Lecture 2 = Anterior Cervical Triangle , Cervical Viscera, and Root of Neck Flashcards
What are the boundaries of the Anterior Cervical Triangle?
midline of neck: anterior
SCM: posterior
inferior border of mandible: superior
What are the muscles of the anterior triangle?
Are grouped by position relative to the hyoid bone (move this for swallowing - doesn’t articulate with another bone):
- suprahyoid mm. = located superior to hyoid bone,
elevates the hyoid bone
* stylohyoid m.
* digastric m. (anterior and posterior bellies w/ an
intermediate tendon)
* mylohyoid m.
* geniohyoid m.
- infrahyoid mm. = located inferior to hyoid bone,
depresses the hyoid bone (aka strap mm.)
*omohyoid m. (most lateral, has a superior and inferior
belly w/ an intermediate tendon)
* sternohyoid m. (between hyoid bone and sternoid)
* thryohyoid m. (between thyroid cartilage and hyoid
bone and is deep to sternohyoid m.)
* sternothyroid m. (deep to sternohyoid m.)
If supra hyoids are contracting, than the infra hyoids have to be relaxed to allow that action –> swallowing.
If both contract, than this will help open the jaw
What is the action and innervation of the stylohyoid m.?
Action: pulls hyoid bone upward (lifts the bone up) in posterosuperior direction
Inn: facial (CN VII) b/c this mm is part of arch # 2 of pharyngeal arch development
NOTE: stylohyoid m. and posterior belly of digastric mm are very close so CN VII comes outs between them
What is the action and innervation of the digastric mm?
Has anterior and posterior belly which is interconnected by an intermediate tendon which inserts on the hyoid bone.
Action:
-if mandible is fixed = contraction of this mm raises hyoid bone for swallowing
- if hyoid bone is fixed = contraction of this mm opens mouth by lowering the mandible
Inner:
- anterior belly = mylohyoid branch of mandibular division of trigeminal n (V3) which arises from the inferior alveolar n. –> arch # 1
- posterior belly = facial n (CN VII) –> arch # 2
NOTE: both originate from different arches so they have different innervations
What is the action and innervation of the mylohyoid mm?
Is found superior to anterior belly of digastric m.
A paired m. which forms floor of mouth
Action: supports and elevates floor of mouth and elevates hyoid bone
Inner: mylohyoid branch of mandibular division of trigeminal n. (V3) —> arch # 1
- this branch comes off of inferior alveolar before it goes into the mandibular canal
What is the action and innervation of the geniohyoid mm?
Is in the oral cavity - superior to mylohyoid m within floor or mouth
Action:
- if mandible is fixed = the contraction of this mm elevates and pulls hyoid forward
- if hyoid is fixed = the contraction of this mm pulls mandible downward and inward
Inn: by a branch from anterior ramus of C1 carried via hypoglossal n. (CN XII)
- innervated by C1 by hitching a ride from the hypoglossal n.
What is the action and innervation of the sternohyoid m?
Action: depresses hypoid bone after swallowing
Inn: anterior rami of C1-C3 via ansa cervicalis (motor compartment of cervical plexus)
What is the action and innervation of the Omohyoid m?
Action: depresses and fixes hyoid bone
Inn: anterior rami of C1-C3 via ansa cervicalis (motor compartment of cervical plexus)
Has a superior and inferior bellies connected via intermediate tendon
What is the action and innervation of the thyrohoid m?
Action: depresses hyoid and when the hyoid is fixed, raises larynx to get it out of the way for swallowing
Inn: fibers from anterior ramus of C1 carried via the hypoglossal n –> form the nerve to thyrohyoid m.
What is the action and innervation of the sternothyroid m?
Action: draws larynx (includes the thyroid cartilage) downward
Inn: anterior rami of C1-C3 via ansa cervicalis
What are the veins of the neck?
- facial v. - continues to drain down till IJV and joins partly with retromandibular v.
- retromandibular v - it bifurcates and posterior portion joins with posterior auricular
- anterior jugular v,
- communicating branch - between common facial and anterior jugular
- Internal jugular v.
- external jugular v.
What is the facial v.?
- originates at angle of eye
- receives tributaries from veins draining face
- drains into internal jugular v.
What’s the retromandibular v.?
- behind mandible
- it is formed by the joining of the superficial temporal v. and maxillary v.
- this vein has an anterior division and posterior division
- The anterior division + facial v. will form the common facial v. which will drain into the internal jugular v.
- the posterior division + posterior auricular v. will form the external jugular v.
What’s the anterior jugular v.?
- in midline of neck and drains to EJV
- drains anterior neck
What’s the communicating branch?
-connects facial v. and AJV
What’s the internal jugular v?
-drains brain, anterior face, and cervical viscera
What are the arteries of the anterior cervical triangle?
Common carotid a.: splits into an internal carotid a. and external carotid a. Bifurcates at C3-C$ vertebral level
- right common carotid a. - indirectly arises from the arch
of the aorta, arising the brachiocephalic trunk, which
splits into the right subclavian a. and the right common
carotid a.
- left common carotid a. - direct branch off arch of aorta
Internal carotid a. - it is important to note that the internal carotid a DOESN’T give off any branches until you get to the brain. There are NO branches off of the internal carotid a. outside of the brain and within the neck.
External carotid a. - immediately gives off branches after bifurcation of common carotid a. supplying of the neck and head. it is important to note that the internal carotid a DOESN’T give off any branches until you get to the brain. There are NO branches off of the internal carotid
What are the branches of the External Carotid Artery?
3 Anterior:
- superior thyroid a. - first branch to come off of external
carotid a.
- lingual a.
- facial a.
3 Posterior:
- ascending pharyngeal a.
- occipital a.
- posterior auricular a.
External carotid a. terminates as 2 arteries: superficial temporal a. and maxillary a.
What is the superior thyroid artery?
-first anterior branch to come off of external carotid a.
-it arises from the anterior surface of ECA, near the bifurcation
-as is passes downward towards the superior pole of the thyroid gland, it gives off the superior laryngeal a. which originates near the upper margin of the thyroid cartilage.
It pieces the thyrohyzid membrane, located between the hyoid bone and thyroid cartilage. The internal branch of the superior laryngeal n. which arises from the vagus n. travels with the superior laryngeal a. and pierces the thyrohyzid membrane to pass into the larynx.
* superior laryngeal a. pierce thyrohyoid membrane together with internal branch of superior laryngeal n.
-the superior thyroid a. passes downward to supply the superior pole of the thyroid gland
What’s the lingual artery?
- is the second anterior branch from the external carotid a.
- arises just above superior thyroid a. at the level of greater horn of the hyoid bone
- it passes through the oropharyngeal (triangle) space to access the deep mm. of the tongue that it supplies
What’s the facial artery?
- it’s the third anterior branch of external carotid a.
- it arises just superior to the lingual a.
- it passes through the submandibular gland and crosses over the inferior border of the mandible to supply the majority of the face.
What’s the ascending pharyngeal artery?
- it’s the first posterior branch of external carotid a.
- arises close to the bifurcation of the common carotid a. into the ECA and ICA
- it ascends superiorly to supply the pharynx and tonsils.
