From the Guidelines
Branchial arch derivatives are structures that develop from the pharyngeal arches during embryonic development, with the first arch giving rise to the mandible, malleus, incus, muscles of mastication, and other key structures, all of which are innervated by the trigeminal nerve (CN V) 1. The development of these derivatives is crucial for understanding head and neck anatomy, as well as the embryological basis of structures in the pharyngeal region. Some of the key derivatives of the branchial arches include:
- The first arch, which gives rise to the mandible, malleus, incus, muscles of mastication, anterior digastric, mylohyoid, tensor tympani, and tensor veli palatini, all of which are innervated by the trigeminal nerve (CN V) 1.
- The second arch, which forms the stapes, styloid process, stylohyoid ligament, lesser horn of hyoid, upper hyoid body, facial muscles, posterior digastric, and stapedius muscle, with facial nerve (CN VII) innervation.
- The third arch, which develops into the greater horn and lower body of hyoid, and stylopharyngeus muscle, innervated by glossopharyngeal nerve (CN IX).
- The fourth arch, which produces laryngeal cartilages (except cricoid), cricothyroid and pharyngeal constrictors, with superior laryngeal branch of vagus nerve (CN X) innervation.
- The sixth arch, which forms the cricoid cartilage and intrinsic laryngeal muscles, innervated by recurrent laryngeal branch of vagus nerve (CN X). Understanding these derivatives is essential for diagnosing and managing congenital anomalies, such as DiGeorge syndrome, Treacher Collins syndrome, and branchial cleft cysts, which can result from defects in branchial arch development 1.
From the Research
Branchial Arch Derivatives
The branchial arches are the embryological precursors of the face, neck, and pharynx 2. They develop into various structures, including:
- Muscles of mastication (first arch)
- Muscles of facial expression (second arch)
- Muscles of pharynx and larynx (third and fourth arches)
Anomalies of Branchial Arches
Anomalies of the branchial arches can occur, resulting in congenital lesions such as cysts, sinuses, and fistulae 2, 3, 4. These anomalies can be classified into different types based on the branchial arch involved:
- First branchial cleft anomalies
- Second branchial cleft anomalies (most common, accounting for approximately 95% of cases) 2
- Third branchial cleft anomalies
- Fourth branchial cleft anomalies
Clinical Presentation and Diagnosis
Branchial arch anomalies can present with various symptoms, including:
- Cervical swelling
- Fistulas
- Superinfection
- Recurrent localized infection 2, 4 Diagnosis can be made using imaging studies such as ultrasound, CT, and MRI, as well as fine needle aspiration cytology (FNAC) 3, 4, 5.
Treatment and Management
Treatment of branchial arch anomalies typically involves surgical excision of the cyst or fistula 2, 3, 4, 5. The goal of treatment is to completely remove the anomaly to prevent recurrence and complications. In some cases, less invasive procedures such as sclerotherapy and endoscopic excision may be used 5.