This slide gives a complete description of Norma Occipitalis (Posterior view of skull)

1. AREEB FATIM A
ST U DENT DOCT OR OF PHYSICA L T HERA PY
GOVERNM ENT COLLEGE U NIVERSIT Y
HUMAN ANATOMY
Head and Neck

2. EXTERIOR OF THE SKULL

3. Norma Occipitalis
 Norma occipitalis is convex upwards and on each side,
and is flattened below.
 Bones:
 Posterior parts of parietal bones.
 Squamous part of Occipital bone.
 Mastoid part of temporal bone.
 Sutures:
 Lambdoid suture: Present between the occipital bone and two
parietal bones.
 Occipitomastoid suture: Present between the occipital bone and
mastoid part of temporal bone.
 Parietomastoid suture: Present between the parietal bone and
the mastoid part of temporal bone.

4. Norma Occipitalis (Continued)

5. Norma Occipitalis (Continued)
 Other features:
 Lambda, obelion, and
parietal foramina.
 External occipital
protuberance:
 Median prominence in the lower
part of this norma.
 Marks the junction of head and
neck.
 Most prominent point on this
protuberance is inion.

6. Norma Occipitalis (Continued)
 Superior nuchal lines:
 Curved bony ridges passing
laterally from the
protuberance.
 Also mark the junction of
head and neck.
 Highest nuchal lines:
 Not always present.
 Curved bony ridges
situated about 1 cm above
the superior nuchal lines.
 More arched than superior
nuchal lines.

7. Norma Occipitalis (Continued)
 Occipital point:
 Median point a little above the inion.
 Farthest point from glabella.

8. Norma Occipitalis (Continued)
 Mastoid foramen:
 Located near the occipitomastoid
suture on the mastoid part of
temporal bone..
 It opens at the sigmoid sulcus.
 It transmits emissary vein and the
meningeal branch of occipital artery.
 Interparietal bone:
 It is large triangular bone located at
the apex of squamous occipital.
 This is not a sutural bone but
represents the membranous part of
the occipital bone which has failed to
fuse with the rest of bone.

9. Norma Occipitalis (Continued)
 Attachments:
Parts Muscle attached
Upper part of external
occipital protuberance.
Origin of trapezius
Lower part of external
occipital protuberance.
Upper end of ligamentum
nuchae.
Medial one third of superior
nuchal line.
Origin of trapezius
Lateral part of superior
nuchal line
Strenocleidomastoid above,
splenius captis below.
Highest nuchal line Epicranial aponeurosis
medially, occipital belly of
occipitofrontalis muscle
laterally.

10. Norma Occipitalis (Continued)