Anterior triangles of neck

Carotid Triangle
1. Boundaries
  1. a. Antero Superior- posterior belly of the digastric muscle. b. Posteriorly - Medial border of the sternocleidomastoid muscle. c. Postero Inferior- Superior belly of the omohyoid muscle d. Roof : formed by skin, superficial fascia (containing platysma, cervical branch of facial nerve, transverse cutaneous nerve of neck) , investing layer of deep cervical fascia. e. Floor formed by 1. Middle constrictor of pharynx 2. Inferior constrictor of pharynx 3. Thyrohyoid membrane
2. Contents
  1. Arteries: a. Common carotid artery ( bifurcates into ECA & ICA) b. Internal carotid artery c. External carotid artery with its superior thyroid, lingual, facial, ascending pharyngeal & occipital branches
  2. Veins: 1. Internal jugular vein 2. Veins draining into internal jugular veins: common facial , pharyngeal, lingual veins
  3. Nerves: 1. Vagus nerve & its branch Superior laryngeal, dividing into external & internal laryngeal nerves. 2. Spinal accessory N 3. Hypoglossal N
  4. Lymph Nodes : Deep cervical lymph nodes , include jugulodigastric & jugulo- omohyoid
3. Clinical
  1. It contains Carotid sinus ( with special baroreceptor cells) a dilated portion of CCA & ICA. This baroreceptor cells helps in regulating Blood pressure via glossopharyngeal N
  2. Carotid body : for PH Monitoring
  3. In extreme Hpertensive pt’s massage at this place is done to lower down BP
  4. Some pt’s are hypersensitive to stretch & pressure application in this area cause decrease in BP & HR & brain becomes underperfused leading to syncope
Submental Triangle
1. Boundaries
  1. Situated underneath the chin
  2. Inferiorly - hyoid bone
  3. Medially - Midline of the neck
  4. Laterally- Ant. Belly of digastric
  5. Floor of submental triangle is formed by MYLOHYOID Muscle
2. Contents
  1. Submental lymph nodes, which filter lymph draining from a . Superficial surface below the chin b. Central part of lower lip c. Ant. Part of floor of mouth d. Tip of the tongue
  2. Ant. Jugular vein
Submandibular Triangle/ Digastric Triangle
1. Boundaries
  1. Located underneath the Body of the Mandible.
  2. Superiorly: body of the mandible
  3. Anteriorly: Anterior belly of the digastric muscle
  4. Posteriorly: posterior belly of the digastric muscle
  5. Roof: formed by 1. Skin 2. Superficial fascia containing platysma & cervical branch of facial nerve 3. Deep fascia enclosing submandibular salivary gland
  6. Floor: Formed by 1. Mylohyoid muscle anteriorly 2. Hyoglossus posteriorly 3. Middle constrictor muscle
2. Contents
  1. Anterior part of the Triangle 1. Superficial part of submandibular salivary gland 2. Facial artery & vein & submandibular LN 3. Submental artery 4. Mylohyoid nerve & vessels 5. Hypoglossal nerve
  2. Posterior part of the Triangle 1. Superficial : parotid gland & external carotid artery 2. Deep structures, passing between external & internal carotid arteries are: a. Styloglossus b. Stylopharyngeus c. Glossopharyngeal nerve d. Pharyngeal branch of vagus nerve 3. Deepest structure a. Internal carotid artery b. Internal jugular vein c. Vagus nerve
3. Clinical
  1. Ludwig’s angina: potentially life threatening infection of floor of mouth, that spreads into submandibular triangle & beyond
Muscular Triangle/ Inferior carotid triangle
1. Boundaries
  1. Situated more inferiorly than the other subdivisions & has 4 borders
  2. Anteriorly: Ant. Median line of neck from hyoid bone to sternum
  3. Posterosuperiorly: superior belly of omohyoid muscle.
  4. Posteroinferiorly: lower part of ant. Border of sternocleidomastoid muscle
2. Contents
  1. Infrahyoid muscles : 1) Thyrohyoid: Origin- oblique line of thyroid cartilage Insertion- Inf border of body & greater horn of hyoid bone 2) omohyoid origin- upper body of scapula Insertion- Hyoid bone 3) sternohyoid origin- post surface of manubrium sterni & sternoclavicular joint Insertion- lower body of hyoid bone 4) sternothyroid origin -Manubrium Insertion- Thyroid cartilage
    1. Strap like muscle are located Ribbon like, parallel muscle fasciculi
  2. Pharynx , Thyroid & parathyroid glands
  3. Superior thyroid artery, ant. Jugular & inf. Thyroid veins & ansa cervicalis.
Characteristics
1. Ant. Triangle is situated at front of neck. It is bounded by:
  1. Superiorly: Inferior border of Mandible
  2. Laterally : anterior border of sternocleidomastoid
  3. Medially: sagittal line down the midline
2. Investing fascia covers the roof of the triangle, while visceral fascia covers the floor.
3. It is subdivided further into 4 triangles
  1. 1. Carotid Triangle 2. Submental Triangle 3. Submandibular Triangle 4. Muscular Triangle
4. Hyoid bone & other structures
  1. Deep structures lying above the hyoid bone
    1. 1) Mylohyoid muscle & is overlapped by: 2) Ant. Belly of digastric 3) superficial part of submandibular salivary gland 4) Mylohyoid nerve & vessels 5) submental branch of facial artery
  2. Deep structures lying below the hyoid bone
    1. 1. Infrahyoid muscles/ strap muscles a. Sternohyoid b. Sternothyroid c. Superior belly of omohyoid d. Thyrohyoid
      1. All strap muscles are supplied by Ansa Cervicalis except THYROHYOID which is supplied by C1
    2. 2. Pretrachial fascia & thyroid pretrachial fascia forms the false capsule of thyroid gland & suspensory ligament of Berry
    3. 3. Deep to pretracheal fascia , are a. Thyrohyoid membrane b. Thyroid cartilage c. Cricothyroid membrane d. Arch of cricoid cartilage e. Cricothyroid muscle f. Trachea g. Carotid sheaths
5. ANSA CERVICALIS OR ANSA HYPOGLOSSI
  1. Thin nerve loop that is embedded in ant. Wall of carotid sheath over lower part of larynx. It supplies INFRAHYOID MUSCLES….except Thyrohyoid
  2. Formed by superior & inferior root Superior root: Hypoglossal nerve + ventral ramus of C1 ( cervical N ) it decends over ICA & CCA Inferior root: Ventral ramus of C2 & C3 ( cervical N), winds around internal jugular vein Both join infront of CCA
    1. Distribution Superior rooth : sup. Belly of omohyoid Ansa cervicalis : sternohyoid & sternothyroid Inferior root: Inf belly of omohyoid
Common carotid artery
1. Right CCA is a branch of brachiocephalic artery & left CCA is branch of arch of aorta.
2. Gives two branches:
  1. External Carotid artery
    1. Main artery for head & neck region & gives branches like
      1. Anterior 1. Superior Thyroid 2. Lingual 3. Facial
      2. Posterior 4. Occipital 5. Posterior auricular
      3. Medial 6. Ascending pharyngeal
      4. Terminal 7. Maxillary 8. Superficial temporal
  2. Internal Carotid artery
    1. Supplies the ant. Portion of brain