Neck Triangles Flashcards
hyoid bone
- U-shaped
- located at C3, palpable
- suspended by stylohyoid ligament
- aids in tongue movement
anterior triangle borders
inferior border of mandible
anterior border of SCM
midline of neck
anterior triangle fascia
roof = deep investing
floor = pretracheal, carotid sheath
anterior triangle subdivisions
- submandibular
- submental
- carotid
- muscular
submandibular anterior triangle
submandibular gland, lymph nodes, parts of CN XII, mylohyoid nerve, part of facial artery/vein
submental anterior triangle
under tip of chin
submental lymph nodes, small veins
carotid anterior triangle
between SCM + omohyoid superior belly
contains;
- thyroid gland, larynx, pharynx, carotid sheath, branches of cervical plexus, superior root of anse cervicalis, lymph nodes, part of CN XI + XII
muscular anterior triangle
between SCM, omohyoid
contains sternohyoid, sternohyoid, thyroid, parathyroid glands
carotid sheath contains
medially
- common carotid artery
- internal carotid artery
- external carotid artery
laterally
- internal jugular vein
posteriorly
- CN X
common carotid bifurcates into internal and external
how to tell them apart?
internal carotid supplies the brain
external supplies head and neck = branches off to supply the thyroid [superior thyroid] and others
suprahyoid muscles list
- mylohyoid
- digastric
- stylohyoid
- geniohyoid
suprahyoid muscles function
raise the hyoid bone, as required for swallowing
mylohyoid location and action
location = originates at mylohyoid line of mandible, inserts body of hyoid and fibres of opposite mylohyoid
action = elevates hyoid and forms the floor of the oral cavity
digastric location and actions
anterior and posterior belly
location
ANTERIOR = digastric fossa on lower mandiblE
POSTERIOR = originates on mastoid notch of mastoid process
both insert at attachment of intermediate tendon at hyoid
actions
ANTERIOR = raises hyoud and opens mouth by lowering mandible
POSTERIOR = elevates and retracts hyoid bone
stylohyoid location and action
location = originates at stylohyoid prcoess and inserts into body of hyoid
action = pulls hyoid bone upward
geniohyoid location and action
location = orginates from mandible, inserts at body of hyoid, superior to mylohyoid
action = fixed mandible, elevates and pulls hyoid forward
fixed hyoid, pulls mandible downward and inward
innervation of suprahyoid muscles
mylohyoid = CN V3 inferior alveolar [nerve to mylohyoid]
anterior digastric = nerve to mylohyoid
posterior digastric = digastric branch of CN VII
stylohyoid = CN VII
geniohyoid = anterior ramus of C1, travels wth CN XIII
infrahyoid muscles list
- sternohyoid
- omohyoid
- thyrohyoid
- sternothyroid
infrahyoid function
‘strap’ muscles
depress of fix hyoid bone, provide attachment for suprahyoid muscles
sternohyoid location and action
location = originates at posterior surface of sternoclavicular joint, inserts into body of hyoid medially
action = depresses hyoid after elevation during swallowing
omohyoid location and action
inferior and superior
superior = inserts into body of hyoid laterally
inferior = inferior belly orginates at superior border of scapula
attached by a tendon which attaches to clavicle with fascia sling
actions = depresses and fixes hyoid
thyrohyoid location and action
location = originates at oblique line at thyroid cartilage, inserts into greater horn and adjacent body of hyoid
actions = depresses hyoid, raise larynx when hyoid is fixed
sternohyoid location and action
location = orginates at posterior surface of manubrium, inserts into oblique line on thyroid cartilage
action = draws the larynx downward
infrahyoid muscles innervation
sternothyroid, omohyoid, sternohyoid = anterior rami of C1 - C3
thyrohyoid = anterior rami of C1 but fibres run with CN XII
common carotid artery can be split into right and left
where are they branches from
right = branch of brachiocephalic trunk
left = direct branch from aortic arch
where do the ICA and ECA come from
branches of common carotid
at level C3/C4
does the internal carotid artery have branches
no
ascends to enter carotid canal and supply the brain
external carotid artery branches
8 branches [SAOLFPSM]
- superior thryoid
- ascending pharyngeal
- occipital
- lingual
- facial
- posterior auricular
- superficial temporal
- maxillary
internal jugular vein functions
drains blood from brain, skull, face and parts of the neck
continuation of sigmoid sinus, exits skulls via jugular foramen and enters carotid sheath, lateral to CCA
veins draining into internal jugular vein
inferior petrosal sinus
pharyngeal
occipital
facial
lingual
superior thyroid
middle thyroid
what does the internal jugular vein join as it reaches the clavicle
joins subclavian vein to become brachiocephalic vein
thyroid gland 4 features
pyramidal lobe [central]
right lobe
isthmus
left lobe
thyroid gland features = where on the neck
within visceral neck component
R+L extends from thryoid cartilage to 5th tracheal ring
isthmus = 3rd tracheal ring
thyroid gland arterial supply and venous drainage
ARTERIAL
- superior thyroud artery [ECA]
- inferior thyroid artery [branch of thyrocervical from subclavian]
VENOUS
- superior thyroid vein [into IJV]
- middle thyroid vein [into IJV]
- inferior thyroid vein [into bracheocephalic]
parathyroid gland
2 pairs of small glands, posterior surface of thyroid
inferior thyroid artery supplies it
venous drainage same as thyroid
relationship of thyroid and parathyroid
both innervated by thyroid branches from cervical (sympathetic) ganglia
recurrent laryngeal nerve palsy
concern of neck surgery[cervical spine]
due to the proximity of recurrent laryngeal nerves to trachea and oesophagus and glanfs
posterior triangle borders
posterior border of SCM
anterior border of trapezius
middle 3rd of clavicle and occipital bone
posterior triangle fascia
roof = deep investing, around muscles
floor = prevertebral fascia
what is fascia
thin connective tissue
posterior triangle muscles
- sternocleidomastoid
- trapezius
- anterior scalene
- middle scalene
- posterior scalene
sternocleidomastoid location and action
location = sternal head from manubrium of sternum, clavicular head from medial 3rd of clavicle
actions = draws head forward, tilts head towards ipsilateral shoulder while turning face contralaterally
trapezius location and action
location = superior nuchal line, inserts into lateral 3rd of clavicle
actions = rotating scapula during abduction of humerus, upper fibres elevate, middle abduct, lower depresses scapula
CN XII importance in posterior triangle
spinal accessory
innervates SCM and trapezius
controls px ability to shrug shoulders
levator scapulae location and action
location = C1-C4, inserts into scapula [upper medial border]
action = elevates scapula
innervation = C3, C4 and dorsal scapular nerve C4 C5
anterior scalene location and action
location = C3-C6, inserts into upper surface of rib 1
action = elevates 1st rib
middle scalene location and action
location = originates C4-C7, inserts into rib 1
action = elevates 1st rib
anterior and middle scalene is innervated by;
anterior rami of C4-C7 [and C3 for anterior]
cervicular plexus
Complex neurological structure located within head and neck - communication between anterior divisions of C1-C4 nerves
Located in posterior triangle, halfway up SCM within prevertebral fascia
Formed by the anterior rami of C1-C4
muscular branches of cervicular plexus
- phrenic nerve [C3,4,5]
- asna cervicalis [C1,2,3]
- ## branches to prevertebral and vertebral muscles
cutaneous branches of cervical plexus
- C2 [ lesser occipital nerve]
- C2,3 [great auricular, transverse cervicular nerve]
- C3,4 [supraclavicular nerve]
superficial venous drainage of the neck done by;
external jugular vein - crosses SCM, drains into subclavian
anterior jugular vein - draisn into external jugular vein
hypoglossal nerve CN XII
passes inferior angle of mandible, crosses ICA/ECA to tongue
innervates extrinsic and intrinsic muscles of tongue
phrenic nerve
orginates from cervical necks in neck C3,4,5
innervates diaphragm - crucial role in breathing
runs posterior to subclavian vein
subclavian artery and vein
lies below clavicle
provides blood supply to bilateral extremities with contributions to head/neck
Horner’s syndrome
caused due to damage to cervical sympathetic trunk
anterior approach to cervical spine
