Triangles Of The Neck Flashcards
What is the subcutaneous layer of the superficial fascia of the neck?
Thin CT lying between the dermis and investing layer of deep cervical fascia
What are the contents of the subcutaneous layer of superficial fascia of the neck?
Sensory nerves, blood and lymph vessels, superficial LNs, fat, and playsma muscle
Describe the playsma muscle
Muscle of facial expression
Innervation: facial nerve
What are some landmarks in the neck?
Vertebra prominens (C7) Hyoid bone Thyroid and cricoid cartilages (level of C6) Clavicle and sternum Mandible
Describe the hyoid bone
Body at C3-4 axial level
Suspended by muscles
Body plus greater and lesser horns
What is the retromandibular vein?
Junction of superficial temporal vein and maxillary vein (runs deep within parotid gland)
What is the external jugular vein?
Crosses over upper 2/3 SCM muscle
May even be absent
What is the anterior jugular vein?
Runs just off the midline to the root of the neck and connects with subclavian
The superficial veins of the neck overly what?
The surface of investing fascia
The superficial cutaneous nerves of the neck all originate from what?
The cervical plexus and emerge from posterior margin of mid-sternocleidomastoid muscle
What are the superficial cutaneous nerves of the neck?
Lesser occipital, transverse cervical, greater auricular and supraclavicular nerves
What is the lesser occipital nerve?
C2-3
Runs along border of SCM relaying scalp sensory information
What is the transverse cervical nerve?
C2-3
Supplies skin overlying anterior triangle of neck
Crosses SCM
What is the greater auricular nerve?
C2-3 anterior rami from cervical plexus
Runs with EJV on surface of SCM muscle
Supplies posterior auricle and area extending from mandibular angle to mastoid process
What is the supraclavicular nerve?
C3-4
Supplies root of neck in the area of clavicle, acromion and sternum
What is the nerve point of the neck?
Site of application of anesthetic (mid-SCM)
What is investing fascia?
Most superficial
Surround entire neck and encloses SCM and trapezius muscles and parotid and submandibular glands
What is the pretarcheal fascia?
Located in anterior of neck and blends with pericardium
Contains infrahyoid muscles and buccopharyngeal fascia
What is prevertebral fascia?
Encloses vertebral column and associated muscles
Extends laterally as axillary sheath into arm
What is the carotid sheath?
Fascia covering the carotids, IJV and vagus nerve
Runs along and then under the anterior border of SCM
IJV most lateral
Vagus nerve most posterior
What is the retrhopharyngeal space?
Posterior to pharynx and esophagus
Bounded by buccopharyngeal and prevertebral fascia and carotid sheath
Extends from base of skull to mediastinum
Permits movement of pharynx, larynx and esophagus during swallowing
Easy route for upper respiratory or oral infections to spread
What are the different fascia of the neck?
Investing fascia, pretracheal fascia, prevertebral fascia, carotid sheath, retropharyngeal space
What is torticollis?
Pathology of the SCM causing head to turn to side and the face to turn away from affected side
What is congenital torticollis?
Fibrous tissue tumor within SCM that develops in utero
Causes head to turn to side and the face to turn away from affected side - shortens SCM
What is muscular torticollis?
Occasionally SCM may be injured during difficult childbirth, tearing its fibers leading to hematoma that develops into fibrotic mass that entraps part of CN 11 effectively denervating it
Stiffness of neck then results from fibrosis and shortening of SCM
May require surgical detaching of SCM
Describe the innervation of the sternocleidomastoid
Innervated by spinal accessory nerve (CN 11) and with propiosensory information returning via C2-4
CN 11 exits via jugular foramen and lies posterior to the SCM
Then emerges about 1/3 does along posterior margins of SCM to cross the posterior triangle to innervate the trapezius
What is the cervical plexus?
From ventral rami of C1-4
Each divides into ascending and descending branches (except C1) that forms a loop with the next one
Loops like anterolateral to levator scapulae and middle scalene muscles
Forms cutaneous nerves of posterior triangle but also supplies adjacent prevertebral muscles, phrenic nerve and strap muscles (Ansa cervicalis)
What is the course of the phrenic nerve in the neck?
Runs anterior to the surface of the anterior scalene muscle
Descends obliquely with IJV deep to prevertebral fascia and posterior to suprascapular and transverse cervical artery off the thyrocervical trunk
Runs posterior to the subclavian vein but anterior to internal thoracic artery as it enters the thorax
What forms the phrenic nerve?
Roots of C3 and C4 of cervical plexus + ventral rami of C5
What occurs with severance of the phrenic or phrenic nerve block?
Paralysis of that side of the diaphragm
Describe the first part of the subclavian artery
Lies medial to anterior scalene and at apex of lung and cervical pleura
Branches include internal thoracic and vertebral arteries and thyrocervical trunk (inferior thyroid, transverse scapular, suprascapular)
Describe the second part of the subclavian artery
Behind anterior scalene gives off costocervical trunk (superior intercostal and deep cervical arteries)
Describe the third part of the subclavian artery
Lateral to the anterior scalene lying anterior to brachial plexus within the posterior triangle
In contact with the first rib
Dorsal scapular artery often off this segment
Compression of the subclavian artery against the rib can control what?
Bleeding in upper limb
What is the Ansa cervicalis?
Consists of anterior branches off ventral rami of cervical plexus forming a loop innervating infrahyoid muscles and geniohyoid muscles
Loops vary in length
Branches off the Ansa cervicalis supply which muscles?
Sternohyoid, sternothyroid, thyrohyoid and omohyoid muscles
Describe the superior part of the loop of Ansa cervicalis
Originates from C1 of the cervical plexus that soon joins hypoglossal nerve
Fibers run with hypoglossal nerve and then leave to descend in front of internal carotid arteries are superior limb/loop
This loop/limb gives off a nerve to thyrohyoid (C1) and geniohyoid muscle (c1)
Then swings down to meet the inferior limb giving off a branch to superior omohyoid belly
Describe the inferior part of the loop of Ansa cervicalis
Formed by branches of C2 and C3
Descends behind carotid sheath and then winds lateralward and emerges from behind carotid sheath to joint the superior limb
What is the carotid sheath?
Fascia covering surrounding IJV, carotid artery and vagus nerve
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What are the arteries of the anterior triangle?
Carotid sinus, internal carotid and external carotid
Describe the carotid sinus
Located at the site of bifurcation of common carotid
Contains chemoreceptors and baroreceptors for monitory O2 and BP levels
Does the internal carotid artery have any branches in the neck?
No
Describe the external carotid artery
Terminates by dividing into maxillary and superficial temporal arteries
Branches include ascending pharyngeal, superior thyroid, lingual, facial, occipital, and posterior auricular
Describe the thyroid gland
Lies deep to sternothyroid and sternohyoid muscles from levels C5-T1
Consists of two lobes that are anteriolateral to larynx and trachea
Has isthmus uniting lobes overlying trachea at 2nd/3rd tracheal rings
What are the unpaired laryngeal cartilages?
Thyroid (thyroid prominence and superior thyroid notch), epiglottis (elastic cartilage), cricoid (located at C6)
What are the paired laryngeal cartilages?
Arytenoid (vocal cords attached), comiculate and cuneiform
What are the ligaments/membranes of the laryngeal cartilages?
Vocal ligament (lies under vocal cord), thyrohyoid membrane and cricothyroid membrane
What are the vocal folds?
Contain elastic vocal ligaments running between the thyroid and arytenoid cartilages
Generates sound by vibrating air passing by
Force of air control the volume; tension of folds determines pitch
Describe the laryngeal innervation
Superior laryngeal nerve (internal/sensory and external/motor to cricothyroid muscle)
Inferior laryngeal nerve which is the terminal branch of recurrent laryngeal nerve and provides motor innervation to intrinsic laryngeal muscles
Describe the thyroid blood supply
Superior to thyroid from external carotid
Inferior thyroid from thyrocervical trunk
Parallel veins
May have thyroid ima artery—branch directly off brachiocephalic trunk to inferior thyroid gland
Describe the laryngeal blood supply
Superior laryngeal artery off superior thyroid artery
Inferior laryngeal artery off inferior thyroid artery
Injury to what nerve causes loss of vocalization?
Recurrent laryngeal nerve
Describe the cervical sympathetic chain
No white rami in neck (presynaptic fibers from superior thoracic spinal nerves)
Fibers pass to cervical spinal nerves via gray rami or leave as visceral branches (splanchnic) into thorax
Branches to head run via vascular plexus
What are the three cervical ganglia of the cervical sympathetic chain?
Superior ganglia, middle ganglia, and inferior ganglion
Describe the superior ganglia
Level C1/2
Post synaptic fibers form an internal carotid periarterial plexus that enters cranium
Also sends fibers to cervical plexus as well as cardiopulmonary branches
Describe the middle ganglia
May be absent
Lies over inferior thyroid artery at level of cricoid cartilage and transverse processes of C6
Distributed via periarterial plexes and cardiopulmonary splanchnic nerves
Describe the inferior ganglion
Lies anterior transverse process of C7 just superior to neck of 1st rib
Some post-ganglionic fibers enter the brachial plexus, run to heart (inferior cervical cardiac nerve)
Others go to periarterial plexus of vertebral artery
Describe the superficial cervical LNs
Located along EJV draining superficial tissues of neck
Describe the inferior deep cervical LNs
Drain lateral cervical area and run along path of CN XI
Describe the lymphatics of the neck
All drain into nodes and lymphatics running along IJV
Lymphatics join to form lymphatic trunks that then join to form lymphatic ducts that empty into subclavian vein near its junction with IJV
The prevertebral muscles are all posterior to what?
Retropharyngeal space and innervated by cervical plexus and/or brachial plexus
Describe the structures of the thyroid gland
Dense CT attaches it to cricoid cartilage and superior tracheal rings
Parathyroid glands lie on posterior aspect of thyroid gland in own capsule
What regulates tension in the vocal folds?
Intrinsic muscles innervated y the vagus nerve (CN X)
What are ventricular folds?
False cords
Brought together when holding your breath while straining
Do not contain vocal ligaments
What is dysphonia?
Disorder of the voice
Hoarseness-inflammation of the vocal cords
Laryngitis-inflammation of vocal cords where they no longer vibrate
