the aortic arch, begins in the superior mediastinum
What is the subclavian artery divided into?
3 parts by the scalenus anterior muscle
1st part of subclavian artery
From origin to medial border of scalenus anterior
2nd part of the subclavian artery
Posterior to scalneus anterior
3rd part of the subclavian artery
From lateral border of scalenus anterior to lateral border of 1st rib, where it becomes continuous with axillary artery
What are the branches of the 1st part of the subclavian artery?
- vertebral artery
- thyrocervical trunk
- internal thoracic artery
Branches of the second part of the subclavian artery
Costocervical trunk (may originate from the 1st part
Branches of the 3rd part of the subclavian artery
Gives rise to dorsal subscapular artery or may have no branches
-if its there it runs through the brachial plexus
Where does the vertebral artery originate from?
1at part of subclavian artery
What are the parts of the vertebral artery?
- 1st (prevertebral) part
- 2nd (cervical) part
- 3rd (atlantic) part
- 4th (intracranial) part
1st (prevertebral) part of the vertebral artery
What lies posterior to the 1st (prevertebral) part of the vertebral artery?
Inferior cervical sympathetic ganglion
2nd part (cervical) of the vertebral artery
Ascends through transverse foramina of C6 to C1, anterior to ventral rami of corresponding spinal nerves
3rd part (atlantic) part of the vertebral artery
- runs medically, posterior to lateral mass of atlas, and enters vertebral canal passing under posterior Atlanto-occipital membrane
- it lies in a groove on superior surface of posterior arch of atlas and it is within the suboccipital triangle
What triangle is the 3rd (atlantic) part of the vertebral located within?
Suboccipital triangle
4th (intracranial) part of the vertebral artery
Pierces dura mater and arachnoid and ascend into cranial cavort (within subarachnoid space) via foramen magnum
Where do the major branches of the vertebral artery come off of?
The 4th part (intracranial)
What part of the vertebral artery gives off small muscular and spinal branches?
2nd part (cervical)
Where does the thyrocervical trunk originate from?
1st part of subclavian artery, just medial to scalenus anterior muscle and opposite origin of internal thoracic artery
When does the thyrocervical trunk divide and into what?
After a short course, it divides into inferior thyroid, superficial (transvers) cervical, and suprascapular arteries
What are the branches of the thyrocervical trunk?
- inferior thyroid artery
- superficial (transverse) cervical artery
- suprascapular artery
What does the inferior thyroid artery contribute to?
To supply
- larynx
- trachea
- pharynx
- esophagus
- thyroid
- parathyroid
What does the inferior thyroid artery originate from?
Thyrocervical trunk
Route of the inferior thyroid artery
Ascends to level of cricoid cartilage and then arches medically, posterior to carotid sheath, to reach lower part of lobe of thyroid gland
Inferior thyroid artery as it approaches the thyroid gland
It is closely related to recurrent laryngeal nerve
Ascending cervical artery
- originates from inferior thyroid artery as it arches medically
- ascends on scalenus anterior muscle
- supplies adjacent muscles and gives 1 or 2 spinal branches
Where does the superficial (transverse) cervical artery originate from?
Thyrocervical trunk
What is the route of the superficial (transverse) artery?
Runs laterally and posteriorly, passing anterior to scalenus anterior, phrenic nerve, and brachial plexus
What does the superficial (transverse) cervical artery supply?
Muscle of upper back
When is the superficial (transverse( artery referred to as “superficial cervical?”
If dorsal subscapular artery originates directly from subclavian artery
When is the superficial (transverse) cervical artery known as “transverse cervical artery?”
When it gives off the dorsal scapular artery
Suprascapular artery originates from where?
Thyrocervical trunk
How does the suprascapular artery run?
Parallel and inferior to superficial (transverse) cervical artery
WHat nerve joins the suprascapular artery as it approaches the scapula?
Suprascapular artery
What does the suprascapular artery supply?
Muscles on posterior aspect of scapula
Where does the costocervical trunk originate from?
Usually the 2nd part of subclavian artery
How does the costocervical trunk run?
Passes posteriorly, over cervical pleura, toward neck of 1st rib, where it divides into supreme (superior) intercostal and deep cervical arteries
Supreme (superior) intercoastal atery
- from costocervical trunk
- descends in front of neck and 1st and 2nd ribs
- gives off posterior intercostal arteries of upper 2 intercostal spaces
Deep cervical artery
- comes from costocervical trunk
- passes, posteriorly, between transverse processes of C7 and neck of 1st rib, ascends between semispinalis capitis and emispinalis cervicis muscles, then ends by anastomising with a branch of occipital artery
What does the deep cervical artery supply?
Deep muscles of the back of the neck
Where does dorsal scapular artery originate from?
May originate from transverse cervical artery or directly from subclavian artery (usually 3rd part)
How does the dorsal scapular artery run?
- runs through brachial plexus
- passes deep to levator scapulae to reach superior angle of scapula
- descends along medial border of scapula, deep to rhomboid muscles, with dorsal scapular nerve
What does the dorsal scapular artery supply?
Neighboring muscles and anastomoses with branches of suprascapular artery (branch of thyrocervical trunk) and subscapular artery (branch of axillary artery)
Where does the subclavian vein originate from?
Begins at lateral border of 1st rib, as a continuation of axillary vein
How does the subclavian vein run?
Passes over 1st rib, anterior and slightly inferior to subclavian artery (separated from it by scalenus anterior muscle)
Where does the subclavian vein end?
Ends posterior to sternoclavicular joint by joining internal jugular vein to form brachiocephalic vein
What is the only constant tributary of the subclavian vein?
External jugular vein
What kind of fibers do the Vagus Nerve contain?
Motor and sensory fibers
-also parasympathetic
What is the route of the vagus nerve?
Descends in neck within carotid sheath, first between internal jugular vein and internal carotid artery, and more inferiorly between internal jugular vein and common carotid artery
What are the two sensory ganglion that the vagus nerve contain?
- superior ganglion
- inferior ganglion
Superior ganglion
- sensory ganglion on the vagus nerve
- small, lies on vagus nerve within jugular foramen
Inferior ganglion
- sensory ganglion on vagus nerve
- larger, lies on vagus nerve just inferior to jugular foramen
Vagus nerve branches within jugular foramen
- meningeal branch
- auricular branch
Meningeal branch of vagus nerve
- within jugular foramen
- supplies dura mater of posterior cranial fossa
Auricular branch of the vagus nerve
- within jugular foramen
- runs within temporal bone and contributes to supply auricle, external acoustic meatus, and tympanic membrane
Vagus nerve branches of the neck
- pharyngeal branch
- superficial laryngeal nerve
- cardiac branches
- right recurrent laryngeal nerve
Pharyngeal branch of vagus nerve
- in neck
- supplies motor innervation to most muscles of pharynx and soft palate
- joins pharyngeal branches of glossopharyngeal nerve and superior cervical ganglion of sympathetic trunk to form pharyngeal plexus
Superior laryngeal nerve
- neck branch of vagus nerve
- divides into internal and external laryngeal nerves
Internal laryngeal nerve
- branch of superior laryngeal nerve, which is a neck branch of vagus nerve
- sensory
- pierces thyrohyoid membrane with superior laryngeal vessels
- supplies sensory innervation to mucosa of laryngopharynx, larynx, and small area on posterior part of tongue
External laryngeal nerve
- branch of superior laryngeal nerve which is a neck branch of the vagus nerve
- motor
- supples cricothyroid muscle, and part of inferior pharyngeal constrictor muscle
Cardiac branch of vagus nerve
- branch in neck
- end in cardiac plexus in thorax
- comes off up high
Right recurrent laryngeal nerve
- branch of vagus nerve in neck
- curves around inferior aspect of right subclavian artery, close to its origin
- ascends to larynx in groove between trachea and esophagus, on right side
What kind of fibers does the accessory nerve have?
Motor fibers, spinal root
Where does accessory nerve originate?
C1 to C5 segment of spinal cord
How does the accessory nerve ascend?
Ascends in vertebral canal, posterior to denticulate ligament
How does the accessory nerve enter cranial fossa
Through foramen magnum
What happens after accessory nerve enters the cranial fossa
After a short course, it exits posterior cranial fossa through jugular foramen, descends obliquely, lateral or medial, to internal jugular vein
WHat does the accessory nerve supply?
Enters deep surface of sternocleidomastoid and supplies it
What is the course of the accessory nerve after it enters the sternocleidomastoid muscle?
Emerges above midpoint of posterior border of sternocleidomastoid, crosses posterior triangle of neck (on levator scapulae) and disappears under anterior border of trapezius to supply it
What kind of fibers does hypoglosssal nerve have?
Motor fibers that supply the tongue
Where does the hypoglossal nerve originate?
From medulla oblong at a and exits skull via the hypoglossal canal
What is the course of the hypoglossal nerve?
- descends between internal carotid artery and internal jugular vein to approximately level of angle of mandible
- curves around accipital artery and turns forward
- passes superficial to external carotid artery, origin of lingual arter, and hypoglossus muscle, and it passes deep to posterior belly of digastric, stylohyoid, and mylohyoid muscles
What is the hypoglossal nerve joined by?
Opposite atlas, it is joined by fibers from ventral rami of C1 and C2 spinal nerves
What supplies the motor innervation to infrahyoid muscles and geniohyoid, and sensory innervation to dura mater of posterior cranial fossa?
Hypoglossal nerves joined by fibers from ventral rami of C1 and C2 spinal nerves
What are the branches of the hypoglossal nerve branches?
- meningeal branch
- upper root of ansa cervicalis
- nerves to thyroid and geniohyloid
- terminal branches
Meningeal branch of hypoglossal nerve
- not a “true” branch
- arises from hypoglossal nerve within hypoglossal canal
- supplies dura mater of posterior cranial fossa
- contains sensory fibers from C1 and C2 spinal nerves
Upper root of ansa cervicalis
- not a true branch of hypoglossal nerve
- consists of C1 motor fibers
Nerves to thyroid and geniohyoid
- not true branches of hypoglossal nerve
- consist of C1 motor fibers
Terminal branches of hypoglossal nerve
- only branches that contain true hypoglossal fibers
- supply intrinsic and extrinsic muscles of tongue
What is the upward continuation of the thoracic trunk?
Cervical part of the sympathetic trunk
How does the cervical part of the sympathetic trunk lie?
Posterior to carotid sheath and anterior or prevertebral muscles
Fibers of cervical part of the sympathetic trunk
- receives no white communicating rami (above T1-L2)
- preganglionic fibers for cervical symp ganglio orginiate from upper thoracic segments of spinal cord
- leave spinal cord at T1 to T4 spinal nerves
- enter upper thoracic symp trunk to reach cervical ganglia
What interconnected ganglia do the cervical part of symp trunk consist of?
- superior, middle, and inferior cervical ganglia
- sometimes a 4th (vertebral) ganglion is present on anterior aspect of vertebral artery, close to its origin
All branches that originate from the interconnected ganglia of the cervical part of the symp trunk contain what?
Postganglionic sympathetic fibers
No splanchnic
What is the largest cervical ganglion?
Superior cervical ganglion
Branches of the superior services ganglion
- internal carotid nerve
- external carotid nerves
- gray communicating rami to spinal nerves C1 to C4
- pharyngeal branches
- superior cervical cardiac nerve
Internal carotid nerve
- branch of the superior cervical ganglion
- upward continuation of superior cervical ganglion
- divides into branches that form the plexus around internal carotid artery and its branches
External carotid nerves
- branch of superior cervical ganglion
- join external carotid artery
- form plexus around external carotid artery and its branches
Pharyngeal branches (nerves)
- branches of superior cervical ganglion
- join pharyngeal branches of glosspharyngeal and vagus nerves to form pharyngeal plexus
Superior cervical cardiac nerve
- branch od superior cervical ganglion
- ends in cardiac plexus
What is the smallest and most variable of cervical ganglia?
Middle cervical ganglion
Where does the middle cervical ganglion lie?
Commonly lie at level of cricoid cartilage, close to arch of inferior thyroid artery
Branches of the middle cervical ganglion
- gray communicating rami for spinal nerves C5 and C6
- middle cervical cardiac plexus (ends in cardiac plexus)
- thyroid branches (follow inferior thyroid artery to thyroid gland)
What does the inferior cervical ganglion commonly fuse with?
The first thoracic ganglion to form cervicalthoracis (Stella the) ganglion
Where does the inferior cervical ganglion lie?
Between transverse process of C7 vertebra and neck of 1st rib, posterior to 1st part of vertebral artery
Branches of the inferior cervical ganglion
- gray communicating rami to spinal nerves C7 an C8
- branches that accompany vertebral and subclavian arerteis
- inferior cervical cardiac nerve (ends in cardiac plexus)
- ansa subclavia
Ansa subclavian
- branch of inferior cervical ganglion
- thin nerve bundle connecting middle and inferior cervical ganglia that loops around subclavian artery
What is the cervical plexus formed by?
Ventral rami of C1 to C4 spinal nerves
How are C1 to C4 ventral rami connected?
By nerve loops located anterior to origin as of levator scapulae and scalenus medius, and deep to sternocleidomastoid
Branches of the cervical plexus
- cutaneous branches: lesser occipital, great auricular, transverse cervical, and supraclavicular nerves
- ansa cervicalis
- phrenic nerve (C3 to C5)
- muscular branches
Phrenic nerve (C3 to C5)
- branch of cervical plexus
- descends anterior to scalenus anterior muscle
- at root of neck passes anterior to 1st part of subclavian artery
- descends through superior and middle parts of mediastinum to reach diaphragm
Muscular branches of cervical plexus
-supply anterior vertebral muscles, scalenus medius, levator scapulae, trapezius (proprioceptive), and sternocleidomastoid (proprioceptive)
Thyroid gland
Endocrine gland
- secretes thyroxine (T4) and triiodothyronine (T3), which stimulate metabolic rate
- secretes calcitonin, which lowers blood calcium levels
Where does the thyroid gland originate from?
The endoderm of floor of pharynx ( in region where tongue develops)
Development of thyroid gland
- migrates inferiorly to assume its final position in neck
- its point of origin is indicated on dorsal surface of tongue by foramen cecum
- during its migration, thyroid gland remains connected to tongue by narrow canal, thyrogloassal duct (later disappears)
Thyroglossal cysts
- cysts caused by persistence of a segment of thyroglossal duct
- located in anterior midline of neck, usually close to hyoid bone
What are the lobes of the thyroid?
- two lobes (right and left)
- isthmus
- pyramidal lobe (not always present)
Thyroid lobes
- roughly pear shaped
- apex directed upward (reaches oblique line of thyroid cartilage)
- base directed downward (reaches 4th or 5th tracheal cartilages)
Isthmus of thyroid gland
Extends across midline anterior to 2nd and 3rd tracheal cartilages
Pyramidal lobe of thyroid
- projects upward from isthmus (not always there)
- represents distal part of thyroglossal duct that does not disappear
Anterolateral relation of thyroid lobes
Sternothyroid (covers gland directly), sternohyoid, anterior border of sternocleidomastoid
Posterolateral relation of the thyroid lobes
Carotid sheath with its contents
Medial relation of the thyroid lobes
Larynx, trachea, pharynx, esophagus, external laryngeal nerve, recurrent laryngeal nerve
Posterior relation to the thyroid lobes
Parathyroid glands
Anterior relation to isthmus
Sternothyroid, sternohyoid, anterior jugular vein (strap muscles)
Posterior relation to the isthmus
2nd and 3rd tracheal cartilages
Arteries of the thyroid gland
- superior thyroid artery (1st anterior branch od external carotid artery)
- inferior thyroid artery (branch of thyrocervical trunk [from 1st part of subclavian artery])
- thyroid ima (lowest) artery
Thyroid (lowest) ima artery
- present in 10% of people
- usually originates from brachiocephalic trunk or aortic arch
- ascends on anterior surface of trachea to reach isthmus of thyroid gland
- possible present of this artery must be considered when performing procedures in midline of neck, inferior to isthmus
Veins of the thyroid gland
- superior and middle thyroid veins
- inferior thyroid vein
Superior and middle thyroid veins
Drain into internal jugular vein
Inferior thyroid vein
- descends anterior to trachea and posterior to manubrium if sternum
- drains into corresponding brachiocephalic vein (sometimes right and left inferior thyroid veins join to form a single trunk, which drains into left brachiocephalic vein)
Number of parathyroid glands
-usually 4 in number (two superior and two inferior)
What are the parathyroid glands?
Flattened, oval bodies located on posterior aspect of lobes of thyroid gland, under its fascia sheath
Superior parathyroid glands
Lie approximately at level of lower border of cricoid cartilage (pretty consistent)
Inferior parathyroid glands
Lie near inferior pole of lobes of thyroid gland
- less consistent in position
- sometimes found below level of thyroid gland, even in superior mediastinum, close to thymus
What does the parathyroidgland secrete
Parathormone
-increases blood calcium levels
Removal of parathyroid gland
Cannot remove all 4 or calcium levels will go crazy
Arterial supply to parathyroid gland
Superior and inferior thyroid arteries
Veins of parathyroid gland
Parathyroid veins drain into thyroid venous plexus
