Neck Triangles (A13)

Question 1

All neck triangles are on both sides therefore there are two of each, which is the exception

Answer 1

sub mental

Question 2

division of neck triangles

Answer 2

• posterior

- anterior

Question 3

4 types anterior neck triangles

Answer 3

• submandibular
• submental
• muscular
• carotid

Question 4

posterior neck triangle:
1-borders
2-apex
3-roof
4-floor
5-contents

Answer 4

1-posterior border of SCM , middle third of clavicle, anterior border of trapezius
2-point between anterior border of trapezius and posterior border of SCM SUPERIORLY at the base of the skull on superior nuchal line
3-investing layer of deep fascia
4-deep cervical fascia covering muscles (prevertebral fascia)
5-(spinal) accessory nerve (CNXI)

Question 5

origin of spinal accessory nerves (CNXI)

Answer 5

-mostly arise from spinal cord rather than the base of the brain

Question 6

borders of posterior neck triangle

Answer 6

posterior border of SCM , middle third of clavicle, anterior border of trapezius

Question 7

apex of posterior neck triangle

Answer 7

point between anterior border of trapezius and posterior border of SCM SUPERIORLY at the base of the skull

Question 8

roof of posterior neck triangle

Answer 8

investing layer of deep fascia

Question 9

floor of posterior neck triangle

Answer 9

deep cervical fascia covering muscles (prevertebral fascia)

Question 10

contents of posterior neck triangle

Answer 10

(spinal) accessory nerve (CNXI)

Question 11

route of (spinal) accessory nerves from spinal cord to muscles

Answer 11

• branches from C1-4 (can be C5/6 too) anterior spinal nerve roots pass up and over foramen magnum to enter cranial cavity and join with vagus
• traverses the posterior cranial fossa to reach the jugular foramen, briefly meets the cranial portion of the accessory nerve, before exiting the skull (along with the glossopharyngeal and vagus nerves) through jugular foramen and splits to supply 2 muscles
• outside the cranium, the spinal part descends along the internal carotid artery to reach the sternocleidomastoid muscle, which it innervates. It then moves across the posterior triangle of the neck to supply motor fibres to the trapezius.

Question 12

which 2 muscles are supplied by the (spinal) accessory nerve and which type of innervation is this

Answer 12

• SCM and trapezius (SOMATIC MOTOR innervation only)

- enters the deep surface of both muscles

Question 13

clinical testing of (spinal) accessory nerves

Answer 13

test the movements that the muscles they innervate carry out:
-movement of head to side and look up (SCM)
-shrug shoulders (trapezius)
(if patients can do the above movements, the nerve is working)

Question 14

which type of innervation do you get from dorsal spinal roots

Answer 14

sensory

Question 15

which type of innervation do you get from anterior spinal roots

Answer 15

motor innervation

Question 16

anterior neck triangle (as a whole):
1-borders
2-apex
3-roof
4-floor
5-contents

Answer 16

1-inferior border of mandible, anterior border of SCM muscles, clavicle (and midline divides further)
2-jugular notch
3-subcutaneous tissue with platysma
4-pharynx, larynx and thyroid gland
5-discussed more within each individual anterior neck triangle division (submandibular, submental, muscular and carotid triangles)

Question 17

what divides the anterior neck triangle in two (left and right)

Answer 17

anterior midline of the neck

Question 18

what does the hyoid bone divide anterior triangles into

Answer 18

• suprahyoid triangles (above)

- infrahyoid triangles (below)

Question 19

suprahyoid triangles

Answer 19

• submental triangle

- submandibular triangles

Question 20

which bone in the body doesn’t attach to any other bone (floating bone)

Answer 20

hyoid bone

Question 21

why is the submental triangle different to the rest of the anterior neck triangles

Answer 21

only 1 - present in middle below mandible (there isn’t one on left and right side)

Question 22

submental neck triangle:
1-borders
2-apex
3-roof
4-floor
5-contents

Answer 22

1-medial border of anterior belly of digastric (on both sides), imaginary midline of the neck, hyoid bone
2-mental protuberance
3-fascia and skin (subcutaneous tissue with platysma)
4-mylohyoid muscle
5-start/origin of anterior jugular vein (small veins that unite to form anterior jugular vein), submental lymph nodes

Question 23

submental lymph nodes

Answer 23

drain lymph from tongue tip, lower lip and lower incisors

Question 24

mylohyoid muscle

Answer 24

• forms floor of mouth

- runs from mandible to hyoid bone

Question 25

``` submandibular neck triangles: 1-borders 2-apex 3-roof 4-floor 5-contents ```

Answer 25

1-body of mandible, anterior belly of digastric, posterior belly of digastric 2-hyoid bone (point between anterior and posterior belly of digastric) 3-fascia and skin (subcutaneous tissue with platysma) 4-? 5-submandibular salivary gland (fills most of triangle), facial artery, facial vein, submandibular lymph nodes (sit all over triangle), hypoglossal nerve (CNXII)

Question 26

facial artery and vein

Answer 26

- supply/drain blood to and from face | - pass over body of mandible right at anterior border of masseter

Question 27

submandibular lymph nodes

Answer 27

-drain most of tongue, more of teeth (not lower incisors) and area covering eyes

Question 28

hypoglossal nerve

Answer 28

- CNXII - hypo=under, glossal=tongue (passes under tongue) - supplies ALL of the intrinsic muscles of the tongue (APART from the palatoglossus muscle) - has branch that comes down to supply loop of ansa cervicalis (descendens hypoglossi)

Question 29

only intrinsic muscle of the tongue not supplied by the hypoglossal nerve

Answer 29

palatoglossus

Question 30

infrahyoid (anterior) neck triangles

Answer 30

- carotid triangles | - muscular triangles

Question 31

``` carotid neck triangles: 1-borders 2-apex 3-roof 4-floor 5-contents ```

Answer 31

1-posterior belly of digastric, superior border of omohyoid, anterior border of SCM 2-point between omohyoid and posterior belly of digastric, superiorly at attachment to hyoid bone 3-? 4-? 5- carotid sheath, common carotid artery (which bifurcates within the carotid triangle into the external and internal carotid arteries), the internal jugular vein, deep cervical lymph nodes and the hypoglossal and vagus nerves

Question 32

carotid sheath definition

Answer 32

connective tissue tunnel that surrounds different structures

Question 33

deep cervical lymph nodes

Answer 33

drain deep lymph of head and neck

Question 34

contents of carotid sheath

Answer 34

- internal jugular vein - common carotid artery (then internal carotid artery) - vagus nerve - deep cervical lymph nodes

Question 35

area of bifurcation of common carotid artery into internal and external

Answer 35

laryngeal prominence

Question 36

laryngeal prominence

Answer 36

- adams apple | - formed by joining of 2 thyroid cartilages

Question 37

ansa cervicalis

Answer 37

-formed from 2 different nerve fibre bundles -loop of hypoglossal nerve -C1,C2,C3 motor fibres -motor supply to 'strap muscles' (except thyrohyoid- supplied by C1) -C1 motor fibres (descendens hypoglossi) -C2,C3 motor fibres (descendens cervicalis) (fibres descend from cervical spinal roots to form loop that supply strap muscles, motor fibres from C1 hitch a ride with the hypoglossal nerve then they split, descendens hypoglossi is where it splits from hypoglossal nerve to meet with descendens cervicalis to form ansa cervicalis, and C1 continues along beside hypoglossal nerve to supply thyrohyoid)

Question 38

location of ansa cervicalis

Answer 38

not embedded within carotid sheath, either sits just on top of sheath or is imbedded in the connective tissue of the sheath

Question 39

which strap muscle is not supplied by ansa cervicalis

Answer 39

- thyrohyoid | - supplied by C1

Question 40

muscular triangles of the neck: 1-borders 2-contents

Answer 40

1-hyoid bone, imaginary midline of neck, inferior portion of anterior border of SCM, superior belly of the omohyoid muscle 2-strap muscles and nerve supply (ansa cervicalis, C1,C2,C3)

Question 41

strap muscles (in muscular triangle of the neck)

Answer 41

-looks like ribbons/straps -aka infrahyoid muscles 1-omohyoid 2-sternohyoid 3-sternothyroid 4-thyrohyoid

Question 42

mylohyoid muscle (attachments, actions and innervation)

Answer 42

- suprahyoid muscle - the mylohyoid muscle is a broad, triangular shaped muscle - forms the floor of the oral cavity, thus supporting the floor of the mouth - attachments: originates from the mylohyoid line of the mandible, and attaches onto the hyoid bone - actions: elevates the floor of the mouth and the hyoid bone. - innervation: inferior alveolar nerve, a branch of the mandibular nerve (which is derived from the trigeminal nerve)

Question 43

digastric muscle (attachments, actions and innervation)

Answer 43

- suprahyoid muscle - comprised of two muscular bellies, connected by a tendon - attachments: the anterior belly arises from the digastric fossa of the mandible, the posterior belly arises from the mastoid process of the temporal bone, the two bellies are connected by an intermediate tendon, which is attached to the hyoid bone via a fibrous sling. - actions: depresses the mandible and elevates the hyoid bone. - innervation: the two parts of the digastric muscle have different innervations; the anterior belly is innervated by the inferior alveolar nerve, a branch of the mandibular nerve (which is derived from the trigeminal nerve, CN V) and the posterior belly is innervated by the digastric branch of the facial nerve

Question 44

thyroid cartilage

Answer 44

gives rise to adams apple

Question 45

function of strap muscles

Answer 45

help depress hyoid bone and help anchor larynx

Question 46

4 suprahyoid muscles

Answer 46

- stylohyoid - digastric - geniohyoid - mylohyoid

Question 47

stylohyoid muscle (attachments, actions and innervation)

Answer 47

-suprahyoid muscle

Question 48

geniohyoid (attachments, actions and innervation)

Answer 48

- suprahyoid muscle - located deep to the mylohyoid muscle, the geniohyoid lies close to the midline of the neck - attachments: arises from the inferior mental spine of the mandible, it then travels inferiorly and posteriorly to attach to the hyoid bone. - actions: depresses the mandible and elevates the hyoid bone. - innervation: C1 nerve roots that run within hypoglossal nerve

Question 49

omohyoid muscle (attachments, actions and innervation)

Answer 49

- strap muscle/infrahyoid muscle - innervation:ansa cervicalis - split into two bellies, connected by a muscular tendon. It is located slightly laterally to the sternohyoid. - attachments: the inferior belly of the omohyoid arises from the scapula. It runs superiomedially, moving underneath the sternocleidomastoid. Here, it is attached to the the superior belly by an intermediate tendon. This tendon is attached to the clavicle by the deep cervical fascia. The superior belly ascends to attach to the hyoid bone. - actions: Depresses the hyoid bone. - innervation: anterior rami of C1-C3, carried by a branch of the ansa cervicalis

Question 50

sternohyoid muscle (attachments, actions and innervation)

Answer 50

- strap muscle/infrahyoid muscle - innervation:ansa cervicalis - along with the omohyoid, the sternohyoid lies superficially in the neck. - attachments: the sternohyoid muscle originates from the sternum and sternoclavicular joint. It ascends to insert onto the hyoid bone. - actions: depresses the hyoid bone. - innervation: anterior rami of C1-C3, carried by a branch of the ansa cervicalis

Question 51

sternothyroid muscle (attachments, actions and innervation)

Answer 51

- strap muscle/infrahyoid muscle - innervation:ansa cervicalis - deep to sternohyoid and omohyoid - this muscle is wider and deeper than the sternohyoid - attachments: the sternothryoid runs from the manubrium of the sternum to the thyroid cartilage. - actions: depresses the thyroid cartilage. - innervation: anterior rami of C1-C3, carried by a branch of the ansa cervicalis.

Question 52

thyrohyoid muscle (attachments, actions and innervation)

Answer 52

- strap muscle/infrahyoid muscle - deep to sternohyoid and omohyoid - innervation:has its own nerve supply from C1 (not ansa cervicalis) - the thryrohyoid muscle is a short band of muscle, located underneath the posterior portions of the omohyoid and sternohyoid muscles. It is a continuation of the sternothyroid muscle. - attachments: It arises from the thyroid cartilage of the larynx, and ascends to attach to the hyoid bone. - actions: it depresses the hyoid, however, if the hyoid is fixed, it can raise the larynx. - innervation: anterior ramus of C1, carried within the hypoglossal nerve