Skull

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Skull Summary

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Dictionary of Biological Psychology

skull

(from Middle English, scolle) The term skull is in fact a rather colloquial term for what is more strictly called the CRANIUM (from Greek, kranion). The cranium is that part of the SKELETON associated with the head, face and lower jaw (the mandible). It forms part of the axial skeleton, which includes the cranium, vertebral column (the spinal column), ribs and sternum (breastbone), this being in contrast to the appendicular skeleton, which includes those parts associated with the arms and legs.

The cranium is not a solid box but an integrated selection of individual bones (see the adjacent table, The bones of the human skull’). The CRANIAL BONES are those that enclose the brain (forming the CRANIAL CAVITY, where the brain resides), while the FACIAL BONES are those that underlie the face and do not form part of the braincase (that is, the part of the cranium enclosing the brain: it is also known as the NEUROCRANIUM). The term CALVARIA is also used to describe the cranium without the facial bones (and the term CALOTTE refers to the calvaria without its base) and the term SPLANCHNOCRANIUM refers to the facial bones alone.

The various bones of the cranium may be paired or unpaired: paired bones are obviously found on either side of the head, while the unpaired bones cross the MIDLINE. The lines where bones meet are plainly visible; they are known as SUTURES. The table lists the principle bones of the skull, indicating their approximate position.

The cranium is obviously intended to protect the brain, which is suspended within the MENINGES inside the cranial cavity. As such it is rarely of particular interest to biological psychologists. However, note that during STEREOTAXIC SURGERY, skull landmarks—BREGMA and LAMBDA—are used in order to locate positions in the underlying brain tissue. Any STEREOTAXIC ATLAS will also use these

The bones of the skull
Paired cranial bones
PARIETAL BONES	top of the cranium, paired right and left, covering approximately the area of the PARIETAL LOBE
TEMPORAL BONES	to the sides, paired left and right, covering approximately the area of the TEMPORAL LOBE: the AUDITORY MEATUS is present
Unpaired cranial bones
FRONTAL BONE	covering the FRONTAL LOBES from the parietal bones behind to the tops of the ORBITS OF THE EYE (the eye sockets)
OCCIPITAL BONE	covering the OCCIPITAL LOBES at the back of the head; contains the FORAMEN MAGNUM, through which the spinal cord joins the brain
SPHENOID BONE	at the base of the brain; connects facial and cranial bones
ETHMOID BONE	at the base of the brain; forms the CRIBRIFORM PLATE
Paired facial bones
LACHRYMAL BONES	(also spelt lacrimal bones); form the medial part of the orbits of the eye, by the tear ducts
NASAL BONES	form the bridge of the nose
ZYGOMATIC BONES	form part of the cheek, connecting frontal and temporal bones
MAXILLAE	form the upper jaw and teeth and the area immediately above, below the nose
PALATINE BONES	form part of the palate and nose
INFERIOR NASAL CONCHAE	form the lateral part of the nose
Unpaired facial bones
VOMER BONE	forms the nasal septum; see VOMERONASAL ORGAN
MANDIBLE	the lower jaw and teeth
HYOID BONE	found at the front of the throat above the LARYNX; does not connect to any of the other bones of the cranium