Connection Of Posterior Occipital Muscle And Dura Mater Of Siamese Crocodile

PURPOSE: In 1995, Hack et first proposed the concept of myodural bridge, the structure is located between deep muscle at the suboccipital and dura mater.Over the past 30 years, many literature reported that the myodural bridge is associated with chronic cervicognic headache. In 2013, Sui Hongjin also proposed a new hypothesis, that the myodural bridge is associated with the circulation of cerebral spinal fluid, the movements of the head and neck; the suboccipital muscle contracted; can affect the circulation of cerebral spinal fluid through myodural bridge. So far, the existence of the myodural bridge has been widely proved, but their origins and functions still have So many problems to discuss. Human has myodural bridge structure, therefore this structure also the same exist in other vertebrates as well? What in the reptile? We represented by Crocody siamesis, observe anatomical structure of the suboccipital area of the reptiles, as expectation, will provide more valuable morphological data for myodural bridge research.METHODS: 1.This experiment selected two samples of fresh siamese crocodile corpse of a normal death, dissection in the occipitopost region. Observe the enthesis of the occipitovertebrales(rectus capitis dorsalis major、rectus capitis dorsalis minor) and the organizational relationships between the occipitovertebrales the proatlas, the atlas, and the dura mater. 2.The other four fresh Crocody siamesis corpse of a normal death, deel with P45 sheet plastination, in the middle of sagittal serial section and observe. Take pictures record and described the structure course between the occipitovertebrales(rectus capitis dorsalis major、rectus capitis dorsalis minor) and describe the connection’s course of the sample of the myodural bridge structure.RESULTS: 1.The result of gross anatomy The proatlas is covered by three blocks of muscles: rectus capitis posterior minor muscle in the innermost region near the midline, rectus capitis posterior major muscle in the middle and semispinalis capitis muscle in outermost site. The myodural bridge-like structure presented between posterior occipital muscle and dura mater of Siamese crocodile’s; Muscles in the deep posterior occipital region contain rectus capitis posterior major muscle and rectus capitis posterior minor muscle; Rectus capitis posterior minor muscle originates from supraoccipital bone and terminates in the front end of the C2 spinous process, neural arch of atlas, proatlas and the membrane structure between proatlas and atlas; Rectus capitis posterior major muscle originates from exoccipital bone and terminates in the front end of the C2 spinous process and atlantal arch, dense connective tissue connects to proatlas、atlas in the ventral part of rectus capitis posterior major muscle. in the ventral part of proatlas, atlas and the membrane structure between them connects to dorsal surface of spinal dura mater. At the level of proatlas to anterior border of C2 lamina of vertebral arch, many trabecular structures of connec tive tissue existed in the ―inverted triangle‖ area(wide cephalic region, narrow caudal region) in posterior wall of the spinal canal. These connective tissues connect dural sac to the posterior wall of the spinal canal。Moreover, trabecular structure of connective tissue was dense between proatlas and intervertebral foramen of atlas。In the caudal axis, Y-shaped potential lacuna was visible between the posterior wall of the spinal canal and dura mater。 In both sides of the potential lacuna, discontinuous sheet-like structure emitted from lateral posterior wall of the spinal canal connected to the dura mater, and the sheet-like structure was dense around the intervertebral foramen 。Moreover, trabecular structure of connective tissue was dense between proatlas and intervertebral foramen of atlas 。The potential lacuna extended towards two sides of the ―inverted triangle‖ connective tissues and reached the interspace(the first cervical nerve root) between atlas and occipital bone. 2. Observation results of P45 sheet plastination technology Median sagittal sections of four samples showed vertebral occipital muscles originated from occipital bone and moved downwards. Dense connective tissue in the deep region of muscles connected to the proatlas. At the level of proatlas to anterior border of C2 lamina of vertebral arch, dural sac connected to the posterior wall of the spinal canal through trabecular structure of connective tissue.Conclusion 1. The proatlas is covered by three blocks of muscles: rectus capitis posterior minor muscle in the innermost region near the midline, rectus capitis posterior major muscle in the middle and semispinalis capitis muscle in outermost site. In addition, dense connective tissue in the deepest place of above muscles connects to its deep structure(proatlas, atlas and the membrane structure between them). The myodural bridge-like structure presented between posterior occipital muscle and dura mater of Siamese crocodile’s. 2. The structural connection of v ertebral occipital muscle �' proatlas �' dura mater probably exerts myodural bridge-like effects in reptiles. It is assumed that the function of above connection may be associated with the power of cerebrospinal fluid circulation.