Carotid Body and Carotid Sinus -- General Information

last modified on: Wed, 12/06/2017 - 11:43

Carotid Body and Carotid Sinus – General Information

See also: Carotid Body Paragangliomas, Carotid Body Tumor Case Example, and Carotid Body Tumor Resection

  1. Carotid Body

    1. The carotid body is a chemoreceptor located in the adventitia of the bifurcation of the common carotid artery

    2. Chemoreceptor function:

      1. Carotid body monitors the blood’s pH, pCO2, and pO2 and thereby modulates cardiovascular and respiratory function primarily through sympathetic tone

      2. When the carotid body senses acidemia, hypercapnea, or hypoxia, autonomic firing leads to increased blood pressure, heart rate, and respiratory rate

      3. The function of the carotid body is complemented by other chemoreceptors, most notably the aortic body located in the aortic arch

    3. Anatomy:

      1. Located in the bifurcation of the common carotid artery

      2. Average size of carotid body is 3-5 mm in diameter and average weight is 12 mg

      3. Blood supply: from external carotid through Mayer’s ligament (provides attachment to carotids)

      4. Innervation: Hering’s nerve (aka carotid sinus nerve), a branch of the glossopharyngeal (CN IX), originating 1.5 cm distal to jugular foramen

    4. Composed of two receptor cell types:

      1. Chief cells (Type I): derived from neural crest, release ACh, ATP, dopamine in response to activation

      2. Sustentacular cells (Type II): supporting cells

  2. Carotid Sinus

    1. The carotid sinus is a baroreceptor that senses changes in systemic blood pressure and is located in the adventitia of the carotid bulb of the internal carotid artery

    2. Due to its location the carotid sinus is an intimately related but distinct organ from the carotid body

    3. Innervation: same as carotid body (Hering’s nerve, aka carotid sinus nerve, a branch of CN IX)

    4. The function of the carotid sinus can be affected by carotid body tumor resection (see below)

    5. Carotid sinus syndrome (syncopal episodes due to inadvertant triggering of the carotid sinus) is a pathology of the carotid sinus, in addition, carotid massage triggers the carotid sinus pathway (increased pressure on carotid sinus due to massage → sends signal to decrease systemic BP)
  3. SUGGESTED READING
    1. Netterville, James L., et al. "Carotid body tumors: a review of 30 patients with 46 tumors." The Laryngoscope 105.2 (1995): 115-126
    2. Flint: Cummings Otolaryngology: Head & Neck Surgery, 5th ed. Chapter 118: Neoplasms of the Neck.