ulna
Information about ulna
| Bone: Ulna | ||
|---|---|---|
) | ||
| Upper extremity | ||
| Ulna is #2 | ||
| subject #52 214 | ||
| MeSH | Ulna | |
| Dorlands/Elsevier | u_01/12835497 | |
Articulations
The ulna articulates with:- the humerus, at the right side elbow as a hinge joint.
- the radius, near the elbow as a pivot joint, this allows the radius to cross over the ulna in pronation.
- the distal radius, where it fits into the ulna notch.
- the radius along its length via the interosseous membrane that forms a syndesmoses joint.
Proximal and distal aspects
The ulna is broader proximally, and narrower distally.Proximally, the ulna has a bony process, the olecranon process, a hook-like structure that fits into the olecranon fossa of the humerus. This prevents hyperextension and forms a hinge joint with the trochlea of the humerus. There is also a radial notch for the head of the radius, and the ulnar tuberosity to which muscles can attach.
Distally (near the hand), there is a styloid process.
Overview of body and two extremities
It is divisible into a body and two extremities.- Upper extremity of ulna: of great thickness and strength, forms a large part of the elbow-joint; the bone diminishes in size from above downward,
- Lower extremity of ulna: very small, and excluded from the wrist-joint by the interposition of an articular disk.
- Body of ulna: has three borders and three surfaces.
Structure
The long, narrow medullary cavity is enclosed in a strong wall of compact tissue which is thickest along the interosseous border and dorsal surface.At the extremities the compact layer thins.
The compact layer is continued onto the back of the olecranon as a plate of close spongy bone with lamellæ parallel.
From the inner surface of this plate and the compact layer below it trabeculæ arch forward toward the olecranon and coronoid and cross other trabeculæ, passing backward over the medullary cavity from the upper part of the shaft below the coronoid.
Below the coronoid process there is a small area of compact bone from which trabeculæ curve upward to end obliquely to the surface of the semilunar notch which is coated with a thin layer of compact bone.
The trabeculæ at the lower end have a more longitudinal direction.
See also
- Bone terminology
- Terms for anatomical location
- Ossification of ulna
Additional images
) Ulna l. dx. - ant. view | ) Ulna l. dx. - lat. view | ){kind=small} Right posterior human radius and ulna | ) Bones of left forearm. Anterior aspect. |
) The radius and ulna of the left forearm, posterior surface. | ) Left elbow-joint, showing anterior and ulnar collateral ligaments. | Cross-section through the middle of the forearm. | The Supinator. |
) Transverse section across distal ends of radius and ulna. |
External links
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. Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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prism is a polyhedron made of an n-sided polygonal base, a translated copy, and n faces joining corresponding sides. Thus these joining faces are parallelograms. All cross-sections parallel to the base faces are the same. A prism is a subclass of the prismatoids.
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For the firearm component, see .
The forearm is the structure on the upper limb, between the elbow and the wrist.[1]. This term is used in anatomy to distinguish it from the arm (or upper arm)...... Click the link for more information.
The radius is the bone of the forearm that extends from the outside of the limb to the phlangx (lateral) of the elbow to the thumb side of the wrist. The radius is situated on the lateral side of the ulna, which exceeds it in length and size.
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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. On a skeleton, it fits between the scapula and the ulna. It consists of the following three sections:
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- Upper extremity of humerus
- Body of humerus
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elbow-joint is a ginglymus or hinge joint. Three bones form the elbow joint: the humerus of the upper arm, and the paired radius and ulna of the forearm.
The bony prominence at the very tip of the elbow is the olecranon process of the ulna.
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The bony prominence at the very tip of the elbow is the olecranon process of the ulna.
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In the hinge joint (ginglymus), the articular surfaces are moulded to each other in such a manner as to permit motion only in one plane, forward and backward, the extent of motion at the same time being considerable.
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The radius is the bone of the forearm that extends from the outside of the limb to the phlangx (lateral) of the elbow to the thumb side of the wrist. The radius is situated on the lateral side of the ulna, which exceeds it in length and size.
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Pivot joint (trochoid joint, rotary joint): Where the movement is limited to rotation, the joint is formed by a pivot-like process turning within a ring, or a ring on a pivot, the ring being formed partly of bone, partly of ligament.
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Pronation is an anatomical term to describe a rotation movement[1]. Such movement can occur in the forearm (at the radioulnar joint) and the foot (at the subtalar and talocalcaneonavicular joints)<ref name="Kendall et al." />[2].
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The distal end of the radius is large and of quadrilateral form.
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Articular surfaces
It is provided with two articular surfaces - one below, for the carpus, and another at the medial side, for the ulna...... Click the link for more information.
The articular surface for the ulna is called the ulnar notch (sigmoid cavity) of the radius; it is narrow, concave, smooth, and articulates with the head of the ulna.
This article was originally based on an entry from a public domain edition of Gray's Anatomy.
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This article was originally based on an entry from a public domain edition of Gray's Anatomy.
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An interosseous membrane is a broad and thin plane of fibrous tissue that separates many of the bones of the body. It is an important component of many joints.
Interosseous membranes in the human body:
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Interosseous membranes in the human body:
- Interosseous membrane of the forearm
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Syndesmoses are joints at which two bones are bound together by a ligament only. Syndesmoses are the most movable of the fibrous joints. The radius and ulna are bound to each other side by side, as are the tibia and fibula, by a syndesmosis in with the ligament forms a broad sheet
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In anatomy, a process (Latin: processus) is a projection or outgrowth of tissue from a larger body.
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Examples
Examples of processes include:- the mastoid process
- the xyphoid process
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The olecranon is a large, thick, curved eminence, situated at the upper and back part of the ulna.
It is bent forward at the summit so as to present a prominent lip which is received into the olecranon fossa of the humerus in extension of the forearm.
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It is bent forward at the summit so as to present a prominent lip which is received into the olecranon fossa of the humerus in extension of the forearm.
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Above the back part of the trochlea of the humerus is a deep triangular depression, the olecranon fossa, in which the summit of the olecranon is received in extension of the forearm.
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Extension is a movement of a joint. For example, extension is produced by extending the flexed elbow. The arm is now straight; it has been extended. If the head is tilted all the way back, it is said to be extended.
The movement in the opposite directions is called flexion.
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The movement in the opposite directions is called flexion.
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The medial portion of the articular surface of the humerus is named the trochlea, and presents a deep depression between two well-marked borders; it is convex from before backward, concave from side to side, and occupies the anterior, lower, and posterior parts of the extremity.
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The radial notch of the ulna (lesser sigmoid cavity) is a narrow, oblong, articular depression on the lateral side of the coronoid process; it receives the circumferential articular surface of the head of the radius.
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The upper extremity of the radius (or proximal extremity) presents a head, neck, and tuberosity.
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- The radial head has a cylindrical form, and on its upper surface is a shallow cup or fovea for articulation with the capitulum (or capitellum) of the humerus.
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tuberosity of the ulna (or ulnar tuberosity), which gives insertion to a part of the Brachialis; to the lateral border of this tuberosity the oblique cord is attached.
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The styloid process of the ulna projects from the medial and back part of the bone; it descends a little lower than the head, and its rounded end affords attachment to the ulnar collateral ligament of the wrist-joint.
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The upper extremity of the ulna (or proximal extremity) presents two curved processes, the olecranon and the coronoid process; and two concave, articular cavities, the semilunar and radial notches.
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The lower extremity of the ulna (or distal extremity) is small, and presents two eminences; the lateral and larger is a rounded, articular eminence, termed the head of the ulna; the medial, narrower and more projecting, is a non-articular eminence, the styloid process.
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The body of the ulna at its upper part is prismatic in form, and curved so as to be convex behind and lateralward; its central part is straight; its lower part is rounded, smooth, and bent a little lateralward.
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In sciences dealing with the anatomy of animals, precise anatomical terms of location are necessary for a variety of reasons. Non-scientists often wonder why zoological and human anatomists use complex terminology to describe locations on a body, when common terms like "up",
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The ulna is ossified from three centers: one each for the body, the inferior extremity, and the top of the olecranon.
Ossification begins near the middle of the body, about the eighth week of fetal life, and soon extends through the greater part of the bone.
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Ossification begins near the middle of the body, about the eighth week of fetal life, and soon extends through the greater part of the bone.
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