Plan Of Neck

Plan Of Neck

1. Bony landmark of the neck:

   • Upper Limit
     • Inferior border of the mandible
     • Mastoid process of the temporal bone
     • External occipital protuberance
   • InferiorlY
     • Upper border of manubrium sterni
     • Clavicle

2. IMPORTANT MIDLINE SURFACE LANDMARKS

   • Hyoid Bone
     • U-shaped with a body, lesser and greater horns.
     • Is the first resistant structure that can be felt in the midline inferior to the chin.
     • Level of C3 vertebra.
     • Moves during swallowing.
     • Is suspended from the styloid process by stylohyoid ligaments.
     • Muscles connect the hyoid bone to the tongue, mandible, sternum, larynx, and pharynx.
     • Consequently, following fracture of the hyoid bone the fine balance of these muscles would be disturbed, causing problems in breathing, speaking, and swallowing
   • Laryngeal Prominence
     • Formed by the thyroid cartilage.
     • More prominent in the male & rises with swallowing
     • Lies at the level of the C4 & 5 vertebrae.
     • It rises during swallowing.
   • Cricoid Cartilage
     • Can be felt inferior to the laryngeal prominence.
     • Level of C6 vertebra.
     • At C6- pharynx continues - esophagus and the larynx - trachea

3. Respiratory-Digestive Block

   • Located anteriorly.
   • Contains the pharynx and larynx which form the esophagus and trachea at the level of C6.
   • The contents are partially enclosed in a much thinner sheath of fascia called the PRE-TRACHEAL FASCIA
   • Trachea in front and the esophagus behind together enclosed in the thin pre-tracheal fascia, which also encloses the thyroid gland.
   • The recurrent laryngeal nerve occupies the groove between the trachea and esophagus.

4. Musculo-Vertebral Block

   • Located posteriorly.
   • Consists of the cervical vertebrae and the muscles around them.
   • Plastered by a dense layer of PREVERTEBRAL FASCIA
   • The whole neck is enclosed in a musculo-fascial tube composed of :
     • Sternomastoid muscle
     • Trapezius muscle
     • Investing Layer of Deep Fascia of the neck
   • Carotid sheath: Fills in the angle between the vertebral block and the respiratory-digestive block
   • Longus colli: Immediately in front of the vertebral bodies.
   • Scalenus anterior: Arises from the anterior tubercles of transverse processes.
   • Scalenus medius & posterior: Arises from the posterior tubercles.
   • Levator scapulae and deep muscles of the neck arise further posteriorly.

5. Deep Fascia of Neck

   • Investing layer.
   • Pre-tracheal fascia
   • Carotid Sheath
   • Prevertebral Fascia

6. MUSCLES!!

   • Sternocleidomastoid muscle
   • Digastric muscle
   • Omohyoid muscle

7. Subdivisions of Neck

   • Posterior Triangle
     • Anteriorly: Sternomastoid
     • Posteriorly: Trapezius
     • Apex: Meeting between trapezius & sternomastoid at the back of the skull.
     • Base: Middle third of the clavicle, between the attachment of sternomastoid and trapezius.
   • Anterior Triangle
     • Boundaries
       • Anterior: Median line
       • Posterior: Sterno cleidomastoid
       • Base: Mandible + Line from angle to mastoid
       • Apex: Suprasternal notch
     • Subdivisions
       • Submandibular triangle.
       • Carotid triangle.
       • Muscular triangle.
       • Submental triangle.
     • Suprahyoid muscles
       • Digastric muscle
       • Stylohyoid
         • Above post belly of digastric muscle.
         • Extends between styloid process & hyoid bone.
       • Mylohyoid
         • Extends between mandible and hyoid bone.
         • Is attached to a midline raphe.
       • Geniohyoid: Extends between mandible and hyoid bone.
       • Hyoglossus: Extends between hyoid bone & tongue.
     • Infrahyoid Muscles
       • Sternohyoid: Superficial to sternothyroid & thyrohyoid. Between the manubrium & hyoid bone.
       • Omohyoid
       • Sternothyroid:Extends between the manubrium and the oblique line of thyroid cartilage.
       • Thyrohyoid: From the oblique line of the thyroid cartilage to the hyoid bone.
     • Ansa Cervicalis
       • Superficial to the carotid sheath
       • A loop formed by 2 components:
         • Superior Loop C1 (Descending Hypoglossi)
         • Inferior Loop from cervical plexus C2 and C3
           • Innervation: All infrahyoid muscles except thyrohyoid (C1 through hypoglossal nerve