Anterior Triangle Flashcards
What forms the anterior boundaries of the neck?
The inferior border of the mandible to the superior border of the sternum
What are the posterior boundaries of the neck?
The superior nuchal line (occipital bone) to the C7/T1 vertebral disk.
The “danger space” is formed by what two fascial layers?
The buccopharyngeal fascia and pre vertebral fascia.
The “danger space” connects what two areas of the body?
The base of the skull and the posterior mediastinum.
What muscle is contained within the superficial fascia of the neck?
Platysma
The investing layer of deep cervical fascia encloses what muscles?
Sternocleidomastoid and trapezius
What deep fascial layer of the neck encloses the infrahyoid muscles?
The Infrahyoid (muscular) fascia
What is contained within the carotid sheath?
Carotid artery
Internal jugular vein
Vagus Nerve (CNX)
The pretrachial layer of deep neck fascia encloses what structures?
Trachea
Esophagus
Thyroid
The posterior portion of the pretrachial fascia is called….?
Buccopharyngeal (back of pharynx)
The retropharyngeal space is located between what two fascial layers, and is also called what?
The buccopharyngeal fascial layer and the pre vertebral fascia.
Also called the danger space.
The vertebral column and associated musculature are enclosed by what fascial layer?
Prevertebral fascia
What nerve innervates the Platysma muscle?
Facial- CN XII
The Accessory Nerve (CN XI) innervates what two muscles of the neck?
The sternocleidomastoid and the trapezius
note: trapezius also innervated by C3-C4 ventral rami, but SCM exclusively innervated by CN XI
What nerve runs deep to, the pierces the sternocleidomastoid muscle?
CN XI - Accessory Nerve (external branch)
At what vertebral level is the HYOID bone located?
C3
Name the origin and insertion of the sternocleidomastoid.
O- Maubrium of sternum and medial 1/3 of clavicle
Ins- Lateral aspect of mastoid process of Temporal Bone
Name the actions of the sternocleidomastoid muscle.
1- Rotates head OPPOSITE of the contracted side
2- Laterally flexes the neck TO the contracted side
3- Bilaterally flexes the neck
What is the origin of the anterior belly of the digastric muscle?
Posterior?
Anterior- Digastric Fossa inside the Mandible bone (CHIN)
Posterior- Mastoid notch of the Mastoid process of the Temporal Bone (on the medial side)
What is the common attachment of the bellies of the Digastric Muscle?
Tendon attached to the Hyoid Bone
What nerve innervates each belly of the Digastric Muscle?
Ant - Mylohyoid N from V3
Post- Facial Nerve (CN VII)
Name the actions of the individual bellies of the digastric muscle.
Ant- Moves hyoid superiorly, opens mouth by lowering mandible
Post- Pulls Hyoid superiorly and backwards.
What is the boundary between the anterior and posterior cervical triangles?
SCM Muscle
What are the boundaries of the Anterior Cervical Triangle?
Inf. Margin of Mandible
Median vertical line of the neck
Anterior margin of the Sternocleidomastoid muscle
The Anterior Cervical Triangle is further subdivided into which 4 “mini” triangles?
Submental (under chin)
Submandibular (submand. gland)
Carotid (sheath)
Muscular (infrahyoids)
Name the boundaries of the Posterior Cervical Triangle?
Posterior Margin of SCM
Trapezius
Clavicle
The Hyoid bone is located at vertebral level C3, just superior to what?
The Larynx
When they hyoid bone is fractured, what do most people die of? WHy?
Asphyxiation. Punctured larynx.
In hanging, the hyoid bone is displaced….
Outwards (due to increase in divergence of the arch)
In manual strangulation, the fractured hyoid bone is displaced….
Inwards (due to compressive force of fingers)
Name the 4 infra hyoid muscles.
Omohyoid
Sternohyoid
Sternothyroid
Thyrohyoid
Name the origin, insertion, innervation, and action of the omohyoid muscle.
O- Medial margin of the Suprascapular Notch
Ins- Hyoid bone
Inn- C1-C3 via Ansa Cervicalis
Act- Fixes and Depresses Hyoid
Origin, Insertion, innervation, and action of the sternohyoid muscle.
O- Manubrium of the sternum
Ins- Hyoid bone
Inn- C1-C3 via Ansa Cervicalis
Act- Depresses Hyoid
Origin, Insertion, innervation, and action of the Sternothyroid muscle.
O- Manubrium of the Sternum
Ins- Oblique line of Thyroid Cartilage
Inn- C1-C3 via Ansa Cervicalis
Act- Depresses Hyoid, DEPRESSES LARYNX
Origin, Insertion, innervation, and action of the Thyrohoid muscle.
O- Oblique line of Thyroid Cartilage
Ins- Hyoid Bone
Inn- C1 branch traveling with Hypoglossal nerve (CN XII)
Act- Depresses Hyoid, RAISES LARYNX.
The two bellies of the omohyoid muscle are joined by….? Which anchors the omohyoid muscle to…?
The intermediate tendon of the omohyoid- attached to the medial end of the clavicle.
(gives the muscle a sling-like function)
Name the 2 terminal branches of the External Carotid Artery.
Maxillary and Superficial Temporal Ateries
What is the first branch off the External Carotid?
Superior Thyroid Artery
What branch of the External Carotid supplies the meninges of the brain? What is that branch called?
Maxillary artery gives off the Middle meningeal artery
The internal jugular vein is formed by…..
Cranial sinuses
The EXTERNAL jugular vein is formed by….
The Posterior Auricular Artery and the Retromandibular artery.
Where does the External Jugular vein terminate?
Runs superficially to the SCM muscle to terminate in the subclavian vein.
Where does the Anterior Jugular Vein (variable origin) terminate?
In the External Jugular Vein.
What is the general origin of the Anterior jugular vein?
Submandibular veins.
What 3 structures run in the carotid sheath?
Internal Jugular Vein
Internal Carotid Artery
Vagus Nerve
What structure is most lateral in the Carotid Sheath?
Internal Jugular Vein
What structure is most posterior in the Carotid Sheath?
Vagus Nerve
Name the spinal segments of the Lesser Occipital Nerve.
C2
Spinal segments of the Transverse Cervical Nerve.
C2-C3
Spinal Segments of the Greater Auricular Nerve
C2-C3
Spinal segments of the supraclavicular nerve.
C3-C4
Name all of the branches of the Cervival Plexus (Ventral Rami)
Lesser Occipital
Greater Auricular
Transverse Cervical
Supraclavicular
What are the spinal segments that contribute to the INFERIOR ROOT of the Ansa Cervicalis?
C2-C3 ventral rami
What spinal cord segments contribute to the SUPERIOR ROOT of the Ansa Cervicalis
C1 Ventral Ramus
What nerve supplies motor innervation to 3/4 infrahyoid muscles? What is the muscle left out?
The SUPERIOR ROOT of the Ansa Cervicalis (C1) innervates all the infra hyoid muscles except the THYROHYOID.
(Thyrohyoid is innervated by C1 traveling with the Hypoglossal Nerve)
The inferior belly of the Omohyoid muscle is innervated by what nerve?
The INFERIOR ROOT of the Ansa Cervicalis.
WTF is the carotid sinus?
A dilation at the bifurcation of the internal and external carotid arteries containing baroreceptors (monitoring blood pressure)
What nerve innervates the carotid sinus?
Glossopharyngeal (CN IX)
WTF is the carotid body?
An accumulation of chemoreceptors at the bifurcation of the internal and external carotid arteries. (detects changes in blood chemistry, esp O2 content)
What nerveS innervate the carotid body?
Glossopharyngeal and Vagus (CN IX and CN X)
What type of nerve fibers innervate the carotid body and sinus?
GVA- they are both sensory areas for BP and blood chemistry sending afferent information.
Name the boundaries of the muscular triangle. (within the Anterior Cervical Triangle)
Hyoid Bone
Superior belly of Omohyoid muscle
Anterior border of SCM muscle
Midline of the Neck
The arterial supply to the infra hyoid muscles comes from which 3 arteries?
Superior Thyroid, Inferior Thyroid, and Internal Thoracic
What else is located within the muscular triangle (other than muscles)?
Thyroid/Parathyroid glands.
The sole function of the Parathyroid glands is….
control of calcium levels in the blood
What 2 nerves are superficial to the carotid sheath?
The Ansa Cervicalis and the Hypoglossal Nerve (CN XII)
What lies posterior to the Carotid sheath?
The sympathetic trunk
