Description

This video covers the anatomy of the scapula.
Structures covered in this video:

Surfaces and Fossae:
• Anterior surface of scapula
• Posterior surface of scapula
• Subscapular fossa (Fossa subscapularis)
• Supraspinous fossa (Fossa supraspinata)
• Infraspinous fossa (Fossa infraspinata)

Processes and Projections:
• Coracoid process (Processus coracoideus)
• Acromion (Acromion)
• Spine of scapula (Spina scapulae)
• Acromial angle (Angulus acromialis)
• Deltoid tubercle

Angles and Borders:
• Superior angle (Angulus superior)
• Inferior angle (Angulus inferior)
• Lateral angle (Angulus lateralis)
• Superior border (Margo superior)
• Medial border / Vertebral border (Margo medialis)
• Lateral border / Axillary border (Margo lateralis)

Articular Surfaces and Joints:
• Glenoid cavity (Cavitas glenoidalis)
• Supraglenoid tubercle (Tuberculum supraglenoidale)
• Infraglenoid tubercle (Tuberculum infraglenoidale)
• Acromioclavicular joint (Articulatio acromioclavicularis)
• Clavicular facet (Facies articularis clavicularis)
• Neck of scapula (Collum scapulae)

Notches and Ligaments:
• Suprascapular notch (Incisura scapulae)
• Spinoglenoid notch (Incisura spinoglenoidalis)
• Coracoacromial ligament (Ligamentum coracoacromiale)
• Superior transverse scapular ligament

Muscles Associated with the Scapula:
• Subscapularis
• Supraspinatus
• Infraspinatus
• Teres major
• Teres minor
• Deltoid
• Trapezius
• Levator scapulae
• Rhomboid major
• Rhomboid minor
• Serratus anterior
• Pectoralis minor
• Biceps brachii (long head and short head)
• Triceps brachii (long head)
• Omohyoid (inferior belly)

Neurovascular Structures & Clinical Mnemonics:
• Suprascapular nerve
• Suprascapular artery
• Suprascapular vein
• “Army over Navy” (Artery over ligament, Nerve under)
• Spinoglenoid notch syndrome
• SLAP lesion (Superior Labrum Anterior Posterior tear)

Functions and Clinical Relevance:
• Scapular stabilization and mobility
• Role in shoulder abduction, elevation, and rotation
• Rotator cuff anchoring
• Glenohumeral joint support
• Scapular winging (due to serratus anterior weakness)
• Impingement and rotator cuff pathology
• Muscle attachment site for upper limb motion

Sources:
• Kozlowski, T. (2017). Memorix Anatomy, 2nd ed.
• Standring S. (2020). Gray’s Anatomy, 42nd edition
• Tubbs RS, Shoja MM, Loukas M. (2016). Bergman’s Encyclopedia of Human Anatomic Variation
• White TD, Folkens PA. (2005). The Human Bone Manual

Programs used: Complete Anatomy, Biorender, PowerPoint

Transcript

Introduction & Content
0:00
This is the shoulder blade, or in other words what we call scapula. The scapula is the bone that fits
0:06
right about here. Visually on the posterior view and moves according the movement of your
0:11
arm. This is the root of your upper limb, this is the bone that allows free movement of your arm.
0:17
The scapula is the second bone in our upper limb series after the clavicle.
0:21
So let’s make you an expert on the scapula, by going through its parts, borders and surfaces
0:26
What’s up everyone, my name is Taim. I’m a medical doctor,
0:29
and I make animated medical lectures to make different topics in medicine visually easier
0:33
to understand. If you’d like a PDF version or a quiz of this presentation, you can
0:36
find it on my website, along with organized video lectures to help with your studies.
Scapula Anatomy
0:40
Alright, let’s get started. Let’s first test your visual memory,
0:44
are we looking at this bone from the backside, or front side right now?
0:47
We’re looking at it from the posterior view, or backside. So we’ll cover all the parts of this
0:52
bone while viewing both the anterior and posterior side. And the first part of this bone that I
Coracoid Process
0:58
wanna start with is the coracoid process. This outgrowth is the coracoid process.
1:03
The coracoid process is a bony projection on the anterior surface of the scapula. It
1:08
looks like a bent finger pointing forward and a bit laterally. The name “coracoid”
1:12
means “like a raven’s beak” in Greek. Anyways it works like an anchor point.
1:18
First for the pectoralis minor, as you see here. This muscle originates from the 3rd to 5th ribs
1:23
and inserts directly onto the coracoid process. It pulls the scapula forward and downward,
1:28
stabilizing the scapula during upper limb movements like pushing or reaching forward.
1:33
The other muscle that attaches to it is the short head of the biceps muscle.
1:37
Yes, your biceps has two heads, the short head originates from the coracoid process,
1:42
while the long head comes from inside the shoulder joint at the supraglenoid tubercle. Together,
1:47
they flex the elbow and help with forearm supination. But the short head also plays
1:52
a stabilizing role for the shoulder anteriorly. Next landmark is very prominent from the posterior
Spine of Scapula & Acromion
1:59
view: It’s first the spine of the scapula, which continues laterally, and just at the point where
2:04
it bends, we call this the acromial angle. This marks the transition between the spine and the
2:10
acromion. Now, the acromion itself is a flat bony part that forms the highest point of the shoulder,
2:17
and it articulates with the clavicle through something called the clavicular
2:21
facet. Another anatomical structure is, just below the spine on the lateral edge,
2:27
you’ll find the deltoid tubercle. This serves as a site where the deltoid muscle originates.
2:32
Ok, let’s add some structures to see how this looks. Here we see the
2:36
deltoid muscle. This powerful shoulder muscle originates from the clavicle, the acromion,
2:41
and the spine of the scapula, including the deltoid tubercle we just mentioned. It inserts
2:46
on the deltoid tuberosity of the humerus, and its primary function is to lift your arm to the side.
2:51
The trapezius muscle is another one here, it’s a large superficial back muscle that
2:56
also attaches to the spine of the scapula and the acromion. It elevates, retracts,
3:01
and rotates the scapula. Together with the deltoid, it forms the shoulder contour.
3:07
If we now turn this image to the front, we can see the clavicular facet articulating with the
3:12
clavicle, with an acromioclavicular joint between them. This joint is involved every
3:17
time you shrug, raise, or rotate your arm. Another thing is, a structure that might
3:22
not get as much attention but is super important is the coracoacromial ligament.
3:28
It runs from the coracoid process to the acromion, forming the coracoacromial
3:32
arch. Why is this important? It’s important because it acts as a protective roof over
3:38
the head of the humerus. It prevents superior displacement of the humeral head, basically,
3:44
it keeps your shoulder joint from popping upward. Alright, let’s keep this going. We’re now focusing
3:49
on the posterior surface. Above the spine is the supraspinous fossa,
Supraspinous & Infraspinous Fossa
3:54
and below is the infraspinous fossa. These depression function as beds for certain muscles,
4:00
and these muscles are the supraspinatus muscle, which sits on the supraspinous fossa. This is one
4:06
of the four rotator cuff muscles and initiates shoulder abduction, helping the deltoid kick in.
4:12
Below that is the infraspinatus muscle, sitting on the infraspinous fossa. It’s
4:17
also part of the rotator cuff, and its job is external rotation of the humerus.
4:22
Together, these rotator cuff muscles stabilize the glenohumeral joint,
4:26
holding the head of the humerus firmly against the shallow glenoid cavity of the scapula.
Subscapular Fossa
4:32
Okay, awesome. Another shallow depression we have
4:35
is on the front side, called subscapular fossa. This anterior surface of the scapula forms a bed
4:42
that contains a muscle. And that muscle is called the subscapularis. As you see here it
4:47
sits perfectly over the subscapular fossa. This is the largest and most powerful of the rotator cuff
4:54
muscles, and its main job is internal rotation of the humerus. It also helps hold the head of
5:00
the humerus firmly into the glenoid cavity, especially when you lift your arm up above
5:04
your head. If this muscle is torn or inflamed, it can significantly reduce arm rotation and
5:10
contribute to instability of the shoulder. Now. Just medial to the glenoid cavity is
Neck of Scapula & Glenoid Cavity
5:17
the neck of the scapula. It’s a narrowed region that helps support the glenoid,
5:22
like a stem supports a flower. The glenoid cavity itself is the pear-shaped articular surface that
5:30
connects with the head of the humerus, to form the glenohumeral joint. This is the shoulder joint,
5:36
and it’s the most mobile joint in the human body, but that mobility comes at the cost of stability,
5:42
making it one of the most commonly dislocated joints. We’ll pull back here to see the glenoid
5:48
cavity in context. This cavity is bordered by two small but significant tubercles.
5:54
Just below the glenoid, we have the infraglenoid tubercle. This is where the long head of the
5:59
triceps brachii originates. It’s the only head of the triceps that crosses the shoulder joint,
6:05
and it’s involved in elbow extension and shoulder stabilization. Now above the glenoid cavity,
6:12
we have the supraglenoid tubercle, and this is where the long head of the biceps brachii
6:17
originates. Remember earlier we talked about the short head originating from the coracoid
6:21
process? This long head takes a more scenic route, passing through the shoulder joint capsule and the
6:27
intertubercular sulcus of the humerus. Because of that path, it’s often involved in shoulder pain,
6:33
tendinopathy, or even dislocation when the labrum is torn, what we call a SLAP tear.
6:39
Now, another landmark we can see on the scapula is the spinoglenoid notch. This notch lies just
6:45
under where the spine of the scapula meets the glenoid, and it serves as a passageway for
6:50
the suprascapular nerve and vessels as they make their way to the infraspinatus muscle.
Borders of the Scapula
6:56
Okay now let’s look at the edges of this bone. Superior of the scapula,
7:01
we can see the superior border, and we can see here the suprascapular notch. This notch
7:07
is bridged by the superior transverse scapular ligament, which converts it into a foramen. The
7:13
suprascapular artery and vein pass above this ligament, while the suprascapular nerve travels
7:18
underneath it. A nice clinical mnemonic here is “Army over Navy”, so artery over, nerve under.
7:26
Another thing here, we can see the inferior belly of the omohyoid muscle attaching to the superior
7:32
border of the scapula. It crosses the posterior triangle of the neck and serves as an important
7:37
surgical landmark, although functionally it helps with depressing the hyoid bone.
7:43
Now let’s look at the rest of the angles and borders that define the shape of the scapula.
7:48
The superior angle is where the superior and medial borders meet. The medial border,
7:54
also called the vertebral border, runs along the edge closest to the spine.
7:58
The inferior angle is the lowest point of the scapula and is easily palpable. And finally,
8:03
the lateral border runs upward toward the glenoid and provides attachment for several muscles.
8:09
Speaking of which, let’s now bring in some of the muscles related to these landmarks. At the
8:14
superior angle, the levator scapulae inserts and helps elevate the scapula. Running along
8:20
the medial border we have the rhomboid minor and rhomboid major, which retract and rotate
8:25
the scapula. The anterior surface of this medial border is where the serratus anterior attaches.
8:31
This muscle is important for protraction and rotation of the scapula, and weakness here
8:36
causes scapular winging. On the lateral border, we find the insertions of the teres major and
8:43
teres minor. The teres major assists in adduction and internal rotation of the humerus, while the
8:49
teres minor is part of the rotator cuff, helping with external rotation and joint stabilization.
Outro & Next Topic
8:55
So.. that’s it. If you’re still here, good job. Try to review all parts of the scapula
9:00
and see if you remember everything. So, we’ve now covered all landmarks
9:04
and parts of the scapula. It comes right after the clavicle in our upper limb series.
9:09
In the next video, we’ll focus on this area shown in red, which is the shoulder
9:13
joint itself, and talk specifically about the glenohumeral joint, and in more depth
9:18
about what the rotator cuff actually is, and how they provide stability to the shoulder.
9:23
Click the next video and I’ll see you there. If you want a handmade PDF version of this
9:27
lecture, take a quiz to test your knowledge, or access an organized list of all my videos,
9:31
you can find everything on my website. Thanks for watching! See you in the next one.