Posterior Triangle Flashcards
What are the boundaries of the posterior triangle? Anterior border: Posterior border: Inferior border: Roof: Floor: Subdivisions:
Anterior border: Sternocleidomastoid
Posterior border: trapezius m.
Inferior border: clavicle
Roof: investing fascia, platysma, superficial fascia, skin
Floor: deep (prevertebral) fascia over scalene muscles
Subdivisions: omohypoid m. into occipital triangle superiorly, and Omoclavicular or Supraclavicular triangle inferiorly
What are the muscles within the posterior triangle?
omohyoid
splenius capitis
levator scapulae
scalene muscles
OINF Anterior scalene
O: anterior tubercles of transverse processes C3-6
I: scalene tubercle of 1st rib (of Lisfranc)
N: C4-6
F: elevate 1st rib (forced inspiration), flex and laterally flex neck
OINF Middle scalene (largest and longest)
O: transverse processes C1-2 posterior tubercles of transverse processes C3-7
I: upper surface of 1st rib
N: C3-8
F: elevate 1st rib (forced inspiration), laterally flex neck
OINF Posterior scalene
O: posterior tubercles of transverse processes C4-6
I: upper surface of 2nd rib
N: C5-7
F: elevate 2nd rib (forced inspiration), laterally flex neck
Describe carotid sheath.
carotid artery, internal jugular vein, vagus nerve (important reference point)
contains 3 vessels: internal carotid, common carotid, and internal jugular
2 nerves: vagus and superior ramus of ansa cervicalis
Where can I find the phrenic nerve? What is its function?
on top of anterior scalene, immediately deep to subclavian vein
(3,4,5 keep diaphragm alive)
innervates diaphragm.
The inferior belly of the omohyoid muscle divides the posterior triangle into two smaller triangles. What/where are they?
Occipital triangle- above omohyoid omoclavicular triangle (supraclavicular)- below omohyoid
Describe where the scalene muscles originate and insert.
Originate from transverse processes. Insert on 1st rib (middle and anterior scalene) and on 2nd rib (posterior scalene).
Middle scalene (biggest) … C2-C6
Anterior scalene- C3,4,5
cutaneous branches of cervical plexus
From C2 and C3:
great auricular nerve
lesser occipital nerve
transverse cervical nerves
From C3 and C4: supraclavicular nerves (splits into three branches; medial (or anterior) intermediate lateral) lays on clavicle
(assessory nerve also in occipital triangle but is MOTOR branch)
Describe accessory nerve.
From medulla oblongata. motor to sternocleidomastoid and trapezius muscles.
What is Erb’s point?
area halfway along the posterior border of the sternocleidomastoid muscle. important nerves emerge. (great auricular, transverse cervical, supraclavicular, accessory nerve)
What does the motor portion of the cervical plexus consist of? Where is it found?
C1-C4
Lies deep to the sensory portion and much of it can be found in the carotid triangle. Lays on carotid sheath.
Consists of: phrenic n, ansa cervicalis and C1 branches, ventral rami
What are the two limbs/roots of the Ansa Cervicalis?
C1 ventral ramus - provides separate motor innervation to the thyrohyoid and geniohyoid muscles and also forms superior root of the Ansa Cervicalis
C2 and C3 rami- combine to form Inferior root of Ansa Cervicalis, innervates sternohyoid, sternothyroid and omohyoid mm.
Where does ventral rami (of motor portion of cervical plexus) go?
directly to rectus capitis lateralis, rectus capitis anterior, longus capitis, longus colli, levator scapulae and scalene muscles
