Health Sciences 2300A/B Lecture Notes - Lecture 4: Radial Notch, Gluteal Tuberosity, Temporal Styloid Process

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Lecture 4: The Boney Skeleton
The Appendicular Skeleton:
The Humerus: Proximal:
Moving down from the shoulder joint we reach the humerus, which articulates into the glenoid fossa
The humerus is a typical long bone (classical example)
Proximal to distal end of the bone: We first have the humeral head, which is a typical feature on long
bones
Half way down we have the deltoid tuberosity (tubercle) which is a bump that is an attachment for
muscles or ligaments this tubercle is where the deltoid muscle attaches.
Just down from the head, we have another two tubercles: Greater tubercle (larger and more lateral)
and lesser tubercle they are important attachments for muscles and ligaments.
In between the two tubercles there is a “groove” called the bicipital groove: running along it is the
bicep muscle (which is a superficial muscle in the anterior of the arm). Also called the intertubercular
groove. (inter = between)
Neck of the bone: just down from the head. The area that is usually most often broken from this bone
is down from the tubercles surgeons commonly call this area the surgical neck this is the area
down from the tubercles and above the deltoid tuberosity. In anatomy: the anatomical neck is just
down from the head and ABOVE the tubercles.
Humerus: Distal
FIRST ORIENT YOURSELF! What is anterior and what is posterior? Need to situate in the
anatomical position need to use the anatomical structures to identify the anterior/posterior.
In the humerus, there are a lot of different structures on the DISTAL end to help us.
On the distal ANTERIOR SIDE we have unusual structures on the side, looks like a spool of thread
(side hour glass) this is visible on the ANTERIOR side only.
On the POSTERIOR we can see a deep fossa
Usually on the proximal end, we have the head of the bone, and on the distal end, we call it condyles
which are just rounded ends of the bones (remember occipital condyles where C1 articulates!)
On the distal end, this condyle is unique called the medical epicondyle this is on the medial side
epi means above. So, just above the condyles we have the epicondyle this is very prominent on
the humerus (can feel it; the funny bone gives us a tingling sensation because there is a nerve that
runs through it. When we hit this nerve adds pressure sends tingling sensation to all of the
muscles this nerve innervates).
*****USE THE MEDIAL EPICONDYLE TO ORIENT IT SHOULD BE ON THE MEDIAL
SIDE (can use to tell left and right)
The half “hour glass” on the side is called the trochlea and the rounded end is called the capitulum
The capitulum is more lateral than the trochlea and it is very rounded
We can see the trochlea both on the anterior and the posterior sides we can see the trochlea slightly
from the posterior side (bottom half) but the anterior we can see the whole thing.
We also have fossa on the anterior side, but not as prominent as the posterior those are the fossa
where the bones of the forearm are going to be situated on during the flexion of the elbow.
Coronoid fossa : it is above the trochlea. Right above the capitulum we have the radial fossa
On the posterior side we have the olecranon fossa this is a large fossa that can be used to identify
the posterior side.
Ulna and Radius:
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Those are the bones of the forearm. The Ulna is more medial than the radius
How to differentiate between them?? The radius goes from SMALL to BIG at the elbow where it
starts the bone is very small and contributes minorly to the articulating surface. (small head on the
radius) as we move distally, it moves larger and it contributes greatly to the articulation at the wrist
joint, whereas the ulna not as much.
The ulna opposite largely contributes to the articulation at the elbow at the wrist it becomes
smaller.
The heads of the radius and ulna are more proximal we see two important tuberosity’s (which are
just on the bones for muscle attachment). Bicipital (radial) tuberosity is on the radius named after
the fact that the bicep muscle attaches here. Ulnar tuberosity just medial to it but on the ulna.
The distal ends of the bones 2 notable features: styloid processes: they come off both the radius and
the ulna (styloid processes of the radius and ulna) they are attachment for ligaments to support the
wrist bones.
**Slide #45 anterior or posterior view??? Right or left??? RIGHT ARM
**Be able to determine even without the hand (STYLOID OF RADIUS IS FACING OUTSIDE AND
THE RADIAL TUBEROSITY IS ANTERIOR)
Distal Humerus:
Picture shown: this is the LEFT ARM
We can see the trochlea which is the “half hour glass” on the side and the coronoid fossa is above it
while the radial fossa is right above the capitulum.
Looking at where the radius and the ulna we see that this is the LEFT here the arm is not in the
anatomical position (need to rely on what structures are lateral/anterior/posterior in the anatomical
positon to determine).
Radial and Ulnar Details:
Left picture Ulna Ulnar head looks like a “monkey wrench” it has two main important features
that come off the head. 1) Olecranon process: this is the top part this process ARTICULATES INTO
THE OLECRANON FOSSA (on the posterior humerus) 2) Trochlear notch: this is a carving on the
bone NAMED BASED ON STRUCUTRE IT SITS ON the trochlea sits IN it.
Coronoid process: the coronoid fossa on the anterior humerus. This process fits into this fossa.
THEREFORE, THE NOTCHES/FOSSAARE USUALLY NAMED BASED ON THE SRUCTURES
THAT ARE SITUATED IN THEM.
Radial notch: THIS IS ON THE ULNA!!!!!!!!!!!! this is because the head of the radius fits inside
this small notch.
Ulnar notch: this is on the RADIUS it is a small notch on the radial head the ulna fits into that
notch.
DON’T CONFUSE THIS NAMING!!! notches/fossa named on the structures that have NOT THE
BONE THAT THEY ARE ON.
Interosseous membrane: this is a membrane that runs between the radius and the ulna this is
functioning to keep the two bones together. When we fall, this membrane forces the bones not
separate.
Looking at the lateral view of the ulna, we can use those notches to determine left or right ulna.
We have the proximal ulnar radial joint the bones articulate at the head in the TOP allows the
bones to stay attached together.
The ulnar notch is at the bottom it is on the DISTAL RADIAL ULNAR joint
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