anterior triangle of the neck Flashcards
what muscle forms the posterior border of the anterior triangle of the neck ?
sternocleidomastoid
what are the boundaries of the anterior triangle of the neck?
anterior border - imaginary midline of the neck
posterior boundary - anterior border of SCM
base - mandible
what are the divisions of the anterior triangle of the neck?
submental
submandibular
carotid
muscular
what is the platysma?
a thin layer that covers the anterior and lateral surfaces of the neck
what muscle group is platysma classified as part of?
classified as a muscle of facial expression
what is the function of platysma?
acts to tighten the skin of the neck
what nerve innervates platysma?
CN 7 (facial nerve)
where do the internal and external jugular veins lie?
external jugular vein - anterior to SCM (in posterior triangle of the neck )
internal jugular vein- posterior to SCM (in anterior triangle of the neck)
where does the facial vein drain into?
into the internal jugular vein
what vein does the internal jugular vein join with and what vein do these two veins form?
the internal jugular vein joins w/ the subclavian vein to form the brachiocephalic vein (one on either side)
what is the cervical plexus formed from?
the anterior rami of C1-C4
what is the function of the cervical plexus?
the nerves from the cervical plexus give motor supply to some of the muscles of the anterior triangle and the sensory nerves supply the skin of the neck
how do the motor branches from the cervical plexus supply the supra and infra hyoid muscles of the neck?
the motor branch form a loop of nerve tissue (ansa cervicalis) to supply some of the supra and infrahyoid muscles
the ansa cervicalis contains nerve fibres from where?
C1-C3
where does the ansa cervicalis sit?
on the anterior surface of the carotid sheath
where does the hyoid bone lie?
between the mandible and the larynx
what muscles attach to the hyoid bone?
suprahyoid muscles and infra hyoid muscles
what is the general function of the supra hyoid muscles?
generally act to raise the hyoid bone
what are the supra hyoid muscles?
mylohyoid
digastric
stylohyoid
geniohyoid
describe digastric muscle
digastric has two muscle bellies that are divided by a small tendon that passes through a loop of connective tissue that is attached to the hyoid bone
where does the anterior belly of digastric attach?
the mandible
where does the posterior belly of digastric attach?
the mastoid process of the temporal bone
where does stylohyoid attach?
to the styloid process of the temporal bone
where does mylohyoid attach?
to the mylohyoid line of the mandible
what muscles forms a diaphragm in the floor of the oral cavity?
mylohyoid
what muscle lies deep to mylohyoid?
geniohyoid
where does geniohyoid attach?
to the inferior genial tubercle of the mandible
what nerve innervates the posterior head of digastric and stylohyoid?
the facial nerve
what nerve supplies the muscles of mastication?
the mandibular division of the trigeminal nerve
describe the innervation of geniohyoid
geniohyoid is supplied by nerve fibres from the C1 nerve root that are carried to geniohyoid via the hyoglossal nerve (CN11)
what is the general function of the infrahyoid muscles?
generally act to depress the hyoid bone and thyroid cartilage
what are the superficial infrahyoid muscles?
omohyoid
sternohyoud
what are the deeper infrahyoid muscles?
sternothryoud
thryohyoid
describe the innervation of the infrahyoid muscles
they are all innervated by the ansa cervicalis except thryhyoid which is innervated by C1 via the hyoglossal nerve
where do the supra hyoid bones lie?
between the hyoid bone and the skull or mandible
where do the infrahyoid bones lie?
between the hyoid bone and the sternum or thyroid cartilage
where does the left common carotid arise from?
a direct branch of the aorta
where does the right common carotid artery arise from?
the brachiocephalic trunk
what is the standard branching pattern of the common carotid artery?
typically only branches into its terminal branches of internal and external carotid arteries
where does the common carotid artery bifurcate into internal and external carotid arteries?
between the thyroid cartilage and the hyoid bone (C3-C4)
what is the organisation of structures in the carotid sheath?
the vagus nerve lies between the common carotid artery and the internal jugular vein
what are the three branches of the external carotid artery?
the superior thyroid artery
the inguinal artery
the facial artery
where do the three branches of the external carotid lie?
in the anterior triangle of the neck
where does the superior thyroid artery go?
down the neck to the thyroid gland
where does the lingual artery go?
into the floor of the oral cavity to supply the tongue
where does the facial artery go ?
crosses the anterior surface of the mandible to supply the face
via which branch does the subclavian artery supply the thoracic wall?
via the internal thoracic branch
via which branch does the subcialvian artery supply the brain?
the vertebral branch
via which branch does the subclavian artery supply the structures in the neck?
thryocervical trunk
what is cranial nerve 10?
the vagus nerve
how does the vagus nerve supply the structures of the neck?
via its laryngeal branches
describe the course of the recurrent laryngeal nerve
the recurrent laryngeal nerve descends into the thorax where it wraps around the arch of the aorta on the left and the subclavian artery on the right before ascending the neck, lying between the oesophagus and trachea
what does the recurrent laryngeal nerve supply?
many intrinsic muscles of the larynx
where does the thyroid gland lie?
deep in the anterior triangle covered by the infrahyoid muscles
describe the structure of the thyroid gland
it is formed from 2 lobes connected by an isthmus
what lies on the posterior surface of the thyroid gland?
the parathyroid glands
describe the arterial supply to the thyroid gland
there is one superior thryoid artery and one inferior thyroid artery on each side
where does the superior thyroid artery arise from?
it is the first anterior branch of the external carotid artery
where does the inferior thyroid artery arise from?
it is a branch of the thryocervical trunk from the subclavian artery
describe the venous drainage of the thyroid gland
there are three thyroid veins either side (superior middle and inferior)
where do the superior thyroid veins drain into?
the internal jugular vein
where do the middle thyroid veins drain into?
the internal jugular vein
where do the inferior thyroid veins drain into?
the L brachiocephalic trunk (both left and right inferior thyroid veins drain into the L brachiocephalic vein)
what are the three sets of salivary glands?
parotid
submandibular
sublingual
what is the function of all salivary glands?
all salivary glands act to pass saliva into the mouth to lubricate the bolus of food and make it easier to swallow
describe the location of the submandibular salivary gland
the small outer part of the submandibular salivary gland lies in the anterior triangle and is crossed by the facial nerve
the rest of the submandibular salivary gland lies in the floor of the mouth
how does the submandibular salivary gland pass saliva into the mouth?
via a duct between the first and second lower incisor teeth
what is the innervation of the submandibular salivary gland?
the facial nerve supplies parasympathetics and secretomotor supply to the submandibular gland
where does the thoracic duct empty lymph into the venous system?
deep in the anterior triangle
usually at the junction of the internal jugular and subclavian veins as they form the brachiocephalic vein
