Anterior Triangle Flashcards
What are the boundaries of the posterior triangle?
bounded anteriorly by the posterior border of the sternocleidomastoid muscle, posteriorly by the anterior border of the trapezius muscles, and inferiorly by the middle third of the clavicle.
What are the four sub-triangles of the anterior triangle?
the submandibular, submental, carotid and muscular triangles.
What is the platysma innervated by?
the cervical branch of the facial nerve [VII]
What are the boundaries of the carotid triangle?
Anterior boundary- Superior belly of the Omohyoid.
Posterior Boundary- Anterior border of the sternocleidomastoid muscle.
Superior Boundary- Post. belly of the digastric
What is the floor of the carotid triangle composed of?
Thyrohyoid, Middle pharyngeal constrictor, Inferior pharyngeal constrictor
What are the contents of the carotid triangle?
Carotid Sheath with Carotid A., Internal Jugular V., Vagus Nerve, Ansa Cervicalis.
What are the boundaries of the muscular triangle?
Anterior boundary- Median plane of the neck.
Inferior Boundary- Anterior border of the sternocleidomastoid muscle.
Superior Boundary- Superior belly of the Omohyoid.
What is the floor of the muscular triangle composed of?
Thyroid and cricoid cartilages, Middle pharyngeal constrictor, Inferior pharyngeal constrictor.
What are the contents of the muscular triangle?
Neck viscera including thyroid and parathyroid glands; Infrahyoid muscles, terminations of Ansa Cervicalis, Superior thyroid artery, Sup. laryngeal artery, internal and external laryngeal NN., Recurrent laryngeal N.
What are the boundaries of the submental triangle?
Lateral Boundary- Right and LeZ anterior bellies of the Digastrics. Inferior Boundary- Body of the Hyoid. Apex- Symphysis men@.
What is the floor of the submental triangle composed of?
Both Mylohyoids.
What are the contents of the submental triangle?
Ant. Jugular V., lymph nodes.
What are the boundaries of the submandibular triangle?
Anterior Boundary- Ant. belly of the digastric. Posterior Boundary- Post. belly of the digastric. Superior Boundary-Inferior border of mandible.
What is the floor of the submandibular triangle composed of?
Floor- Mylohyoid, Hyoglossus, Middle pharyngeal constrictor
What are the contents of the submandibular triangle?
Contents- Submandibular Gland, Hypoglossal Nerve (CN XII), Nerve to the Mylohyoid, Facial Artery and Vein.
Where do the two heads of the SCM originate from?
one from the upper, anterior surface of the manubrium, the other from the superior medial third of the clavicle
Where do the heads of the SCM insert?
It inserts into the mastoid process and extends along the lateral half of the nuchal line
What is the SCM innervated by?
It is innervated by CN XI (Accessory Nerve) and by anterior rami of C2 and C3
Where does the posterior belly of the digastric m. originate?
The posterior belly arises from the mastoid notch on the medial side of the mastoid process of the temporal bone
Where does the anterior belly of the digastric m. originate?
digastric fossa
the tendon between the two bodies of the digastric m is attached to what?
attached to the body of the hyoid bone (and is the insertion of both)
What are the possible actions of the digastric muscle?
the muscle has multiple actions depending on which bone is fixed: when the mandible is fixed, the digastric muscle raises the hyoid bone; when the hyoid bone is fixed, the digastric muscle opens the mouth by lowering the mandible
What is the innervation to the posterior belly of the digastric m.?
facial nerve [VII]
What is the innervation to the anterior belly of the digastric m.?
the mandibular division [V3] of the trigeminal nerve [V]
What is the investing fascia of the neck attached to posteriorly?
the ligamentum nuchae and
the spinous process of the CVII vertebra
What muscles does the investing fascia split to encircle?
this fascial layer splits as it passes forward to enclose the trapezius muscle, reunites into a single layer as it forms the roof of the posterior triangle, splits again to surround the SCM muscle, and reunites again to join its twin from the other side
Anteriorly, what is the investing fascia anterior to?
the infrahyoid muscles
What are the attachments of the investing fascia?
The investing fascia is attached: superiorly to the external occipital protuberance and the superior nuchal line; laterally to the mastoid process and zygomatic arch; and inferiorly to the spine of the scapula, the acromion, the clavicle, and the manubrium of sternum
What veins pierce the investing fascia?
The external and anterior jugular veins, and the lesser occipital, great auricular, transverse cervical, and supraclavicular nerves, all branches of the cervical plexus, pierce the investing fascia.
What does the prevertebral fascia envelop?
the vertebral column and the muscles associated with it. Muscles in this group include the prevertebral muscles, the anterior, middle, and posterior scalene muscles, and the deep muscles of the back
What is the posterior attachment of the prevertebral fascia?
The prevertebral fascia is attached posteriorly along the length of the ligamentum nuchae, and superiorly forms a continuous circular line attaching to the base of the skull
What are the attachments of the prevertebral fascia?
This circle begins: anteriorly as the fascia attaches to the basilar part of the occipital bone, the area of the jugular foramen, and the carotid canal; continues laterally, aFaching to the mastoid process; and continues posteriorly along the superior nuchal line ending at the external occipital protuberance, where it associates with its partner from the opposite side.
Anteriorly, the prevertebral fascia is attached to the anterior surfaces of the transverse processes and bodies of vertebrae CI to CVII
What does the pretracheal layer of fascia surround?
surround the trachea, esophagus, and thyroid gland (begins anteriorly just posterior to the infra hyoid muscles)
Where does the pretracheal fascia span vertically?
begins superiorly at the hyoid bone and ends inferiorly in the upper thoracic cavity
Posteriorly, the pretracheal layer is referred to as what?
the buccopharyngeal fascia (separates the pharynx and the esophagus from the prevertebral layer)
The buccopharyngeal fascia begins superiorly at the base of the skull and ends inferiorly in the thoracic cavity.
What triangle are the infrahyoid muscles in?
the muscular triangle of the anterior triangle
the “strap muscles.”
What is the sternohyoid innervated by?
ventral rami C1-C3 through the ansa cervicalis
action: It depresses the hyoid bone
Where does the sternohyoid originate?
originating from the posterior aspect of the sternoclavicular joint and adjacent manubrium of the sternum
Where is the origin of the inferior belly of the omohyoid muscle?
the superior border of the scapula, medial to the supra scapular notch in the POSTERIOR TRIANGLE
Does the omohyoid attach to the hyoid bone medial or lateral to the sternohyoid?
just lateral
The intermediate tendon of the omohyoid is attached to what? By what?
the intermediate tendon is attached to the clavicle, near its medial end, by a fascial sling
What does the omohyoid do?
The omohyoid depresses and fixes the hyoid bone
What innervates the omohyoid?
the anterior rami of C1 to C3 through the ansa cervicalis
What is the thyrohyoid innervated by?
fibers from the anterior ramus of C1 that travel with the hypoglossal nerve [XII]
What does the thyrohyoid do?
Generally, it depresses the hyoid, but when the hyoid is fixed it raises the larynx (e.g., when high notes are sung)
Where does the sternothyroid run?
It arises from the posterior surface of the manubrium of sternum and passes upward to attach to the oblique line on the lamina of the thyroid cartilage
What does the sternothyroid do?
draws the larynx (thyroid cartilage) downward
What is the sternothyroid innervated by?
anterior rami of C2 to C3 through the ansa cervicalis
The cervical plexus is formed from what?
the anterior rami of cervical nerves C2 to C4, and possibly a contribution from the anterior ramus of cervical nerve C1
Where do the cutaneous nerves of the cervical plexus become subcutaneous?
about halfway down the SCM on the posterior margin
The lesser occipital nerve arises from what nerve root?
C2
The lesser occipital nerve distributes to what areas?
sensory to the skin of the neck and scalp posterior to the ear
emerges from the posterior side of the SCM
The great auricular nerve arises from what nerve roots?
C2 and C3
The great auricular nerve distributes to what areas?
sensory over the skin of the parotid region, the ear, and the mastoid area
The transverse cervical nerve arises from what nerve roots?
C2-C3
The transverse cervical nerve distributes to what areas?
sensory to the anterior triangle of the neck.
Arises from the posterior aspect of the SCM and wraps around anteriorly on top of the SCM to the anterior aspect of the neck
The supraclavicular nerve arises from what nerve roots?
C3 and C4
The supraclavicular nerve distributes to what areas?
sensory supply to the skin
over the clavicle and shoulder as far inferiorly as rib II.
What is the nerve point of the neck?
located on the posterior border of the sternocleidomastoid and is a place were four sets of nerves emerge.
the Lesser Occipital, Great Auricular, Transverse Cervical, and Supraclavicular nerves (medial, intermediate and lateral)
Where does the common carotid branch into the internal and external carotid arteries?
at the level of the hyoid bone
What are the branches of the internal carotid artery in the neck?
There are none. it is the main blood supply of the brain
What are the anterior branches of the external carotid artery?
Superior Thyroid, Lingual, and Facial AA
What are the posterior branches of the external carotid artery?
Occipital and Posterior Auricular AA
What are the medial/terminal branches of the external carotid artery?
Maxillary and Superficial Temporal AA
T or F. The superior thyroid artery branches from the external carotid deep to the infrahyoid muscles?
What does it supply?
T. Arises just inferior to the greater horn of the hyoid bone
the superior aspect of the thyroid gland, the larynx, and the infrahyoid muscles
Where does the inferior thyroid artery come from?
the thyrocervical trunk off the subclavian artery (just distal to the branching of the common carotid artery)
The lingual artery lies on what muscle?
middle pharyngeal constrictor muscle
What does the lingual artery pass deep to?
hypoglossal n. (CN XII), the stylohyoid muscle and the posterior belly of the digastric
What does the lingual artery supply?
the tongue
Where does the facial artery branch? Where does it go?
Arises either in common with the lingual a or just superior to it. It runs superficial to the bellies of the digastric and the stylohyoid m. and courses either superficial or in a groove of the submandibular gland to reach the side of the face around the edge of the mouth where it ascends to the lateral aspects of the nose
Where does the ascending pharyngeal artery branch from the external carotid?
just superior to the bifurcation of the common carotid. (variable!)- goes deep
What does the ascending pharyngeal artery supply?
It is distributed to pharynx, prevertebral muscles (middle pharyngeal constrictor), middle ear and meninges
Where does the occipital artery branch?
Arises off the posterior side of the Ext. Carotid Artery at the level of the Facial artery
Where does the occipital artery run?
Passes posteriorly along the inferior border of the posterior belly of the digastric. Is distributed to the scalp over the occiput. Has several branches
runs in the cleft behind the mastoid process
Where does the posterior auricular artery run?
Arises off the posterior side of the Ext. Carotid Artery at the level of the posterior belly of the digastric. Passes posteriorly along the superior border of the posterior belly of the digastric.
Ascends posterior to the external acoustic meatus to supply regions around parotid gland, temporal bone, the auricle and the scalp.
After giving off the maxillary artery, what does the external carotid artery become?
the superficial temporal artery
Where is the external jugular vein formed?
formed posterior to the angle of mandible as the posterior auricular vein and the retromandibular vein join:
What areas does the posterior auricular vein drain?
the scalp behind and above the ear
How is the retromandibular vein formed?
formed when the superficial temporal and maxillary veins join in the substance of
the parotid gland
How does the retromandibular vein run?
descends to the angle of mandible where it divides into an anterior and a posterior division the posterior division joins the posterior auricular vein to form the external jugular vein, the anterior division joins the facial vein, to form the common facial vein, which passes deep and becomes a tributary to the internal jugular vein.
How does the external jugular vein run?
Once formed, the external jugular vein passes straight down the neck in the superficial fascia and is superficial to the sternocleidomastoid muscle throughout its course, crossing it diagonally as it descends.
Reaching the lower part of the neck, just superior to the clavicle and immediately posterior to the sternocleidomastoid muscle, the external jugular vein pierces the inves@ng layer of cervical fascia, passes deep to the clavicle, and enters the subclavian vein.
What are the tributaries received by the external jugular vein during its course?
the posterior external jugular vein (draining superficial areas of the back of the neck) and the transverse cervical and suprascapular veins (draining the posterior scapular region).
The anterior jugular veins form from variable veins in the neck and drain into what?
the subclavian vein
How does the anterior and external jugular veins communicate?
via a connecting jugular venous arch in the area of the suprasternal notch
What does the carotid sheath contain?
the common carotid artery, the internal carotid artery, the internal jugular vein, and the vagus nerve
The carotid sheath is continuous inferiorly with what?
the connective tissue around the great vessels of the heart
Superiorly, the carotid sheath is said to terminate where?
at the level of the thyroid cartilage
What branches does the internal jugular vein receive?
It receives lingual, facial and superior and middle thyroid veins. It receives no branches below the middle of the thyroid
What muscle does the phrenic nerve descent on top of?
the anterior scalene
Does the carotid sheath lie deep or superficial to the omohyoid muscle?
deep
What is found immediately posterior to the carotid sheath and superficial to the prevertebral fascia?
Sympathetic Trunk and Ganglia
What are the three cervical chain ganglia and where are they found?
The inferior (or stellate) is at the level of C7. When it merges with the first thoracic ganglion it is called the cervicothoracic). The middle (when present) is at the level of C6. The Superior is the largest ganglion and is at the level of C1-C2
Where are the parathyroid glands found in relation to the thyroid?
posterior (there are typically four)
What muscle does the superior thyroid artery run on top of?
the thyrohyoid
What is the route of branching of the superior thyroid artery?
It descends, passing along the lateral margin of the thyrohyoid muscle, to reach the superior pole of the lateral lobe of the gland where it divides into anterior and posterior glandular branches: the anterior glandular branch passes along the superior border of the thyroid gland and anastomoses with its twin from the opposite side across the isthmus; the posterior glandular branch passes to the posterior side of the gland and may anastomose with the inferior thyroid artery
The inferior thyroid artery is a branch of what?
the thyrocervical trunk
What muscle does the inferior thyroid run on top of?
the anterior scalene (posteriorly to the carotid sheath)
What is the route of branching of the inferior thyroid artery?
At the thyroid gland the inferior thyroid artery divides into an: inferior branch, which supplies the lower part of the thyroid gland and anastomoses with the posterior branch of the superior thyroid artery; and an ascending branch, which supplies the parathyroid gland
What is the venous drainage of the thyroid gland?
Three veins drain the thyroid gland: the superior thyroid vein primarily drains the area supplied by the superior thyroid artery; the middle and inferior thyroid veins drain the rest of the thyroid gland
The superior and middle thyroid veins drain into the internal jugular vein, and the inferior thyroid veins empty into the right and left brachiocephalic veins, respectively
What is the lymph drainage of the thyroid gland?
Lymphatic drainage of the thyroid gland is to nodes beside the trachea (paratracheal nodes) and to deep cervical nodes inferior to the omohyoid muscle along the internal jugular vein.
What is the innervation to the carotid body and sinus?
Hering’s nerve, aka carotid sinus nerve, a branch of CN IX
What is the blood supply to the carotid body?
from external carotid through Mayer’s ligament
What are the two types of cells in the carotid body?
Chief cells (Type I): derived from neural crest, release ACh, ATP, dopamine in response to activation
• Sustentacular cells (Type II): supporting cells
Where is the carotid sinus located?
in the adventitia of the carotid bulb of the internal carotid artery
What does the carotid sinus do?
a baroreceptor that senses changes in systemic blood pressure
What does the carotid body do?
monitors the blood’s pH, pCO2, and pO2 and thereby modulates cardiovascular and respiratory function primarily through sympathetic tone
The function of the carotid body is complemented by other chemoreceptors, most notably the aortic body located in the aortic arch
