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Flashcards in Mod 2: Lecture 1 - Shoulder Deck (54)
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Presentation Overview
(don't need to know)

- osteology
- articulations and associated structures
- kinematics
- musculature
---- extrinsic
---- intrinsic



- sternum
- clavicle
- scapula
- humerus


Osteology: Sternum

- Manubrium: top end
---- jugular Notch: palpable indent at the top center of the manubrium
---- sternal angle: the joint where the body and manubrium meet
- Body: middle shaft
- Xiphoid Process: bottom end


Osteology: Clavicle

- Sternal End: round and roller like
---- articulates with the manubrium of the sternum
- Acromial end: flattened
---- articulates with the acromion of the scapula


Borders and Surfaces of the Scapula

- Posterior Surface: convoluted
- Ventral Surface: smooth
- Medial/Vertebral Border: long straight end closest to the spine
- Lateral/Axillary Border: long diagonal side closest to the armpit


Posterior Surface of the Scapula

- convoluted, back side
- spine: divides the scapula into the supraspinous fossa and infraspinous fossa
- acromion process: sticking out end of the spine, where the clavicle meets the scapula, forms a curve that is clear from the lateral view


Suprascapular Notch

- on the top edge of the scapula
- suprascapular neurovascular bundle runs through to get to the other structures (muscle and stuff) on the scapula


Glenoid Cavity

- seen from a lateral view of the scapula
- circular indentation on the biggest sticking out thing
- on the upper part of the scapula
- supraglenoid tubercle: bump on the superior side of the glenoid cavity, site of attachment for the long head of the biceps
-infraglenoid tubercle: bump on the inferior side of the glenoid cavity, site of attachment for the long head of the triceps


Coracoid Process

- seen from a lateral view of the scapula
- on the top of the scapula
- little sticking out thing to the ventral side of the acromion process and superior to the glenoid cavity


Osteology: Humerus

- Head: smooth, articular surface, the part that fits and rotates in the glenoid cavity of the scapula
- Two Necks: Anatomical and Surgical
- Greater and Lesser Tubercle
- Deltoid Tuberosity: bump in the middle of the shaft, attachment site for the deltoid muscle


Greater and Lesser Tubercle of the Humerus

- big bumps below the head/neck
- sites for muscle attachment
---- rotator cuff muscles
- greater is below the acromion process
- lesser is below the coracoid process
- intertubercular groove: runs in between the tubercles, tendon of the long head of the biceps travels here


Two Necks of the Humerus

- Anatomical Neck: located between the head and the tubercles, a very thick neck
- Surgical Neck: located below the tubercles and above the shaft
--- common site of fracture because it narrows between the wide head and the thin shaft


Joints of the Shoulder Complex

- Sternoclavicular (SC): between the manubrium and the clavicle
- Acromioclavicular (AC): between the acromion of the scapula and the clavicle
- Glenohumeral (GH): between the glenoid cavity of the scapula and the humerus
- Scapulothoracic (ST): between the scapula and the back of the ribs


Sternoclavicular Joint

- Articular Components: sternal end of the clavicle and the manubrium of the sternum
- Joint Type: modified saddle type synovial joint
- Movements: elevation/depression, protraction/retraction, rotation
- only site of bony attachment of the upper extremity to the axial skeleton


Acromioclavicular Joint

- Articular Components: acromial end of the clavicle and the acromion process of the scapula
- Joint Type: plane type synovial joint
---- two flat surfaces coming against each other
- Movements: rotation (scapula on clavicle)


Associated Structures of the Sternoclavicular Joint

- fibrocartilage disc: absorb pressure that is transmitted to axial skeleton, located in the synovial joint
- ligaments:
---- sternoclavicular: bilateral
---- interclavicular: connecting the clavicles across the sternum
---- costoclavicular: bilateral


Associated Structures of the Acromioclavicular Joint

- fibrocartilage disc: in the articulation
- ligaments:
---- acromioclavicular
---- coracoclavicular: connects the coracoid process of the scapula with the clavicle


Glenohumeral Joint

- Articular Components: humeral head and glenoid fossa/cavity
- Joint Type: ball and socket type synovial joint
---- this is the joint you normally think of as your shoulder
---- triaxial joint
- Features: the glenoid fossa is 1/3 the size of the humeral head
---- bowling ball on a golf tee
---- makes the joint inherently unstable
- Both non-contractile and contractile structures enhance G-H stability


Ligamentous (non-contractile) Stability of the Glenohumeral joint

- Coracoacromial Ligament: between the coracoid and acromion processes of the scapula
- Superior, Middle, and Inferior Glenohumeral Ligaments: run along the posterior side of the scapula near the edge with the glenoid fossa
---- reinforce the joint capsule
---- stabilize the joint


Coracoacromial Arch

- an extrinsic, protective, osseoligamentous structure
- formed by the smooth inferior aspect of the acromion and the coracoid process of the scapula with the coracoacromial ligament spanning between them
- overlies the humeral head, protecting it and preventing its superior displacement from the glenoid cavity
- the tendon of the supraspinatus muscle passes under this arch
---- tight space puts it at risk for injury


Additional (not ligaments) Non-Contractile Structures Contributing to Glenohumeral Stability

- Glenoid Labrum
---- a fibrocartilagenous ring that attaches to the outer rim of the glenoid fossa
---- builds up the glenoid cavity to make it deeper which enhances stability


Scapulothoracic Joint

- not a traditional anatomical joint, but a physiological one
---- movement occurs between musculoskeletal structures (between the scapula and the associated muscles and the thoracic wall)
- Movements: elevation/depression, protraction/retraction/ rotation
---- movement is of the scapula, such as when you swing your arms


GH Joint Movement in a Sagittal Plane

* From the anatomical position

- Flexion: bringing the arm forward
---- can swing 180 deg from starting position
- Extension: bringing the arm backward
--- can swing 60 deg from the starting postion


GH Joint Movement in a Coronal Plane

- Abduction: lifting the arm up and away from the body
- Adduction: bringing the arm back toward the body from its abducted position


GH Joint Movement in a Horizontal Plane

* Start from a position with the arm out in front of you - so that you can get the whole arm in a horizontal plane
- Abduction: swinging the arm laterally away from the body
- Adduction: swinging the arm across the body


Rotation at the GH Joint

* Start with arm bent at the elbow like you are going to shake someone's hand
- Internal/Medial Rotation: move the hand inward across the body
---- up to 80 deg of movement
---- note how the humerus moves
- External/Lateral Rotation: move the hand out, away from the body
----up to 60 deg of movement
---- note how the humerus moves


Movement at the ST Joint in the frontal plane

- Elevation/Depression: moving the scapula up (shrugging the shoulders) and down
- Upward Rotation: lift your arms above your head
---- the glenoid fossa rotates up (since it has to follow the humerus)
- Downward Rotation: return to anatomical position
---- glenoid fossa moves down


Movement at the ST Joint in the Sagittal Plane

- Adduction (Retraction)/ Abduction (Protraction) - swing/stretch the arms behind and in front of your back
---- the scapulas gets closer to the spine and farther from it


Scapulohumeral Rhythm

- describes the relative contributions to upper extremity motion at the GH Joint and ST Joint
---- movement of the scapula is essential for upper extremity function
---- you cannot have a full range of motion without engaging the scapula


Abduction at the Shoulder
1) Abduction at GH joint only
2) From 30 - 90 deg of movement, what is the ratio of movement at the GH to ST joints?
3) Above 90 deg of movement, what is the ratio of movement at the GH to ST joints?

1) only up to 30 degrees, after that you have to move your scapula
---- so past 30 deg, you use the ST joint as well
2) 2 : 1
---- so for every 2 degrees you move at the GH joint, you have to move (upward rotate) your scapula 1 deg
3) 1 : 1
---- so for every degree you move at the GH joint, you have to move your scapula 1 deg