Updated: 12/21/2018

Branchial Apparatus

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Overview
  •  Branchial apparatus (pharyngeal apparatus)
    • branchial clefts (branchial grooves)
      • derived from ectoderm located between the arches
    • branchial arches
      • derived from mesoderm (muscles, arteries) and neural crest cells (bones, cartilage)
      • each arch is associated with a cranial nerve
    • branchial pouches
      • derived from endoderm which line the foregut
Branchial arch innervation
  • 1st arch derivatives 
    • CN V2 and V3: muscles for "chewing"
  • 2nd arch derivatives
    • CN VII: muscles for "facial expression"
  • 3rd arch derivatives
    • CN IX
  • 4th and 6th arch derivatives 
    • supplied by CN X: muscles for  "swallowing" and "speaking"
  • CN V3, VII, IX, and X are both sensory and motor. 
  • CN V2 is only sensory
Branchial arch derivatives
 
Deriv.
Cartilage
Muscles
Nerves
Arteries
Syndromes
1
  • Meckel's cartilage
    • mandible
    • malleus
    • incus
    • sphenomandibular ligament
  • Muscles of mastication
    • temporalis
    • masseter
    • lateral and medial pterygoids
  • Mylohyoid
  • Anterior belly of digastric
  • Tensor tympani
  • Tensor veli palatini
  • Anterior 2/3 of tongue
CN V2 and V3 Maxillary artery, external carotid artery
  • Treacher Collins syndrome 
    • neural crest cells fail to migrate into arch 1
    • results in underdeveloped zygomatic bones, mandibular hypoplasia, lower eyelid colobomas, and malformed ears
  • Pierre Robin syndrome
    • small jaw, tongue falls back into throat causing choking and difficulty breathing
2
  • Reichert's cartilage
    • stapes
    • styloid process
    • lesser horn of hyoid
    • stylohyoid ligament
  • Muscles of facial expression
  • stapedius
  • stylohyoid
  • posterior belly of digastric
CN VII Stapedial artery, hyoid artery
  • Congenital pharyngocutaneous fistula 
    • persistence of cleft and pouch
    • fistula between internal tonsillar area and external neck
    • found along anterior border of sternocleidomastoid
3
  • Cartilage
    • greater horn of hyoid
  • Stylopharyngeus
CN IX Common carotid, internal carotid arteries  
4-6
  • Cartilages
    • thyroid
    • cricoid
    • arytenoids
    • corniculate
    • cuneiform
4th arch
  • pharyngeal constrictors except stylopharyngeus
  • cricothyroid
  • muscles of soft palate except tensor veli palatini

6th arch

  • intrinsic muscles of larynx except cricothyroid
  • upper muscles of esophagus
4th arch

CN X: superior laryngeal branch (swallowing)

6th arch

CN X: recurrent laryngeal branch (speaking)

4 - Right: subclavian artery; Left: aortic arch


6 - Right: pulmonary artery; Left: pulomonary artery & ductus arteriosus 

 

 

Branchial cleft derivatives
  • 1st cleft
    • develops into epithelial lining of external auditory meatus
  • 2nd - 4th cleft
    • forms temporary cervical sinuses
    • later obliterated by proliferation of 2nd arch
  • Persistent cervical sinus
    • branchial cleft cyst within lateral neck/angle of mandible
Branchial pouch derivatives
  • 1st pouch 
    • forms
      •  epithelial (endoderm derived) lining of middle ear cavity and eustachian tube
      • mastoid air cells
  • 2nd pouch
    • forms epithelial lining of palatine tonsil
  • 3rd pouch
    • dorsal wings
      • forms inferior parathyroids
    • ventral wings
      • forms thymus 
    • 3rd pouch derivatives end up below the 4th derivatives
  • 4th pouch dorsal wings 
    • forms superior parathyroids 
  • DiGeorge syndrome (22q11 deletion)
    • 3rd and 4th pouches fail to differentiate into thymus and parathyroid glands
    • Symptoms
      • ↓ PTH due to parathyroid aplasia
        • tetany due to hypocalcemia
      • T cell deficiency due to thymic aplasia
        • recurrent viral/fungal infections
        • cell mediated immunity still functional and can fight bacterial infections
      • congenital heart and great vessel defects
      • absent thymic shadow on CXR
  • MEN 2A
    • mutation of germline RET (neural crest cells)
      • pheochromocytoma
      • parathyroid tumor
        • derived from 3rd/4th pharyngeal pouch
      • medullary thyroid cancer
        • derived from parafollicular cells from the 4th/5th pharyngeal pouch 
        • NOTE: 5th pouch degenerates during development
 

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Questions (9)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M1.EB.42) A 47-year-old female undergoes a thyroidectomy for treatment of Graves' disease. Post-operatively, she reports a hoarse voice and difficulty speaking. You suspect that this is likely a complication of her recent surgery. What is the embryologic origin of the damaged nerve that is most likely causing this patient's hoarseness? Review Topic

QID: 101936
1

1st pharyngeal arch

0%

(0/15)

2

2nd pharyngeal arch

7%

(1/15)

3

3rd pharyngeal arch

33%

(5/15)

4

4th pharyngeal arch

7%

(1/15)

5

6th pharyngeal arch

53%

(8/15)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

(M1.EB.3) A newborn male born prematurely at 33 weeks is noted to have mild dyspnea and difficulty with feeding. Examination reveals bounding peripheral radial pulses and a continuous 'machine-like' murmur. The patient is subsequently started on indomethacin. Which of the following is the embryologic origin of the structure most likely responsible for this patient's presentation? Review Topic

QID: 101897
1

1st branchial cleft

0%

(0/17)

2

4th branchial arch

6%

(1/17)

3

4th branchial pouch

12%

(2/17)

4

6th aortic arch

71%

(12/17)

5

6th branchial pouch

12%

(2/17)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

(M1.EB.41) A 26-year-old female presents to your clinic with complaints of increasing muscle fatigue that worsens after periods of sustained activity. She also reports both ptosis and diplopia that make reading in the late afternoon and evenings difficult. An edrophonium test is performed and is positive, demonstrating resolution of the patient's weakness. Which of the following embryologic structures gives rise to the organ commonly affected as a complication of this patient's condition? Review Topic

QID: 101935
1

1st branchial pouch

18%

(8/44)

2

2nd branchial cleft

23%

(10/44)

3

3rd branchial arch

23%

(10/44)

4

3rd branchial pouch

14%

(6/44)

5

4th branchial pouch

9%

(4/44)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 4
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