| Bone: Ulna | |
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| Upper extremity | |
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| Ulna is #2 | |
| Gray's | subject #52 214 |
| MeSH | Ulna |
| Dorlands / Elsevier |
u_01/12835497 |
The ulna (elbow bone) is a long bone, prismatic in form, placed at the medial side of the forearm, parallel with the radius. Introduction ( classes Long bones body or Diaphysis Medullary canal Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Elsevier, the world's largest Publisher of Medical and Scientific literature, forms part of the Reed Elsevier group General right and uniform prisms A right prism is a prism in which the joining edges and faces are perpendicular to the base faces In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species The forearm is the structure on the Upper limb, between the elbow and the Wrist. The radius is the Bone of the Forearm that extends from the lateral side of the elbow to the Thumb side of the Wrist.
Contents |
Articulations
The ulna articulates with:
- the humerus, at the right side elbow as a hinge joint. The humerus is a Long bone in the Arm or Forelimb that runs from the Shoulder to the Elbow. The elbow is the region surrounding the elbow-joint&mdashthe ginglymus or Hinge joint in the middle of the Arm. 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
- the radius, near the elbow as a pivot joint, this allows the radius to cross over the ulna in pronation. The radius is the Bone of the Forearm that extends from the lateral side of the elbow to the Thumb side of the Wrist. Pivot joint ( trochoid joint, rotary joint) Where the movement is limited to Rotation, the Joint is formed by a pivot-like process turning within In Anatomy, pronation is a rotational movement of the forearm (at the radioulnar joint or foot (at the subtalar and talocalcaneonavicular joints
- the distal radius, where it fits into the ulna notch. The distal end of the radius is large and of quadrilateral form 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
- the radius along its length via the interosseous membrane that forms a syndesmoses joint. An interosseous membrane is a broad and thin plane of fibrous tissue that separates many of the Bones of the body Syndesmoses are Joints at which two bones are bound together by a Ligament only
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. In Anatomy, a process ( Latin: processus) is a projection or outgrowth of tissue from a larger body The olecranon is a large thick curved eminence situated proximal end of the Ulna in the Forearm. 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 This prevents hyperextension and forms a hinge joint with the trochlea of the humerus. Extension is a movement of a joint that results in increased angle between two bones or body surfaces at a joint 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 There is also a radial notch for the head of the radius, and the ulnar tuberosity to which muscles can attach. 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 head of the radius 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 At the junction of the antero-inferior surface of the coronoid process with the front of the body is a rough eminence the tuberosity of the Ulna (or
Distally (near the hand), there is a styloid process. 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
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.
Muscle attachments
| Muscle | Direction | Attachment |
| Triceps brachii muscle | Insertion | Olecranon process (via common tendon) |
| Anconeus muscle | Insertion | Olecranon process (lateral aspect) |
| Brachialis muscle | Insertion | Coronoid process of the ulna |
| Pronator teres muscle | Origin | Coronoid process (also shares origin with medial epicondyle of the humerus) |
| Flexor carpi ulnaris muscle | Origin | Olecranon process and posterior surface of ulna (also shares origin with medial epicondyle of the humerus) |
| Flexor digitorum superficialis muscle | Origin | Coronoid process (also shares origin with medial epicondyle of the humerus and shaft of the radius) |
| Flexor digitorum profundus muscle | Origin | Coronoid process, anteromedial surface of ulna (also shares origin with the interosseous membrane) |
| Pronator quadratus muscle | Origin | Distal portion of anterior ulnar shaft |
| Extensor carpi ulnaris muscle | Origin | Posterior border of ulna (also shares origin with lateral epicondyle of the humerus) |
| Supinator muscle | Origin | Proximal ulna (also shares origin with lateral epicondyle of the humerus) |
| Abductor pollicis longus muscle | Origin | Posterior surface of ulna (also shares origin with the posterior surface of the radius bone) |
| Extensor pollicis longus muscle | Origin | Dorsal shaft of ulna (also shares origin with the dorsal shaft of the radius and the interosseous membrane) |
| Extensor pollicis brevis muscle | Origin | Dorsal shaft of ulna (also shares origin with the dorsal shaft of the radius and the interosseous membrane) |
| Extensor indicis muscle | Origin | Posterior surface of distal ulna (also shares origin with the interosseous membrane) |
See also
Additional images
 Ulna l. The triceps brachii ( Latin for "three-headed" of the arm is the large muscle on the back of the human Upper limb. The olecranon is a large thick curved eminence situated proximal end of the Ulna in the Forearm. The anconeus muscle is a small Muscle on the posterior aspect of the elbow joint The brachialis ( brachialis anticus) is a Muscle in the upper Arm that flexes the elbow joint. The coronoid process is a triangular eminence projecting forward from the upper and front part of the Ulna. The pronator teres is a Muscle of the Human body (located mainly in the Forearm) that along with the Pronator quadratus, serves to pronate The medial epicondyle of the Humerus, larger and more prominent than the Lateral epicondyle, is directed a little backward The flexor carpi ulnaris muscle (FCU is a muscle of the human forearm that acts to flex and adduct the hand Flexor digitorum superficialis ( flexor digitorum sublimis) is an extrinsic flexor Muscle of the Fingers at the Proximal interphalangeal joints Remote Authentication Dial In User Service ( RADIUS) is a networking protocol that provides centralized access authorization and accounting management for people or computers In Human anatomy, the flexor digitorum profundus is a Muscle in the Forearm that flexes the Fingers It is considered to be an Extrinsic An interosseous membrane is a broad and thin plane of fibrous tissue that separates many of the Bones of the body Pronator quadratus is a square shaped muscle on the distal Forearm that acts to Pronate (turn so the palm faces downwards the Hand. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species Extensor carpi ulnaris is a Muscle located in the human Forearm that acts to extend and adduct the Wrist. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species The lateral epicondyle of the Humerus is a small tuberculated eminence curved a little forward and giving attachment to the radial collateral ligament of the The supinator is a broad muscle curved around the upper third of the radius. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species The Abductor pollicis longus lies immediately below the Supinator and is sometimes united with it The radius is the Bone of the Forearm that extends from the lateral side of the elbow to the Thumb side of the Wrist. The Extensor pollicis longus is much larger than the Extensor pollicis brevis muscle the origin of which it partly covers 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 The Extensor pollicis brevis lies on the medial side of and is closely connected with the Abductor pollicis longus. The extensor indicis proprius (Extensor indicis is a narrow elongated muscle placed medial to and parallel with the Extensor pollicis longus. Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species The Ulna is Ossified from three centers one each for the body the inferior extremity and the top of the Olecranon. dx. - ant. view |
 Ulna l. dx. - lat. view |
 Right posterior human radius and ulna |
 Human arm bones diagram |
 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. The public domain is a range of abstract materials &ndash commonly referred to as Intellectual property &ndash which are not owned or controlled by anyone Henry Gray's Anatomy of the Human Body (or Gray's Anatomy as it has commonly been shortened is an English-language Human anatomy Textbook 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.
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