hello anatomy friends this is dr alsup and in this video we
will be discussing the osteology for the shoulder brachial plexus and arm session
pay attention to some of these structures as attachment sites for some of the muscles we
will be identifying and discussing today so i'll point those out as we identify the structure
but we will start off easy with the clavicle again this is a bone we have discussed from day one
often referred to as the collarbone and easily palpable from where it articulates with the
sternum to its other major articulation with the acromion so the acromial part of the clavicle
to form the acromioclavicular joint so again here is the acromion
of the scapula to me this is one of the most dominant structures of the scapula and it actually
can vary in width and size and that variability can affect structures that run deep to it so
you're going to have structures running under this area right here such as the supraspinatus tendon
projecting anteriorly as you can see here is the coracoid process so you can see the coracoid
process here as well this process is not nearly as large as the acromion but it has lots of things
attaching to it including ligaments associated with both the acromioclavicular and shoulder
joints additionally muscles attach here as well and we've talked previously that the pectoralis
minor muscle attaches here but more aligned with today's session it will have or it will be a
proximal attachment for the coracobrachialis it has correct go right in its name
as well as the short head of the biceps brachii
only the short head the long head will not attach on the coracoid process
located laterally you will have a shallow depression called the glenoid fossa
sometimes you hear it referred to as the glenoid cavity it's right here and this is the socket in
the shoulder ball and socket joint and this is where the head of the humerus will articulate
and just notice how shallow this region is particularly in comparison to the head
of the humerus so this plays a role in why the shoulder joint is so mobile you don't
have such a tight fit between the bones but also part of the reason why it is less stable
moving to the proximal humerus first off again here is the head of the humerus which is the ball
of the shoulder ball and socket joint and now you can really see the fit between those two
structures opposite the head of the humerus is the greater tubercle so laterally placed on the
proximal humerus i always think opposite the head the head always has to be facing medially
this is called the greater tubercle because it is larger than the lesser tubercle which you can see
right here and this is because it's larger because it will have three of the four rotator
cuff muscles distally attaching here those rotator cuff muscles whose bellies are located posteriorly
now more anteriorly placed is the lesser tubercle which i outlined right here and
this is smaller as only one muscle attaches here one of those rotator cuff muscles
between the greater and the lesser tubercles is a long but slender depression called the
Intertubercular sulcus sometimes you hear it referred to as the bicipital groove and that's
because the proximal tendon of the long head of the biceps brachii muscle will be located here
and during life there will be a ligament that kind of crosses over and connects the two tubercles
and allows kind of like a tunnel like region for that tendon and to keep the tendon
that long long head of the biceps brachii in its place during movements
just distal to the tubercles is a relatively thin portion of the humerus and you can see
it's pretty thick here it starts getting a little bit thicker down here and this region is called
the surgical neck of the humerus and this region is a named region due to the relatively higher
frequency of fractures that occur here when you're talking about the humerus so if you
have a humeral fracture it's not uncommon for it to occur at this surgical neck region the
axillary nerve which is innervating the deltoid muscle and the humeral circumflex arteries of the
axillary artery will wrap around the surgical neck region and may be affected with a fracture here
moving to the distal humerus hopefully a review
from the last session you will have this spool-shaped trochlea
which serves as an articulation site for the trochlear notch of the ulna so this
is forming the humeroulnar joint which is the true
elbow joint even though it's very closely associated with other joints in this region
looking at a lateral view of the ulna i know i'm looking at a lateral view because of this
notch this depression right here and this is called the radial
notch and this will articulate with the head of the radius forming the proximal radial ulnar
joint so this notch needs to be facing laterally in order to articulate with the lateral radius
radius because recall the ulna is medial in the forearm the radius is lateral
the olecranon is this very prominent structure in the proximal and posterior portion of the
ulna it's very robust and this is because it is the distal attachment side of the triceps brachii
muscle which is a very large muscle and just anterior to the olecranon is the trochlear notch
and this is the semilunar shaped notch which will articulate with the trochlea of the humerus
to form the true elbow joint so that trochlea will articulate with the trochlear notch
last for today in terms of the osteology is the radius
always pretty distinctive to me is this proximal button-shaped
head of the radius which will articulate with both the capitulum of the humerus but also the
radial notch of the ulna that we just looked at to form the proximal radial ulnar joint so that
head will fit right here in this radial notch and this allows rotation of the radial head at
the notch just distal to the head of the radius is this buildup of bone called the radial tuberosity
anytime you have a mounding of bone this typically means something attached there like a tendon
or a ligament during life and the more say the individual uses the muscle and pulls on the bone
that will cause more bony buildup in that region and the more likely the bony prominence is larger
in this case the radial tuberosity is the distal attachment of the biceps brachii muscle
allowing it to cross both the elbow as well as the proximal radioulnar joints
thus being able to affect actions at both alright excellent thank you for your time
and attention here and as always please feel free to reach out with any questions