Posterior Triangle

Question 1

What are the boundaries of the Posterior triangle?

Answer 1

1. Anteriorly, by the posterior edge of SCM
2. Posteriorly by anterior edge of trapezius muscle
3. BASE: middle of 1/3 clavicle
4. APEX: the occipital bone just posterior to the mastoid process

Question 2

STERNOCLEIDOMASTOID MUSCLE STERNAL HEAD (4)

Answer 2

1. ORIGIN: upper part of anterior surface of manubrium of sternum
2. INSERTION: lateral 1/2 of superior nuchal line
3. INNERVATION: accessory nerve [XI] and branches from anterior rami of C2 to C3 (C4)
4. FUNCTION:individually tilt head towards shoulder on same side,
   rotating head to turn face to pop side
   - ACTING TOGETHER: draw head forwards

Question 3

STERNOCLEIDOMASTOID MUSCLE - CLAVICULAR HEAD (4)

Answer 3

1. ORIGIN: superior surface of medial 1/3 of clavicle
2. INSERTION: lateral surface of mastoid process
3. INNERVATION: Accessory nerve (XI) and branches from C2-C3(C4)
4. FUNCTION:
   - Individual= tilt head towards shoulder on same side, rotating head turn face opposite side
   ACTING TOGETHER: draw head forwards

Question 4

TRAPEZIUS(4)

Answer 4

1. ORIGIN:
   - superior nuchal line
   - external occipital protuberance
   - ligamentum nuchae
   - spinous processes of vertebrae CVII to TXII
2. INSERTION:
   - lateral 1/3 of clavicle
   - acromion
   - spine of scapula
3. INNERATION: motor accessory nerve (XI); proprioception - C3 AND C4
4. . FUNCTION; assists scapula during abduction go humerus above horizontal
   - upper fibers- elevate
   - middle fibres= ADDUCT
   - lower fibres = depress scapula

Question 5

Splenius Capitis (4)

Answer 5

1. ORIGIN:
   - lower half of ligament nuchal
   - spinous processes of vertebrae CVII to TVI
2. INSERTION:
   - mastoid process,
   - skull below lateral 1/3 of superior nuchal line

3.INNERVATION: posterior rami middle cervical nerves

FUNCTION:
- together draw head backwards individually

• draw and rotate head to one side (turn face to same side)

Question 6

Levator scapulae (4)

Answer 6

1. ORIGIN:Transverse processes of C1 TO C4
2. INSERTION: upper part of medial border of scapula
3. INNERVATION:C3,C4 and dorsal scapular nerve (C4,C5)
4. FUNCTION: elevates the scapula

Question 7

POSTERIOR SCALENE

Answer 7

1. ORIGIN: posterior tubercles of vertebrae CIV to CVI
2. INSERTION: Upper part of medial border of scapula
3. INNERVATION: anterior rami of C5 TO C7
4. F: elevation rib II

Question 8

MIDDLE SCALENE:

Answer 8

1. O: transverse processes of vertebrae CII to CVII
2. I: upper surface of rib 1 between tubercle and groove for subclavian artery
3. INNERVATION: anterior rami of C3-C7
4. FUNCITON: elevation of rib 1

Question 9

Anterior scalene

Answer 9

1. O: Anterior tubercles fo transverse processes of vertebra CIII TO CVI
2. I: scalene tubercle and upper surface of rib I
3. INN: anterior rami of C4 TO C7
4. FUNCTION: el. rib 1

Question 10

OMOHYOID

Answer 10

1. O: superior border fo scapula medial to scapula notch
2. I: inferior border of body of hyoid bone
3. INN: ansa cervicalis; anterior rami of C1 AND C3
4. depress the hyoid bone

Question 11

What divides the posterior triangle and what subdivisions are formed

Answer 11

1. Omohyoid muscle splits the posterior triangle of neck into 2
2. OCCIPITAL TRIANGLE: larger, superior part
3. SUBCLAVIAN TRIANGLE: contains distal portion of the subclavian artery

Question 12

What are the muscle contents of the posterior triangle?

Answer 12

1. OMOHYOID MSUCLES: split into 2 bellies by tendon where the inferior belly crosses post triangle splitting to 2. Then cross underneath SCM to enter anterior triangle of neck
2. VERTEBRAL MUSCLES: ( covered by prevertebral fascia) form the floor of the posterior triangle:
   - spleius capitis
   - levator scapulae
   - anterior, middle and posterior scalene

Question 13

What are the vessel contents in the posterior triangle?

Answer 13

1. EXTERNAL JUGULAR VEIN: in here it will join the subclavian vein
2. SUBCLAVIAN , TRANSVERSE CERVICA, SUPRASCAPULAR VEINS AND ARTERIES

Question 14

Neve contents in the posterior triangle

Answer 14

1. accessory nerve (CN XI)
2. cervical plexus: forms the muscles of the floor of the post triangle
3. phrenic nerve
4. the trunks of the brachial plexus also cross floor of post triangle