Anatomy Unit 17: Anterior Triangle

Front 1

Muscular Triangle Boundaries

Back 1

Anterior border of SCM, superior belly of omohyoid and the median line.

Front 2

Sternohyoid Muscle

Back 2

Origin: Within thorax behind manubrium
Insertion: hyoid bone
Action: depresses larynx
Inervation: Inferior root of ansa cervicalis

Front 3

Omohyoid Muscle

Back 3

Origin: Superior portion of scapula near suprascapular notch
Insertion: Hyoid bone
Actions: Depresses larynx
Innervation: Superior belly by superior root of ansa cervicalis
inferior belly by inferior root of ansa cervicalis

Front 4

Sternothyroid Muscle

Back 4

Origin: Posterior manubrium below sternohyoid
Inserts: Oblique line of thyroid cartilage
Action: Depresses larynx
Inervation: Inferior root of ansa cervicalis

Front 5

Thyrohyoid Muscle

Back 5

Origin: Oblique line of thyroid Cartilage
Inserts: Hyoid Bone
Action: Elevates larynx
Innervation: Superior Root of Ansa Cervicalis

Front 6

First Muscular Plane on neck

Back 6

Sternohyoid and omohyoid

Front 7

Second Muscular plane on neck

Back 7

Sternothyroid and Thyrohyoid

Front 8

Carotid Triangle Boundries

Back 8

Posterior belly of digastric Muscle, superior belly of omohyoid muscle, and anterior border of SCM

Front 9

Branches of Facial artery

Back 9

TAGS
Tonsilar branches
Ascending Palatine Branches
Glandular branches
Submental branches

Front 10

Submental triangle Boundaries

Back 10

2 Anterior bellies of digastric muscle and hyoid bone. Only unpaired triangle in neck.

Front 11

Infrahyoid Muscles

Back 11

Sternohyoid
Omohyoid
Sternothyroid
Thyrohyoid
All have actions on larynx and are inervated by ansa cervicalis

Front 12

Suprahyoid Muscles

Back 12

Digastric Muscle
Stylohyoid
mylohyoid
geniohyoid
hyoglossus
All innervated by cranial nerves.

Front 13

Submandibular Triangle Boundaries

Back 13

2 bellies of digastric muscle and lower border of mandible.

Front 14

Digastric Muscle

Back 14

Origin: Medial aspect of mastoid process (posterior belly)
Insertion: Inner surface of mandible close to mid line.
Intermediate tendon passes through a connective tissue pulley attached to the hyoid bone.
Action: If both bodies work, elevates larynx. If only one, moves hyoid bone anteriorly or laterally.
Innervation: Posterior = Facial Nerve
Anterior = Trigeminal Nerve

Front 15

Styloid Muscle

Back 15

Origin: Styloid Process
Insertion: Hyoid bone. Splits to pass on both sides of the intermediate tendon of the digastric muscle.
Action: Elevates Larynx
Innervation: Facial Nerve

Front 16

Mylohyoid Muscle

Back 16

Origin: Mylohyoid line of mandible
Inserts: On hyoid bone and on some connective tissue which extends from hyoid bone to manidble.
Action: Elevates Larynx. Also forms floor of mouth.
Innervation: Trigeminal Nerve

Front 17

Geniohyoid Muscle

Back 17

Origin: Inferior genial tubercle of mandible.
Insertion: Body of hyoid bone. Are the 2 planks parallel and superficial to the anterior digastric muscles on other side of myohyoid muscle.
Innervation: C1 and 2 of Hyoglossal Nerve.

Front 18

Submandibular Gland Location and Parts

Back 18

Located below and in front of angle of mandible.
Superficial Part: Larger, Lies superficial to the mylohyoid muscle and folds around muscle with deep part of gland.
Deep Part: Lies between mylohyoid muscle and hyoglossus.

Front 19

Submandibular Duct

Back 19

Comes from deep part of gland. Passes between mylohyoid and hyoglussus and opens into oral cavity at sublingual papilla.
Lingual Nerve starts superior and lateral to duct, goes under, and becomes inferior and medial (SLIM).

Front 20

Vessels of submandibular gland

Back 20

Facial Artery
Submental artery - a branch off facial artery
Facial Vein

Front 21

Mylohyoid Nerve

Back 21

Runs on surface of mylohyoid muscle deep to submandibular gland. Sends branches to the mylohyoid muscle and anterior belly of digastric. Is a branch off the trigeminal nerve.

Front 22

Trigeminal Nerve Innervation in this region

Back 22

(CN 5) Nerve to Mylohyoid and anterior belly of digastric muscle (mylohyoid nerve).

Front 23

Facial Nerve

Back 23

(CN 7) Cervical branch supplies platysma. Main trunk supplies sylohyoid and posterior belly of digastric.

Front 24

Glossopharyngeal Nerve

Back 24

(CN 9) Supplies Carotid Sinus - Swelling at bifurcation of internal and external carotid arteries. Monitors BP.

Front 25

Vagus Nerve

Back 25

(CN 10) Passes in Carotid sheath. Gives off:
Superior/Inferior cervical cardiac nerves, Superior Laryngeal Nerve, pharyngeal branch, and recurrent (inferior) laryngeal nerve.

Front 26

Superior/Inferior Cervical Cardiac Nerves

Back 26

Given off by vagus. Visceral branches to the cardiac plexus.

Front 27

Superior Laryngeal Nerve

Back 27

Branch off Vagus.
External Branch: Motor to cricothyroid muscle. Also goes to root of tongue.
Internal: Passes through thyrohyoid membrane with superior laryngeal artery. Is sensory for laryngeal mucosa. Important for cough reflex.

Front 28

Pharyngeal Branch of Vagus Nerve Path

Back 28

Passes between carotid arteries

Front 29

Hypoglossal Nerve

Back 29

(CN 12) Crosses external to both carotid arteries, goes deep to mylohyoid muscle, and wraps around with optical artery.
Fibers from C1of ansa cervicalis hitchhike with Hypoglossal.

Front 30

Ansa Cervicalis

Back 30

Main loop located on anterior surface of Internal Jug. Formed from Branches of C1,2,3.
Anterior Primary Ramus of C1 Hitchhikes along hypoglossal and innervates thyrohyoid and geniohyoid.
Then Gives off Descendens Hypoglossi (superior root) which innervates thyrohyoid and geniohyoid,
C2 and C3 give off Descendens Cervicalis (inferior root) which innervates inferior belly of omohyoid, sternohyoid, and sternothyroid.

Front 31

Superior Cervical Ganglion

Back 31

Grey Communicating rammi to C1-4.
Gives off:
Internal carotid nerve and plexus
Superior cervical cardiac nerve (to cardiac plexus)
Pharyngeal branches
Communications with CN 9, 10, 12.

Front 32

Middle Cervical Ganglion

Back 32

Around level of thyroid cartilage. Grey communicating rammi C5, 6.
Middle cervical cardiac nerve (to cardiac Plexus)

Front 33

Inferior Cervical Ganglion

Back 33

Grey Communicating rammi to C7 and 8.
Inferior cervical cardiac nerve (to cardiac Plexus)
May fuse with first thoracic ganglion to form stellate ganglion.
If vertebral ganglion not present, gives branch to vertebral artery.

Front 34

Thyroid Gland

Back 34

2 lateral lobes which extend usually from oblique line of thyroid cartilage to 6th tracheal ring.
Median Lobe is isthmus. May have a pyramidal lobe extending up from it.

Front 35

Parathyroid Gland

Back 35

Attached to posterior surface of thyroid gland.

Front 36

Thyroid Gland Blood Supply

Back 36

Superior thyroid artery off external carotid
Inferior thyroid of thyrocervical trunk
Little from Thyroid Ima aartery off common carotid or bracheocephalic. Supplies isthmus.

Front 37

Thyroid Bland Venus Drainage

Back 37

Superior thyroid vein drains into internal Jug.
Middle thyroid drains into internal jug.
Inferior thyroid drains into left bracheocephalic vein.