skull

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skull

 [skul]
the skeleton of the head, consisting of the cranium and the mandible. The cranium forms the domed top, back, and sides of the skull; several of its bones are large, smooth, gently curved, and connected to each other by dovetailed joints called sutures, which permit no movement and make the mature skull rigid. They protect the brain, with their curved exterior serving to deflect blows; the eyes, ears, and nose are also protected by being recessed into the skull and surrounded by bone.



At birth the skull joints are flexible, so that the infant's head can be compressed as it emerges from the birth canal. The joints remain flexible to allow expansion until the cranial bones are fully formed, around the second year of life. An infant's skull contains soft areas, or fontanels, where the bones of the cranium do not meet.

The skull is supported by the highest vertebra, called the atlas. This joint permits a back-and-forth, nodding motion. The atlas turns on the vertebra below it, the axis, which allows the skull to turn from side to side.
Disorders of the Skull. The skull is rarely affected by disease. Uncommon ones like osteitis deformans and acromegaly cause the bones to increase in size. Like other bones, the skull may be fractured by blows, falls, or other accidents, but skull fracture can be far more dangerous because of its proximity to the brain.
Skull, midsagittal section. From Applegate, 2000.

cra·ni·um

, pl.

cra·ni·a

(krā'nē-ŭm, -ă), [TA]
The bones of the head collectively. The neurocranium is the part of cranium that forms the bony brain case containing the brain, excluding the bones of the face (viscerocranium).
Synonym(s): skull
[Mediev. L. fr. G. kranion]

skull

(skul) the cranium; the bony framework of the head, composed of the cranial and facial bones.

skull

(skŭl)
n.
The bony or cartilaginous framework of the head, made up of the bones of the braincase and face; cranium.

skull

Etymology: ME, skulle, shell
the bony structure of the head, consisting of the cranium and the skeleton of the face. The cranium, which contains and protects the brain, consists of 8 bones; the skeleton of the face is composed of 14 bones.

skull

(skŭl)
The bones of the head collectively. In a more limited sense, the neurocranium, the bony braincase containing the brain, excluding the bones of the face (viscerocranium).
[Mid. Eng. skulle, a bowl]

skull

(skul)
Enlarge picture
BONES OF SKULL: Cranial bones
Enlarge picture
BONES OF SKULL: Facial bones
The bony framework of the head, composed of 8 cranial bones, the 14 bones of the face, and the teeth. It protects the brain and sense organs from injury. Synonym: calvaria; cranium See: illustration; skeleton

fractured skull

See: fracture of skullillustration

skull

The bony skeleton of the head and the protective covering for the brain. The part of the skull that encloses the brain is called the cranium.

skull

the skeleton of the vertebrate head.

cra·ni·um

, pl. crania (krā'nē-ŭm, -ă) [TA]
The bones of the head collectively.
Synonym(s): skull.
[Mediev. L. fr. G. kranion ]

skull

the bony framework of the head consisting of two parts, the cranium and the facial section.
The cranium is the domed top, back and sides of the skull that protects the brain. It is made up mostly of a roof of flat membrane bones united by sutures in the young, plus a series of cartilage bones at the base (occipital, sphenoid). Paranasal sinuses variably excavate the membrane bones.
The facial bones are mostly membrane bones and serve to support the dental arcades and the respiratory passages of the head.

skull bones
the bones of the skull are the basisphenoid, ethmoid, frontal, hyoid, incisive, interparietal, lacrimal, nasal, occipital, nasal conchal, palatine, parietal, presphenoid, pterygoid, sphenoid, temporal, vomer and zygomatic.
brachycephalic skull
short, broad skull.
dolicocephalic skull
long, narrow skull.
mesaticephalic skull
a medium skull in terms of width and length.
skull symmetry
asymmetry common only in foals in which the lower part of the face is deviated to one side, involving mandibles, maxillae and nasal bones.
References in classic literature ?
Across Tarzan's forehead stood out the broad band of scarlet that marked the scar where, years before, Terkoz had torn a great strip of the ape-man's scalp from his skull in the fierce battle in which Tarzan had sustained his fitness to the kingship of the apes of Kerchak.
Closely I examined the ghastly remains fearful each instant that I should find the dainty skull that would shatter my happiness for life; but though I searched diligently, picking up every one of the twenty-odd skulls, I found none that was the skull of a creature but slightly removed from the ape.
As two of the head hunters closed upon him the brave Chinaman clubbed his weapon and went down beneath them beating madly at the brown skulls.
And, unlike the mere bush dogs, who stole shelter from the rain under overhanging eaves, Jerry was given a dry place under the roof where the heads of bushmen and of forgotten sandalwood traders hung down from above in the midst of a dusty confusion of dried viscera of sharks, crocodile skulls, and skeletons of Solomons rats that measured two-thirds of a yard in length from bone-tip of nose to bone-tip of tail.
The Wieroo raised his wings in a very human shrug and waved his bony claws toward the human skulls supporting the ceiling.
Casting a stealthy glance around, ere Peg withdrew the light, I was relieved to see that there were no skulls in sight.
As Owen has remarked, the benefit derived from the yielding of the separate pieces in the act of parturition of mammals, will by no means explain the same construction in the skulls of birds.
Molly pursued her victory, and catching up a skull which lay on the side of the grave, discharged it with such fury, that having hit a taylor on the head, the two skulls sent equally forth a hollow sound at their meeting, and the taylor took presently measure of his length on the ground, where the skulls lay side by side, and it was doubtful which was the more valuable of the two.
Then, this young gentleman, going to a little cupboard, returned with a thigh-bone, which in former times must have been part and parcel of some individual at least as long as himself, and placed the same in the hands of Mr Tappertit; who, receiving it as a sceptre and staff of authority, cocked his three-cornered hat fiercely on the top of his head, and mounted a large table, whereon a chair of state, cheerfully ornamented with a couple of skulls, was placed ready for his reception.
Tis split, too --that I feel; the jagged edge galls me so, my brain seems to beat against the solid metal; aye, steel skull, mine; the sort that needs no helmet in the most brain-battering fight
Bear in mind, too, that under these untoward circumstances he has to cut many feet deep in the flesh; and in that subterraneous manner, without so much as getting one single peep into the ever-contracting gash thus made, he must skilfully steer clear of all adjacent, interdicted parts, and exactly divide the spine at a critical point hard by its insertion into the skull.
He had, however, put a horse's skull which was lying on the ground, for his pillow, so that he should not be too comfortable and might soon wake up.