LEC 6: HEAD & NECK

• Mastoid process: bony landmark of temporal b. and is superior to mandible.
• Superior Anterior border of neck: defined by mandible
• Superior posterior border: defined by mastoid process
• Posterior neck is HIGHER than the anterior neck. \
• Inferior border of neck:

  Sternum - medially

  clavicle + acromion - laterally

  CVII - most inferior vertebrae
• 4 main compartments of neck:

  1. Visceral - contains digestive and respiratory systems
  2. Vertebral - 1/2 of neck; posterior; contains cervical vertebrae, spinal cord, and muscles
  3. Vascular (x2) - major blood vessels and vagus nerve.
• What is the smallest compartment containing:

  common carotid a.

  internal jugular v.

  X. vagus n.

  
  

  ANSWER: vascular compartment
• Seperated by layer of fascia surrounding

  vertebral compartment : pre-vertebral layer

  visceral compartment: pre-tracheal layer

  vascular compartment: carotid sheath
• Fascia of the neck:

  • Investing layer completely surrounds entire neck
  • Pre-vertebral layer surrounds vertebral column and associated muscles
  • Pre-tracheal layer surrounds trachea, esophagus and thyroid gland
  • Carotid sheath surround common carotid a.
• 7 cervical vertebrae in neck

  Foramina form longiturinal passage for blood vessels

  Characterized by:

  small bodies

  bifid spinous processes

  transverse processes with foramina
• • Occiptal condyle articulates with occipital bone of skull
  • CI - Atlas
  • CII - Axis
  • Atlas allows skull to rotate
  • Axis produced by dens
  • Dens articulates with transverse ligament of atlas
• Atlanto-occipital joint coincides with foramen magnum
• occipital + atlas CI + axis CII = Atlanto-occiptal joint
• hyoid bone:

  • floating bone
  • superior to larynx
  • DOES NOT articulate directly with any other skeletal element
  • strong bony anchor - floor of oral cavity, larynx, pharynx
• Parts of hyoid b. (3):

  • greater horn
  • less horn
  • body
• Stylohyoid:

  • styloid process -> lesser horn of hyoid b.
• Vertebral levels CIII/IV

  • Superior border of thyroid cartilage in larynx
  • Common carotid a. bifurcates --> external + internal carotid a.
• Vertebral levels C5/C6:

  • Lower limit of pharynx and larynx
  • Superior limit of trachea and esophagus
  • INF limit of pharynx (esophagus) + larynx (trachea)
• Triangle of neck:

  • Trapezius and sternocleidomastoid (SCM) define triangles
  • Anterior: structures pass between head and thorax
  • Posterior: structures pass between neck and upper limb
• anterior triangle of neck

  • ANT. border of SCM
  • INF border of mandible
  • Midline of neck
  • L + R unit form together @ midline
• Posterior triangle of neck

  • Posterior border of SCM
  • Anterior border of trapezius
  • Middle 1/3 of clavicle
• Posterior triangle sub triangles (2)

  • occipital triangle - occipital b.
  • omoclavicular/subclavian triangle
• omoclavicular triangle:

  • omohyoid muscle: SUP. border
  • clavicle b. - INF. border
• ligamentum nuchae:

  external occipital protuberance -> median nuchal line ---->> spinous processes of C1-10
• Posterior triangle muscles: SCM

  • two heads: sternal and clavicular
  • Origin SH: ANT. surface of manubrium of sternum
  • Insertion of SH: lateral half of SUP. nuchal line
  • Origin CH: superior surface of middle 1/3 of clavicle
  • Insertion CH: lateral surface of mastoid process
  • Action: Individually - tilt head toward shoulder on same side an rotate head to face opposite side. Together - draw head forward
  • Innvervation: Spinal Accessory n. (XI) and ANT. rami of C2-C3
• SCM + trapezius -> superficial muscle of neck -> deep to SCM + trap -> medial: splenius capitis + levator scapulae -> 3 scalenes: POST, MID, ANT. -> omohyoid muscle
• Posterior Triangle muscles: Trapezius

  Origin: superior nuchal line; external occipital protuberance; ligamentum nuchae; spinous processes of CVII-TXII

  Insertion: lateral 1/3; acromion and spine of scapula

  Action: upper fibers - elevate; middle fibers - adduct; lower fibers - depress scapula

  Innveration: Spinal accessory n. (XI)
• Posterior triangle muscles: spleniuscapitis

  • origin: lower half of ligamentum nuchae; spinous process of CVII - TVI
  • Insertion: mastoid process, skull below lateral 1/3 of of SUP. nuchal line
  • Action: together - draw head backwards; individually draw and rotate head to one side (turn face to same side)
  • Innvervation: POST. rami of middle cervical nerves
• Posterior Triangle Muscles: Levator Scapulae

  • Origin: transverse processes of CI-CIV
  • Insertion: upper part of medial border of scapula
  • Action: elevates scapula
  • Innervation: C3-4 and dorsal scapular n.
• Posterior triangle muscles: Scalenes (3)

  • Post Scalene
  • Middle Scalene
  • Anterior Scalene

  Action: elevate rib 1 and 2
• Posterior triangle muscles: omohyoid

  (omo-clavicle + hyoid)

  origin: superior border of scapula

  insertion: INF. border of body of hyoid b.

  Action: depress hyoid b.

  Innvervation: ansa cervicalis; ANT. rami of C1-3
• Posterior triangle vessels: External jugular v.

  • exits superficially to SCM
  • allows blood to drain from deep part of face + outside of skull including scalp + meninges
• INTERNAL jugular v. --> ANT. triangle --> jugular foramen --> draw blood from brain + SUP. part of neck
• Posterior triangle vessels: Cervical plexus

  • ANT. rami C1-4
  • superficial (cutaneous) branches
  • deep branches (subcutaneous)
  • phrenic n. inn. diaphragm
  • ansa cervicalis inn. infrahyoid muscles
• ANT. triangle:

  • 2 small muscles: suprahyoid + infrahyoid muscles inc. omohyoid
  • contains carotid sinus where CCA divides into INT. + EXT. carotid a. + internal jugular v. + vagus n. (X)
  • has visceral elements: tracha, esophagus, thyroid
• POST. triangle:

  • 8 muscles enable movement of scapula + head
  • incl. external jugular v. + cervical plexus
• Anterior Triangle divided into 4 small triangles:

  • SUP. belly of omohyoid
  • ANT. belly omohyoid
  • POST. belly of omohyoid
  • digastric muscle