Anatomy

• Posterior Triangle Boundaries:

  • Anteriorly: posterior border of sternocleidomastoid
  • Posteriorly: anterior border of trapezius
  • Inferiorly: superior border of clavicle
  • Roof: platysma and investing layer of the deep cervical fascia
  • Floor: splenius capitis, levator scapulae, anterior/middle/posterior scalene muscles
• Posterior Triangle Contents:

  • Accessory nerve
  • Cutaneous branches of cervical plexus
  • External jugular vein
  • Posterior (inferior) belly of the omohyoid – roots and trunks of the brachial plexus
  • Transverse cervical and suprascapular vessels
• Posterior Triangle Division:

  • Further divided into Occipital and Subclavian (Suprascapular or omoclavicular) triangles by the posterior belly of omohyoid
• Anterior Triangle Boundaries:

  • Anteriorly: anteromedian line of the neck
  • Posteriorly: anterior border of sternocleidomastoid
  • Inferiorly: inferior border of the mandible
  • Roof: platysma; investing layer of the deep cervical fascia
• Muscles of the Neck:

  Cervical muscles:

  • Platysma
  • Sternocleidomastoid

  Suprahyoid muscles:

  • Digastric
  • Mylohyoid
  • Stylohyoid
  • Geniohyoid

  Infrahyoid muscles:

  • Sternohyoid
  • Sternothyroid
  • Thyrohyoid
  • Omohyoid
• Nerves Found in the Neck:

  • Accessory nerve formed by the union of cranial and spinal roots
  • Cervical plexus formed by the ventral rami of the first 4 cervical nerves
  • Brachial plexus formed by the union of the ventral rami of C5-C8 and T1 spinal nerves; pass between the anterior scalene and middle scalene muscles
• Blood Vessels:

  Arteries:

  • Subclavian
  • Common carotid
  • Internal Carotid
  • External Carotid
• Veins:

  • Retromandibular vein
  • External jugular vein
  • Internal jugular vein
• Deep Structures of the Neck:

  • Thyroid gland
  • Parathyroid gland
  • Thyroid cartilage
  • Sympathetic trunk
  • Ansa subclavia
• Carotid Sheath:

  • Common and internal carotid arteries
  • Internal jugular vein
  • Vagus nerve
• Cervical Fascia (Fascia of the Neck):

  1. Investing layer of deep cervical fascia surrounds neck and splits around sternocleidomastoid, trapezius, suprahyoid, and infrahyoid

  2. Prevertebral layer surrounds vertebral column and muscles back of neck

  3. Pretracheal layer surrounds trachea, esophagus, and thyroid

  4. Carotid sheath surrounds common and internal carotid, internal and external jugular
• Lymph Drainage of the Head and Neck:

  • Occipital LN
  • Retroauricular LN
  • Parotid LN
  • Buccal (facial) LN
  • Submandibular LN
  • Submental LN
  • Anterior Cervical LN
  • Superficial Cervical LN
  • Retropharyngeal LN
  • Laryngeal LN
  • Tracheal LN
• Thyroid Gland:

  • Right and left lobes connected by a narrow isthmus
  • Pyramidal lobe projects upward from isthmus
  • Attached to the larynx and trachea by a sheath
• Thyroid Gland (Relations of the Lobes):

  • Anteriorly: sternothyroid, superior belly of the omohyoid, sternohyoid, anterior border of sternocleidomastoid
  • Posteriorly: carotid sheath
  • Medially: larynx, trachea, pharynx, esophagus
• Thyroid Gland (Blood Supply: Arteries):

  • Superior thyroid artery branch of external carotid artery
  • Inferior thyroid artery branch of thyrocervical trunk
  • Thyroidea ima from brachiocephalic or aorta
• Thyroid Gland (Blood Supply: Veins):

  • Superior Thyroid Vein drains to internal jugular vein
  • Middle Thyroid Vein drains to internal jugular vein
  • Inferior Thyroid Vein drains into left brachiocephalic vein
• Parathyroid Gland:

  • Ovoid bodies about 6 mm long
  • Usually 4 in number
  • Intimately related to the posterior border of the Thyroid gland
  • Control the body's calcium levels
  • Each gland is about the size of a grain of rice and produces parathyroid hormone (PTH)
• Superior Parathyroid Glands (2):

  • More constant position: middle of the posterior border of the thyroid
• Inferior Parathyroid Glands (2):

  • Close to the inferior pole of the thyroid
• Parathyroid Gland (Blood Supply):

  • Arterial supply is from the Superior and Inferior thyroid arteries
• Posterior Triangle Boundaries:

  • Anteriorly: posterior border of sternocleidomastoid
  • Posteriorly: anterior border of trapezius
  • Inferiorly: superior border of clavicle
  • Roof: platysma and investing layer of the deep cervical fascia
  • Floor: splenius capitis, levator scapulae, anterior/middle/posterior scalene muscles
• Posterior Triangle Contents:

  • Accessory nerve
  • Cutaneous branches of cervical plexus
  • External jugular vein
  • Posterior (inferior) belly of the omohyoid – roots and trunks of the brachial plexus
  • Transverse cervical and suprascapular vessels
• Posterior Triangle Division:

  • Further divided into Occipital and Subclavian (Suprascapular or omoclavicular) triangles by the posterior belly of omohyoid
• Anterior Triangle Boundaries:

  • Anteriorly: anteromedian line of the neck
  • Posteriorly: anterior border of sternocleidomastoid
  • Inferiorly: inferior border of the mandible
  • Roof: platysma; investing layer of the deep cervical fascia
• Muscles of the Neck:

  Cervical muscles:

  • Platysma
  • Sternocleidomastoid

  Suprahyoid muscles:

  • Digastric
  • Mylohyoid
  • Stylohyoid
  • Geniohyoid

  Infrahyoid muscles:

  • Sternohyoid
  • Sternothyroid
  • Thyrohyoid
  • Omohyoid
• Nerves Found in the Neck:

  • Accessory nerve formed by the union of cranial and spinal roots
  • Cervical plexus formed by the ventral rami of the first 4 cervical nerves
  • Brachial plexus formed by the union of the ventral rami of C5-C8 and T1 spinal nerves; pass between the anterior scalene and middle scalene muscles
• Blood Vessels:

  Arteries:

  • Subclavian
  • Common carotid
  • Internal Carotid
  • External Carotid

  Veins:

  • Retromandibular vein
  • External jugular vein
  • Internal jugular vein
• Deep Structures of the Neck:

  • Thyroid gland
  • Parathyroid gland
  • Thyroid cartilage
  • Sympathetic trunk
  • Ansa subclavia
• Carotid Sheath:

  • Common and internal carotid arteries
  • Internal jugular vein
  • Vagus nerve
• Cervical Fascia (Fascia of the Neck):

  1. Investing layer of deep cervical fascia surrounds neck and splits around sternocleidomastoid, trapezius, suprahyoid, and infrahyoid

  2. Prevertebral layer surrounds vertebral column and muscles back of neck

  3. Pretracheal layer surrounds trachea, esophagus, and thyroid

  4. Carotid sheath surrounds common and internal carotid, internal and external jugular
• Lymph Drainage of the Head and Neck:

  • Occipital LN
  • Retroauricular LN
  • Parotid LN
  • Buccal (facial) LN
  • Submandibular LN
  • Submental LN
  • Anterior Cervical LN
  • Superficial Cervical LN
  • Retropharyngeal LN
  • Laryngeal LN
  • Tracheal LN
• Thyroid Gland:

  • Right and left lobes connected by a narrow isthmus
  • Pyramidal lobe projects upward from isthmus
  • Attached to the larynx and trachea by a sheath
• Thyroid Gland (Relations of the Lobes):

  • Anteriorly: sternothyroid, superior belly of the omohyoid, sternohyoid, anterior border of sternocleidomastoid
  • Posteriorly: carotid sheath
  • Medially: larynx, trachea, pharynx, esophagus
• Thyroid Gland (Blood Supply: Arteries):

  • Superior thyroid artery branch of external carotid artery
  • Inferior thyroid artery branch of thyrocervical trunk
  • Thyroidea ima from brachiocephalic or aorta
• Thyroid Gland (Blood Supply: Veins):

  • Superior Thyroid Vein drains to internal jugular vein
  • Middle Thyroid Vein drains to internal jugular vein
  • Inferior Thyroid Vein drains into left brachiocephalic vein
• Parathyroid Gland:

  • Ovoid bodies about 6 mm long
  • Usually 4 in number
  • Intimately related to the posterior border of the Thyroid gland
  • Control the body's calcium levels
  • Each gland is about the size of a grain of rice and produces parathyroid hormone (PTH)
  • Superior parathyroid glands more constant position in the middle of the posterior border of the thyroid
  • Inferior parathyroid glands close to the inferior pole of the thyroid
  • Arterial supply is from the Superior and Inferior thyroid arteries
• Posterior Triangle Boundaries:

  • Anteriorly: posterior border of sternocleidomastoid
  • Posteriorly: anterior border of trapezius
  • Inferiorly: superior border of clavicle
  • Roof: platysma and investing layer of the deep cervical fascia
  • Floor: splenius capitis, levator scapulae, anterior/middle/posterior scalene muscles
• Posterior Triangle Contents:

  • Accessory nerve
  • Cutaneous branches of cervical plexus
  • External jugular vein
  • Posterior (inferior) belly of the omohyoid – roots and trunks of the brachial plexus
  • Transverse cervical and suprascapular vessels
• Posterior Triangle Division:

  • Further divided into Occipital and Subclavian (Suprascapular or omoclavicular) triangles by the posterior belly of omohyoid
• Anterior Triangle Boundaries:

  • Anteriorly: anteromedian line of the neck
  • Posteriorly: anterior border of sternocleidomastoid
  • Inferiorly: inferior border of the mandible
  • Roof: platysma; investing layer of the deep cervical fascia