The Neck Flashcards
Surface anatomy of the neck?
Hyoid bone (C3)
Thyroid cartilage (C4,5)
Cricoid cartilage (C6)
tracheal rings
What divides the triangles of the neck
Sternocleidomastoid muscle (anterior and posterior triangles)
What is unique about SCM? What is N and A?
Sternocleidomastoid: two heads (sternal and clavicular)
N: accessory (CN XI) and VR of C2,3
A: flex head and cervical column; one muscle alone tilts head towards shoulder and rotates face up
boundaries of the posterior triangle; subtriangles?
SCM, trapezius, clavicle
occipital triangle and subclavian triangle are divided by inferior belly of omohyoid
muscles of the posterior triangle? what are they covered by?
- splenius capitus
- levator scapulae
3-5. scalenus posterior, medius, anterior
covered by prevetebral layer of deep fascia
What are the N and A of splenius capitus?
N: DR of cervical nerves
A: draw head backward; one muscle alone (with SCM) draws head to one side
What are the N and A of levator scapulae
N: dorsal scapular nerve (from brachial plexus; VR of C5) and VR of C3,4
A: elevate/retract scapula
What are the N and A of the scalenus muscles?
N: VR of cervical nerves (C4,5,6 specifically for anterior)
A: laterally flex and rotate the cervical column; elevate rib 2 (posterior) and rib 1 (medius and anterior)
What are the nerves in the posterior triangle? What do they innervate?
- accessory (CN XI): SCM and trapezius
- dorsal scapular: levator scapulae
- cutaneous branches of cervical plexus
- phrenic (C3,4,5)
- roots of brachial plexus
What is the course of CN XI through the posterior triangle?
- exits skull via jugular foramen
- runs down and lateral to superior border of SCM either pierces or runs deep to SCM, supplying it
- continues down and lateral to trapezius IN THE INVESTING FASCIA (so superficial), supplying it
Describe the origin and course of the dorsal scapular nerve
branch of brachial plexus from VR of C5
pierces scalenus medius (but does not supply it) and goes deep towards levator scapulae
What holds the phrenic nerve down?
subscapular and transverse cervical arteries (branches of the thyrocervical trunk of the subclavian artery) holds it down onto scalenus anterior
Where does the brachial plexus appear?
its roots appear between scalenus anterior and medius.
What are the cutaneous branches of the cervical plexus? and what skin do they supply
- lesser occipital (C2): neck, scalp behind ear
- great auricular (C2,3): ear, parotid gland skin, chin
- transverse cervical (C2,3): front neck
- supraclavicular (C3,4): sternal angle, rib 2, clavicle, scapula
What are the arteries in the posterior triangle?
- third part of subclavian artery
- thyrocervical trunk (from first part of subclavian) and its branches: transverse cervical, subscapular
Veins of the posterior triangle? describe their course
- external jugular (formed by posterior auricular and post. division of retromandibular vein); parallels great auricular nerve on top of SCM; pierces investing layer of deep fascia to go deeper and empty into subclavian
- subclavian vein (deep to SCM, superficial to anterior scalene and phrenic nerve)
Divisions of the Anterior triangle?
- submental
- digastric
- carotid
- muscular
What is in the submental triangle?
- lymph nodes (submental)
- anterior jugular vein
What is in the digastric triangle?
- submandibular gland
- lymph nodes (submandibular)
- facial artery and vein
- hypoglossal nerve (CN XII)
- mylohyoid nerve
What is in the carotid triangle?
- common carotid artery
- internal carotid arteries
- external carotid artery and branches of
- internal jugular vein
- vagues nerve (CN X) and laryngeal branches
- accessory nerve (CN XI)
- hypoglossal nerve (CN XII)
- ansa cervicalis
- lymph nodes (deep cervical)
What is in the muscular triangle?
- sternohyoid
- sternothyroid
- cricothyroid
- larynx and trachea
- thyroid and parathyroid glands
What lymph nodes are in which subtriangles of the anterior triangle?
submental in submental
submandibular in digastric
deep cervical in carotid
What are the suprahyoid muscles? What are their N’s? What is the general A?
- mylohyoid (Trigeminal)
- stylohyoid (facial)
- geniohyoid (VR of C1 via hypoglossal)
- digastric (ant head is trigeminal, post is facial)
A: elevate hyoid or depress mandible (except stylohyoid)
What are the infrahyoid muscles? What are their N’s? What is the general A?
- sternohyoid (strap: ansa cervicalis)
- sternothyroid (ansa c.)
- omohyoid (ansa c.)
- thyrohyoid (VR of C1 via hypoglossal)
A: depress the hyoid
Which muscles have counteracting actions on the larynx?
sternothyroid: draws larynx down
thyrohyoid: raises larynx up (when hyoid is fixed) –> high note singing
What are the fascia layers in the neck and what do they surround?
- investing fascia (important structures)
- pretracheal fascia (viscera)
- prevetebral fascia (vetebrae and muscles around them)
- carotid sheath (neurovascular)
What does the investing fascia split to enclose? What two structures does it create? What pierces it?
sternocleidomastoid and trapezius; parotid gland
- thickens to make stylomandibular ligament separates parotid and submandibular gland
- splits to make suprasternal space of burns contains jugular arch right above manubrium ext and ant jugular veins; cutaneous branche of cervical plexus
What does pretracheal fascia enclose? Trace it superficially to deep.
thyroid gland, trachea, larynx, esophagus, pharynx
strap muscles
—– fascia
thyroid gland
—– fascia
larynx and trachea espophagus and parynx
— buccopharyngeal fascia
— preveterbal fascia
What does the prevetebral fascia cover? What is unique about it?
prevetebral muscles, scalenus, deep muscles of neck (remember it forms the floor of the posterior triangle)
forms axillary sheath (subclavian artery and roots of brachial plexus)
splits into anterior (alar fascia) and posterior lamina at bottom
What are the two lamina of the prevetebral fascia? what spaces do they make?
—– esophagus
retropharyngeal/anterior space until T2
—– Anterior lamina (alar fascia)
danger/posterior space until T12
—– Posterior lamina
What forms the carotid sheath? What is in it?
investing, pretracheal and prevetebral fascias
- internal jugular vein
- common and internal carotid arteries
- vagus nerve
- deep cervical lymph nodes
- ansa cervicalis
Where is the sympathetic trunk in the neck?
BEHIND the carotid sheath IN FRONT OF the prevetebral fascia
How is the subclavian artery divided?
By scalenus anterior
part 1 (medial)
part 2 (behind)
part 3 (lateral)
becomes axillary artery at lateral border of rib1
Branches of subclavian and their branches?
- vetebral artery
- thyrocervical trunk (inferior thyroid, transverse cervical, suprascapular)
- internal thoracic
- costocervical trunk (supreme intercostal, deep cervical)
Where does the vetebral artery enter? What lies behind its origin?
transverse foramen of C6
stellate ganglion
Describe the course of the common carotid arteries.
R (brachiocephalic trunk) and L (aortic arch) common carotids arise at sternoclavicular joints
ascend up in the carotid sheath
common carotids divide into internal and external carotids at superior border of thyroid cartilage (C4,5)
What are the unique receptors of the carotid arteries?
Carotid sinus: Dilation of the carotid bifurcation and first part of the internal carotid; Baroreceptors
Carotid body: Small mass behind the bifurcation; Chemoreceptors CN IX (glossopharyngeal) and X (vagus)
Describe the course of the internal carotid in the neck
No branches ascends medially and enters carotid canal of skull
What are the branches of the external carotid artery? Which are terminal?
- superior thyroid
- lingual
- facial
- ascending pharyngeal
- occipital
- posterior auricular
- maxillary*
- superficial temporal*
What supplies the thyroid and larynx and what are the sources?
- superior thyroid (external carotid) which makes
a. anterior : anterior thyroid
b. posterior branches: posterior thyroid - inferior thyroid (thyrocervical trunk of subclavian): posterior thyroid and parathyroids
3 (maybe). thyroid ima artery (brachiocephalic trunk or arch of aorta, ascends on trachea)
Where and what are the thyroid glands?
Parathyroid glands?
Anterolateral to trachea/larynx, united by isthmus in front of trachea
attached posteriorly to cricoid cartilage and tracheal rings
parathyroids are deep to tyroid glands; have superior and inferior glands but vary in #
What drains the thyroids?
Superior, middle and inferior thyroid veins
Describe the laryngeal nerves involvement with various arteries.
- superior thyroid artery gives off superior laryngeal artery which runs with internal laryngeal nerve, peircing the thyrohyoid membrane
- superior thyroid artery continues on to run with external laryngeal nerve
- inferior thyroid arteru gives off inferior laryngeal artery which runs with recurrent laryngeal nerves
thus surgical lesioning of inferior thyroid artery may damage recurrent laryngeal nerves!
what forms the retromandibular vein and where?
what does it split to?
superficial temporal and maxillary veins in the parotid gland
splits to anterior (join facial vein to make common facial –> internal jugular) and posterior (join posterior auricular to make external jugular –> subclavian)
What forms the cervical plexus?
What kind of plexus is it?
ventral rami of C1-4
Somatic plexus
Describe what happens to the ventral rami of C1.
some fibers hitchhike on hypoglossal (CN XII) and either:
- exits hypoglossal as superior root of ansa cervicalis
- exit as nerve to the thyrohyoid muscle
- exit as nerve to the geniohyoid muscle
What innervates the strap muscles? how is it formed?
Strap muscles (omohyoid, sternohyoid, sternothyroid) are innervated by Ansa cervicalis
superior root is from VR of C1 fibers that hitchhiked on hypoglossal nerve (CN XII)
inferior root is from VR of C2,3
What are branches of the cervical plexus?
- cutaneous branches (lesser occipital, greater auricular, transverse cervical, supraclavicular)
- phrenic nerve
- ansa cervicalis
- other plexus branches (prevetebral, etc.)
