Neck Flashcards
Describe the thyroid gland , an example of an endocrine gland
- 4 parathyroid glands sit on the thyroid, they are crucial for maintaining CALCIUM levels in the blood stream, allowing for normal neuromuscular function
- recurrent laryngeal nerves run behind the thyroid and innervates muscles that move the vocal chords, open and close them (you can’t speak loudly if these are severed)
- sits on the trachea and located just below the inferior border of thyroid cartilage
- the thyroid regulates metabolism, hyperthyroidism can lead to an enlarged thyroid which is called Goiter and needs surgery
- endocrine glands are ductless and secrete their products directly into the blood stream so they are highly vascularized, 4 vessels go into the thyroid gland
What are these neck procedures:
- Cricothyrotomy
- Tracheostomy - incise the trachea (when there is blockage in the trachea)
- Cricothyrotomy: - make an incision in the cricothyroid membrane > emergency airway
* we choose there because we don’t want to damage the thyroid and its emergency because we might damage the voicebox. - Tracheostomy - incise the trachea (tracheotomy) to make the hole (a tracheostomy)
What is lymphatic drainage in the neck?
lymph in *Deep Cervical nodes
> travel through *Jugular Trunks
> enter *lymphatic ducts
> and empty into the vein (brachiocephalic vein)
Describe the sympathetic chain organizations in the neck.
*the sympathetic trunk runs in the retropharyngeal space (between prevertebral fascia and buccopharyngeal fascia)
The sympathetic ganglia all have gray communicans connecting to cervical nerves
-the ganglia coalesce in the cervical region
Superior Cervical Ganglia: C1-C4 #contains all the postganglionicc sympathetics going to the head
Middle Cervical Ganglia: C5-C6
Stellate Cervical Ganglia: C7,C8,T1
-all sympathetics do is innervate sweat glands
What is the path of sympathetic distribution to the head?
All parasympathetics do is produce saliva and tears
Preganglionic sympathetic cell bodies are in the *lateral horn of T1
> *exit ventral root > spinal nerve> ventral rami > white ramus communicans
> *preganglionic axons travel through the Stellate cervical ganglia
> *synapse on postganglionic body in the *Superior cervical ganglia
> then they travel in *Perivascular nerves and travel on arteries -mainly all they do is vasoconstriction.
Describe the skeletal elements of the anterior neck
All of these are not complete rings
- Hyoid bone (tip is at C3)
—-thyrohyoid membrane connecting the hyoid and thyroid cartilage—–
- Thyroid cartilage (superior border is at C4)
—-cricothyroid membrane connecting thyroid cartilage and cricoid cartilage —-
- Cricoid cartilage (C6)
What are the cervical spinal nerves and their organization ?
A. Dorsal rami - skin on the back and true back muscles
B. Ventral rami:
-cervical plexus (C1-C4)
-sensory nerves
: ansa cervicalis - motor innervation for infrahyoids
-phrenic nerve (C3-C5)
:lies anterior to the anterior scalene muscle
- brachial plexus (C5-C8)
- cervical plexus
Ansa Cervicalis - loopy structures, responsible for innervating the infrahyoid muscles, can be found on the internal jugular vein
Phrenic nerve - vertically running on the anterior scalene. Innervates the diaphragm, keeps you breathing
Brachial plexus - runs out between the anterior and middle scalenes
What is the relationship of hypoglossal nerve and accessory nerve to the carotids and internal jugular?
Vagus runs between both in the carotid sheath going vertically
Hypoglossal nerve runs between both, running lateral to the carotids and going into the floor of the mouth.
Describe the venous drainage in the head/neck
The external jugular vein = superficial head and neck
Internal jugular vein = deep head and neck
- Internal jugular drains the areas supplied by branches of the external carotid artery (facial vein, lingual vein, occipital vein), –is much thicker than external
- drains inside the skull
- external jugular is subcutaneuous (the vein popping in heavy lifters), travels from angle of the jaw and empties into the *Subclavian vein
- face neck
Internal jugular and subclavian veins meet and become known as *Brachiocephalic veins
Two brachiocephalic veins join and form the *Superior vena cava
What is carotid stenosis and two surgical treatments for it?
- atherosclerotic lesions accumulate at the bifurcation of the carotids aka *Carotid Stenosis
- this can lead to Ischemic strokes if a piece of plaque breaks up and as the vessels narrow blocks a cerebral artery, killing that region of the brain it supplies
- Carotid Endarterectomy -
they open up the common carotid and internal carotid arteries and then scrape out the plaque - Carotid Angioplasty - insert a catheter into the region with the stenosis, blow up a balloon to break up the debris and they have a protection device that captures the debris. Then insert a stent to capture to capture future debris
- useful for those who have their bifurcation of the carotids at C2, for those who can’t undergo anesthesia, or have their neck irradiated against cancer
What is the carotid body and sinus?
- Carotid body- at the bifurcation of the carotids contains chemoreceptors
- they send receptors into the bloodstream to sense *Oxygen and Co2 content - Carotid sinus - at the wall of the internal carotid artery, contains barroreceptors which perceives blood pressure of the blood going into the brain
- if pressure is too *high, it SLOWS down blood rate
- pressing on the carotid sinus would have the same effect
Describe the arterial supply of the subclavian artery
Subclavian artery runs through the posterior triangle and generally supplies deep neck and shoulder
Two branches:
- Thryocervical trunk
- Vertebral artery (travels through the transverse foramen of the cervical vertebrae and goes directly to the brain.
What is the retropharyngeal space?
It is the space between the buccopharyngeal fascia and the prevertebral fascia.
Its a potential space for infections/pus to access the thorax if it erodes through the pharynx.
Describe the axillary sheath and the carotid sheath
Carotid sheath -
- Internal jugular vein - anterolateral
- Common carotid artery - posteromedial
- Vagus nerve- running inbetween both and posterior
The carotid sheath is made up of three layers, prevetebral, pretracheal and investing layer
Axillary sheath contains the axillary artery and brachial plexus,
-the scalene interval is covered with prevetebral fascia but only the artery and nerves go through it which is why the vein is running anterior to the anterior scalene and to the members of the sheath
Describe the hyoid muscles which all attach to the hyoid bone
They depress, elevate or hold steady the hyoid bone.
2 classes
- Suprahyoid
- elevators of hyoid bone
- when you swallow, first motion elevates hyoid
- innervated by cranial nerves (branches of trigeminal or facial nerves) - Infrahyoid
- depressors of hyoid bone
- (most of their role can be taken over by gravity but sometimes you dpress the hyoid to make lower pitches
- innervated by ventrla rami of cervical spinal nerves
during development we have a single strip of muscle going from the chin to the pubic bone - hyoid is part of that and so is rectus abdominis.
