Neuroscience - Anterior Triangle of the Neck: Part 1

superficial cervical fascia

• contains neurovascular supply to the skin, superficial veins, superficial lymph nodes, fat, platysma muscle

• lies between the dermis and the deep cervical fascia

deep cervical fascia

• deep to the superficial fascia and platysma muscle and organized into several layers

• investing layer

• pretracheal layer (muscular and visceral parts)

• prevertebral layer

• carotid sheath

Name the 4 layers of deep cervical fascia

investing layer of deep cervical fascia

• most superficial layer

• surrounds all the structures in the neck

• completely surrounds the trapezius and sternocleidomastoid muscles

• can be thought of as a tube with superior, anterior, inferior, and posterior attachments

• external occipital protuberance

• superior nuchal line of skull

• inferior portion of mandible

superior attachment of investing layer of deep cervical fascia

hyoid bone

anterior attachment of investing layer of deep cervical fascia

• spine and acromion process of scapula

• clavicle

• manubrium

inferior attachment of investing layer of deep cervical fascia

• nuchal ligament

• spines of cervical vertebrae

posterior attachment of investing layer of deep cervical fascia

pretracheal layer of deep cervical fascia

• spans between the hyoid bone superiorly and the thorax inferiorly (where it fuses with the pericardium)

infrahyoid muscles

What does the muscular part of the pretracheal layer enclose?

• thyroid gland

• trachea

• esophagus

Name the 3 structures that the visceral part of the pretracheal layer encloses

prevertebral layer of deep cervical fascia

• surrounds the vertebral column and its associated muscles: scalene muscles, prevertebral muscles, and the deep muscles of the back

base of skull

superior attachment of prevertebral layer of deep cervical fascia

transverse processes and vertebral bodies of vertebral column

anterior attachment of prevertebral layer of deep cervical fascia

fused with endothoracic fascia of ribcage

inferior attachment of prevertebral layer of deep cervical fascia

nuchal ligament

posterior attachment of prevertebral layer of deep cervical fascia

carotid sheath

• bilateral structures which enclose an important neurovascular bundle of the neck

• formed by fascial contributions from the pretracheal, prevertebral, and investing fascia layers

• contain common carotid artery, internal jugular vein, vagus nerve, cervical lymph nodes, AND MORE

anterior triangle of neck

Name the space outlined in purple

inferior border of mandible

superior border of anterior triangle of the neck

anterior border of sternocleidomastoid

lateral border of anterior triangle of the neck

median line of neck

medial border of anterior triangle of the neck

investing layer of deep cervical fascia

roof of anterior triangle of the neck

pretracheal layer of deep cervical fascia

floor of anterior triangle of the neck

lymph nodes of head and neck

• peripheral lymphoid organs connected to vascular system by afferent and efferent lymphatic vessels

• ovoid or bean-shaped

• 2-20 mm in longitudinal diameter, usually occur in groups

• ~300 in head and neck

• superficial located in superficial fascia/subcutaneous connective tissue

• deep lie deep to fascia and muscles

• function: play an important role in the defense mechanism of the body by filtering out micro-organisms and foreign substances

• digastric

• mylohyoid

• stylohyoid

• geniohyoid

Name the 4 suprahyoid muscles

digastric

anterior belly of digastric

posterior belly of digastric

mylohyoid

• forms the floor of the mouth

• floor of submental triangle and submandibular triangle

• oral diaphragm =

stylohyoid

geniohyoid

• sternohyoid

• sternothyroid

• thyrohyoid

• omohyoid

Name the 4 infrahyoid muscles

strap muscles

What is another name for the infrahyoid muscles?

sternohyoid

sternothyroid

thyrohyoid

omohyoid

mastication

a vital function that ensures that ingested food is broken down into pieces and prepared for digestion

chewing

What is another name for mastication?

hyoid

• suspended inferior to the mandible

• situated at the root of the tongue

• not directly articulated to any other bone

• attached to thyroid cartilage by thyrohyoid membrane

• attached to styloid process of temporal bone by stylohyoid ligament

• functions: supports the tongue, which is located superior to it; holds up the larynx which is inferior to it; transmits the force of muscles that assist in opening the mouth (depressing the mandible)

submental triangle

Name the space outlined in blue

anterior bellies of digastric

lateral borders of submental triangle

hyoid bone

inferior border of submental triangle

• submental lymph nodes

• small veins

contents of submental triangle

carotid triangle

Name the space outlined in green

posterior belly of digastric

superior border of carotid triangle

medial border of sternocleidomastoid

lateral border of carotid triangle

superior belly of omohyoid

anterior/inferior border of carotid triangle

• larynx

• pharynx

• thyroid gland

• common carotid artery

• external carotid artery

• internal jugular vein

• cervical plexus

• ansa cervicalis

• CN X

• CN XI

• CN XII

• deep cervical lymph nodes

Name the 12 contents of carotid triangle

common carotid artery

external carotid artery

internal carotid artery

carotid body

• small cluster of chemoreceptor cells at bifurcation of the common carotid artery

• function: detects decreases in partial pressure of O₂ and CO₂; thereby modulates cardiovascular and respiratory function

carotid sinus

• a neurovascular structure at the dilation at the beginning of the internal carotid artery

• crucial role in the control of blood pressure and heart rate

• function: parasympathetic baroreceptor that is sensitive to pressure changes in the arterial blood pressure

muscular triangle

Name the space in yellow

hyoid bone

superior border of muscular triangle

midline of neck

medial border of muscular triangle

superior belly of omohyoid

superolateral border of muscular triangle

inferior portion of sternocleidomastoid

inferolateral border of muscular triangle

• infrahyoid muscles

• thyroid gland

• parathyroid glands

contents of muscular triangle

submandibular triangle

Name the space outlined in orange

body of mandible

superior border of submandibular triangle

anterior belly of digastric

anterior border of submandibular triangle

posterior belly of digastric

posterior border of submandibular triangle

• submandibular gland

• lymph nodes

• CN XII

• mylohyoid nerve

• facial artery and vein

contents of submandibular triangle

submandibular gland

• in the submandibular triangle

• lies along the body of the mandible

• partly superior and partly inferior to posterior half of mandible

• partly superficial and partly deep to the mylohyoid