Muscles, Neurovasculature and Triangles of the Neck

Question 1

The origin, insertion, innevertion and action mylohyoid muscle

Answer 1

Originate: mylohyoid line on the mandible
Insertion: on the body of the hyoid bone
innervation: mylohyoid nerve from the inferior alveolar branch of the mandibular nerve

action: supports and elevate the floor of mandible. elevate hyoid bone

Question 2

describe the relations of mylohyoid muscle.

Answer 2

Lies superior to anterior belly of digastric muscle
Forms floor of mouth with contralateral muscle (partner from opposite side)

Question 3

The origin, insertion, innervation and action of geniohyoid muscle.

Answer 3

origin: from the inferior mental spine of the mandible

insertion: anterior surface of body of hyoid bone
action: elevate and pulls hyoid bone anterior and pulls the mandible inferior and inward

Question 4

Describe the Geniohyoid muscle.

Answer 4

Narrow muscle
Lies superior to floor of oral cavity
- Superior to medial part of each mylohyoid muscle
Muscles from each side lie next to each other in midline

Question 5

Name the straps muscles.

Answer 5

Sternohyoid muscle
Omohyoid muscle
Thyrohyoid muscle
Sternothyroid Muscle

Question 6

The origin, insertion, innervation and action of sternohyoid muscle.

Answer 6

it is a long and thin muscle.

origin: Posterior aspect of sternoclavicular joint and adjacent manubrium of sternum

insertion: Body of hyoid bone (medial to attachment of omohyoid muscle)

action: depresses the hyoid bone.

innervation: C1-C3 anterior rami via Ansa cervicalis

Question 7

The origin, insertion, innervation and action of Omohyoid muscle

Answer 7

Lies lateral to sternohyoid muscle
Consists of two bellies with an intermediate tendon

superiorly: at the superior border of the scapula (medial to suprascapular notch)
Then blends into the intermediate tendon.

Inferiorly: Originates at the intermediate tendon
Inserts onto body of the hyoid bone.

innervation: C1 - C3 anterior rami
via Ansa cervicalis

action: Depresses and fixes hyoid bone .

Question 8

Thyrohyoid Muscle

Answer 8

origin; from an oblique line of the thyroid cartilage.

insert: on the greater horn and the body of the hyoid bone.
action: depress hyoid bone and rises the larynx.
innervation: C1

Question 9

The origin, insertion, innervation and action of the sternothyroid muscle.

Answer 9

origin: Posterior surface of manubrium of the sternum.

insertion: Oblique line of thyroid cartilage.

Action: draws the thyroid cartilage downwards.

innervation: Ansa cervicalis

Deep to sternohyoid muscle
Fibres blend in continuity with thyrohyoid muscle

Question 10

The borders and subdivisions of the Anterior triangle of the neck.

Answer 10

Boundaries
Superiorly: Inferior border of mandible
Medially: Midline of neck
Laterally: Anterior border of sternocleidomastoid muscle

Divided into 4 smaller triangles:
Submandibular triangle
Submental triangle
Muscular triangle
Carotid triangle

Question 11

The content and boundaries of submandibular triangle.

Answer 11

Boundaries
Superiorly: Inferior border of mandible
Anteromedially: Anterior belly of digastric muscle
Posterolaterally: Posterior belly of digastric muscle

Major Contents
Submandibular gland and lymph nodes
Hypoglossal and mylohyoid nerves
Facial artery and vein

Question 12

The content and boundaries of the sub Mentalis triangle.

Answer 12

Boundaries
Inferiorly: Hyoid bone
Medially: Midline of neck
Laterally: Anterior belly of digastric muscle

Major Contents
Submental lymph nodes
Tributaries that form anterior jugular vein

Question 13

The content and boundaries of the Muscular triangle.

Answer 13

Boundaries
Superiorly: Hyoid bone
Medially: Midline of neck
Laterally: Superior belly of omohyoid muscle and anterior border of the sternocleidomastoid muscle

Major Contents
Sternohyoid, omohyoid, sternothyroid, and thyrohyoid muscles
Thyroid and parathyroid glands
Pharynx

Question 14

Thecarotid triangle

Answer 14

Boundaries
Superiorly:
- Stylohyoid muscle
- Posterior belly of digastric muscle

Anteroinferiorly:
- Superior belly of omohyoid muscle

Posteriorly:
- Anterior border of sternocleidomastoid muscle

Major Contents
Tributaries of common facial vein
Internal jugular vein
External and internal carotid arteries
Superior thyroid, ascending pharyngeal, lingual, facial and occipital arteries
Cervical branch of facial nerve
Vagus, hypoglossal, and accessory nerves

Question 15

The content of the carotid system.

Answer 15

Common carotid artery branches into internal and external carotid arteries
Supply all structures of head and neck
Pass through anterior triangle of neck

Common carotid artery
- Right and left vessels ascend through neck within
carotid sheath
- Give off no branches as they passes through neck
- Superior part and division into external and internal
carotid arteries occurs in carotid triangle

Question 16

The content of the internal jugular vein.

Answer 16

Associated with the carotid arterial system
Receives blood from all structures of head and neck
Traverses neck within the carotid sheath
- Initially posterior to the internal carotid artery, but
passes to a more lateral position inferiorly
- Remains lateral to common carotid artery through
rest of neck.

Question 17

The content of the internal jugular vein.

Answer 17

Associated with the carotid arterial system
Receives blood from all structures of head and neck
Traverses neck within the carotid sheath
- Initially posterior to the internal carotid artery, but
passes to a more lateral position inferiorly
- Remains lateral to common carotid artery through
rest of neck.

Question 18

The content of the glossopharyngeal nerve

Answer 18

its cranial cavity via jugular foramen
Descends between internal carotid artery and internal jugularEx vein
Distally: Passes forward between internal and external carotid arteries, and curves around stylopharyngeus muscle
- Continues anteriorly to reach base of tongue and
area of palatine tonsil

Question 19

The vagus nerve

Answer 19

Exits cranial cavity via jugular foramen
- Between glossopharyngeal and accessory nerves
Enters the carotid sheath outside skull
Descends through neck medial to internal jugular vein and posterior to internal carotid and common carotid arteries (within sheath)

Question 20

the content of the accessory nerve

Answer 20

Exits cranial cavity via jugular foramen
- Most posterior cranial nerve exiting foramen
Begins descending (through neck) medial to the internal jugular vein
Emerges between internal jugular vein and internal carotid artery
Crosses lateral surface of internal jugular vein
Passes downward and backward to disappear either into or beneath anterior border of sternocleidomastoid muscle

Question 21

Hypoglossal Nerve

Answer 21

Exits cranial cavity via hypoglossal canal
Lies medial to internal jugular vein and internal carotid artery immediately outside skull
Descends through neck
- Passes outward between internal jugular vein and
internal carotid artery
- Passes forward across internal and external carotid
arteries
- Continues deep to posterior belly of digastric and
stylohyoid muscles
- Passes over surface of hyoglossus muscle and
disappears deep to mylohyoid muscle

Question 22

The content of the Ansa Cervicalis.

Answer 22

Loop of nerves: Arises from C1 - C3 anterior rami
Innervates infrahyoid muscles in anterior triangle of neck
Begins as C1 anterior ramus joins hypoglossal nerve
Some nerve fibers leave hypoglossal nerve
- Descend between internal jugular vein and internal/
common carotid arteries
- Form superior root of ansa cervicalis
Direct branch from cervical plexus formed by C2 and C3 anterior rami completes loop
- Forms inferior root of ansa cervicalis
- Descends medial or lateral to internal jugular vein
before turning medially to join superior root

Question 23

Posterior Triangle of Neck

Answer 23

Situated on lateral aspect of neck
- In direct continuity with upper limb

Boundaries
Apex: Occipital bone (posterior to mastoid process)
Base: Middle 1/3rd of clavicle
Anterior: Posterior edge of sternocleidomastoid muscle
Posteriorly: Anterior edge of trapezius muscle
Roof: Investing layer of cervical fascia
Floor: Prevertebral layer of cervical fascia + (superior to inferior) splenius capitis, levator scapulae, and the posterior, middle, and anterior scalene muscles

Inferior belly of omohyoid muscle crosses posterior triangle, forming:

Subclavian (Omoclavicular) triangle
- Inferiorly

Occipital triangle
- Superiorly
- Much larger

Question 24

Name the muscles of the posterior triangle.

Answer 24

Sternocleidomastoid Muscle
Anterior Scalene Muscle
Middle Scalene Muscle
Posterior Scalene Muscle

Question 25

tSternocleidomastoid Muscle

Answer 25

Origin: Anterior surface of
manubrium of sternum

Insertio: Lateral half of superior nuchal line

accessory nerve- C1 and C2

Question 26

External Jugular Vein

Answer 26

Passes straight down neck in superficial fascia
Lies superficial to sternocleidomastoid muscle
After crossing sternocleidomastoid muscle:
- Enters posterior triangle and continues vertical
descent
Lower part of triangle, just superior to clavicle and immediately posterior to sternocleidomastoid muscle:
- Pierces investing layer of cervical fascia, passes
deep to clavicle, and enters subclavian vein

Question 27

Subclavian Artery