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Basic Shoulder Anatomy

Updated on January 21, 2015

What Makes a Shoulder?

Join me on my journey through the world of the human shoulder. We will explore the architecture (bones), the rigging (muscles), the fiberoptics (the nervous system), climate control (circulatory system), and nomenclature. This is just one chapter in a larger story.

Image courtesy of [auro] on Flickr.

Terms of Navigation

Articulation vs Joint

What's the difference? There isn't one. It's two ways to say the same thing in both anatomy and architecture.

Superior vs Inferior

Superior is towards the head, or "above". Inferior is towards the feet, or "below". Like an inferiority complex.

Distal vs Proximal

DISTAL indicates a position along a limb (arm or leg) away from the main part of the body. PROXIMAL indicates a position closer to the body.

Medial vs Lateral

Medial is towards the spine (or midline of the body), lateral is away from the spine.

Anterior vs Posterior

Anterior is the front half of the body. Posterior is the back half.

Musculoskeletal Anatomy Coloring Book

Musculoskeletal Anatomy Coloring Book, 1e
Musculoskeletal Anatomy Coloring Book, 1e

This was the book that finally got me over the hump with identifying muscles. I figured out that when I looked at pictures of muscles in their natural color my mind lumped them all together and I couldn't distinguish individual muscles. With this coloring book I was able to make each muscle a different color and like magic they started popping into place in my mind.

 

Architecture

or, the Skeletal Anatomy of the Shoulder

HUMERUS

The humerus is the approximately foot-long bone of the upper arm. It has bumps and notches on it that become articulations (or joints. On the distal end of the humerus the lower arm bones of the ulna and radius create the humeroulnar joint. On the proximal end of the humerus the glenoid fossa creates the glenohumeral joint.

The bumps and notches (or bony landmarks) are: the head of the humerus, greater tubercle, deltoid tuberosity, medial and lateral epicondyles, medial and lateral supracondylar ridges, olecranon fossa, and trochlea. And that's just the posterior view. On the front are added the medial and lateral condyles, the coronoid fossa, the radial fossa, and the capitulum.

SCAPULA

The scapula is more commonly known as the shoulder blade. There are two of them in the upper back, one on each side of the spinal cord. It has various landmarks: the spine of the scapula, the medial border, the inferior angle, the superior angle, the lateral border, and the infraglenoid tubercle.

What are all these things? Think of the scapula as an almost equal sided triangle. The edge parallel to the spine is the medial border. The bottom angled edge is the lateral border. The ridge that runs through the middle of the posterior scapula, perpendicular to the spine, is the aptly named spine of the scapula. The upper angled corner of the scapula is the superior angle. The lower angled corner of the scapula is the inferior angle. The infraglenoid tubercle is a small spot where the triceps brachii muscle attaches.

Between the borders and spine are hollows or depressions called fossae. Inferior to the spine of the scapula is the infraspinous fossa. Superior to the spine of the scapula is the supraspinous fossa. The subscapular fossa is on the anterior side of the scapula. It can be felt by pushing back from below the armpit.

Image courtesy of joaoc~grando on Flickr.

  • Deltoid
  • Pectoralis major
  • Pectoralis minor
  • Teres major
  • Teres minor
  • Supraspinatus
  • Infraspinatus
  • Subscapularis
  • Biceps brachii
  • Triceps brachii
  • Coracobrachialis
  • Latissimus dorsi
  • Serratus anterior (with origin fixed)
  • Rhomboid major
  • Rhomboid minor
  • Levator scapula
  • Trapezius

Muscles That Flex and Extend the Shoulder - (glenohumeral joint)

Flexion

of the shoulder is moving the arm forward in front of the body (anteriorly), as in handing something to someone straight in front of you.

Extension

of the shoulder is just the opposite, moving the arm straight in back of the torso as in handing off a baton.

  • FLEXION
  • Deltoid (anterior fibers)
  • Pecoralis major (upper fibers)
  • Biceps brachii
  • Coracobrachialis
  • EXTENSION
  • Deltoid (posterior fibers)
  • Pectoralis major (lower fibers)
  • Latissimus dorsi
  • Teres major
  • Teres minor
  • Infraspinatus
  • Triceps brachii (long head)

Shoulder Exension and Flexion Demonstrated

Muscles that Horizontally Abduct and Adduct the Shoulder - (Glenohumeral Joint)

Horizontal Abduction

of the shoulder is moving the arm away from the body (midline) on the horizontal or transverse plane.

Horizontal Adduction

of the shoulder is just the opposite, moving the arm closer to and/or across the body on the horizontal or transverse plane.

  • HORIZONTAL ABDUCTION
  • Deltoid (posterior fibers)
  • Infraspinatus
  • Teres minor
  • HORIZONTAL ADDUCTION
  • Deltoid (anterior fibers)
  • Pectoralis major (upper fibers)

Horizontal Abduction and Adduction of the Shoulder Demonstrated

Muscles that Abduct and Adduct the Shoulder - (Glenohumeral joint)

Abduction

of the shoulder is lifting the arm straight up while holding it straight out to the side of the body such as when doing jumping jacks.

Adduction

of the shoulder is just the opposite, bringing the arm down and closer to the body from holding it straight out to the side of the body.

  • ABDUCTION
  • Deltoid (all fibers)
  • Supraspinatus
  • ADDUCTION
  • Pectoralis major (all fibers)
  • Teres major
  • Teres minor
  • Infraspinatus
  • Latissimus dorsi
  • Triceps brachii (long head)
  • Coracobrachialis

Muscles that Laterally and Medially Rotate the Shoulder - (Glenohumeral joint)

Lateral (External) Rotation

of the shoulder is moving the hands away from the body while keeping the elbows bent close to the torso.

Adduction

of the shoulder is just the opposite, moving the hand back towards the body while keeping elbows bent next to the torso.

  • LATERAL (EXTERNAL) ROTATION
  • Deltoid (posterior fibers)
  • Infraspinatus
  • Teres minor
  • MEDIAL (INTERNAL) ROTATION
  • Deltoid (anterior fibers)
  • Pectoralis major (all fibers)
  • Teres major
  • Subscapularis
  • Latissimus dorsi

Lateral and Medial Rotation of the Shoulder Demonstrated

Muscles that Elevate and Depress the Scapula - (Scapulothoracic joint)

Elevation

of the scapula is pulling your shoulders towards your ears.

Depression

of the scapula is just the opposite, pushing the shoulders downward.

  • ELEVATION
  • Trapezius (upper fibers)
  • Rhomboid major
  • Rhomboid minor
  • Levator scapula

Elevation and Depression of the Scapula Demonstrated

Muscles That Abduct (Protraction) and Adduct (Retraction) the Scapula - (Scapulothoracic joint)

Abduction (Protraction)

of the scapula moving the shoulder forward such as when reaching to grab something without moving the rest of the body.

Adduction (Retraction)

of the scapula is just the opposite, pulling the shoulder backward so that the scapula is squeezing towards the spine.

  • ABDUCTION (PROTRACTION)
  • Serratus anterior (with the origin fixed)
  • Pectoralis minor
  • ADDUCTION (RETRACTION)
  • Trapezius (middle fibers)
  • Rhomboid major
  • Rhomboid minor

Adduction (Retraction) and Abduction (Protraction) of the Scapula Demonstrated

Muscles that Rotate the Scapula Upward and Downward

Upward Rotation

of the scapula is the lifting movement of the shoulder while doing forward shoulder rolls.

Downward Rotation

of the scapula is just the opposite, pushing the shoulder down in backward shoulder rolls.

  • UPWARD ROTATION
  • Trapezius (upper and lower fibers)
  • DOWNWARD ROTATION
  • Rhomboid major
  • Rhomboid minor
  • Levator scapula

Downward Rotation Demonstration

Origins and Insertions of the Shoulder Muscles

Deltoid

Origin: Lateral one-third of the clavicle, acromion and spine of the scapula.

Insertion: Deltoid tuberosity.

Pectoralis major

Origin: Medial half of clavicle, sternum and cartilage of first through sixth ribs.

Insertion: Crest of greater tubercle of humerus.

Pectoralis minor

Origin: Third, fourth and fifth ribs.

Insertion: Coracoid process of the scapula.

Teres major

Origin: Lateral side of the inferior angle and lower half of lateral border of the scapula.

Insertion: Crest of the lesser tubercle of the humerus.

Teres minor

Origin: Superior half of lateral border of the scapula.

Insertion: Greater tubercle of the humerus.

Supraspinatus

Origin: Supraspinous fossa of the scapula.

Insertion: Greater tubercle of the humerus.

Infraspinatus

Origin: Infraspinous fossa of the scapula.

Insertion: Greater tubercle of the humerus.

Subscapularis

Origin: Subscapular fossa of the scapula.

Insertion: Lesser tubercle of the humerus.

Biceps brachii

Origin:

Short head: Coracoid process of scapula.

Long head: Supraglenoid tubercle of scapula.

Insertion:Tuberosity of the radius and aponeurosis fo the biceps brachii.

Triceps brachii

Origin:

Long head: Infraglenoid tubercle of the scapula.

Lateral head: Posterior sruface of proximal half of the humerus.

Medial head: Posterior surface of distal half of the humerus.

Insertion: Olecranon process of the ulna.

Coracobrachialis

Origin: Coracoid process of the scapula.

Insertion: Medial surface of mid-humeral shaft.

Latissimus dorsi

Origin Spinous processes of last thoracic vertebrae, last three of four ribs, thoracolumbar aponeurosis and poserior iliac crest.

Insertion Crest of the lesser tubercle of the humerus.

Serratus anterior (with origin fixed)

Origin Surfaces of upper eight or nine ribs.

Insertion Anterior surface of medial border of the scapula.

Rhomboid major

Origin Spinous processes of T-2 to T-5.

Insertion Spinous processes of C-7 and T-1.

Rhomboid minor

Origin Spinous processes of C-7 and T-1.

Insertion Upper portion of medial border of the scapula, across from spine of the scapula.

Levator scapula

Origin Transverse processes of first through fourth cervical vertebrae.

Insertion Upper region of medial border and superior angle of the scapula.

Trapezius

Origin External occipital protuberance, medial portion of superior nuchal line of the occiput, ligamentum nuchae and spinous processes of C-7 through T-12.

Insertion Lateral one-third of clavicle, acromion and spine of the scapula.

Ligaments of the Shoulder

Image from the Steadman-Hawkins Clinic website. Click on image for more information.

Nervous System Anatomy of the Shoulder

the "fiberoptics"

I found a web page that explains this part of the shoulder much better than I could, complete with a chart.

BBC - The Human Shoulder

Circulatory System of the Shoulder

The axillary vein and the axillary artery pass through the armpit.

For more information see The Circulatory System at the Inner Body website.

Meridians That Pass Through the Shoulder

The Chinese meridian system is a network of energy lines and points along the body. They can be manipulated either through acupuncture or acupressure type massage such as Shiatsu in order to achieve balance and therefore healing. As I am a massage therapist I've highlighted which muscles the main twelve meridians pass through.

Below is a list of meridians that go through the shoulder and which muscles are involved. Click on the meridian to go to a graphic illustration at the Yin Yang House site and learn more about the specific points.

  • Lung: biceps brachii and pectoralis
  • Pericardium: biceps brachii and pectoralis
  • Heart: biceps brachii. serratus anterior, subscapularis
  • Small Intestine: triceps brachii, deltoid, teres major, infraspinatous, supraspinatous, trapezius, rhomboid minor
  • Triple Heater: triceps brachii, infraspinatous, trapezius
  • Large Intestine: biceps brachii, deltoid
  • Spleen: pectoralis minor, pectoralis major
  • Kidney: Pectoralis major
  • Urinary Bladder: rhomboids major and minor, infraspinatous, supraspinatous, trapezius
  • Gall Bladder: Trapezius, supraspinatous
  • Stomach: Pectoralis major

One day Sir Michael and Monsieur Raphael were taking their daily walk along the high ridge beyond Michael's manor house. They came to a sharp drop off. In front of them extended a bowl-shaped valley. The sun streamed down through fair weather clouds onto the green and gold fields below.

"What a happy place this is!" said Monsieur Raphael, feeling the warm energy rising up from the valley.

"Indeed," replied Sir Michael. "It is the Glen of Good Humor. Come, follow me down this path to the valley floor where we will find a pleasant little joint at which we can stop for lunch and have a pint. The shoulder of lamb is particularly good."

Image courtesy of jfairbairn on Flickr.

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    • profile image

      anonymous 5 years ago

      Excellent information in this lens. Definitely gave me better understanding of how the shoulder works.

    • Redneck Lady Luck profile image

      Lorelei Cohen 6 years ago from Canada

      Wow. I think you have covered virtually everything that can be mentioned about the shoulder. Amazing.

    • profile image

      Arc4life 6 years ago

      Great Informative Lens- Lots of people have shoulder injuries. The information presented here will help you understand what your Dr tells you and also help you interpret your x-ray report.

    • ClassyGals profile image

      Cynthia Davis 6 years ago from Pittsburgh

      Thanks for sharing shoulder anatomy, which I personally think is the most sensual part of the human body.

    • profile image

      julieannbrady 8 years ago

      Nicely done -- I know a lot about shoulder anatomy because I have suffered for years with an injured shoulder -- SLAP tear -- that required 3 goes at surgery! Yep. At first they thought I had a frozen shoulder and then discovered just how severed of an injury. A shoulder is a difficult part of the body to 'repair' and return to normal.

    • nightbear lm profile image

      nightbear lm 8 years ago

      Excellent lens, can certainly see why you used this as a study aide, but it is also very interesting. Of course I love medical stuff. You hit my cup of tea.

    • SandyMertens profile image

      Sandy Mertens 8 years ago from Frozen Tundra

      Very interesting. Nice lens.

    • TrinaSonnenberg profile image

      Trina Sonenberg 8 years ago from Nucla, Colorado

      Excellent!

    • Wendy L Henderson profile image

      Wendy Henderson 8 years ago from PA

      excellent lens.