# Cricoid Cartilage: Anatomy and Clinical Relevance The cricoid cartilage is the only complete cartilaginous ring in the airway, shaped like a signet ring with a narrow arch ventrally and a broad lamina dorsally. It sits at the caudal end of the larynx, articulates with the thyroid and arytenoid cartilages, and serves as the structural foundation for airway patency during breathing and the landmark for emergency airway access. The cricoid cartilage matters in veterinary practice because it is the junction between the upper airway and the trachea. It is the narrowest point of the airway in many patients, the anchor for the cricoarytenoid joint that controls vocal fold abduction, and the structure most often compressed during rapid sequence intubation. Conditions ranging from [laryngeal paralysis in dogs](/knowledge/veterinary-medicine/clinical-methods/canine-laryngeal-paralysis-diagnosis-management) to recurrent laryngeal neuropathy in horses to congenital cricoid narrowing in brachycephalic breeds all involve this single ring of cartilage. Understanding its anatomy explains why specific surgical approaches work, why certain intubations are difficult, and why cricothyrotomy is possible at all. ## Anatomy of the Cricoid Cartilage The cricoid cartilage is a ring of hyaline cartilage. Unlike the thyroid cartilage, which is open dorsally, and unlike the tracheal rings, which are C-shaped and incomplete, the cricoid forms a full 360-degree circle. This completeness is its defining feature and the reason it functions as the load-bearing scaffold of the larynx. ### Shape and Regional Anatomy The cricoid is shaped like a signet ring. The narrow ventral portion is called the arch, and the tall dorsal portion is called the lamina. The arch faces the ventral neck, where it is easily palpable just caudal to the thyroid cartilage and cranial to the first tracheal ring. The lamina rises dorsally and provides a broad surface for articulation with the arytenoid cartilages and attachment of the cricoarytenoideus dorsalis muscle. On each side of the lamina, the cricoid bears two articular facets. - A cricothyroid facet on the lateral surface, where the inferior cornu of the thyroid cartilage meets the cricoid. - A cricoarytenoid facet on the craniodorsal border of the lamina, where the base of the arytenoid cartilage sits. These two articulations allow the thyroid, cricoid, and arytenoid cartilages to move relative to one another during swallowing, vocalization, and respiration. The cricoarytenoid joint in particular is a synovial joint with a capsule and ligamentous support, and it permits the rocking and sliding motion that abducts and adducts the arytenoid cartilage. ### Why the Cricoid Is the Only Complete Ring In the trachea, the cartilaginous rings are incomplete dorsally. The gap is bridged by the trachealis muscle, which allows the trachea to change diameter and accommodate a bolus of food passing through the esophagus immediately dorsal to it. The cricoid has no such gap. It is a solid ring because it must stabilize the laryngeal inlet and provide a fixed point of leverage for the muscles that open the glottis. This design has a clinical consequence. Because the cricoid is rigid, any external pressure applied to it is transmitted directly to the airway lumen. During intubation, cricoid pressure narrows the subglottic space. In patients with an already narrow cricoid, this narrowing can make endotracheal tube placement difficult or impossible. Two brachycephalic dogs in one report experienced strong resistance during tube insertion through the subglottic lumen, and CT imaging later revealed a markedly narrower vertical dimension of the cricoid cartilage than is typical even for brachycephalic breeds [1]. ### Articulations and the Laryngeal Framework The cricoid is the keystone of the laryngeal skeleton. It articulates with the thyroid cartilage cranially and laterally and with the arytenoid cartilages dorsocranially. The paired arytenoid cartilages sit on the dorsal lamina of the cricoid and are the mobile elements that control the rima glottidis, the opening of the airway. The arytenoid cartilage has a distinctive composition. It is made of both hyaline and elastic cartilage, which gives it a unique combination of rigidity and flexibility [2]. The arytenoid has a base that articulates with the cricoid, a muscular process for muscle attachment, and a vocal process that projects ventrally toward the vocal fold. When the cricoarytenoideus dorsalis muscle contracts, it pulls the muscular process caudally and medially, which rotates the arytenoid outward and abducts the vocal fold. This is the single most important movement for maintaining airway patency during inspiration. The cricoid also provides the caudal attachment point for the cricothyroid muscle, which tenses the vocal folds, and the cricopharyngeal muscle, which helps close the upper esophageal sphincter during swallowing. Detailed muscle attachments and innervation are beyond the scope of this article, but the key point is that the cricoid is the fixed platform against which all laryngeal motion occurs. ## Comparative Anatomy Across Species ### Dogs In dogs, the larynx is relatively short and wide. The cricoid cartilage forms a distinct ring that is easily palpable in the ventral neck of most breeds. The cricoid arch is narrow, and the dorsal lamina is tall and broad. The cricoarytenoid joint is well developed and permits a wide range of arytenoid motion. Breed variation matters. Brachycephalic dogs such as Pekingese and French Bulldogs can have a cricoid with a reduced vertical dimension, which narrows the subglottic airway [1]. This anatomic variation contributes to the difficult airway management often seen in these breeds during anesthesia. Laryngeal collapse in brachycephalic dogs, particularly grade III collapse involving the corniculate processes of the arytenoid cartilages, is a direct consequence of chronic upper airway obstruction and the resulting negative pressure on the laryngeal framework [3]. ### Cats The feline larynx is smaller and more delicate than the canine larynx. The cricoid cartilage is proportionally similar in shape but smaller in absolute size. The arytenoid cartilages are also smaller, which makes surgical procedures on the feline larynx more technically demanding. Experimental studies on feline larynges have shown that unilateral cricoarytenoid lateralization, a procedure in which a suture is placed between the muscular process of the arytenoid cartilage and the caudolateral aspect of the cricoid cartilage, produces significant abduction of the arytenoid cartilage. One study found that complete cricoarytenoid disarticulation before suture placement resulted in a mean percentage increase in arytenoid abduction of 311.5%, compared with 199.4% when the joint was left intact [4]. This finding highlights how the cricoarytenoid joint and the cricoid's articular surface influence surgical outcomes in cats. ### Horses The equine larynx is large and muscular, reflecting the horse's need for high airflow during exercise. The cricoid cartilage in horses is a substantial ring with a prominent dorsal lamina. Recurrent laryngeal neuropathy, also called laryngeal hemiplegia, is one of the most common upper airway diseases in performance horses. It results from degeneration of the recurrent laryngeal nerve, which leads to atrophy of the cricoarytenoideus dorsalis muscle and failure of arytenoid abduction. Surgical treatment, prosthetic laryngoplasty, involves placing a suture between the muscular process of the arytenoid cartilage and the cricoid cartilage to permanently abduct the arytenoid. Research on equine laryngoplasty has examined how different suture implantation positions in the cricoid cartilage affect the force required for abduction and the degree of laryngeal rotation. One study compared three implantation techniques in the muscular process and three positions in the cricoid cartilage, finding that a titanium corkscrew anchor required less force for optimal abduction (7.45 ± 4 N) and caused less cricoarytenoideus dorsalis muscle indentation and less larynx rotation than standard needle passages [5]. Another biomechanical study compared a tie-bolt implant with a suture anchor and standard suture alone, showing that the tie-bolt construct had less elongation under cyclic loading and greater stiffness [6]. These studies demonstrate that the cricoid cartilage is not just a passive anchor but an active biomechanical component of laryngoplasty. ### Cattle The bovine larynx is large and robust, consistent with the size and neck conformation of cattle. The cricoid cartilage is a thick, complete ring with a broad dorsal lamina. The arytenoid cartilages are correspondingly large. Cattle are susceptible to laryngeal diseases including laryngeal chondritis, an inflammatory condition of the laryngeal cartilages that can cause severe respiratory obstruction. The cricoid, like other laryngeal cartilages, can be affected by chondritis or by ossification with age. The size of the bovine cricoid also makes it a substantial landmark for surgical approaches to the larynx, including tracheostomy and laryngeal surgery. ## Table: Laryngeal Cartilages at a Glance | Cartilage | Location | Shape | Function | |--|--|--|--| | Thyroid | Cranial and lateral larynx | V-shaped, open dorsally, with paired cornua | Shields the laryngeal inlet, articulates with the cricoid, anchors the vocal folds | | Cricoid | Caudal larynx, between thyroid and trachea | Complete signet ring, narrow ventral arch, broad dorsal lamina | Only complete cartilaginous ring in the airway, stabilizes the larynx, articulates with thyroid and arytenoid cartilages, anchors the cricoarytenoid joint | | Arytenoid (paired) | Dorsocranial to the cricoid lamina | Irregular, mixed hyaline and elastic cartilage, with muscular and vocal processes | Mobile elements that abduct and adduct the vocal folds, control the rima glottidis | | Epiglottic | Rostral larynx | Leaf-shaped, elastic cartilage | Closes over the glottis during swallowing, prevents aspiration | | Corniculate (paired) | Apex of each arytenoid | Small, conical, elastic cartilage | Extension of the arytenoid, contributes to the corniculate process that can collapse in brachycephalic dogs | | Cuneiform (paired) | Lateral to the arytenoid, within the aryepiglottic fold | Small, rod-shaped, elastic cartilage | Supports the aryepiglottic fold | ## Clinical Relevance of the Cricoid Cartilage ### Cricoid Pressure During Intubation Cricoid pressure, also called the Sellick maneuver, is a technique in which an assistant applies firm pressure to the cricoid cartilage during rapid sequence induction of anesthesia. The rationale is that the cricoid ring, being complete, can be compressed against the esophagus behind it, which may reduce the risk of gastric content regurgitation and aspiration during intubation. In [veterinary medicine](/blog/careers/veterinary-medicine-careers-from-clinical-practice-to-public-health), the technique is used infrequently but remains relevant in patients at risk for regurgitation, such as dogs with gastrointestinal disease or those undergoing emergency procedures. The anatomy explains both the intent and the limitation. Because the cricoid is a complete ring, pressure on it narrows the airway lumen. If the cricoid is already narrow, as it can be in brachycephalic dogs [1], the reduction in lumen diameter can make tube passage difficult. The clinician must balance the theoretical benefit of preventing aspiration against the real risk of obstructing an already compromised airway. Anesthesia protocols also affect laryngeal motion, which in turn affects visualization and intubation. Studies comparing induction agents in dogs have shown that propofol, alfaxalone, and thiopentone all influence arytenoid cartilage motion to varying degrees [7][8]. In brachycephalic dogs, laryngeal motion may be absent regardless of the induction agent used, which complicates assessment of laryngeal function during anesthesia [7]. ### Cricothyrotomy Landmarks Cricothyrotomy is an emergency procedure in which an incision is made through the cricothyroid membrane, the membrane between the thyroid and cricoid cartilages, to establish an airway when oral or nasal intubation is not possible. The cricoid cartilage serves as the caudal landmark for this procedure. The membrane lies immediately cranial to the cricoid arch. In dogs, the cricothyroid membrane is palpable in the ventral neck, just caudal to the thyroid cartilage. The cricoid arch is the firm ridge immediately caudal to the membrane. In an emergency, the clinician identifies the membrane by palpating the notch between the thyroid and cricoid cartilages and incises through the skin and membrane. The cricoid's completeness ensures that the airway remains open once the membrane is penetrated. In horses and cattle, the cricothyroid membrane is larger and more accessible, which makes cricothyrotomy a more straightforward procedure in these species. The cricoid cartilage is correspondingly larger and provides a clear landmark. ### Laryngeal Paralysis in Dogs Laryngeal paralysis is the inability to abduct the arytenoid cartilages during inspiration, which results in partial to complete airway obstruction [9]. The condition is most commonly seen in older, large breed dogs, though hereditary early onset forms exist in several breeds [10][9]. The cricoarytenoid joint, which sits on the cricoid lamina, is the mechanical link between muscle contraction and arytenoid abduction. When the cricoarytenoideus dorsalis muscle weakens or atrophies, the arytenoid cartilage cannot be pulled open, and the airway narrows during inspiration. Clinical signs include inspiratory stridor, exercise intolerance, and in severe cases, life-threatening respiratory compromise [10]. Surgical treatment aims to abduct one or both arytenoid cartilages. The two most common procedures are cricoarytenoid lateralization (CAL) and thyroarytenoid lateralization (TAL). A prospective clinical trial comparing these techniques in dogs found that the rima glottidis area increased by a mean of 152% immediately after TAL and 205% immediately after CAL compared with preoperative values [11]. At 15 days postoperatively, the increase was 127% for TAL and 199% for CAL, with the CAL group maintaining a more stable result [11]. Other surgical options include unilateral arytenoid lateralization, which can be performed on an outpatient basis with outcomes comparable to hospitalization. In one study of 44 dogs, the overall complication rate was 22.7%, with no significant difference between inpatient and outpatient groups [12]. A novel approach using a 3D printed bilateral arytenoid abductor has been tested ex vivo, showing significantly decreased laryngeal airway resistance at airflows of 15, 30, and 45 L/min when compared with controls [10]. Genetic research has identified a major risk factor for early onset laryngeal paralysis in Miniature Bull Terriers. A 36 bp insertion in exon 15 of the RAPGEF6 gene was found to be associated with a 10- to 17-fold increased risk for the condition in dogs homozygous for the insertion allele [9]. This finding is specific to Miniature Bull Terriers and Bull Terriers and has not been found in other breeds tested [9]. ### Laryngeal Collapse and Other Conditions Grade III laryngeal collapse in brachycephalic dogs involves collapse of the corniculate processes of the arytenoid cartilages and destruction of the dorsal portion of the rima glottidis [3]. The primary cause is chronic upper airway obstruction, which creates negative pressure that weakens the laryngeal framework over time. Surgical treatment options include subtotal epiglottectomy with ablation of one arytenoid cartilage, which has been shown to increase airway flow and improve clinical outcomes in a pilot study of 16 dogs [3]. The cricoid cartilage can also be affected by other conditions. Primary laryngeal blastomycosis, though rare, can cause severe thickening of the arytenoid cartilages and masses that obstruct the airway. One case report described a Labrador Retriever with progressive dyspnea and inspiratory stridor that required a temporary tracheostomy tube until antifungal treatment resolved the obstruction [13]. Laryngeal chondrosarcoma, a rare tumor arising from laryngeal cartilages, can affect the cricoid. A human case report described a low-grade chondrosarcoma arising from the cricoid cartilage in a 61-year-old man who presented with long-standing hoarseness. The tumor was treated with laser resection, and the patient retained laryngeal function with no recurrence at eight-month follow-up [14]. While this case is in a human patient, the anatomy and clinical behavior of cricoid chondrosarcoma are relevant to veterinary clinicians who may encounter similar tumors in animals. Ossification of laryngeal cartilages is an age-related process. A unique anatomical variation was reported in an 84-year-old woman with complete bilateral ossification of the arytenoid cartilages, with the cricoid cartilage remaining non-ossified and the thyroid showing only minor ossification [2]. This case illustrates that ossification patterns can vary and that the cricoid is not always the first cartilage to ossify. ## Clinical Relevance, Limitations and Common Mistakes The cricoid cartilage is a small structure with large clinical implications, and misunderstandings about its anatomy are common. ### Common Mistakes **Mistaking the cricoid for a tracheal ring.** The cricoid is not a tracheal ring. It is a complete ring of hyaline cartilage that sits at the caudal end of the larynx, cranial to the first tracheal ring. Tracheal rings are C-shaped and incomplete dorsally. The cricoid is complete. This distinction matters during surgery and emergency airway access. **Assuming cricoid pressure is always safe.** Cricoid pressure narrows the airway. In patients with a narrow cricoid, especially brachycephalic breeds, the pressure can make intubation more difficult [1]. The technique should be used with an understanding of the individual patient's anatomy. **Confusing the cricoid with the thyroid cartilage.** The thyroid cartilage is larger, V-shaped, and open dorsally. The cricoid is smaller, ring-shaped, and complete. The cricothyroid membrane between them is the landmark for cricothyrotomy, not the cricoid itself. **Overlooking the cricoid in laryngeal paralysis.** Laryngeal paralysis is often described as a disease of the arytenoid cartilages, but the cricoarytenoid joint on the cricoid lamina is equally important. Surgical procedures such as cricoarytenoid lateralization work because they stabilize the arytenoid in an abducted position relative to the cricoid [11]. ### Limitations Individual anatomy varies. The size and shape of the cricoid cartilage differ across breeds and species, and imaging or direct visualization is often needed to assess the airway accurately. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Review - The cricoid cartilage is the only complete cartilaginous ring in the airway. - It is shaped like a signet ring with a narrow ventral arch and a broad dorsal lamina. - It articulates with the thyroid cartilage laterally and the arytenoid cartilages dorsocranially. - The cricoarytenoid joint is the mechanical link that allows arytenoid abduction during inspiration. - Cricoid pressure during intubation narrows the subglottic airway and can complicate tube placement in brachycephalic breeds. - The cricothyroid membrane, immediately cranial to the cricoid arch, is the landmark for emergency cricothyrotomy. - Laryngeal paralysis results from failure of arytenoid abduction, and surgical treatment stabilizes the arytenoid relative to the cricoid. ## Frequently Asked Questions ### What is the cricoid cartilage? The cricoid cartilage is the only complete ring of cartilage in the airway, located at the caudal end of the larynx. It is shaped like a signet ring with a narrow arch ventrally and a broad lamina dorsally. ### Why is the cricoid cartilage important during intubation? The cricoid is the narrowest part of the airway in many patients. External pressure on the cricoid narrows the subglottic lumen, which can make endotracheal tube placement difficult, especially in brachycephalic breeds with a congenitally narrow cricoid [1]. ### What is cricothyrotomy? Cricothyrotomy is an emergency procedure that creates an airway through the cricothyroid membrane, which lies between the thyroid and cricoid cartilages. The cricoid arch is the caudal landmark for identifying the membrane. ### How does the cricoid relate to laryngeal paralysis in dogs? Laryngeal paralysis prevents the arytenoid cartilages from abducting, which narrows the airway during inspiration [9]. Surgical treatments such as cricoarytenoid lateralization anchor the arytenoid to the cricoid to hold the airway open [11]. ### Do all animals have the same cricoid shape? No. The cricoid is a complete ring in all domestic mammals, but its size and proportions vary. Dogs have a relatively short, wide cricoid. Horses have a large, robust cricoid that anchors laryngoplasty sutures [5]. Cattle have a thick cricoid that can be affected by chondritis. Cats have a smaller, more delicate cricoid [4]. ### Can the cricoid cartilage become diseased? Yes. The cricoid can be affected by chondrosarcoma [14], and the arytenoid cartilages can ossify with age [2]. Laryngeal chondritis in cattle and laryngeal collapse in brachycephalic dogs both involve the laryngeal cartilages, including the cricoid [3]. ## Related Articles - [Equine Forelimb Tendon and Ligament Anatomy: Clinical Relevance](/knowledge/veterinary-medicine/veterinary-anatomy-physiology/equine-forelimb-tendon-ligament-anatomy-clinical-relevance) - [MAPK Pathway: Mechanism, Function, and Clinical Relevance](/knowledge/molecular-biology/mapk-pathway) - [Telomere Testing: Methods, Meaning, and Clinical Relevance](/knowledge/molecular-biology/telomere-testing) - [Cellular Signaling: Principles, Pathways, and Clinical Relevance](/knowledge/molecular-biology/cellular-signaling) - [RNA Helicase: Mechanisms, Functions, and Clinical Relevance](/knowledge/molecular-biology/rna-helicase) - [DNA Repairsomes: Assembly, Function, and Clinical Relevance](/knowledge/molecular-biology/dna-repairsomes) - [Epiphyseal Plate: Growth, Anatomy and Clinical Notes](/knowledge/veterinary-medicine/veterinary-anatomy-physiology/epiphyseal-plate-growth-anatomy-and-clinical-notes) - [Vertebral Artery: Course, Branches, and Clinical Relevance](/knowledge/veterinary-medicine/veterinary-anatomy-physiology/vertebral-artery-course-branches-and-clinical-relevance) ## Sources 1. [Unrecognized difficult airway management during anesthesia in two brachycephalic dogs with narrow cricoid cartilage.](https://pubmed.ncbi.nlm.nih.gov/33390360/) 2. [Complete Bilateral Ossification of the Arytenoid Cartilages With Minimal Involvement of the Laryngeal Skeleton: A Unique Anatomical Variation.](https://pubmed.ncbi.nlm.nih.gov/40062052/) 3. [Subtotal Epiglottectomy and Ablation of Unilateral Arytenoid Cartilage as Surgical Treatments for Grade III Laryngeal Collapse in Dogs.](https://pubmed.ncbi.nlm.nih.gov/35565545/) 4. [Evaluation of two unilateral laryngoplasty techniques and their effect on arytenoid cartilage abduction in cats.](https://pubmed.ncbi.nlm.nih.gov/37204131/) 5. [Equine laryngoplasty: Effects of three anchoring techniques in the muscular process and three positions for suture implantation in the cricoid cartilage.](https://pubmed.ncbi.nlm.nih.gov/38787348/) 6. [Biomechanical testing of three constructs for prosthetic laryngoplasty in horses demonstrates advantages of differing metallic implants in the arytenoid cartilage.](https://pubmed.ncbi.nlm.nih.gov/40785216/) 7. [A comparison of the effect of propofol and alfaxalone on laryngeal motion in nonbrachycephalic and brachycephalic dogs.](https://pubmed.ncbi.nlm.nih.gov/30316695/) 8. [Effects of thiopentone, propofol and alfaxalone on laryngeal motion during oral laryngoscopy in healthy dogs.](https://pubmed.ncbi.nlm.nih.gov/28599889/) 9. [A RAPGEF6 variant constitutes a major risk factor for laryngeal paralysis in dogs.](https://pubmed.ncbi.nlm.nih.gov/31647804/) 10. [Effects of a novel, 3D printed bilateral arytenoid abductor on canine laryngeal airway resistance ex vivo.](https://pubmed.ncbi.nlm.nih.gov/35596179/) 11. [Comparison of immediate and short-term outcomes of cricoarytenoid and thyroarytenoid lateralization in dogs with idiopathic laryngeal paralysis.](https://pubmed.ncbi.nlm.nih.gov/35107177/) 12. [Outcome following elective unilateral arytenoid lateralization performed in an outpatient manner is comparable to hospitalization for dogs with laryngeal paralysis.](https://pubmed.ncbi.nlm.nih.gov/37225155/) 13. [Upper Airway Obstruction Due to Primary Laryngeal Blastomycosis in a Dog.](https://pubmed.ncbi.nlm.nih.gov/32182114/) 14. [Low Grade Laryngeal Chondrosarcoma of the Cricoid Cartilage: A Case Report.](https://pubmed.ncbi.nlm.nih.gov/40532295/)