Week 2: Head and Neck 1 - Front of neck Flashcards
Where is the hyoid bone located?
- C3 Vertebral level
- just above the thyroid cartilage
At what vertebral level is the thyroid cartilage?
C4-5
Where is the cricoid cartilage?
- below the thyroid cartilage
- C6 vertebral level
Where is the trachea?
- can be felt at the anterior neck below the larynx
- spans vertebral levels C6-T4
Where does the sternocleidomastoid muscle run between?
from the mastoid process of temporal bone (behind ear) to the sternum
What are the anterior and posterior triangles of the neck divided by?
sternocleidomastoid muscle
What are the boundaries of the posterior triangle?
base - clavicle
anterior boundary - posterior margin of sternocleidomastoid
posterior boundary - anterior margin of trapezius
What are the contents of the posterior triangle?
- trunks of the brachial plexus
- spinal accessory nerve (CN VI)
- inferior belly of omohyphoid muscle
- external jugular vein
Stab wounds in the posterior triangle may damage the upper trunk of the brachial plexus and/or the apex of the lung - why?
apex of lung is between the clavicles and the cricoid cartilage
What would happen if the external jugular vein is severed?
air will be drawn into the vein, producing cyanosis and can stop blood flow through the right atrium
Which muscles are supplied by the accessory nerve? (CN XI)
- sternocleidomastoid muscle
- trapezius
Explain how we can follow the external jugular vein down its course?
- forms near the angle of the mandible and descends through the neck coursing medially to laterally across the sternocleidomastoid muscle towards the middle of the clavicle to drain into the subclavian vein
- follow imaginary line from earlobe, across angle of mandible to the middle of clavicle, passing superficial to SCM
What are the boundaries of the anterior triangle?
posterior boundary - anterior margin of sternocleidomastoid
anterior boundary - midline of neck
What are the contents of the anterior triangle?
- lobes of the thyroid gland
- suprahyoid muscles
- infrahyoid muscles
- common carotid artery
- internal and external carotid arteries
- internal jugular veins
Where do the infra hyoid muscles lie?
distal to the hyoid bone
What is the function of the infra hyoid muscles?
depressing the hyoid bone during swallowing
What are the 4 infra hyoid muscles?
- sternohyoid
- sternothyroid
- thyrohyoid
- omohyoid
Which two infra hyoid muscles are superficial?
omohyoid and sternohyoid
Which two infra hyoid muscles are deeper?
sternothyroid and thyrohyoid
Which nerve are the infra hyoid muscles innervated by?
sternohyoid, sternothyroid, omohyoid - ansa cervicalis
thyrohyoid - branch of the ventral ramus of C1 from the cervical plexus
Where are the supra hyoid muscles?
- lie above the hyoid bone
- form the floor of the mouth
What is the function of the supra hyoid muscles?
moving the hyoid bone during swallowing
What are the two bellies of digastric muscle and where do they arise from?
anterior belly - arises from the digastric fossa of the mandible
posterior belly - arises from the mastoid process of the temporal bone
What are the functions of the digastric muscles?
- stabilises the hyoid during swallowing - this protects the airway while eating
- depresses the mandible for jaw opening, chewing and speech
What are the 4 suprahyoid muscles?
- mylohyoid muscle
- digastric muscle
- stylohyoid muscle
- geniohyoid muscle