Neck and Submandibular Region Flashcards
Why is the laryngeal prominence (thyroid cartilage adam’s apple) a helpful landmark in terms of vasculature of the neck?
It’s at the level where the common carotic artery bifurcates into external and internal branches
What bone lies above the thyroid cartilage? WHat is it’s purpose?
the hyoid bone
It is a U-shaped bone consisting of a bocy an dposterolateral free portions - the greater cornua
it’s mostly for muscular and ligaentous attachments related to the naterior neck and tongue
How are the sternocleidomastoid muscles innervated?
Efferent innervation is from the accessory nerve
Afferent innervation is from C2, but the fibers run with the accessory nerve
Where does the sternocleidomastoid originate and insert?
originates on the sternum and medial end of the clavicle (by the jugular notch) and inserts into the mastoid process behind the ear
What two landmarks does the sternocleidomastoid divide the neck into?
the posterior and anterior triangles
What is the function of the sternodleidomastoids?
Individually, they draw the head toward the shoulder and rotate, pointing the chin cranially an dto the opposite side.
Together, they flex the neck
What is torticollis?
Can be congenital or spasmodic
It’s a contraction or shortening of the cervical muscles producing twisting of the neck and slanting of the head
typically the sternocleidomastoids - treatment may involve surgical release of the SCM
What muscle largely covers the SCM and inserts below the clavicle?
WHat is it’s function
the platysma - innervated by CN7
it depresses the lower jaw and lip
tenses and rdiges the skin of the neck
The deep cervical fascia is arranged in layers that cover the musculature and other structures of the neck. What are the 5 layers nad what do they cover?
- Investing Layer - covers ALL structures
- Infrahyoid layer - covers the strap muscles
- Visceral layer = pretracheal layer - surrounds the chief cervical viscera
- Prevertebral layer - surrounds the cervical vertebral column and associated musculature
- carotid sheath (formed by contributions from other layers) surrounds the neurovascular channel
Why is the retropharyngeal space important clinically?
It estends from the powerior mediastinum behind the heart up to the base of the skull.
Its an area of loose cnonective tissue that is a potential pathway for pathogenic organisms to track along vehind hte viscera of the neck
From what levels do the sensory branches of the cervical plexus come from?
the anterior primary rami of C2, C3, and C4
What are the 4 sensory nerves in the neck that come off the cervical plexus? Where do they emerge?
- supraclavicular nerves
- transverse cervical nerves
- great auricular nerve
- lesser occipital nerve
they come out from behind the mid-posterior border of the SCM
What are the two SUPERFICIAL veins of th enekc?
the external jugular
anterior jugular (runs along the anterior neck and empties into external jugular)
What happens in paralysis of the platysma muscle?
the skin will fall away from the neck in folds
Prominence of the external jugular vein on exam may suggest what chronic condition?
CHF
What happens if the external juglar vein is severed lateral to the SCM?
- it’s held open by the surrounding fascia
- negative intrathoracic pressure will suck air into the vein, causing a churning noise in the thorx and cyanosis = this is a venous air embolism
- This wille ventually fill the right side of the ehart with froth, nearly stopping blood flow thorugh it, resulting in dyspnea
this is why application of firm pressure to the severed jugular vein is very important
What are the contents of the carotid sheath?
- internal jugular vein
- common carotid artery
- vagus nerve
The internal jugular vein joins the subclavian vein to form what?
What lymphatic channel joins this region of ocnfluence?
the brachiocephalic veins
the thoracid duct is the lymphatic channel (the largest one in the body actually)
At the bifurcation of the common carotid into the internal and external carotids there is a slight dilation called the _____
what is it’s purpose?
the carotid sinus
it’s an arterial blood pressure regulating area (pressure receptor)
What other receptor is located near the carotid sinus and what is its function?
the carotid body
it’s a chemoreceptor that responds to either increased CO2 tension or decreased O2 tension in the blood
Both the carotid sinus and the carotid body are innervated by what nerve?
the glossopharyngeal nerve (with some minor contributionsf orm the vagus)
What are the major branches of the vagus nerve in the neck?
the superior laryngeal nerve (external and internal branches)
recurrent laryngeal nerve
What is another term for the infrahyoid muscles and what are they?
the strap muscles
- sternohyoid
- sternothyroid
- thyrohyoid
- omohyoid
How are the strap muscles innervated?
by the ansa cervicalis, formed by the anterior primary rami of C1-C3
Note that some of the C1 fibers joint CN12 and later leave i to supply the thyrohyoid and genioyoid
Where does the sternohyoid attach and what is its function?
hyoid bone to the manubrium of the sternum and medial end of clavicle
it depresses tte larynx and hyoid bone, steadies the hyoid
Where does the sternothyroid muscle attach and what is its function?
extends form the thyroid cartilage to the posterior surface of the manubrium of sternum
depresses the larynx and thyroid carilage
Where does the thyrohyoid muscle attach and what is its function?
extends from the hyoid bone to the oblique line of the thyroid cartilage
it depresses the larynx na dhyoid bone while elevating the thyroid cartilage
Where does the omohyoid muscle attach and what is its function?
extends from the inferior border of hyoid down to the superior border of the scapula near the suprascapular notch
it steadies the hyoid bone, depresses and retracts the hyoid bone an dlarynx
What is the suprahyoid muscle that extends from the inferior mental spins of the mandible down to the body of the hyoid bone?
the geniohyoid muscle
Which carotid artery gives branches to the face and which does not?
the external does, the internal doesn’t branch til it’s in the cranial cavity