Anatomy of neck

Question 1

what nerve innervates sternoclaidomastoid + trapezius?

Answer 1

the spinal accessory nerve (CN XI) innervates both trapezius + sternoclaidomastoid

n.b. all 3 (spinal accessory, trapezius,sternoclaidomastoid) all found in posterior triangle of neck

Question 2

what vein crosses the sternoclaidomastoid + why is it clinically significant

Answer 2

the external jugular vein crosses the sternoclaidomastoid; if it is bulging out its a sign of raised central venous pressure (indicative of heart failure)

Question 3

what spinal rootlets does the spinal accessory nerve form from? Which foramen does this nerve ascend the cranial cavity through, and which foramen does this nerve exit through/

Answer 3

spinal accessory nerve (CN XI)
* nerve forms from C1-5 spinal cord rootlets (purely motor cranial nerve)
* ascend into cranial cavity via foramen magnum
* exit through jugular foramen (vagus also exits thru jugular foramen)

Question 4

a patient had metastasis in lymph nodes in neck, surgery was performed to remove, unfortunately spinal accessory nerve was damaged. What clinical signs will u see?

Answer 4

spinal accessory nerve (CN XI)
= weakened shrugging shoulder, atrophy of trapezius, drooping shoulder

n.b. patient won’t be able to shrug shoulder on affected side

Question 5

what is the cervical plexus made up of + name some important regions it innervates

Answer 5

C1-4
* branches emerge around middle of posterior border of sternoclaidomastoid
* phrenic nerve (C3 +C4)
* ansa cervicalis (C1-3) is motor to infrahyoid muscles

Question 6

what boundaries make up the carotid triangle; within this triangle what nerves + which artery and vein travel here?

Answer 6

Boundaries:
Posterior belly of digastric
Superior belly of omohyoid
Anterior border of SCM

Highly vascular area=
* Common carotid artery
* At anterior border of SCM at level of thyroid cartilage
Pulse indicates a systolic of at least 40mmHg

Carotid bifurcation – superior border thyroid cartilage
Carotid sinus (IX) baroreceptors
Carotid body (IX X) chemoreceptors

• Internal and external carotid arteries
• Internal jugular vein

Nerves=
Glossopharyngeal
Vagus
Spinal accessory
Hypoglossal
Cervical sympathetic trunk
Ansa cervicalis

Question 7

name the branches of the external carotid artery

Answer 7

Some Anatomists Like Frolicking, Others Prefer Scaring Medical students

Branches of External Carotid:
* Superior Thyroid artery
* Ascending pharyngeal
* Lingual (lower jaw) !
* Facial (to face)!
* Occipital
* Posterior auricular
* Superficial temporal
* Maxillary (to maxilla; inside the skull)!

Question 8

what do u have inside carotid sheath

Answer 8

Carotid sheath:
Common and internal carotid arteries, internal jugular vein and CNX
- Escaping upper sheath are CN IX, superior laryngeal N. spinal root of CN XI and CN XII
- Ansa cervicalis is over IJV (internal jugular vein)
Ascending sympathetic fibres use internal carotid artery for support

Question 9

which nerve lies between the internal jugular vein + common carotid artery

Answer 9

The vagus nerve accompanies the internal jugular vein medially in the carotid sheath and lies between the IJV and the common carotid artery

Question 10

during a carotid triangle surgery, a patient came out with an alteration in voice. What nerves have been damaged?

Answer 10

damage or compression of vagus or recurrent laryngeal nerves during surgery may produce an alteration in voice as these nerves supply laryngeal muscles

Question 11

how do we do an IJV puncture

Answer 11

we know its infront of carotid artery, it is next to sternoclaidomastoid. We now use a ultrasound to identify this!

Question 12

do the following veins have valves:
1) vena cava
2) brachiocephalic vein

Answer 12

there are NO VALVES in vena cava or brachiocephalic vein

Question 13

the jugular venous pulse (JVP) is pulsations from which jugular vein, and what info does JVP give us

Answer 13

JVP is pulsations from INTERNAL JUGULAR VEIN

gives us info about right atrial pressure

Question 14

1) which muscles depress the hyoid bone + larynx during swallowing + speaking.

2) which muscles move larynx as a whole

Answer 14

1) infrahyoid (strap) muscles depress hyoid + larynx during swallowing + speaking

3) extrinsic muscles (suprahyoid + infrahyoid muscles) move larynx as a whole; these muscles are innervated by the facial nerve, the mandibular branch of trigeminal nerve and ansa cervicalis

Question 15

Intrinsic muscles move the laryngeal components (aka components of larynx), altering the length and tension of the vocal folds and size and shape of rima glottides(aperture between vocal folds) = so that we can speak. What is the innervation of these muscles

Answer 15

innervated by vagus CN X

specifically:

* Cricothyroid  - superior laryngeal N (CN X)

• All others in larynx - recurrent laryngeal N (CN X)

n.b the rima glottidis looks like the opening of a vagina

Question 16

when u whisper, the vocal ligaments are strongly adducted but which muscles are relaxed?

Answer 16

Whispering ;
Vocal ligaments strongly adducted but relaxed arytenoids

Question 17

explain the muscle movements with the following
* normal respiration
* deep respiration
* phonation (speaking)

Answer 17

Rima glottidis = aperture between vocal folds

Normal respiration:
Laryngeal muscles relaxed and rima glottidis narrow slit

Deep respiration:
Vocal ligaments abducted by contraction of posterior cricoarytenoid muscles – rima glottidis opens widely

Phonation:
Arytenoid muscles adduct arytenoid cartilages at same time lateral cricoarytenoids moderately adduct vocal ligaments

Air forced between vocal ligaments = sound

Question 18

the recurrent laryngeal nerve (branch of CN X) is a motor to most muscles of larynx
* which artery does the left recurrent laryngeal nerve loop under
* which artery does the right recurrent laryngeal loop under?

Answer 18

Recurrent laryngeal nerve:
Motor to all other intrinsic muscles of the larynx and sensory to area below vocal folds
* On **left **recurrent laryngeal loops under the arch of the aorta
* On right recurrent laryngeal loops under the **right subclavian **artery

Question 19

what are the symptoms of the superior laryngeal nerve

Answer 19

Can occur during thyroidectomy or through compression or goitre

it will cause:

• Anaesthesia of superior laryngeal mucosa
• absence of cough reflex (an important protective mechanism)
• A monotonous voice; because paralysed cricothyroid (unable to vary length and tension – but may go unnoticed)