anterior triangle Flashcards
boundaries
Anteriorly: midline of neck
Posteriorly: anterior border of sternocleidomastoid
Superiorly: inferior border of body of mandible
muscle groups
- infrahyoid muscles
- suprahyoid muscles
- anterior vertebral muscles
infrahyoid muscles
- below the hyoid bone
- thin, strap like muscles
- sternohyoid
- sternothyroid
- thyrohyoid
- omohyoid(superior belly)
Sternohyoid
-located superficially, medial to superior belly of omohyoid
Origin: posterior surfaces of manubrium of sternum and sternal end of clavical
Insertion: body of hyoid
Nerve supply: ansa cervicalis(C1-C3)
Action: depress hyoid bone
Sternothyroid
-located deep to sternohyoid
Origin: posterior surface of manubrium of sternum
Insertion: oblique line of thyroid cartilage
Nerve Supply: ansa cervicalis(C1-C3)
Action:depress larynx
thyrohyoid
-upward continuation of sternothyroid
Origin: oblique line of thyroid cartilage
Insertion: runs superiorly over thyrohyoid membrane, inserts into greater horn and body of hyoid
Nerve Supply: C1 fibers via hypoglossal nerve
Action: depress hyoid bone or elevate larynx
ansa cervicalis
-nerve loop that contains fibers from ventral rami of C1 to C3 spinal nerves
lower root of ansa cervicalis
- direct branch of cervical plexus
- contains fibers from ventral rami of C2 and C3
- passes superficial(or deep) to internal jugular vein
Upper root of ansa cervicalis
- appears to originate from hypoglossal nerve, but contains no hypoglossal fibers
- consists of C1 fibers that join hypoglossal nerve and travel with it
what does the ansa cervicalis supply?
-branches supply sternohyoid, sternothyroid, and both bellies of the omohyoid
do all C1 fibers branch off hypoglossal to form ansa cervicalis?
- nope
- some continue with it and supply thyrohyoid and geniohyoid muscles
suprahyoid muscles
- above the hyoid bone
- digastric
- stylohyoid
- mylohyoid
- geniohyoid
Digastic
-consists of posterior and anterior bellies connected by an intermediate tendon
Digastric posterior belly
- attaches to digastric notch
- runs anteriorly and inferiorly
digastric intermediate tendon
-pierces stylohyoid and runs in fibrous sling connected to body and greater horn of hyoid
Digastric inferior belly
- runs anteriorly and superiorly
- attaches to digastric fossa of mandible
nerve supply of digastric
Posterior belly: facial nerve
Anterior: nerve to myohyoid
Action of digastric
-depress mandible and elevate hyoid bone
stylohypid
Origin: styloid process
Insertion: passes anterior and inferior, inserts into hyoid bone at junction of body and greater horn
Nerve Supply: facial nerve
Action: elevates hyoid bone and draws it backwards
stylohyoid piercing???
-pierced near its insertion by intermediate tendon of digastric
mylohyoid
- lies superior to anterior belly of digastric
- two mylohyoid muscles form muscular floor of oral cavity
mylohyoid origin and insertion
Origin: mylohyoid line of mandible
Insertion: attach to body of hyoid bone OR in midline raphe extending from mandible to hyoid
Mylohyoid nerve supply
nerve to mylohyoid
Mylohyoid action
elevates floor of mouth during swallowing
- elevates hyoid bone
- depresses mandible
geniohyoid
-narrow muscle that lies above mylohyoid
Origin: mental spine
Insertion: anterior surface of body of hyoid
Nerve supply: C1 fibers via hypoglossal nerve
Action: elevates hyoid bone and draws it forward, depresses mandible
anterior vertebral muscles
- longus capitis
- longus coli
- rectus capitis anterior
- rectus capitis lateralis
Longus capitis
Origin: transvers process of C3-C6 vertebrae
Insertion: inferior surface of basilar part of occipital bone
Nerve supply: ventral rami of C1-C3
Action: flexion of head and neck
what are the subunits of longus colli?
inferior oblique
superior oblique
vertical part
inferior oblique part
-extends from bodies of thoracic vertebrae to transverse processes of C5 and C6
Superior oblique part
-extends from transverse process of C3 to C5 to anterior tubercle of atlas
Vertical part
-extends from bodies of upper 3 thoracic and lower 3 cervical vertebrae to bodies of C2-C4 vertebrae
Nerve supply of longus colli
-branches from ventral rami of C2 to C6 spinal nerves
Action of longus colli
flexion of neck
Rectus capitis anterior
-located posterior to upper part of longus capitis
Origin: anterior surface of lateral mass of atlas and root of its transverse process
Insertion: inferior surface of basilar part of occipital bone
rectus capitis anterior nerve supply
branches from loop between ventral rami of C1 and C2 spinal nerves
Action of rectus capitis anterior
flexion of the head
Rectus capitis lateralis
Origin: upper surface of transverse process of atlas
Insertion: inferior surface of jugular process of occipital bone
Rectus capitis lateralis nerve supply
branches from loop between ventral rami of C1 and C2 spinal nerves
Action of rectus capitis lateralis
lateral flexion of head to same said of contracting muscle
subdivisions of the anterior triangle
- submandibular triangle
- carotid triangle
- muscular triangle
- submental triangle
submandibular triangle borders
Anteriorly: anterior belly of digastric
Posteriorly: posterior belly of digastric and stylohyoid
Superiorly: inferior border of body og mandible
Floor: mylohyoid and hypoglossus muscles
Contents of submandibular triangle
- submandibular gland
- facial vessels
- submandibular lymph nodes
- hypoglossal nerve
- mylohyoid nerve and vessels
Carotid triangle borders
Anteriorly and superiorly: posterior belly of digastric
Anterioinferiorly: superior belly of omohyoid
Posteriorly: anterior border of sternocleidomastoid
Contents of carotid triangle
-Arteries:common carotid, initial segments of external and internal carotid
-Veins: internal jugular and some of its tributaries
Nerves: vagus, accessory, hypoglossal, ansa cervicalis, internal and external laryngeal
Nodes: deep cervical lymph nodes
Muscular triangle borders
Anteriorly: anterior midline of neck
Posteriosuperiorly: superior belly og omohyoid
Posterioinferiorly: anterior border of sternocleidomastoid
Contents of muscular triangle
- sternohyoid and sternothyroid muscles
- viscera of the neck
Viscera of the neck
- thyroid and parathyroid glands
- larynx
- trachea
Submental triangle boundaries
Laterally: anterior bellies of digastric
Inferiorly: body of hyoid
Floor: mylohyoid muscles(deep)
Contents of submental triangle
- submental lymph nodes
- small veins that join to make the internal jugular veins
- mostly connective tissue
