The inferior articular surfaces have the same direction as those of the other cervical vertebrae. The superior vertebral notches are very shallow, and lie behind the articular processes. The inferior vertebral notches lie in front of the articular processes, as in the other cervical vertebrae. The spinous process is large, very strong, deeply channelled on its under surface, and presents a bifurcated extremity. Variation
Contact sports are contraindicated for individuals with anomalous dens, as any violent impact may result in a catastrophic injury. This is because a malformed odontoid process may lead to instability between the atlas and axis (the C1 and C2 cervical vertebrae). Development
The axis is ossified from five primary and two secondary centres. The body and vertebral arch are ossified in the same manner as the corresponding parts in the other vertebrae, viz., one centre for the body, and two for the vertebral arch. The centres for the arch appear about the seventh or eighth week of fetal life, while the centres for the body appear in about the fourth or fifth month. The dens, or odontoid process, consist originally of a continuation upward of the cartilaginous mass, in which the lower part of the body is formed.
Ethinylestradiol/drospirenone (EE/DRSP), sold under the brand name Yasmin among others, is a combination of ethinylestradiol (EE), an estrogen, and drospirenone (DRSP), a progestin, antimineralocorticoid, and antiandrogen, which is used as a birth control pill to prevent pregnancy in women. It is also indicated for the treatment of moderate acne, premenstrual syndrome (PMS), premenstrual dysphoric disorder (PMDD), and dysmenorrhea (painful menstruation) in women. The medication is taken by mouth and contains 30 μg EE and 3 mg DRSP per tablet (brand names Yasmin, others) or 20 μg EE and 3 mg DRSP per tablet (brand names Yaz, Yasminelle, Nikki, others). A formulation with levomefolic acid (vitamin B9) has also been marketed (brand names Beyaz, Safyral, others), with similar indications. EE/DRSP is marketed widely throughout the world.In 2019, it was the 148th most commonly prescribed medication in the United States, with more than 4 million prescriptions. See also
Ethinylestradiol/drospirenone/levomefolic acid
Ethinylestradiol/drospirenone/prasterone
Estradiol/drospirenone
List of combined sex-hormonal preparations § Estrogens and progestogens

References
External links
"Drospirenone mixture with estradiol". Drug Information Portal. U.S. National Library of Medicine.