Hand atlas of human anatomy - EducationNest

Margo lambcloideu.4
Margo mastoideus
Pars lateralis
Bones of the Skull.
Pars basllaris
Sulcus sagittalis
Protuberantia occipitalis
interna
Sulcus transversus
Processus jugularis
^ Sulcus transversus
Canalis condyloideus
s Incisura jugularis
_, Manama
occipitalis
\ Probe in canalis hypoglossi
\ Processus intrajugularis
Tuberculura jugulare
Sulcus petrosus inferior
1. Occipital bone, os occipiiale, from in front.
The impaired os occipitale (occipital hone) (see also Kgs. 2, 3, 55, 56 and 59— 66)
forms the posterior inferior part of the sknll. It is divisible into four parts ; an unpaired basilar
part (pars basilarisj; an unpaii-ed squamo-oocipital part (squama occipitalis) and the paired
lateral parts (partes laterales). These parts are so arranged around the large occipital
foramen (foramen occipitale magnum) that the pars basUaris lies in front of the foramen,
the squama occipitalis behind and above it, while the partes laterales lie lateral fi'om it.
Through the great occipital foramen pass the meningeal rami of the vertebral arteries, the
vertebral arteries themselves, the anterior and posterior spinal arteries, the basilar plexus,
the nn. accessorii, the roots of the nn. cervicales I, and the medulla oblongata.
The pars basilaris presents, up to about the twentieth year of life,' a rough surface
in front correspontling to its attachment to the body of the sphenoid bone; the union is
effected by a layer of hyaline cartilage which ossifies later (fissura and synchondrosis sphenooccipitalis).
The two lateral slightly jagged edges lie upon the posterior angle of the petrous
portion of the temporal bone (fissura and synchondrosis petroocipitalis) ; on the upper siuface
is situated the gi'oove, formed by the two bones in common, corresponding to the sulcus
petrosus inferior (for the sinus petros. inf.). The posterior border, sharp in the middle, is
smooth and concave, and forms the anterior cii-cimiferenoe of the for. occip. mag. The superior
surface is smooth and slightly concave in a frontal direction; it helps to form the clivus inasmuch
as it is directly continuous with the posterior surface of the dorsum seUae of the sphenoid.
The clivus gives support to the pons, the vertebral arteries, the basilar artery and their branches.
The inferior surface presents in the median line a small projection, the pharyngeal tubercle (tuberculum
pharyngeum) (for the attachment of the lig. longitud. ant. and the m. constrictor
pharyngis sup.), and also alternating ledges for the m. rectus capitis ant. and the m. longus capitis.
Spalteholz, Atlas. \