Neck Triangles Flashcards
What is unique about the hyoid bone and where is it?
U-shaped bone located at C3 in anterior neck
does not articulate with any skeletal elements
What are the borders of the anterior triangle?
Bounded by inferior border of mandible, anterior border of SCM & midline of neck
What type of fascia is at the roof of the anterior triangle?
deep investing fascia around msucles
What type of fascia is at the floor of the anterior triangle?
pretracheal fascia and carotid carotid sheath (posterolaterally)
What are the subdivisions of the anterior triangle?
submandibular
submental
carotid
muscular triangles
What does the submandibular (digastric) triangle contain?
Contains submandibular gland, lymph nodes, (parts of) CN XII, mylohyoid nerve & parts of the facial artery & vein
What does the submental triangle contain?
Contains submental lymph nodes & some small veins
What does the carotid triangle contain?
Contains thyroid gland, larynx, pharynx, carotid sheath (& its contents), branches of cervical plexus, superior root of the ansa cervicalis, deep cervical lymph nodes & (parts of) CN XI & XII
What does the muscular (omotracheal) triangle contain?
Contains sternohyoid & sternothyroid muscles, thyroid & parathyroid glands
What are the contents of the carotid sheath?
medially, laterally, posteriorly
Medially
* Common carotid artery (CCA)
* Internal carotid artery (ICA)
* External carotid artery (ECA; part)
Laterally
* Internal jugular vein (IJV)
Posteriorly
* CN X
What does the common carotid artery bifurcate into?
internal
external carotid arteries
What are the anterior triangle muscles?
suprahyoid
infrahyoid
What are the suprahyoid muscles?
mylohoid
geniohyoid
diagastric
stylohyoid
What are the infrahyoid (strap) muscles?
omohyoid
sternohyoid
thyrohyoid
sternothyroid
What do suprahyoid muscles do?
raise the hyoid bone as required during swallowing
Where does the mylohyoid originate and where does it insert?
originates at mylohyoid line on mandible
inserts into body of hyoid & fibres of opposite mylohyoid
What are the actions of the mylohyoid?
Elevates the hyoid & forms the floor of the oral cavity
What is on top of the mylohyoid?
the geniohyoid
Where do both parts of digastric originate and insert?
muscle has anterior & posterior bellies;
anterior belly originates at digastric fossa on mandible
posterior belly originates at mastoid notch on temporal bone
both insert at attachment of their intermediate tendon at hyoid
What are the actions of the digastric?
Anterior belly elevates hyoid and depresses mandible;
posterior belly elevates & retracts hyoid bone
What is the mylohyoid innervated by?
CN V3 - inferior alveolar branch
What is the digastric innervated by?
- Anterior belly – nerve to mylohyoid
(CN V3) - Posterior belly – Digastric branch of
CN VII
What are origins/insertions of stylohyoid and what is it’s action?
originates at the styloid process & inserts into body of hyoid (laterally)
Action: Pulls hyoid bone upward (posterosuperior direction)
What is the innervation of the stylohyoid?
CN VII
What are the origins/insertions of the geniohyoid?
originates from the mandible (mental spine) & inserts at body of hyoid (located superior to mylohyoid; floor of oral cavity)
What are the actions of the geniohyoid?
Fixed mandible – elevates & pulls hyoid forward;
Fixed hyoid – pulls mandible downward & inward
What is the innervation of the geniohyoid?
anterior ramus of C1 (travels with CNXII)
What are the origins/insertions of the sternohyoid and what is it’s action?
originates at posterior surface of sternoclavicular joint & manubrium; inserts into body of hyoid medially
Action: Depresses hyoid after elevation during swallowing
What are the origins/insertions of the omohyoid and what is it’s action?
inferior/superior belly
Superior belly originates at its intermediate tendon & inserts into body of hyoid laterally
Inferior belly originates at superior border of scapula & inserts/ends at its intermediate tendon in posterior triangle
Actions: Depresses & fixes the hyoid
How does the intermediate tendon of the omohyoid attach to the clavicle?
via a fascial sling
What are the origins/insertions of the thyrohyoid and what is it’s action?
originates at oblique line on thyroid cartilage; inserts into greater horn & adjacent body of hyoid
Actions: Depresses the hyoid; can raise larynx when hyoid is fixed