The Anterior Neck and Thyroid gland Flashcards
Why is the neck prone to injury?
it is slender to allow optimal positioning of head
spine is fexible
Where and what is the hyoid bone
- anteriorly in upper neck
inferior to mandible - helps keep pharynx open
provides attachment point for several neck muscles and tongue muscle
How many vertebrae in the neck? What kind?
7 cervical vertebrae
How are cervical vertebrae adapted for the neck?
Small
Articulate at facet joints, orientated obliquely
allows for good range of flexion and extension compared to thoracic spine
What is the larynx?What is its function?
Voice box
Small cartilages connected by membranes and small joints
Protects the airway
muscles attach to laryngeal cartilages and move them (to move vocal chords for phonation)
What are the triangles in the neck?
Anterior and posterior triangles, separated by the sternocleidomastoid muscle
Sternocleidomastoid muscle…
Where is it?
What can it do?
What innervates it?
- Attached to sternum, clavicle and mastoid
process - acts unilaterally or bilaterally
- accessory nerve (CN XI)
What are the boundaries of the anterior triangle?
Anteriorly- midline of neck
Posteriorly - anterior border of sternocleidomastoid
Superiorly - lower border of the mandible
What does the anterior triangle contain?
(11)
- trachea
- larynx
- thyroid gland, parathyroid glands
- submandibular salivary glands
- suprahyoid muscles
- infrahyoid muscles
- common carotid artery
- branches of external carotid atrery
- internal jugular vein
- branches of CN VII, IX, X, XI, XII
- ansa cervicalis
What do suprahyoid muscles do?
Connect hyoid to skull
form floor of mouth, move hyoid and larynx in speech and swallowing
What do infrahyoid muscles do?
Also ‘strap muscles’
connect hyoid to sternum and scapula
move hyoid and larynx in speech and swallowing
Which is CN VII
facial nerve
which is CN IX
glossopharyngeal nerve
which is CN X
vagus nerve
which is CN XI
accessory nerve
which is CN XII
hypoglossal nerve
What are the ansa cervicalis?
fibres from C1-C3 that innervate infrahyoid muscles
What are the boundaries of the posterior triangle?
Anteriorly- posterior border of sternocleidomastoid
Posteriorly - anterior border of trapezius
Inferiorly - the clavicle
What does the posterior triangle contain?(6)
- Muscles that move the head
- part of subclavian artery and vein
- external jugular vein
- accessory nerve CN XI
- roots of brachial plexus
- phrenic nerve
What does the external jugular vein do?
Drains the scalp and face of blood
What is the brachial plexus?
Spinal nerves that supply the upper limbs
Name the 4 paired suprahyoid muscles
Mylohyoid, geniohyoid, stylohyoid and digastric
Name the 4 paired infrahyoid muscles
Superficially - sternohyoid and omohyoid
Deep - sternothyroid and thyrohyoid
What do the 4 infrahyoid muscles attach to each other?
Sternohyoid - hyoid to sternum
Omohyoid - hyoid to scapula
Sternothyroid - sternum to thyroid cartilage
Thyrohyoid - thyroid cartilage to hyoid
Describe the position of the thyroid
Right and left lobes
lateral to the lower larynx and upper trachea
deep to the sternothyroid muscle
2 lobes joined by isthmus, anterior to trahcea
Function of thyroid? What regulates it?
Produces hormones for regulation of metabolic processes
Pituitary gland regulates its hormone secretion
What arteries supply the thyroid gland?
L/R superior thyroid arteries
(branched from external carotid)
L/R inferior thyroid arteries
(branched from thyrocervical trunks [branched from subclavian])
some have an additional thyroid ima artery
What drains the thyroid gland?
Superior, middle and inferior thyroid veins
What are the 4 parathyroid glands?
Right and left superior and inferior glands
Posterior to the thyroid gland
They produce parathyroid hormone - helps in calcium regulation
Typically supplied by inferior thyroid arteries
What vessels can be found in the neck?
Common carotid arteries bifurcate into…
Internal carotid artery
External carotid artery
Where it bifurcates, there is the carotid sinus (baroreceptors)
Thyrocervical trunk (branch of subclavian artery)
Gives rise to inferior thyroid artery
Internal jugular vein
Unites with subclavian vein to form brachiocephalic vein
L/R unite to superior vena cava
External jugular vein also join subclavian vein
Describe common carotid arteries in the neck
Ascend in the left and right ride of the neck
Bifurcates into internal and external carotid arteries
At bifurcation is the carotid sinus
What is the carotid sinus
At bifurcation of common carotid artery
Contains baroreceptors that monitor arterial blood pressure
Info relayed to CNS by glossopharyngeal nerve (CN IX)
Describe the internal carotid artery in the neck
Doesn’t give rise to branches in the neck
Enters cranium and supplies the brain
Describe the external carotid artery in the neck
Gives rise to several branches that supply the head and neck, inc pharynx, scalp, thyroid gland, tongue and face
What does the subclavian artery give rise to that is in the neck?
thyrocervical trunk, that gives rise to the inferior thyroid artery
Describe the veins in the neck
Internal jugular vein drains blood from the brain and part of the face
Unites with subclavian vein to form brachiocephalic vein
External jugular vein drains scalp and face, it joins subclavian vein
Left and right brachiocephalic veins join to form superior vena cava
Facial nerve no. and function
CN VII
supplies platysma in the neck
Glossopharyngeal nerve no. and function
CN IX
supplies pharynx (sensory innervation)
carotid sinus (visceral sensory fibres)
Vagus nerve no. and function
CN X
Supplies muscles of pharynx (motor innervation)
the larynx (motor and sensory)
Describe the position of the vagus nerve in the neck
Between internal jugular vein and internal carotid artery(above bifurcation)
Between internal jugular vein and common carotid artery(below bifurcation)
the three structures run together in a fascial sleeve called the carotid sheath
What is the carotid sheath?
Fascial sleeve containing vagus nerve, internal jugular vein, common carotid artery/internal carotid artery
Accessory nerve no. and function
CN XI
Supplies sternocleidomastoid and trapezius muscles
Hypoglossal nerve no. and function
CN XII
Supplies motor to muscles of the tongue
Doesn’t supply structures in the neck but runs through it.
Lateral to internal carotid artery, deep to the external jugular vein
Phrenic nerve description and function
Formed by C3 C4 C5 nerve fibres
Descends through the neck to enter the thorax
Innervates the diaphragm
Describe sympathetic nerves in the neck
Sympathetic trunk extends up to the base of the skull
Sympathetic ganglia in the neck are
Superior, middle, inferior cervical ganglia
Post ganglionic fibres from them innervate the head and neck
What is a thyroidectomy
Removal of the thyroid gland
Risks injury to recurrent laryngeal nerves - results in inability to move ipsilateral vocal chord, affects quality of voice
Risks removal of parathyroid glands, disturbing calcium homeostasis
After, hormone replacements must be taken
What is carotid artery stenosis
Atheroma (fatty plaque) narrows lumen of carotid artery, impeding blood flow to the brain.
If it breaks up, fragments can be carried into cerebral arteries, causing a stroke
Atheroma can be removed surgically from the wall in a carotid endarterectomy. Risk of severe bleeding and stroke.
How are penetrating injuries to the neck dangerous?
Vital neurovascular structures located close together in neck. One injury could affect multiple structures badly.
What is a central line insertion into the internal jugular vein
Very unwell patient needing fluid/drugs intravenously
Large line with multiple ports placed into a large central vein
IJV is relatively easy to access and ultrasound can be used to locate it
