x
Search
Exact matches only
Search in title
Search in content
Search in excerpt
Search in comments
Filter by Custom Post Type
feedback

Occipital Bone

The occipital bone is located in the posterior part of the skull. It’s identified by the presence of the large foramen magnum.

Interactive Anatomical Interface

Highlight
Frontal
parietal
Temporal
Sphenoid
Zygomatic
maxilla
Nasal
Lateral cartilage
greater alar cartilage
Mandbile
thyrohyoid membrane
thyroid cartilage
cricoid cartilage
cricotracheal ligament
ANterior longitudinal ligament
teeth
cervical vertabrae
first rib
second rib

Highlight
Frontal
parietal
Temporal
Sphenoid
Zygomatic
maxilla
Nasal
Lateral cartilage
greater alar cartilage
Mandbile

Highlight
thyrohyoid membrane
thyroid cartilage
cricoid cartilage
cricotracheal ligament
ANterior longitudinal ligament
teeth
cervical vertabrae
first rib
second rib
Highlight
frontal
Parietal
Sphenoid
temporal
Zygomatic
Maxilla
stylomandibular ligament
Lateral cartilage
posterior atlantoaxial ligament
lateral ligament
greater alar cartilage
teeth
mandible
hyoid
occipital bone
first rib
posterior atlanto-occipital memebrane
thyrohyoid membrane
thyroid cartilage
ricothyroid membrane and ligament
cricoid cartilage
cricotracheal ligament
t1 vertebra
stylohyoid ligament
joint capsule
Anterior longitudinal ligamnent
nuchal ligament
Cervical Vertebra
lacrimal

Highlight
frontal
Parietal
Sphenoid
temporal
Zygomatic
Maxilla
Lateral cartilage
greater alar cartilage
mandible
hyoid
thyrohyoid membrane
thyroid cartilage
ricothyroid membrane and ligament
cricoid cartilage
lateral ligament
cricotracheal ligament

Highlight
stylohyoid ligament
Anterior longitudinal ligamnent
nuchal ligament
Cervical Vertebra
first rib
t1 vertebra
lacrimal
occipital bone
teeth
posterior atlanto-occipital memebrane
posterior atlantoaxial ligament
joint capsule
stylomandibular ligament
-
Highlight
nasal
temporal bone
occipital bone
Internal auditory meatus
Stylomastoid foramen
Temporal
sphenoid
ethmoid
zygomatic bone
zygomatic bone
lacrimal bone
perpendicular plate
lacrimal bone
nasal cartilage
vomer
Nasal concha
Mandible
tectorial membrane of atlanto-axial joint
foramen magnum
tectorial membrane
c1 atlas
crista galli
ethmoidal sinuses
cribriform plate
foramen rotundum
optic foramen
superior orbital fissure
palatine
nuchal ligament
c01 atlas
posterior atlantoaxial ligament
c2 axis
c03 vertebrae
c04 vertebrae
C5 vertebrae

Highlight
nasal
temporal bone
occipital bone
Stylomastoid foramen
Temporal
sphenoid
ethmoid
zygomatic bone
zygomatic bone
lacrimal bone
perpendicular plate
posterior atlantoaxial ligament
nasal cartilage
vomer
Nasal concha
palatine
tectorial membrane of atlanto-axial joint

Highlight
foramen magnum
tectorial membrane
c1 atlas
crista galli
lacrimal bone
Mandible
ethmoidal sinuses
cribriform plate
foramen rotundum
Internal auditory meatus
optic foramen
superior orbital fissure
nuchal ligament
c01 atlas
c2 axis
c03 vertebrae
c04 vertebrae
C5 vertebrae
-

Please hover over the figure to get a brief info about the body parts. To get the elaborated info click on the body part.
 
Please rotate the device for better visual interaction.
 

Parts

It is composed of the following 4 parts:

  • Squamous part
  • 2 condylar parts
  • Basilar part

Squamous Part

It’s an enlarged plate above and behind the foramen magnum. It presents 2 surfaces and 3 angles.

1. External surface: It’s convex and reveals these features:

  • A median elevation in the point of its maximum convexity called External occipital protuberance. The most notable point of the protuberance is referred to as inion.
  • A bony crest running down-wards from external occipital protuberance to the foramen magnum called External occipital crest.
  • 2 superior nuchal lines, 1 on every side, arch laterally from external occipital protuberance.
  • 2 inferior nuchal lines, 1 on every side curve laterally from the middle of the external occipital crest.

2. Internal surface: It’s concave and reveals these features:

  • Internal occipital protuberance, a bony elevation near the center.
  • Internal occipital crest, a vertical bony crest which runs downwards from the internal occipital protuberance in the direction of the foramen magnum. Near the foramen magnum it divides to create a triangular depression referred to as vermian fossa.
  • Cruciate arrangement of 4 grooves, radiating from the internal occipital protuberance:
  • Sagittal sulcus/groove, runs upwards in the direction of the superior angle it’s inhabited by superior sagittal sinus.
  • Transverse sulcus/groove, 1 on every radiate in the direction of the lateral angle; it’s inhabited by the transverse sinus.
  • A groove descends downwards in the direction of the foramen magnum. It’s inhabited by the occipital sinus.
  • The small parts of grooves for sigmoid and inferior petrosal sinuses are also viewed on the internal surface.

Clinical Significance

The squamous part of temporal bone below the highest nuchal line is ossified in cartilage from 2 centers- 1 on every side in the 7th prenatal week and shortly joins with every other. The squamous part above the highest nuchal line is ossified in membrane from 2 centers- 1 on every side in the 8th prenatal week and shortly fuses with every other.

The 2 portions, upper and lower, of squamous part generally connect with every other in the third month after beginning when the baby begins holding his neck.

Occasionally the part above the highest nuchal line stays different and continues as interparietal bone.

Condylar Parts

It’s situated 1 on every side of the foramen magnum. The medial part bears occipital condyles. The lateral part, a quadrilateral plate projecting laterally from the posterior half of the occipital condyle is termed jugular process.

The outer opening of hypoglossal canal carrying hypoglossal nerve is located lateral to the anterior part of the occipital condyle.

The depression just behind the occipital condyle is referred to as condylar fossa. Occasionally it presents a foramen in its floor referred to as posterior condylar canal.

The anterior margin of jugular process presents a concave jugular notch which with quite similar notch on the petrous temporal bone creates the jugular foramen.

The superior surface of the condylar part presents the jugular tubercle.

Basilar Part (Basiocciput)

It’s a wide bar of bone which is located in front of the foramen magnum and articulates in front together with the body of sphenoid to create the basisphenoid joint (a primary cartilaginous joint).

The upper surface of the basisphenoid presents a shallow gutter, which slopes downwards and backwards from dorsum sellae to the foramen magnum. It’s referred to as clivus. The inferior surface of the basilar part presents a pharyngeal tubercle in median plane, about 1 cm in front of the foramen magnum.

The basisphenoid joint accounts for development of the skull in length.

Clinical Significance

Medigolegal significance of basisphenoid joint: The basisphenoid joint is of medicolegal significance in evaluating the exact age of the individual. It’s the primary cartilaginous joint with plate of hyaline cartilage between the basilar part of the occipital bone and posterior part of the body of sphenoid bone. This cartilaginous plate is entirely replaced by the bone (synostosis) by the 25th year of the age.


Rate this Article: 1 Star2 Stars3 Stars4 Stars5 Stars (37 votes, average: 4.57 out of 5)
Loading...

By | 2018-02-13T10:34:36+00:00 July 24th, 2017|Anatomy, Bones and Cartilages, Head and Neck|0 Comments