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Gross Anatomy > Mod 2: Lecture 1 - Shoulder > Flashcards

Mod 2: Lecture 1 - Shoulder Flashcards

1
Q 
Presentation Overview
(don't need to know)
A
  • osteology
  • articulations and associated structures
  • kinematics
  • musculature
  • — extrinsic
  • — intrinsic
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2
Q

Osteology

A
  • sternum
  • clavicle
  • scapula
  • humerus
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3
Q

Osteology: Sternum

A
  • 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
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4
Q

Osteology: Clavicle

A
  • Sternal End: round and roller like
  • — articulates with the manubrium of the sternum
  • Acromial end: flattened
  • — articulates with the acromion of the scapula
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5
Q

Borders and Surfaces of the Scapula

A
  • 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
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6
Q

Posterior Surface of the Scapula

A
  • 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
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7
Q

Suprascapular Notch

A
  • on the top edge of the scapula

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

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8
Q

Glenoid Cavity

A
  • 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
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9
Q

Coracoid Process

A
  • 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
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10
Q

Osteology: Humerus

A
  • 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
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11
Q

Greater and Lesser Tubercle of the Humerus

A
  • 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
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12
Q

Two Necks of the Humerus

A
  • 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
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13
Q

Joints of the Shoulder Complex

A
  • 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
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14
Q

Sternoclavicular Joint

A
  • 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
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15
Q

Acromioclavicular Joint

A
  • 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)
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16
Q

Associated Structures of the Sternoclavicular Joint

A
  • 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
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17
Q

Associated Structures of the Acromioclavicular Joint

A
  • fibrocartilage disc: in the articulation
  • ligaments:
  • — acromioclavicular
  • — coracoclavicular: connects the coracoid process of the scapula with the clavicle
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18
Q

Glenohumeral Joint

A
  • 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
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19
Q

Ligamentous (non-contractile) Stability of the Glenohumeral joint

A
  • 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
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20
Q

Coracoacromial Arch

A
  • 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
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21
Q

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

A
  • 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
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22
Q

Scapulothoracic Joint

A
  • 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
23
Q

GH Joint Movement in a Sagittal Plane

  • From the anatomical position
A
  • 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
24
Q

GH Joint Movement in a Coronal Plane

A
  • Abduction: lifting the arm up and away from the body

- Adduction: bringing the arm back toward the body from its abducted position

25
Q

GH Joint Movement in a Horizontal Plane

A
  • 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
26
Q

Rotation at the GH Joint

A
  • 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
27
Q

Movement at the ST Joint in the frontal plane

A
  • 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
28
Q

Movement at the ST Joint in the Sagittal Plane

A
  • 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
29
Q

Scapulohumeral Rhythm

A
  • 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
30
Q

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?

A

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

31
Q

Why does the Scapula have to move with the humerus? What if the scapula was fixed?

A
  • bc the glenoid fossa is so shallow
  • — bowling ball on a golf tee
  • the humeral head would roll out of the glenoid fossa if the scapula was fixed
  • so the scapula has to move with the humerus in order to keep the humeral head in the glenoid fossa
32
Q

Shoulder Musculature

  1. Extrinsic
  2. Intrinsic
A
  1. have an attachment outside the osteology of the shoulder
    - — and one in the region
  2. have both attachments within the osteology/region of the shoulder
33
Q

Extrinsic Posterior Muscles of the Shoulder

*look up attachments, action, and innervation for all of them

A
  • Superficial Layer:
  • — Trapezius
  • — Latissimus Dorsi
  • Deeper Layer:
  • — Levator Scapulae
  • — Rhomboid Major
  • — Rhomboid Minor
34
Q

Trapezius Muscle

  1. Attachments
  2. Action
  3. Innervation
A
    • superior nuchal line, external protuberance, nuchal ligament, spinous processes of C7 - T12
      - scapula spine, acromion, lateral 1/3 of the clavicle
    • upper fibers: elevates and upwardly rotates the scapula
      - middle fibers: adducts/retracts scapula
      - lower fibers: depresses and upwardly rotates the scapula
    • CN XI (very unusual for upper extremity)
      - C3, C4
35
Q

Latissimus Dorsi

  1. Attachments
  2. Action
  3. Innervation
A
    • spinous processes of T7 - T12, iliac crest, thoracolumbar fascia, ribs 9-12
      - floor of intertubercular groove of humerus
    • shoulder extension, adduction, and internal rotation
    • thoracodorsal nerve
36
Q

Levator Scapulae

  1. Attachments
  2. Action
  3. Innervation
A
    • transverse processes of C1 - C4
      - superior medial border of scapula
    • elevates and downwardly rotates scapula
    • dorsal scapular nerve (C5) and ventral rami of C3 and C4
37
Q
  • ** Rhomboid Minor and Major
    1. Attachments
    a. Minor
    b. Major
    2. Action
    3. Innervation
A

1a. - spinous processes of C7 and T1
- medial scapular border at the level of root of scapular spine
1b. - spinous processes T2-T5
- medial scapular border from level of spine to inferior angle
2. - adducts/retracts and downwardly rotates scapula
3. dorsal scapular nerve

38
Q

Extrinsic Muscles of the Shoulder: Anterior

A
  • pectoralis major
  • pectoralis minor
  • serratus anterior
  • subclavius
39
Q

Pectoralis Major

  1. Attachments
  2. Action
  3. Innervation
A
    • clavicular head: medial half of clavicle
      - sternocostal head: anterior sternum, upper six costal cartilages
      - intertubercular groove of humerus
  2. adducts and medially rotates humerus
  3. lateral and medial pectoral nerves
40
Q

Pectoralis Minor

  1. Attachments
  2. Action
  3. Innervation
A
  1. -ribs 3-5
    - coracoid process of scapula
    • stabilizes scapula
    • medial pectoral nerve
41
Q

Serratus Anterior

  1. Attachments
  2. Action
  3. Innervation
A
    • external surfaces of lateral parts of ribs 1-8
      - anterior surface of medial border of scapula
    • protracts and upwardly rotates the scapula
      - hold the scapula against the thoracic wall
  3. long thoracic nerve
42
Q

Subclavius

  1. Attachments
  2. Action
  3. Innervation
A
    • junction of the first rib and costal cartilage
      - interior surface of medial third of clavicle
  2. anchors and depresses clavicle
  3. nerve to subclavius
43
Q

Intrinsic muscles of the shoulder

A
  • coracobracialis
  • deltoid
  • teres major
  • teres minor
  • supraspinatus
  • infraspinatus
  • subscaularis
44
Q

Coracobrachialis

  1. Attachments
  2. Action
  3. Innervation
A
    • tip of coracoid process
      - medial, middle 1/3 of humerus (the middle of the shaft)
    • flex and adducts shoulder
  3. musculocutaneous nerve
45
Q

Deltoid

  1. Attachments
  2. Action
  3. Innervation
A
    • scapula spine, acromion, lateral 1/3 of clavicle
      - deltoid tuberosity of humerus
    • anterior: shoulder flexion
      - middle: shoulder abduction
      - posterior: shoulder extension
  3. axillary nerve
46
Q

Teres Major

  1. Attachments
  2. Action
  3. Innervation
A
    • inferior lateral aspect of posterior surface of scapula
      - medial lip of intertubercular groove of humerus
    • shoulder medial/internal rotation
  3. lower subscapular nerve
47
Q

Rotator Cuff Muscles

A
  • supraspinatus
  • infraspinatus
  • teres minor
  • subscapularis
48
Q

Supraspinatus

  1. Attachments
  2. Action
  3. Innervation
A
  • found on the dorsal side of the scapula
    1. - supraspinous fossa
  • superior facet of greater tubercle
  • — must pass under the coracoacromial arch to reach the greater tubercle - this puts it at risk for impingement
    2. shoulder abduction
    3. suprascapular nerve
49
Q

Infraspinatus

  1. Attachments
  2. Action
  3. Innervation
A
  • found on the dorsal side of the scapula
    1. - infraspinous fossa
  • inferior facet of greater tubercle
    2. shoulder lateral/external rotation
    3. suprascapular nerve
50
Q

Teres Minor

  1. Attachments
  2. Action
  3. Innervation
A
  • found on the dorsal side of the scapula
    1. - middle part of lateral border of scapula
  • inferior facet of greater tubercle
    2. shoulder lateral/external rotation
    3. axillary nerve
51
Q

Subscapularis

  1. Attachments
  2. Action
  3. Innervation
A
  • found on the ventral side of the scapula
    1. - subscapular fossa
  • lesser tubercle
    2. shoulder medial/internal rotation
    3. upper subscapular nerve and lower subscapular nerve
52
Q

Dynamic Stability of the GH Joint: Muscles of the Rotator Cuff

A
  • the tendons of the 4 rotator cuff muscles blend with the fibrous capsule forming a cuff which reinforces the joint capsule and provides active GH stability
53
Q

Clinical Correlation: Rotator Cuff Injury

A
  • repetitive use of the rotator cuff muscles when using the upper limb above the horizontal (eg during throwing and swimming) may allow the humeral head and rotator cuff to impinge on the coracoacromial arch
  • this may produce irritation of the arch and inflammation of the rotator cuff
  • — esp the supraspinatus tendon
  • rupture of the supraspinatus tendon results in an upward shift of the head of the humerus
  • — high-riding humerus
54
Q

The shoulder achieves __(1)__ while maximizing __(2)__

A
  1. stability

2. mobility

Gross Anatomy (14 decks)

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