Ulna

10 Ulna



Orientation and general presentation (Figs 10.1 & 10.2)


The ulna (1) is located on the medial aspect of the forearm. It articulates with the humerus (2) proximally, the wrist complex (3) distally, and the radius (4) laterally. The proximal epiphysis of the ulna bone shows a joint cavity, the semilunar notch or greater sigmoid cavity (5), which can be divided into two segments: a horizontal segment, the coronoid process (UCP), and a vertical segment, the olecranon (UOA, apex; UOM, medial aspect; UOL, lateral aspect). The lateral edge of the olecranon starts at UOL (green line). This edge meets the medial edge of the olecranon (blue line), starting from UOM. Both edges join at the base of the olecranon (UOB). The posterior ulnar edge (6, black line) runs below UOB. The distal epiphysis of the ulna comprises a head (UHE) and the ulnar styloid process (USP). The ulnar head (UHE) articulates with the radius via the distal radioulnar joint (URU). The most medial aspect of UHE is called the ulnar dome (UHD).


image

Figure 10.1 Ulna (3D model).


General position (foream in neutral position): A lateral view; B medial view. Isolated bone: C posterior view; D anterior view; E medial view.


image

Figure 10.2 Ulna (anatomic specimen).


Proximal epiphysis: A anterior view; B posterior view. Distal epiphysis: C lateral view; D posterior view; E medial view.



Ulna – OLecranon (UOA, UOM, UOL)[R,L] H|Anim



Landmark UOA, UOM, UOL


Large tuberosity located at the posterior aspect of the proximal epiphysis (see Figs 10.1 & 10.2). Three points are palpated.



image


image

image The palpator is behind the sitting subject, whose elbow is flexed (90°).


With a forefinger, locate the olecranon at the posterior aspect of the elbow joint.


The finger pulp is placed on the apex of the olecranon (UOA).


image Then place both thumb and middle finger of the same hand on the medial (UOM) and lateral (UOL) aspects of the olecranon respectively.



image Observe the ulna bone from a posterior and slightly superior view.


Select the apex of the olecranon (UOA, in red).


Rotate the ulna bone along a lateral view (the coronoid process must be horizontal; red line). Make sure UOA (in red) is on the apex of the olecranon. Then, from that point, draw a line (in green) running forward parallel to the coronoid process. UOL (in green) is midway between UOA and the semilunar notch.


Observe the model from a medial view, and process in a similar way for UOM (in blue).



Ulna – Olecranon Basis (UOB)[R,L]



Landmark UOB


Point located at the basis of the posterior aspect of the olecranon (see Figs 10.1 & 10.2). This point is at the junction between the epiphysis and diaphysis of the bone.



image

image The palpator is behind the sitting subject, whose shoulder is slightly extended and elbow flexed (90°).


First locate UOL and UOM (see p. 72) with the first and second fingers respectively.


Then glide down, following the lateral (in green) and medial (in blue) edges of the olecranon.



image

image The point to select is at the junction where the two edges meet.




NOTE


The medial and lateral edges of the olecranon join each other at this point to give the ulnar posterior edge, which runs distally (solid line).



image Observe the ulna bone from a posterior and slightly superior view.


From UOM (in blue; see p. 72), follow the medial edge (blue line) down until it joins the lateral edge (green line). The junction point is the landmark to select (in red). (In green: UOL, see p. 72.)

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Sep 9, 2016 | Posted by in MANUAL THERAPIST | Comments Off on Ulna

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