THE SKULL

The average skull measures 8 ½ inches high, 7 ½ inches deep and 6 inches wide. Skull height is the usual module for comparative measure on the human figure.

The CRANIUM and FACE are the two main sections of the skull.

 

CRANIUM:

Skull segments, except for the lower jaw) interlock in suture joints. The cranium is made up of 8 segments which encase the brain. Six of these segments are important to the artist as they are visible at the surface. The shape of the cranium resembles an egg with the large end at the back.

Cranial segments:

FRONTAL BONE (1): broad bone of the forehead and forward roof of the skull. There are two lateral swellings above the brow ridges: frontal eminences. These are more pronounced in a child’s skull. Below the forehead, just above the orbits (eye sockets) are the supercilliary crests (brow ridges). The brow ridges are more pronounced in the male skull, smoother in the female. The ridges nearly meet above the root of the nose. A small depression called the glabella separates them.

OCCIPITAL (1): at the back of the head. Its under surface rests on the spinal column. The occipital crest in the median line terminates at the occipital protuberance. This line and crest form important attachment points for muscles and ligaments of the neck. The nuchal lines lie to either side of the occipital protuberance and are the attachment points for the nuchal ligament. This ligament helps shape the back of the neck.

The PARIETALS (2): these bones lie between the frontal and occipital bones to form the upper side and rear vaulted roof of the skull meeting at a middling. The widest points of the skull are formed by the parietal eminences. The highest point of the skull is in the parietal region.

The TEMPORALS (2): these somewhat small and thin bones form the lower side walls of the cranium. The ear hole is located in the temporal. The hinge of the jaw is just ahead of the ear hole. A bulge just below and behind the ear hole is the mastoid process which is the point of insertion for the sterrno-mastoid muscle. The zygomatic arch springs from this region to join the zygomatic bone (cheek bone). The temporal line, arising from the zygotic bone at the outer edge of the frontal bone and arching backward over the cranium, is an important construction line. The temporal fossa, is a depression in the side wall of the temporal region. In the living figure it is filled with a jaw muscle, the temporalis muscle.

The SPHENOID (1): this bone forms the under surface of the cranium and appears in both side walls between the temporal and frontal bones in the region called the temples. In the living figure this area is filled with jaw muscle.

 

THE FACE

The facial region hangs like a mask beneath the frontal bone of the cranium- Bones of structural importance to the artist are the zygomatics, nasals, maxillae and the mandibula for a total of 7 bones.

The ZYGOMATIC BONES (2): these are prominent angular plates with 3 spurs or processes. One spur rises to the zygomatic process of the frontal bone and forms the outer rim of the orbit. A second spur meets the zygomatic arch and the third reaches towards the nose forming the lower rim of the orbit. The prominence of the zygomatic bone varies with individuals.

The NASAL BONES (2): project from beneath the glabella and are only about an inch long. These create the sloping bridge of the nose.

The MAXILLARY BONES (maxillae) (2): these form the upper jaw and are the roots of its teeth. Above each maxilla joins the zygomatic, nasal and frontal bones to complete the margin of the orbit.

The MANDIBULA (1): the mandible, or lower jaw, is roughly horseshoe shaped and is the only moveable bone in the skull. A projection at the chin is called the mental protuberance. The rear "corner" of the jaw, called the angle of the mandibula is an important construction point. The coronoid process projects upward beneath the zygomatic bone to serve as an attachment for the temporalis muscle (used for chewing). Another projection, the condyloid process, articulates with a socket just in front of the ear hole in the temporal bone (hinge Joint).

 

SUMMARY

The Skull (8" X 7 1/2" X 6")

Cranium: 8 bones in all — note 7: 1 frontal - front and top 2 parietals - back and top 2 temporals -lower side towards back 2 sphenoids - underside and lower side towards front 1 occipital - lower back

Face - 14 bones in all, note 9:

Important construction lines and points of the head. and neck:

Muscles of the skull and neck that directly influence form:

 

Distinctions of sex:

The female head is smaller than the male; the forehead smoother and more rounded and set more nearly perpendicular. Brow ridges are nearly absent and there is no special prominence at the center above the nose. Facial features are smaller in the female and the neck appears more slender in relation to adjacent features. The collarbones are shorter and straighter thus reducing the width of the shoulders in relation to the trunk. In the female the collarbones are usually horizontal or even sloped somewhat laterally. This makes the neck appear longer. Male collarbones rise laterally. The female neck is often encircled by creases (rings of Venus). The throat shows a flattened thyroid cartilage (Adam’s Apple) and a full thyroid gland. In the male the thyroid cartilage is prominent and the gland is lean.

 

Distinctions of race:

Since racial distinctions are more of a cultural custom and are very difficult to define in terms of human anatomy, skin color, etc. the art student is cautioned to set assumptions about racial characteristics aside and pay close attention to the model's specific characteristics.

Camper’s angle (the degree of facial angle found at the intersection of a horizontal line from the ear hole to the base of the nose with an oblique line from the forehead to upper teeth) ranges from 62 to 85 degrees. This is a characteristic that the student of anatomy should pay attention to when doing a portrait.

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