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Ulna

 
Ulna

 
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Ulna
 
 
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The ulna (elbow bone) is a long bone, prism
Prism (geometry)

In geometry, an n-sided prism is a polyhedron made of an n-sided polygon base, a Translation copy, and n faces joining corresponding sides....
atic in form, placed at the medial
Anatomical terms of location

Standard anatomical terms of location are employed in sciences dealing with the anatomy of animals to avoid ambiguities which might otherwise arise....
 side of the forearm
Forearm

The forearm is the structure on the upper limb, between the Elbow-joint and the wrist.. This term is used in anatomy to distinguish it from the arm ....
, parallel with the radius
Radius (bone)

The radius is the bone of the forearm that extends from the lateral side of the Elbow-joint 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....
.

ulna articulates with:

ulna is broader proximally, and narrower distally.

Proximally, the ulna has a bony process
Process (anatomy)

In anatomy, a process is a projection or outgrowth of tissue from a larger body....
, the olecranon process, a hook-like structure that fits into the olecranon fossa
Olecranon fossa

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....
 of the humerus.






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The ulna (elbow bone) is a long bone, prism
Prism (geometry)

In geometry, an n-sided prism is a polyhedron made of an n-sided polygon base, a Translation copy, and n faces joining corresponding sides....
atic in form, placed at the medial
Anatomical terms of location

Standard anatomical terms of location are employed in sciences dealing with the anatomy of animals to avoid ambiguities which might otherwise arise....
 side of the forearm
Forearm

The forearm is the structure on the upper limb, between the Elbow-joint and the wrist.. This term is used in anatomy to distinguish it from the arm ....
, parallel with the radius
Radius (bone)

The radius is the bone of the forearm that extends from the lateral side of the Elbow-joint 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....
.

Articulations

The ulna articulates with:
  • the humerus
    Humerus

    The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow.Anatomically, it connects the scapula and the ulna, and consists of the following three sections:...
    , at the right side elbow as a hinge joint
    Hinge joint

    In the hinge joint , 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....
    .
  • the radius
    Radius (bone)

    The radius is the bone of the forearm that extends from the lateral side of the Elbow-joint 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....
    , near the elbow as a pivot joint
    Pivot joint

    A Pivot joint is a joint that moves by rotating. For example, the joint that allows humans to rotate their heads on their necks is a pivot joint....
    , this allows the radius to cross over the ulna in pronation
    Pronation

    In anatomy, pronation is a rotational movement of the forearm at the radioulnar joint, or of the foot at the subtalar joint and talocalcaneonavicular joints....
    .
  • the dist where it fits into the [[ulna notch]].
  • the radius along its length via the interosseous membrane
    Interosseous membrane

    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....
     that forms a syndesmoses
    Syndesmoses

    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 which the ligament forms a broad sheet called an interosseous membrane along the shafts of the two...
     joint.


Proximal and distal aspects

The ulna is broader proximally, and narrower distally.

Proximally, the ulna has a bony process
Process (anatomy)

In anatomy, a process is a projection or outgrowth of tissue from a larger body....
, the olecranon process, a hook-like structure that fits into the olecranon fossa
Olecranon fossa

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....
 of the humerus. This prevents hyperextension and forms a hinge joint with the trochlea of the humerus. There is also a radial notch
Radial notch

The radial notch of the ulna 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....
 for the head of the radius, and the ulnar tuberosity to which muscles can attach.

At the distal end of the ulna is a styloid process
Ulnar 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 ulnar collateral ligament of the wrist-joint....
.

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 lamellę parallel.

From the inner surface of this plate and the compact layer below it trabeculę arch forward toward the olecranon and coronoid and cross other trabeculę, 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 trabeculę curve upward to end obliquely to the surface of the semilunar notch which is coated with a thin layer of compact bone.

The trabeculę at the lower end have a more longitudinal direction.

Muscle attachments


Triceps brachii muscle
Triceps brachii muscle

The triceps brachii is the large muscle on the back of the human upper limb. It is the muscle principally responsible for extension of the elbow joint ....
  >
Muscle Direction Attachment
Insertion Olecranon process (via common tendon) |- | Anconeus muscle
Anconeus muscle

The anconeus muscle is a small muscle on the posterior aspect of the Elbow-joint joint.Some consider anconeus to be a continuation of the triceps brachii muscle....
  		Insertion - | Brachialis muscle
Brachialis muscle

The brachialis is a muscle in the upper arm that flexes the elbow. It lies just deep of the biceps brachii, and is a synergist that assists the biceps brachii in flexing at the elbow....
  		Insertion Coronoid process of the ulna
Coronoid process of the ulna

The coronoid process is a triangular eminence projecting forward from the upper and front part of the ulna.Its base is continuous with the body of the bone, and of considerable strength....
 |- | Pronator teres muscle
Pronator teres muscle

The pronator teres is a muscle of the human body that, along with the pronator quadratus, serves to pronate the forearm ....
  		Origin Coronoid process (also shares origin with medial epicondyle of the humerus
Medial epicondyle of the humerus

The medial epicondyle of the humerus, larger and more prominent than the lateral epicondyle, is directed a little backward. In birds, where the arm is somewhat rotated compared to other tetrapods, it is called ventral epicondyle of the humerus....
) |- | Flexor carpi ulnaris muscle
Flexor carpi ulnaris muscle

The flexor carpi ulnaris muscle is a muscle of the human forearm that acts to flex and Adduction the hand....
  		Origin - | Flexor digitorum superficialis muscle
Flexor digitorum superficialis muscle

Flexor digitorum superficialis is an extrinsic flexor muscle of the fingers at the proximal interphalangeal joints.It is in the anterior compartment of the forearm....
  		Origin Coronoid process (also shares origin with medial epicondyle of the humerus and shaft of the radius
RADIUS

Remote Authentication Dial In User Service is a networking protocol that provides centralized access, authorization and accounting management for people or computers to connect and use a network service....
) |- | Flexor digitorum profundus muscle
Flexor digitorum profundus muscle

In human anatomy, the flexor digitorum profundus is a muscle in the forearm that flexes the fingers. It is considered to be an extrinsic muscle because its action is at a different location than the main body of the muscle....
  		Origin Coronoid process, anteromedial surface of ulna (also shares origin with the interosseous membrane
Interosseous membrane

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....
) |- | Pronator quadratus muscle 		Origin Distal portion of anterior ulnar shaft |- | Extensor carpi ulnaris muscle
Extensor carpi ulnaris muscle

Extensor carpi ulnaris is a muscle located in the human forearm that acts to extend and adduct the wrist.Being an extensor muscle, extensor carpi ulnaris is on the posterior side of the forearm....
  		Origin Posterior border of ulna (also shares origin with lateral epicondyle of the humerus
Lateral epicondyle of the humerus

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 elbow-joint, and to a tendon common to the origin of the Supinator and some of the Extensor muscles....
) |- | Supinator muscle
Supinator muscle

The supinator is a broad muscle, curved around the upper third of the radius ....
  		Origin Proximal ulna (also shares origin with lateral epicondyle of the humerus) |- | Abductor pollicis longus muscle
Abductor pollicis longus muscle

The Abductor pollicis longus lies immediately below the Supinator and is sometimes united with it....
  		Origin Posterior surface of ulna (also shares origin with the posterior surface of the radius bone) |- | Extensor pollicis longus muscle
Extensor pollicis longus muscle

The Extensor pollicis longus is much larger than the Extensor pollicis brevis muscle, the origin of which it partly covers....
  		Origin Dorsal
Dorsal

Dorsal is an adjective which means being at the back.Dorsal may refer to:* Dorsum , a part of an animal* A dorsal consonant, in linguistics...
 shaft of ulna (also shares origin with the dorsal shaft of the radius and the interosseous membrane) |- | Extensor pollicis brevis muscle
Extensor pollicis brevis muscle

The Extensor pollicis brevis lies on the medial side of, and is closely connected with, the Abductor pollicis longus.Origin and insertion...
  		Origin - | Extensor indicis muscle Origin Posterior surface of distal ulna (also shares origin with the interosseous membrane)

See also

  • Bone terminology
    Bone

    Bones are rigid organ that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red blood cell and white blood cells and store minerals....
  • Terms for anatomical location
  • Ossification of ulna
    Ossification of ulna

    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....


Additional images


External links