Posterior & Anterior Triangles

Posterior & Anterior Triangles

1. neck

   • facial plane divide neck into 4 main facial compartments
     • 1st compartment
       • largest; includes other 3
       • surrounded by investing fascia
         • surrounds superficial mm. (trapezius & SCM)
     • 2. anterior or visceral compartment
       • contains parts of digestive, respiratory system, several endocrine glands (*buccopharyngeal*)
       • surrounded by pretracheal layer (fascia)
         • muscular portion
           • pretracheal lamina encloses infrahyoid mm.
         • visceral fascia
           • Thyroid, pharynx*, larynx, esophagus*, trachea
     • 3. posterior cmpt
       • contains cervical vertebrae, spinal cord, cervical nn., mm. assoc. w/ vertebral column (support column)
       • surrounded by prevertebral layer (fascia)
         • surrounds epaxial mm., scalene mm., vertebra in continuous sheath
     • 4. vascular cmpt
       • one on each side, lateral, contain vagus n. (X) and major BV
       • surrounded by carotid sheath
         • surrounds carotid a., internal jugular v. , vagus n.
     • provide ideal pthwy for spread of infection from oral cavity to thorax
       • "danger space"
         • between pretracheal (buccopharyngeal) & prevertebral fascial
           • 2 parts
             • retropharyngeal space
               • base of skull to C7
             • prevertebral space
               • base of skull to diaphragm
         • communicate w/ post. mediastinum; spread infection from head/neck to thorax

2. SCM divides neck into ant. & post triangles

   • posterior triangle
     • boundaries
       • anterior
         • posterior border of SCM
       • base
         • superior border of clavicle
       • posterior
         • anterior border of trapezius
       • floor
         • prevertebral fascia & splenius capitis, levator scapulae, all 3 scalenes
           • CN XI crosses levator scapulae anteriorly
           • anterior scalene
             • phrenic nerve crosses anteriorly
     • divided into 2 smaller triangles by inferior belly of omohyoid
       • occipital
       • supraclavicular (subclavian)
         • contains subclavian a.
     • contents
       • nerves
         • brachial plexus (C5-8, T1)
           • provides motor & sensory information for the upper limb
         • cervical plexus C1-4
           • sensory innervation to upper thorax & neck
           • Erb's pont
             • lesser occipital
             • Transverse cutaneous (cervical) nerve of the neck
             • Gr. auricular
             • supraclavicular
         • spinal accessory n. CN XI
           • innervates SCM & trapezius
           • found on top of levator scapulae m.
       • aa. & vv.
         • subclavian a. & v.
     • Clinical
       • Cervical plexus block
       • brachial plexus block
       • accessory n. CN XI
         • unilateral paralysis of trapezius is noticeable by a shoulder drop
           • torticollis
   • innervated by CN XI (accessory n.); action unilateral & bilateral contraction

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