Anterior Triangle Of the Neck Flashcards
Boundaries of the Anterior Triangle
Anteriorly: midline of neck
Posteriorly: anterior border of sternocleidomastoid
Superiorly: inferior border of body of mandible
Muscle groups of the Anterior Triangle
Infrahyoid muscles
Suprahyoid muscles
Anterior vertebral muscles
Infrahyoid muscles
Thin, strap-like muscles
4 types:
- Sternohyoid
- Sternothyroid
- Thyrohyoid
- Omohyoid
Sternohyoid
Location, Origin, Insertion, Nerve supply, and action
L: superficially, medial to superior belly of omohyoid
O: posterior surfaces of manubrium of sternum and sternal end of clavicle
I: body of hyoid
N: ansa cervicalis (C1-C3)
A: depresses hyoid bone
Sternothyroid
Location, Origin, Insertion, Nerve supply, and action
L: deep to sternohyoid
O: posterior surface of manubrium of sternum
I: oblique line of thyroid cartilage
N: ansa cervicalis (C1-C3)
A: depresses larynx
Thyrohyoid
Location, Origin, Insertion, Nerve supply, and action
L: Upward continuation of sternothyroid
O: oblique line of thyroid cartilage
I: runs superiorly over thyrohyoid membrane, inserts into greater horn and body of hyoid
N: C1 fibers via hypoglossal nerve
A: depresses hyoid bone or elevates larynx
Nerve loop that contains fibers from ventral rami of C1 to C3 spinal nerves
Ansa Cervicalis
Lower root of ansa cervicalis is…
A direct branch of cervical plexus
- contains fibers from ventral rami of C2 to C3
- passes superficial (or deep) to internal jugular vein
- joins upper root to form ansa
Upper root of Ansa Cervicalis
Appears to originate from hypoglossal nerve, but contains no hypoglossal fibers
Consists of C1 fibers that join CN XII and travel with it for a distance
separate from CN XII and form upper root of ansa cervicalis
Joins lower root to form ansa
Ansa cervicalis gives branches that supply ___________, __________, and both bellies of __________
Sternohyoid, sternothyroid, omohyoid
Some C1 fibers continues with CN ___ (after it has given off upper root) and supply __________ and ________ muscles.
XII, thyrohyoid, geniohyoid
Suprahyoid muscles
Digastric
Stylohyoid
Mylohyoid
Geniohyoid
Digastric muscle consists of posterior and anterior bellies connected by an ….
Intermediate tendon
Posterior belly attaches to ________ _______, then becomes continuous with ___________ ________
Digastric (mastoid) notch
Intermediate tendon
Intermediate tendon pierces ___________ then becomes continuous with. ________ _____
Stylohyoid, anterior belly or digastric
Anterior belly attaches to what?
Digastric fossa of mandible
Nerve supply of Digastric
Posterior Belly: facial nerve
Anterior belly: nerve to mylohyoid (branch of inferior alveolar nerve, from V3)
Actions of Digastric
Depresses mandible and elevates hyoid bone
Stylohyoid
O, I, N, A
Pierced where and by what?
O: styloid process
I: hyoid bone at junction of body and greater horn
N: facial nerve
A: elevates hyoid bone and draws it backward
Pierce: near its insertion by intermediate tendon of digastric
Mylohyoid
LOINA
2 mylohyoids form what?
L: superior to anterior belly of digastric
O: mylohyoid line of mandible
I: most posterior fibers attach to body of hyoid bone, others terminate in midline raphe extending from mandible to hyoid
N: nerve to mylohyoid
A: elevates floor of mouth during swallowing, elevates hyoid bone, depresses mandible
2 mylohyoid muscles form muscular floor of oral cavity
Geniohyoid
LOINA
L: above mylohyoid
O: mental spine
I: anterior surface of body of hyoid
N: C1 fibers via hypoglossal nerve
A: elevates hyoid bone and draws it forward, depresses mandible
Anterior vertebral muscles
Longus capitus
Longus coli
Rectus capitis anterior
Rectus capitis lateralis
Longus Capitis
OINA
O: transverse processes of C3 to C6 vertebrae
I: inferior surface of basilar part of occipital bone
N: branches from ventral rami of C1 to C3 nerves
A: flexion of head and neck
What are the 3 parts of Longus Coli?
LOINA
Inferior oblique, superior oblique, and vertical
L/O/I:
-inferior oblique: extends from bodies of first 2 or 3 thoracic vertebrae to transverse processes of C5 and C6 vertebrae
- superior oblique: extends from transverse processes of C3 to C5 vertebrae to anterior tubercle of atlas
- vertical: extends from bodies of upper 3 thoracic and lower 3 cervical vertebrae to bodies of C2 to C4 vertebrae
N: branches from ventral rami of C2 to C6 spinal nerves
A: flexion of neck
Rectus Capitis Anterior
LOINA
L: posterior to upper part of longus capitis
O: anterior surface of lateral mass of atlas and root of atlas’ transverse process
I: inferior surface of basilar part of occipital bone, immediately anterior to occipital condyle
N: branches from loop between ventral rami of C1 and C2 spinal nerves
A: flexion of head
Rectus Capitis Lateralis
OINA
O: upper surface of transverse process of atlas
I: inferior surface of jugular process of occipital bone
N: branches from loop between ventral rami of C1 and C2 spinal nerves
A: lateral flexion of head to same side of contracting muscle
Subdivisions of the Anterior Triangle
Submandibular (digastric) triangle
Carotid triangle
Muscular triangle
submental triangle
Submandibular triangle
Boundaries and contents
Boundaries
– Anteriorly: anterior belly of digastric
– Posteriorly: posterior belly of digastric and stylohyoid
– Superiorly: inferior border of body of mandible
– Floor: mylohyoid and hyoglossus muscles
Contents: – Submandibular gland (superficial part) – Facial vessels (a. and v.) – Submandibular lymph nodes – Hypoglossal nerve – Mylohyoid nerve and vessels (a. and v.)
Carotid Triangle
B&C
Boundaries
– Anteriorly and superiorly: posterior belly of digastric
– Anteriorly and inferiorly: superior belly of omohyoid
– Posteriorly: anterior border of sternocleidomastoid
Contents
– Arteries: common carotid, initial segments of external and
internal carotid, some branches of external carotid
– Veins: internal jugular and some of its tributaries
– Nerves: vagus, accessory, hypoglossal, ansa cervicalis,
internal and external laryngeal
– Deep cervical lymph nodes
Muscular triangle
B&C
Boundaries
– Anteriorly: anterior midline of neck
– Posteriorly and superiorly: superior belly of omohyoid
– Posteriorly and inferiorly: anterior border of
sternocleidomastoid
Contents
– Sternohyoid and sternothyroid muscles
– Viscera of neck (e.g.: thyroid and parathyroid glands, larynx, trachea)
Submental Triangle
B&C
Boundaries
– Laterally: anterior bellies of digastric muscles
– Inferiorly: body of hyoid
– Floor: mylohyoid muscles
Contents
– Submental lymph nodes
– Small veins that join to form anterior jugular veins
