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The occipital bone [Fig. 1&2], a bone situated at the back and lower part of the cranium, is trapezoid in shape and curved on itself. It is pierced by a large oval aperture, the foramen magnum, through which the cranial cavity communicates with the vertebral canal. Grays illustration of a human femur, a typically recognized bone. ...
Cranium can mean: The brain and surrounding skull, a part of the body. ...
In anatomy, the foramen magum is the large hole through the occipital bone in the base of the skull, through which the medulla oblongata (an extension of the spinal cord) exits the skull vault. ...
 Figure 1 : Occipital bone, outer surface. The curved, expanded plate behind the foramen magnum is named the squama; the thick, somewhat quadrilateral piece in front of the foramen is called the basilar part, whilst on either side of the foramen is the lateral portion. Image File history File links From Grays Anatomy File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Image File history File links From Grays Anatomy File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
The squama
The squama (squama occipitalis), situated above and behind the foramen magnum, is curved from above downward and from side to side.
Surfaces The external surface is convex and presents midway between the summit of the bone and the foramen magnum a prominence, the external occipital protuberance. Extending lateralward from this on either side are two curved lines, one a little above the other. The upper, often faintly marked, is named the highest nuchal line, and to it the galea aponeurotica is attached. The lower is termed the superior nuchal line. That part of the squama which lies above the highest nuchal lines is named the planum occipitale, and is covered by the Occipitalis muscle; that below, termed the planum nuchale, is rough and irregular for the attachment of several muscles. From the external occipital protuberance a ridge or crest, the median nuchal line, often faintly marked, descends to the foramen magnum, and affords attachment to the ligamentum nuchæ; running from the middle of this line across either half of the nuchal plane is the inferior nuchal line. Several muscles are attached to the outer surface of the squama, thus: the superior nuchal line gives origin to the Occipitalis and Trapezius, and insertion to the Sternocleidomastoideus and Splenius capitis: into the surface between the superior and inferior nuchal lines the Semispinalis capitis and the Obliquus capitis superior are inserted, while the inferior nuchal line and the area below it receive the insertions of the Recti capitis posteriores major and minor. The posterior atlantoöccipital membrane is attached around the postero-lateral part of the foramen magnum, just outside the margin of the foramen. The Occipitalis muscle is a muscle of the human body. ...
Trapezius In human anatomy, the trapezius is a large superficial muscle on a persons back. ...
 Figure 2 : Occipita bone, inner surface. The internal surface is deeply concave and divided into four fossæ by a cruciate eminence. The upper two fossæ are triangular and lodge the occipital lobes of the cerebrum; the lower two are quadrilateral and accommodate the hemispheres of the cerebellum. At the point of intersection of the four divisions of the cruciate eminence is the internal occipital protuberance. From this protuberance the upper division of the cruciate eminence runs to the superior angle of the bone, and on one side of it (generally the right) is a deep groove, the sagittal sulcus, which lodges the hinder part of the superior sagittal sinus; to the margins of this sulcus the falx cerebri is attached. The lower division of the cruciate eminence is prominent, and is named the internal occipital crest; it bifurcates near the foramen magnum and gives attachment to the falx cerebelli; in the attached margin of this falx is the occipital sinus, which is sometimes duplicated. In the upper part of the internal occipital crest, a small depression is sometimes distinguishable; it is termed the vermian fossa since it is occupied by part of the vermis of the cerebellum. Transverse grooves, one on either side, extend from the internal occipital protuberance to the lateral angles of the bone; those grooves accommodate the transverse sinuses, and their prominent margins give attachment to the tentorium cerebelli. The groove on the right side is usually larger than that on the left, and is continuous with that for the superior sagittal sinus. Exceptions to this condition are, however, not infrequent; the left may be larger than the right or the two may be almost equal in size. The angle of union of the superior sagittal and transverse sinuses is named the confluence of the sinuses (torcular Herophili), and its position is indicated by a depression situated on one or other side of the protuberance. Image File history File links From Grays Anatomy File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Image File history File links From Grays Anatomy File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Lateral parts The lateral parts (pars lateralis) are situated at the sides of the foramen magnum; on their under surfaces are the condyles for articulation with the superior facets of the atlas. The condyles are oval or reniform in shape, and their anterior extremities, directed forward and medialward, are closer together than their posterior, and encroach on the basilar portion of the bone; the posterior extremities extend back to the level of the middle of the foramen magnum. The articular surfaces of the condyles are convex from before backward and from side to side, and look downward and lateralward. To their margins are attached the capsules of the atlantoöccipital articulations, and on the medial side of each is a rough impression or tubercle for the alar ligament. At the base of either condyle the bone is tunnelled by a short canal, the hypoglossal canal (anterior condyloid foramen). This begins on the cranial surface of the bone immediately above the foramen magnum, and is directed lateralward and forward above the condyle. It may be partially or completely divided into two by a spicule of bone; it gives exit to the hypoglossal or twelfth cerebral nerve, and entrance to a meningeal branch of the ascending pharyngeal artery. Behind either condyle is a depression, the condyloid fossa, which receives the posterior margin of the superior facet of the atlas when the head is bent backward; the floor of this fossa is sometimes perforated by the condyloid canal, through which an emissary vein passes from the transverse sinus. Extending lateralward from the posterior half of the condyle is a quadrilateral plate of bone, the jugular process, excavated in front by the jugular notch, which, in the articulated skull, forms the posterior part of the jugular foramen. The jugular notch may be divided into two by a bony spicule, the intrajugular process, which projects lateralward above the hypoglossal canal. The under surface of the jugular process is rough, and gives attachment to the Rectus capitis lateralis muscle and the lateral atlantoöccipital ligament; from this surface an eminence, the paramastoid process, sometimes projects downward, and may be of sufficient length to reach, and articulate with, the transverse process of the atlas. Laterally the jugular process presents a rough quadrilateral or triangular area which is joined to the jugular surface of the temporal bone by a plate of cartilage; after the age of twenty-five this plate tends to ossify.
The upper surface of the lateral part presents an oval eminence, the jugular tubercle, which overlies the hypoglossal canal and is sometimes crossed by an oblique groove for the glossopharyngeal, vagus, and accessory nerves. On the upper surface of the jugular process is a deep groove which curves medialward and forward and is continuous with the jugular notch. This groove lodges the terminal part of the transverse sinus, and opening into it, close to its medial margin, is the orifice of the condyloid canal.
Basilar part The basilar part (pars basilaris) extends forward and upward from the foramen magnum, and presents in front an area more or less quadrilateral in outline. In the young skull this area is rough and uneven, and is joined to the body of the sphenoid by a plate of cartilage. By the twenty-fifth year this cartilaginous plate is ossified, and the occipital and sphenoid form a continuous bone.
Surfaces On its lower surface, about 1 cm. in front of the foramen magnum, is the pharyngeal tubercle which gives attachment to the fibrous raphé of the pharynx. On either side of the middle line the Longus capitis and Rectus capitis anterior are inserted, and immediately in front of the foramen magnum the anterior atlantoöccipital membrane is attached.
The upper surface presents a broad, shallow groove which inclines upward and forward from the foramen magnum; it supports the medulla oblongata, and near the margin of the foramen magnum gives attachment to the membrana tectoria. On the lateral margins of this surface are faint grooves for the inferior petrosal sinuses.
Foramen magnum The foramen magnum is a large oval aperture with its long diameter antero-posterior; it is wider behind than in front where it is encroached upon by the condyles. It transmits the medulla oblongata and its membranes, the accessory nerves, the vertebral arteries, the anterior and posterior spinal arteries, and the membrana tectoria and alar ligaments.
Angles The superior angle of the occipital bone articulates with the occipital angles of the parietal bones and, in the fetal skull, corresponds in position with the posterior fontanelle. The inferior angle is fused with the body of the sphenoid. The lateral angles are situated at the extremities of the grooves for the transverse sinuses: each is received into the interval between the mastoid angle of the parietal and the mastoid part of the temporal.
Borders The superior borders extend from the superior to the lateral angles: they are deeply serrated for articulation with the occipital borders of the parietals, and form by this union the lambdoidal suture. The inferior borders extend from the lateral angles to the inferior angle; the upper half of each articulates with the mastoid portion of the corresponding temporal, the lower half with the petrous part of the same bone. These two portions of the inferior border are separated from one another by the jugular process, the notch on the anterior surface of which forms the posterior part of the jugular foramen.
 Figure 3 : Occipital bone at birth. Image File history File links From Grays Anatomy File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Image File history File links From Grays Anatomy File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Structure The occipital, like the other cranial the outer and inner tables, between which is the cancellous tissue or diploë; the bone is especially thick at the ridges, protuberances, condyles, and anterior part of the basilar part; in the inferior fossæ it is thin, semitransparent, and destitute of diploë.
Ossification The planum occipitale [Fig. 3] of the squama is developed in membrane, and may remain separate throughout life when it constitutes the interparietal bone; the rest of the bone is developed in cartilage. The number of nuclei for the planum occipitale is usually given as four, two appearing near the middle line about the second month, and two some little distance from the middle line about the third month of fetal life. The planum nuchale of the squama is ossified from two centers, which appear about the seventh week of fetal life and soon unite to form a single piece. Union of the upper and lower portions of the squama takes place in the third month of fetal life. An occasional center (Kerckring) appears in the posterior margin of the foramen magnum during the fifth month; this forms a separate ossicle (sometimes double) which unites with the rest of the squama before birth. Each of the lateral parts begins to ossify from a single center during the eighth week of fetal life. The basilar portion is ossified from two centers, one in front of the other; these appear about the sixth week of fetal life and rapidly coalesce. Mall states that the planum occipitale is ossified from two centers and the basilar portion from one. About the fourth year the squama and the two lateral portions unite, and about the sixth year the bone consists of a single piece. Between the eighteenth and twenty-fifth years the occipital and sphenoid become united, forming a single bone. A biological membrane or biomembrane is a membrane which acts as a barrier within or around a cell. ...
Articulations The occipital articulates with six bones: the two parietals, the two temporals, the sphenoid, and the atlas. The parietal bones (os parietale) are bones in the human skull and form, by their union, the sides and roof of the cranium. ...
The temporal bones (os temporales) are situated at the sides and base of the skull. ...
Figure 1 : Sphenoid bone, upper surface. ...
First cervical vertebra, or Atlas In anatomy, the Atlas (C1) is the topmost (first) cervical vertebra of the spine. ...
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant. The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ...
Henry Grays Anatomy of the Human Body, commonly known as Grays Anatomy, is an anatomy textbook widely regarded as a classic work on human anatomy. ...
See also | Human Bones | | | SKULL: cranial (frontal | parietal | temporal | occipital | sphenoid | ethmoid) | facial (zygomatic | maxilla | nasal | mandible | palatine | lacrimal | vomer | inferior nasal conchae) | ossicles (malleus | incus | stapes) | other (hyoid)
Grays illustration of a human femur, a typically recognized bone. ...
Comparative anatomy is the study of similarities and differences in organisms. ...
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Occipital bun is a morphological term used to describe a prominent bulge, or projection, at the back of the skull. ...
In zootomy, several terms are used to describe the location of organs and other structures in the body of bilateral animals. ...
A typical adult human skeleton consists of the following 206 bones. ...
Image File history File links Stapes_gray. ...
A hippopotamuss skull A skull, or cranium, is a bony structure of Craniates which serves as the general framework for a head. ...
The frontal bone (os frontale) is a bone in the human skull that resembles a cockle-shell in form, and consists of two portions—a vertical portion, the squama, corresponding with the region of the forehead; and an orbital or horizontal portion, which enters into the formation of the roofs...
The parietal bones (os parietale) are bones in the human skull and form, by their union, the sides and roof of the cranium. ...
The temporal bones (os temporales) are situated at the sides and base of the skull. ...
Figure 1 : Sphenoid bone, upper surface. ...
Your skull is in your back (this is obviously not true, I was just testing the website to see if it really works) The ethmoid bone (os ethmoidale) is a bone in the skull that separates the nasal cavity from the brain. ...
The zygomatic bone (also known as the zygoma; Os Zygomaticum; Malar Bone) is a paired bone of the human skull. ...
The maxillae are the largest bones of the face, except for the mandible, and form, by their union, the whole of the upper jaw. ...
The Nasal Bones (Ossa Faciei & Ossa Nasalia) are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face, and form, by their junction, the bridge of the nose. ...
The mandible (inferior maxillary bone) (together with the maxilla) is the largest and strongest bone of the face. ...
The palatine bone is a bone situated at the back part of the nasal cavity between the maxilla and the pterygoid process of the sphenoid. ...
The lacrimal bone (Os Lacrimale), the smallest and most fragile bone of the face, is situated at the front part of the medial wall of the orbit . ...
The vomer bone is one of the unpaired facial bones of the skull. ...
The inferior nasal concha (Concha Nasalis Inferior; Inferior Turbinated Bone) extends horizontally along the lateral wall of the nasal cavity [Fig. ...
The ossicles (also called auditory ossicles) are the three smallest bones in the human body. ...
The malleus is hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum. ...
The incus is the anvil-shaped small bone or ossicle in the middle ear. ...
stapes The stapes or stirrup is the stirrup-shaped small bone or ossicle in the middle ear which attaches the incus to the fenestra ovalis, the oval window which is adjacent to the vestibule of the inner ear. ...
The hyoid bone (Os Hyoideum; Lingual Bone) is a bone in the human neck, not articulated to any other bone; it is supported by the muscles of the neck and in turn supports the root of the tongue. ...
UPPER LIMBS: arm (humerus | ulna | radius) | carpus (scaphoid | lunate bone | triquetral | pisiform | trapezium | trapezoid | capitate | hamate) | metacarpals | phalanges (proximal | intermediate | distal)
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The humerus is a long bone in the arm or fore-legs (animals) that runs from the shoulder to the elbow. ...
The ulna (along with the radius) is one of the two bones in the forearm. ...
The radius and ulna of the left forearm, posterior surface. ...
In Greek mythology, Carpus fruit was a son of Chloris and Boreas. ...
The scaphoid bone of the wrist is found on the thumb side of the hand, within the anatomical snuffbox. ...
The lunate bone (os lunatum; semilunar bone) is a bone in the human hand that may be distinguished by its deep concavity and crescentic outline. ...
The triquetral bone (also called triquetral, os triquetrum, cuneiform bone, pyramidal bone, cubital bone, os pyramidale, os triangulare, three-cornered bone, and triangular bone) is a type of carpal bone. ...
The pisiform bone (also called pisiform or pisiforme os or lentiform bone) is a small knobbly, pea-shaped wrist bone. ...
The trapezium is a bone in the human hand. ...
In human anatomy, the trapezoid bone (lesser multangular bone; os multangulum minus) is a bone in the hands. ...
The capitate bone (os capitatum; os magnum) is a bone in the human hand. ...
The hamate bone (os hamatum; unciform bone) is a bone in the human hand that may be readily distinguished by its wedge-shaped form, and the hook-like process which projects from its volar surface. ...
The metacarpus is the intermediate part of the hand skeleton that is located between the fingers distally and the carpus which forms the connection to the forearm. ...
Proximal phalanges are bones found in the limbs of most vertebrates. ...
Intermediate phalanges are bones found in the limbs of most vertebrates. ...
Distal phalanges are bones found in the limbs of most vertebrate skeletons. ...
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In human anatomy, the shoulder joint is composed of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone). ...
Left clavicle - from above Left clavicle - from below In human anatomy, the clavicle or collar bone is a bone that makes up part of the shoulder girdle. ...
Left scapula - front view () Left scapula - rear view () In anatomy, the scapula, or shoulder blade, is the bone that connects the humerus (arm bone) with the clavicle (collar bone). ...
Sternum or breastbone is a long, flat bone located in the center of the thorax (chest). ...
The human rib cage. ...
A diagram of a thoracic vertebra. ...
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First cervical vertebra, or Atlas In anatomy, the Atlas (C1) is the topmost (first) cervical vertebra of the spine. ...
In anatomy, the second cervical vertebra (C2) of the spine is named the axis or epistropheus. ...
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Categories: Anatomy stubs | Anatomy ...
The coccyx is formed of four fused vertebrae. ...
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LOWER LIMBS: leg (femur | patella | fibula | tibia) | tarsus (calcaneus | talus | navicular | cuneiform | cuboid ) | metatarsals | phalanges (proximal | intermediate | distal)
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Anterior view of the femur The femur or thigh bone is the longest (length), largest (volume) and strongest (mechanical ability to resist deformity) bone of the human body. ...
Left patella - anterior aspect Left patella - posterior aspect The patella or kneecap is a thick, triangular bone which articulates with the femur and covers and protects the front of the knee joint. ...
The fibula (Calf Bone) is a bone placed on the lateral side of the tibia, with which it is connected above and below. ...
Figure 1 : Upper surface of right tibia. ...
In tetrapods, the tarsi are the cluster of bones in the foot between the tibia and fibula and the metatarsus. ...
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In anatomy, the talus bone of the ankle joint connects the leg to the foot. ...
The navicular bone (also called the navicular or scaphoid) is a small boat-shaped human bone of the tarsus. ...
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The cuboid bone is one of seven Tarsal bones. ...
The metatarsus consists of the five long bones of the foot, which are numbered from the medial side (ossa metatarsalia I.-V.); each presents for examination a body and two extremities. ...
Proximal phalanges are bones found in the limbs of most vertebrates. ...
Intermediate phalanges are bones found in the limbs of most vertebrates. ...
Distal phalanges are bones found in the limbs of most vertebrate skeletons. ...
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