A9 - Shoulder and elbow joints, and their muscles

Question 1

Shoulder joint (art. humeri)

Answer 1

• Classification:
  
  • Synovial
    
    • ​Spheoid joint (multiaxial) (but functions as a hinge joint)
  • Articulatio simplex
• ​Movement:
  
  • Eq, ru: only flexion - extension
  • Ca: also rotation, abduction - adduction
• With cavum glenoidale → caput humeri
• One joint capsule with 3 cranial and 2 caudal pouches
• Labrum glenoidale
  
  • ​Ligg. glenohumeralia (eq, ca)
    
    • Thickened part of the capsule in:
      
      • Ca: medial and lateral walls
      • Eq: medial, lateral and cranial walls
  • Lig. coracohumerale (eq, ru)
    
    • Capsular ligament between scapula → humerus
• No collateral ligament, instead:
  
  • M. infraspinatus (lateral)
  • M. subscapularis (medial)
• Ca: part of the joint capsule surrounds tendon of m. biceps brachii and forms vagina synovialis intertubercularis
• Eq, bo: bursa bicipitalis under tendon of m. biceps brachii

Question 2

Shoulder joint (art. humeri)

List the flexors and extensors of the shoulder joint

Answer 2

Flexors of the shoulder (ca):

1. ​M. deltoideus
   
   1. ​Pars acromialis
   2. Pars scapularis
2. M. infraspinatus
3. M. teres minor
4. M. teres major
5. M. triseps brachii, caput longum
6. M. subscapularis

Extensors of the shoulder (ca)

1. M. supraspinatus
2. M. biceps brachii
3. M. coracobrachialis
4. M. subscapularis

Question 3

Give the lateral shoulder muscles

Answer 3

Question 4

M. supraspinatus

Answer 4

• Origin: Fossa supraspinatus and the cranial border of the scapula
• Insertion: T**uerculum major of the humerus
• Action:
  
  • Extend shoulder joint
  • Stabilize shoulder joint

Question 5

M. infraspinatus

Answer 5

• Origin:
  
  • Fossa infraspinatus
  • Spina scapula
  • Margo caudalis scapulae
• Insertion: Facies m. infraspinati of humerus
• Action:
  
  • Flexes shoulder joint
  • Acts as a lateral collateral ligament for shoulder joint
  • Ca: Assists in supination and abduction of the humerus

Question 6

M. deltoideus

Answer 6

• In ca and ru it can be divided into:
  
  1. Pars acromialis
  2. Pars scapularis
• Origin:
  
  • Pars scapularis: Caudal edge of spina scapulae
  • Pars acromialis: Acromium of the scapula
  • Eq, sus: Spina scapula (the two parts of the muscle are fused)
• Insertion: The tuberosita deltoidea of humerus
• Action: Flex shoulder joint

Question 7

M. teres minor

Answer 7

• Origin:
  
  • Tuberculum infraglenoidale
  • Distal part of margo caudalis scapulae
• Insertion: Tuberculum teres minor of the humerus (laterally)
• Action: Flexes shoulder joint

Question 8

Give the medial shoulder muscles

Answer 8

Question 9

M. subscapularis

Answer 9

• Origin: F**ossa subscapularis
• Insertion: Tuberculum minus of humerus
• Action:
  
  • Extend shoulder joint (and helps with flexion)
  • Act as a collateral ligament
  • Adduct
  • Stabilize the shoulder joint

Question 10

M. teres major

Answer 10

• Origin:
  
  • Margo caudalis scapulae
  • Angulus caudalis scapulae
• Insertion: Tuberculum teres major of the humerus (same as latissimus dorsi)
• Action:
  
  • ​Flex the shoulder joint
  • Rotates the limb inwards (medially)

Question 11

M. coracobrachialis

Answer 11

• Origin: Processus coracoideus of the scapula
• Insertion: Crista tuberculi minor of humerus
• Action:
  
  • Extend shoulder joint
  • Adduct

Question 12

M. articularis humeri

Answer 12

Eq, and sometimes Sus

• Action: To tense the joint capsule

Question 13

Give the other muscles that take part in the flexion/extension of the shoulder joint

Answer 13

1. Lateral head of m. triceps brachii – Flexion
2. M. latissimus dorsi - Flexion
3. M. biceps brachii – Extension

Question 14

Elbow joint (art. cubiti)

1. Features
2. Ligaments
3. Draw art. cubiti

Answer 14

• Hinge joint(monoaxial)
  
  • ​Flexion - extension
• Composite joint
• ​Between:
  
  • Humerus (condyle)
  • Radius (caput)
  • Ulna (incisura trochlearis)
• ​Three joints:
  
  • Art. circumferentia → art. radio ulna
  • Art. humeroradialis
  • Art. humeroulnaris

​

• Capsula articularis
  
  • ​Recessus cranialis
  • Recessus caudalis (large)
  • Epicondyles and olecranon is outside of the capsule

Ligaments:

• Lig. collaterale cubiti mediale
  
  • ​E**picondylus medialis → radius (ca: and ulna)
• Lig. collaterale cubiti laterale
  
  • Epicondylus lateralis → radius (ca, ru: and ulna)
• Lig. olecrani (Ca)
  
  • Fossa olecrani of humerus → olecranon of ulna

Question 15

Give the muscles of art. cubiti

Answer 15

• Mainly situated around humerus
• Origin: humerus and scapula
• Insertion: proximally on radius/ulna
• Action: mainly flexion/extension

Flexors of the elbow (ca):

• M. biceps brachii
• M. brachialis

Extensors of the elbow (ca):

• M. triceps brachii
  
  • ​Caput longum
  • Caput laterale
  • Caput mediale
  • Caput accessorium (ø eq)
• M. anconeus
• M. tensor fasciae antebrachii

Question 16

M. brachialis

Answer 16

• Origin: Caudally on collum humeri (then it will twist laterally, then cranio-medially in sulcus m. brachialis towards antebrachium)
• Insertion: (same as m. biceps brachii)
  
  • Tuberositas radii
  • Tuberositas ulnae (proc. coronoideus medialis)
• Action: Flexes elbow joint

Question 17

M. biceps brachii

Answer 17

• Origin: Tuberculum supraglenoidale
  
  • ​A retinaculum transversum fixes its tendon in the intertubercular groove (between tuberculum majus and minus)
• Insertion: (same as m. brachialis)
  
  • Tuberositas radii
  • Tuberositas ulnae (proc. coronoideus medialis)
• Action:
  
  • Extends the shoulder
  • Flexes the elbow joint

Question 18

M. anconeus

Answer 18

• Origin:
  
  • Crista supracondylaris lateralis
  • L​**ateral and medial epicondyles of the humerus
• Insertion: Laterally on olecranon
• Action: Extends elbow joint

Question 19

M. tensor fascia antebrachii

Answer 19

• Origin: Detatching from m. latissimus dorsi
• Insertion:
  
  • Medially on tuber olecrani
  • In the antebrachial fascia
• Action:
  
  • Extends elbow joint
  • Tense the antebrachial fascia

Question 20

M. triceps brachii, caput longum

Answer 20

• Origin: M**argo caudalis scapulae, distal 2/3
• Insertion:Tuber olecrani of the ulna
• Action:
  
  • Flexes shoulder joint
    Extends elbow joint

Question 21

M. triceps brachii, caput mediale

Answer 21

• Origin: The medial surface of the humerus
• Insertion: Tuber olecrani (medial side)
• Action: Extends elbow joint

Question 22

M. triceps brachii, caput laterale

Answer 22

• Origin: Linea m. tricipitis of humerus
• Insertion: Tuber olecrani (lateral side)
• Action: Extends elbow joint

Question 23

M. triceps brachii, caput accessorium

Answer 23

Ø eq

• Origin: Collum humeri (caudal)
• Insertion: Tuber olecranii
• Action: Extends elbow joint