Neck: anterior triangle

Question 1

borders of posterior triangle?

Answer 1

roof: cervical investing fascia
anterior: SCM
posterior: trapezius
inferior: clavicle
floor: prevertebral fascia

• passage of omohyoid divides posterior triangle into occipital triangle superiorly and smaller supraclavicular triangle *

Question 2

what is contained in the posterior triangle?

Answer 2

• external jugular v.
• cutaneous n. plexus
• spinal accessory nerve
• brachial plexus
• inferior belly of omohyoid
• third portion of subclavian a, transverse cervical, suprascapular, descending/dorsal scapular and occipital aa.
• deep cervical lymph nodes

Question 2

spinal accessory n.

Answer 2

CN XI
GSE
- exits jugular foramen b/w internal carotid artery and vein.
- provides innervation to SCM, exits muscle on its medial posterior surface.
- crosses floor of posterior triangle obliquely and will pass deep to trapezius to innervate it (along with C3 and 4)

Question 2

what part of brachial plexus is seen in posterior triangle? where does it pass? clinical correlation?

Answer 2

roots of ventral rmi of spinal nn. C5-T1

• pass between the anterior and middle scalene muscle
• hypertrophy of the middle scalene and anterior scalene can cause thoracic outlet syndrome
• the axillary sheath, trunks and chords of the pass through the cervicoaxillary canal to enter axilla.

Question 2

what 5 branches of brachial plexus are present in the neck?

Answer 2

1. dorsal scapular n (C5): goes to levator scapulae
2. accessory phrenic n: (branch of C5) descends parallel to phrenic n. on lateral surface of anterior scalene.
3. nerve to subclavius: upper trunk of C5,6: descends anterior to brachial plexus, dives into subclavius muscle.
4. suprascapular n (C5,6): goes to supraspinatus and infraspinatus muscle
5. long thoracic n (C5,6,7): descends on lateral surface of serratus anterior

Question 2

occipital artery

Answer 2

5th branch of external carotid artery, passes from behind SCM at apex of triangle and ascends posterior to scalp along with greater occ. n.

Question 2

Transverse cervical and suprascapular artery

Answer 2

branches of the thyrocerviclal trunk (from 1st portionof subclavian a.)
- cross triangle inferiorly and deep to belly of inferior omohyoid

• transverse cervical a (above) exits posterior triangle deep to trapezius which it supplies
• suprascapular: passes to the scapular region

Question 2

what portion of subclavian is located in posterior triangle?

Answer 2

third portion
- located in anterior inferior portion of triangle, it passes between the anterior and middle scalene muscles along with brachail plexus, invested in prevertebral fascia

Question 2

what are the deep nodes of the posterior triangle?

Answer 2

1. Accessory Nodes (accompany spinal accessory n.):
   - receive lymph from superficial nodes behind the ear (retro-auricular and occipital)
2. Transverse cervical nodes (accompany transverse cervical n.) - receive lymph from under trapezius through accessory chain of nodes
   * both drain to inferior deep cervical nodes (along internal jugular v. to jugular lymphatic trunk to internal jugular/subclavian v.)