Anterior Triangle Of the Neck

Question 1

Boundaries of the Anterior Triangle

Answer 1

Anteriorly: midline of neck

Posteriorly: anterior border of sternocleidomastoid

Superiorly: inferior border of body of mandible

Question 2

Muscle groups of the Anterior Triangle

Answer 2

Infrahyoid muscles

Suprahyoid muscles

Anterior vertebral muscles

Question 3

Infrahyoid muscles

Answer 3

Thin, strap-like muscles

4 types:

1. Sternohyoid
2. Sternothyroid
3. Thyrohyoid
4. Omohyoid

Question 4

Sternohyoid

Location, Origin, Insertion, Nerve supply, and action

Answer 4

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

Question 5

Sternothyroid

Location, Origin, Insertion, Nerve supply, and action

Answer 5

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

Question 6

Thyrohyoid

Location, Origin, Insertion, Nerve supply, and action

Answer 6

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

Question 7

Nerve loop that contains fibers from ventral rami of C1 to C3 spinal nerves

Answer 7

Ansa Cervicalis

Question 8

Lower root of ansa cervicalis is…

Answer 8

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

Question 9

Upper root of Ansa Cervicalis

Answer 9

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

Question 10

Ansa cervicalis gives branches that supply ___________, __________, and both bellies of __________

Answer 10

Sternohyoid, sternothyroid, omohyoid

Question 11

Some C1 fibers continues with CN ___ (after it has given off upper root) and supply __________ and ________ muscles.

Answer 11

XII, thyrohyoid, geniohyoid

Question 12

Suprahyoid muscles

Answer 12

Digastric

Stylohyoid

Mylohyoid

Geniohyoid

Question 13

Digastric muscle consists of posterior and anterior bellies connected by an ….

Answer 13

Intermediate tendon

Question 14

Posterior belly attaches to ________ _______, then becomes continuous with ___________ ________

Answer 14

Digastric (mastoid) notch

Intermediate tendon

Question 15

Intermediate tendon pierces ___________ then becomes continuous with. ________ _____

Answer 15

Stylohyoid, anterior belly or digastric

Question 16

Anterior belly attaches to what?

Answer 16

Digastric fossa of mandible

Question 17

Nerve supply of Digastric

Answer 17

Posterior Belly: facial nerve

Anterior belly: nerve to mylohyoid (branch of inferior alveolar nerve, from V3)

Question 18

Actions of Digastric

Answer 18

Depresses mandible and elevates hyoid bone

Question 19

Stylohyoid

O, I, N, A

Pierced where and by what?

Answer 19

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

Question 20

Mylohyoid

LOINA

2 mylohyoids form what?

Answer 20

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

Question 21

Geniohyoid

LOINA

Answer 21

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

Question 22

Anterior vertebral muscles

Answer 22

Longus capitus

Longus coli

Rectus capitis anterior

Rectus capitis lateralis

Question 23

Longus Capitis

OINA

Answer 23

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

Question 24

What are the 3 parts of Longus Coli?

LOINA

Answer 24

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

Question 25

Rectus Capitis Anterior LOINA

Answer 25

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

Question 26

Rectus Capitis Lateralis OINA

Answer 26

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

Question 27

Subdivisions of the Anterior Triangle

Answer 27

Submandibular (digastric) triangle Carotid triangle Muscular triangle submental triangle

Question 28

Submandibular triangle Boundaries and contents

Answer 28

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.) ```

Question 29

Carotid Triangle B&C

Answer 29

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

Question 30

Muscular triangle B&C

Answer 30

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)

Question 31

Submental Triangle B&C

Answer 31

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