Floor Of The Posterior Triangle

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The prevertebral fascia forms the floor of the posterior triangle of the neck (Figure 26-1C and D).

The following structures are superficial to the prevertebral tascia:

Interior belly ot the omohyoid muscle. Courses from the hyoid bone en route to the scapula within the pretracheal fascia.

Transverse cervical artery. A branch from the thyrocervical trunk that courses along the floor of the posterior triangle en route to the deep surface of the trapezius muscle. The artery bifurcates into a superficial branch, which courses superficial to the rhomboid muscles, and a deep branch, which courses deep to the rhomboid muscles.

Suprascapular artery. The most inferior branch from the thyrocervical trunk, the suprascapular artery courses across the anterior scalene muscle and the phrenic nerve, where it crosses over the superior transverse scapular ligament to enter the supraspinous fossa.

Spinal accessory nerve [cranial nerve (CN) XI]. Exits the jugular foramen and obliquely descends along the preverte-bral fascia en route to the sternocleidomastoid and trapezius muscles.

VThe spinal accessory nerve is one of the more vulnerable structures during any surgical procedure involving the posterior triangle of the neck. During surgery, careful isolation and protection of this nerve is essential to avoid spinal accessory nerve damage.

The following structures are deep to the prevertebral fascia: Cervical muscles, from superior to inferior:

• Splenius capitis

• Levator scapulae

• Posterior scalene

• Middle scalene

• Anterior scalene (notice that the phrenic nerve descends vertically along the anterior surface of the anterior scalene muscle en route to the thoracic cavity). ▼

Brachial plexus and subclavian artery. The brachial plexus and the subclavian artery course between the anterior and middle scalene muscles, and as the nerve plexus and artery emerge from those muscles, they carry an extension of the prevertebral fascia along to form the axillary sheath.

V Thoracic outlet syndrome consists of a group of disorders related to the exit of the brachial plexus and the subclavian artery between the neck and the upper limb. Most disorders are caused by compression of the brachial plexus or subclavian artery. Compression may be caused by the clavicle, movement of the shoulder joint, or an enlargement of muscles surrounding the plexus or vessel. ▼

VThe region between the anterior and middle scalene muscles where the brachial plexus exits is referred to as the interscalene triangle. This region serves as a chosen site to administer nerve blocks for shoulder surgeries because the sensory branches to the shoulder and upper limb exit within the brachial plexus at this point. ▼

Investing fascia forming the roof over — the posterior triangle

1. Sternocleidomastoid m.

2. Trapezius m.

Investing fascia forming the roof over — the posterior triangle

Lesser occipital n.

Great auricular n.

Deep investing fascia

Lesser occipital n.

Great auricular n.

Deep investing fascia

Supraclavicular

External jugular v.

Transverse cervical n.

Supraclavicular nn.

External jugular v.

Transverse cervical n.

Supraclavicular nn.

Prevertebral fascia covering the floor of the posterior triangle

1. Anterior scalene m.

2. Middle scalene m.

3. Posterior scalene m.

Prevertebral fascia covering the floor of the posterior triangle

Prevertebral fascia covering the floor of the posterior triangle

Tmt Gelenk

Investing fascia (cut edges)

Inferior belly of omohyoid m.

Investing fascia (cut edges)

Inferior belly of omohyoid m.

KEY

1.

Anterior scalene m.

2.

Middle scalene m.

3.

Posterior scalene m.

4.

Levator scapulae m.

S.

Spenius capitis m.

e.

Trapezius m.

Phrenic n.

Transverse cervical a.

Sternocleidomastoid m (cut)

Spinal accessory n (CN XI)

Phrenic n.

Transverse cervical a.

Brachial plexus and subclavian a.

Suprascapular a.

Sternocleidomastoid m (cut)

Spinal accessory n (CN XI)

Brachial plexus and subclavian a.

Suprascapular a.

Neck Sheath

Inferior thyroid a.

Thyrocervical trunk

Subclavian a.

Figure 26-1: A. Boundaries of the posterior triangle of the neck. B. Cross-section and lateral view of the deep investing fascia surrounding the sternocleidomastoid and trapezius muscles. C. Cross-section and lateral view of the prevertebral fascia covering the prevertebral muscles. D. Prevertebral fascia removed from the posterior triangle of the neck.

Inferior thyroid a.

Thyrocervical trunk

Subclavian a.

External jugular v. (cut) entering the subclavian v.

Figure 26-1: A. Boundaries of the posterior triangle of the neck. B. Cross-section and lateral view of the deep investing fascia surrounding the sternocleidomastoid and trapezius muscles. C. Cross-section and lateral view of the prevertebral fascia covering the prevertebral muscles. D. Prevertebral fascia removed from the posterior triangle of the neck.

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Responses

  • rowan
    What is floor of posterior triangle?
    2 years ago
  • Iolo
    What is in the interscalene triangle?
    1 year ago

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