The parietal bone is ossified in membrane from a single center, which appears at the parietal eminence about the eighth week of fetal life. Ossification gradually extends in a radial manner from the center toward the margins of the bone; the angles are consequently the parts last formed, and it is here that the fontanelles exist. Occasionally the parietal bone is divided into two parts, u ...

See also:

Parietal bone, Parietal bone - Surfaces, Parietal bone - External, Parietal bone - Internal, Parietal bone - Borders, Parietal bone - Angles, Parietal bone - Ossification

Read more here: » Parietal bone: Encyclopedia II - Parietal bone - Ossification

The upper surface of the labyrinth [Fig. 1] presents a number of half-broken cells, the walls of which are completed, in the articulated skull, by the edges of the ethmoidal notch of the frontal bone. Crossing this surface are two grooves, converted into canals by articulation with the frontal; they are the anterior and posterior ethmoidal canals, and open on the inner wall of the orbit. The posterior surface presents large irregular cellular cavities, which are closed in by articulation with the sphenoidal concha and orbital process of the ...

See also:

Ethmoid bone, Ethmoid bone - Cribriform plate, Ethmoid bone - Perpendicular plate, Ethmoid bone - Labyrinth, Ethmoid bone - Surfaces, Ethmoid bone - Ossification, Ethmoid bone - Articulations

Read more here: » Ethmoid bone: Encyclopedia II - Ethmoid bone - Surfaces

The ethmoid articulates with fifteen bones: four of the cranium—the frontal, the sphenoid, and the two sphenoidal conchæ; and eleven of the face—the two nasals, two maxillæ, two lacrimals, two palatines, two inferior nasal conchæ, and the vomer. 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 As such, some of the information contained herein may be outdated.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 wh ...

See also:

Ethmoid bone, Ethmoid bone - Cribriform plate, Ethmoid bone - Perpendicular plate, Ethmoid bone - Labyrinth, Ethmoid bone - Surfaces, Ethmoid bone - Ossification, Ethmoid bone - Articulations

Read more here: » Ethmoid bone: Encyclopedia II - Ethmoid bone - Articulations

('corpus mandibulæ') The body is curved somewhat like a horseshoe and has two surfaces and two borders. Mandible - Surfaces. The external surface [Fig. 1] is marked in the median line by a faint ridge, indicating the symphysis or line of junction of the two pieces of which the bone is composed at an early period of life. This ridge divides below and encloses a triangular eminence, the mental protuberance, the base of which is depressed in the center but raised on eit ...

See also:

Mandible, Mandible - The body, Mandible - Surfaces, Mandible - Borders, Mandible - The ramus, Mandible - Surfaces, Mandible - Borders, Mandible - Processes, Mandible - Ossification, Mandible - Articulations, Mandible - Changes produced in the mandible by age

Read more here: » Mandible: Encyclopedia II - Mandible - The body

('ramus mandibulæ; perpendicular portion') The ramus is quadrilateral in shape, and has two surfaces, four borders, and two processes. Mandible - Surfaces. The lateral surface [Fig. 1] is flat and marked by oblique ridges at its lower part; it gives attachment throughout nearly the whole of its extent to the masseter. The medial surface [Fig. 2] presents about its center the oblique mandibular foramen, for the entrance of th ...

See also:

Mandible, Mandible - The body, Mandible - Surfaces, Mandible - Borders, Mandible - The ramus, Mandible - Surfaces, Mandible - Borders, Mandible - Processes, Mandible - Ossification, Mandible - Articulations, Mandible - Changes produced in the mandible by age

Read more here: » Mandible: Encyclopedia II - Mandible - The ramus

The mandible is ossified in the fibrous membrane covering the outer surfaces of Meckel's cartilages. These cartilages form the cartilaginous bar of the mandibular arch (see p. 66), and are two in number, a right and a left. Their proximal or cranial ends are connected with the ear capsules, and their distal extremities are joined to one another at the symphysis by mesodermal tissue. They run forward immediately below the condyles and then, bending downward, lie in a groove near the lower border of the bone; in front of the canine to ...

See also:

Mandible, Mandible - The body, Mandible - Surfaces, Mandible - Borders, Mandible - The ramus, Mandible - Surfaces, Mandible - Borders, Mandible - Processes, Mandible - Ossification, Mandible - Articulations, Mandible - Changes produced in the mandible by age

Read more here: » Mandible: Encyclopedia II - Mandible - Ossification

At birth [Fig. 7] the body of the bone is a mere shell, containing the sockets of the two incisor, the canine, and the two deciduous molar teeth, imperfectly partitioned off from one another. The mandibular canal is of large size, and runs near the lower border of the bone; the mental foramen opens beneath the socket of the first deciduous molar tooth. The angle is obtuse (175°), and the condyloid portion is nearly in line with the body. The coronoid process is of co ...

See also:

Mandible, Mandible - The body, Mandible - Surfaces, Mandible - Borders, Mandible - The ramus, Mandible - Surfaces, Mandible - Borders, Mandible - Processes, Mandible - Ossification, Mandible - Articulations, Mandible - Changes produced in the mandible by age

Read more here: » Mandible: Encyclopedia II - Mandible - Changes produced in the mandible by age

It consists of five segments: a body, two greater cornua, and two lesser cornua. Hyoid bone - The body or basihyal. The body (corpus oss. hyoidei) or central part is of a quadrilateral form. Its anterior surface [Fig. 1] is convex and directed forward and upward. It is crossed in its upper half by a well-marked transverse ridge with a slight downward convexity, and in many cases a vertical median ridge divides it into two lateral halves. The portion of the vertical ridge above ...

See also:

Hyoid bone, Hyoid bone - Segments, Hyoid bone - The body or basihyal, Hyoid bone - The greater cornua or thyrohyals, Hyoid bone - The lesser cornua or ceratohyals, Hyoid bone - Ossification, Hyoid bone - Fracture

Read more here: » Hyoid bone: Encyclopedia II - Hyoid bone - Segments

The head of the humerus (caput humeri) articulates with the glenoid cavity of the scapula at the glenohumeral joint. Also known as the "shoulder joint," it is a ball-and-socket joint, which allows a wide range of movement. This joint has two bursae: the subacromial bursa and the subscapular bursa. The subacromial bursa separates the tendon of the supraspinatus muscle from the deltoid muscle. The subscapular bursa separates the scapular fossa from the tendon of the subscapularis muscle. The glenohumeral joint is stabilized by the rotator cuff muscles and the tendon of th ...

See also:

Humerus, Humerus - Articulations, Humerus - Muscle attachments, Humerus - Rotator Cuff Muscles, Humerus - Structure, Humerus - Upper extremity, Humerus - Borders, Humerus - Surfaces, Humerus - The lower extremity, Humerus - Ossification, Humerus - Clinical Considerations

Read more here: » Humerus: Encyclopedia II - Humerus - Articulations

A variety of muscles attach to the humerus. These enable movement at the elbow and at the shoulder. Anconeus muscle - attaches to the lateral surface of the olecranon (and also to the superior part of the posterior surface of the ulna) Brachioradialis muscle - attaches to the proximal two-thirds of the lateral supracondylar ridge Coracobrachialis muscle - attaches to the middle third of the medial humerus Deltoid muscle - attaches to the deltoid tuberosity Extensor carpi radialis brevis muscle ...

See also:

Humerus, Humerus - Articulations, Humerus - Muscle attachments, Humerus - Rotator Cuff Muscles, Humerus - Structure, Humerus - Upper extremity, Humerus - Borders, Humerus - Surfaces, Humerus - The lower extremity, Humerus - Ossification, Humerus - Clinical Considerations

Read more here: » Humerus: Encyclopedia II - Humerus - Muscle attachments

The humerus (arm bone) is the longest and largest bone of the upper extremity; it is divisible into a body and two extremities. The extremities consist of cancellous tissue, covered with a thin, compact layer [Fig. 3]; the body is composed of a cylinder of compact tissue, thicker at the center than toward the extremities, and contains a large medullary canal which extends along its whole length. Humerus - Upper extremity. The upper extremity consists of a large rounded head joined to the body by a constricted portion called the neck, and two eminences, the ...

See also:

Humerus, Humerus - Articulations, Humerus - Muscle attachments, Humerus - Rotator Cuff Muscles, Humerus - Structure, Humerus - Upper extremity, Humerus - Borders, Humerus - Surfaces, Humerus - The lower extremity, Humerus - Ossification, Humerus - Clinical Considerations

Read more here: » Humerus: Encyclopedia II - Humerus - Structure

The body (corpus; shaft) is prismoid in form, and curved, so as to be convex in the longitudinal direction behind, concave in front. It presents three surfaces: medial, lateral, and dorsal. The medial and lateral surfaces are concave, for the attachment of the interosseus muscles, and separated from one another by a prominent anterior ridge. The dorsal surface presents in its distal two-thirds a smooth, triangular, flattened area which is covered in by the tendons of the Extensor muscles. This surface is bounded by two lines, w ...

See also:

Metacarpus, Metacarpus - Common Characteristics of the Metacarpal Bones, Metacarpus - Characteristics of the Individual Metacarpal Bones, Metacarpus - First, Metacarpus - Second, Metacarpus - Third, Metacarpus - Fourth, Metacarpus - Fifth, Metacarpus - Articulations

Read more here: » Metacarpus: Encyclopedia II - Metacarpus - Common Characteristics of the Metacarpal Bones

Metacarpus - First. The first metacarpal bone (os metacarpale I; metacarpal bone of the thumb) [Fig. 1] is shorter and stouter than the others, diverges to a greater degree from the carpus, and its volar surface is directed toward the palm. The body is flattened and broad on its dorsal surface, and does not present the ridge which is found on the other metacarpal bones; its volar surface is concave from above downward. On its radial border is inserted the opponens pollicis muscle; its ulnar border g ...

See also:

Metacarpus, Metacarpus - Common Characteristics of the Metacarpal Bones, Metacarpus - Characteristics of the Individual Metacarpal Bones, Metacarpus - First, Metacarpus - Second, Metacarpus - Third, Metacarpus - Fourth, Metacarpus - Fifth, Metacarpus - Articulations

Read more here: » Metacarpus: Encyclopedia II - Metacarpus - Characteristics of the Individual Metacarpal Bones

The ethmoid articulates with fifteen bones: four of the cranium—the frontal, the sphenoid, and the two sphenoidal conchæ; and eleven of the face—the two nasals, two maxillæ, two lacrimals, two palatines, two inferior nasal conchæ, and the vomer. 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.
See also:

Ethmoid bone, Ethmoid bone - Cribriform plate, Ethmoid bone - Perpendicular plate, Ethmoid bone - Labyrinth, Ethmoid bone - Surfaces, Ethmoid bone - Ossification, Ethmoid bone - Articulations

Read more here: » Ethmoid bone: Encyclopedia II - Ethmoid bone - Articulations

The formation of bone occurs by two methods: intramembranous and endochondral ossification. Intramembranous ossification mainly occurs during formation of the flat bones of the skull; the bone is formed from mesenchyme tissue. Endochondral ossification occurs in long bones, such as limbs; the bone is formed from cartilage. Endochondral ossification begins with points in the cartilage called "primary ossification centers." They mostly appear during fetal development, though a few short bones begin their pri ...

See also:

Bone, Bone - Functions, Bone - Post-mortem functions, Bone - Structure, Bone - Cells, Bone - Matrix, Bone - Formation, Bone - Bone pathologies, Bone - Terminology

Read more here: » Bone: Encyclopedia II - Bone - Formation

('proximal extremity') The upper extremity is large, and expanded into two eminences, the medial and lateral condyles. The superior articular surface presents two smooth articular facets [Fig. 1]. The medial facet, oval in shape, is slightly concave from side to side, and from before backward. The lateral, nearly circular, is concave from side to side, but slightly convex from before backward, especially at its posterior part, where it is prolonged on to the p ...

See also:

Tibia, Tibia - The upper extremity, Tibia - The body or shaft, Tibia - Borders, Tibia - Surfaces, Tibia - The lower extremity, Tibia - Surfaces, Tibia - Structure, Tibia - Ossification

Read more here: » Tibia: Encyclopedia II - Tibia - The upper extremity

('corpus tibiæ') The body has three borders and three surfaces. Tibia - Borders. The anterior crest or border, the most prominent of the three, commences above at the tuberosity, and ends below at the anterior margin of the medial malleolus. It is sinuous and prominent in the upper two-thirds of its extent, but smooth and rounded below; it gives attachment to the deep fascia of the leg. The medial border is smooth and rounded above and below, but more prominent in the center; i ...

See also:

Tibia, Tibia - The upper extremity, Tibia - The body or shaft, Tibia - Borders, Tibia - Surfaces, Tibia - The lower extremity, Tibia - Surfaces, Tibia - Structure, Tibia - Ossification

Read more here: » Tibia: Encyclopedia II - Tibia - The body or shaft

('distal extremity') The lower extremity, much smaller than the upper, presents five surfaces; it is prolonged downward on its medial side as a strong process, the medial malleolus. Tibia - Surfaces. The inferior articular surface is quadrilateral, and smooth for articulation with the talus. It is concave from before backward, broader in front than behind, and traversed from before backward by a slight elevation, separating two depressions. It is ...

See also:

Tibia, Tibia - The upper extremity, Tibia - The body or shaft, Tibia - Borders, Tibia - Surfaces, Tibia - The lower extremity, Tibia - Surfaces, Tibia - Structure, Tibia - Ossification

Read more here: » Tibia: Encyclopedia II - Tibia - The lower extremity

The tibia is ossified from three centers : one for the body and one for either extremity. Ossification begins in the center of the body, about the seventh week of fetal life, and gradually extends toward the extremities. The center for the upper epiphysis appears before or shortly after birth; it is flattened in form, and has a thin tongue-shaped process in front, which forms the tuberosity [Fig. 4]; that for the lower epiphysis appears in the second year. The lower epiphysis joins the body at about the eighteenth, and the upp ...

See also:

Tibia, Tibia - The upper extremity, Tibia - The body or shaft, Tibia - Borders, Tibia - Surfaces, Tibia - The lower extremity, Tibia - Surfaces, Tibia - Structure, Tibia - Ossification

Read more here: » Tibia: Encyclopedia II - Tibia - Ossification

Rib - Typical ribs. The third through ninth ribs are "typical ribs" since they share the same structure. They each have a head that has two facets separated by a crest. One head articulates with the rib's corresponding vertebra and one head articulates with the vertebra superior (above) to it. They have a neck that connects the head with the shaft. The neck meets the shaft at a tubercle. The shaft is thin, flat, and curved. The curve is most prominent at the costal angle. The concave (inside) surface has a groove to protect the intercostal nerve and vessels. See also:

Rib, Rib - Types of Ribs, Rib - Rib Anatomy, Rib - Typical ribs, Rib - Atypical ribs, Rib - Rib Fractures and Associated Injuries, Rib - Bifid rib bifurcated rib, Rib - Biblical Legend

Read more here: » Rib: Encyclopedia II - Rib - Rib Anatomy

The first rib is rarely fractured because of its protected position behind the clavicle (collarbone). However, if it is broken serious damage can occur to the brachial plexus of nerves and the subclavian vessels. The middle ribs are the ones most commonly fractured. Fractures usually occur from direct blows or from indirect crushing injuries. The weakest part of a rib is just anterior to its angle, but a fracture can occur anywhere. A lower rib fracture has the complication of potentially injuring ...

See also:

Rib, Rib - Types of Ribs, Rib - Rib Anatomy, Rib - Typical ribs, Rib - Atypical ribs, Rib - Rib Fractures and Associated Injuries, Rib - Bifid rib bifurcated rib, Rib - Biblical Legend

Read more here: » Rib: Encyclopedia II - Rib - Rib Fractures and Associated Injuries

There is a legend that men have one rib fewer than women, and originates from the Bible's description of the creation of Eve (from the rib of Adam). It is from the Book of Genesis, the first book of the Hebrew Bible (Old Testament). ...

See also:

Rib, Rib - Types of Ribs, Rib - Rib Anatomy, Rib - Typical ribs, Rib - Atypical ribs, Rib - Rib Fractures and Associated Injuries, Rib - Bifid rib bifurcated rib, Rib - Biblical Legend

Read more here: » Rib: Encyclopedia II - Rib - Biblical Legend