A11 - Art. cubiti, art. radioulnaris and their muscles

Question 1

Elbow joint (art. cubiti)

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

Answer 1

• 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 2

Give the muscles of art. cubiti

Answer 2

• 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 3

M. brachialis

Answer 3

• 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
• Innervation: N. musculocutaneous

Question 4

M. biceps brachii

Answer 4

• 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
• Innervation: N. musculocutaneous

Question 5

M. anconeus

Answer 5

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

Question 6

M. tensor fascia antebrachii

Answer 6

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

Question 7

M. triceps brachii, caput longum

Answer 7

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

Question 8

M. triceps brachii, caput mediale

Answer 8

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

Question 9

M. triceps brachii, caput laterale

Answer 9

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

Question 10

M. triceps brachii, caput accessorium

Answer 10

Ø eq

• Origin: Collum humeri (caudal)
• Insertion: Tuber olecranii
• Action: Extends elbow joint
• Innervation: N. radialis

Question 11

Art. radioulanris

Answer 11

• Pivot joint (uniaxial)
• Simplex
• Ca: pronation - supination
• Sus: Radius and ulna are fused together by tough ligaments
• Ru, eq: the two bones are fully fused distally, no movement
• Composed of:
  
  • Art. radioulnaris proximalis
    
    • ​Part of art. cubiti - common joint capsule
    • Circumfirentia articularis proximalis radii ⟷ incisura radialis ulnar
  • Art. radioulnaris distalis
    
    • Circumfirentia articularis ulnae ⟷ incisura unlaris radii​

Structures of art. radioulnaris proximalis:

• Lig. anulare radii (ca)
  
  • Encircles caput radii
  • Runs under collateral ligaments
• Membrana interossea antebrachii (ca)
  
  • Transverse ligament
  • Covers spatium interosseum
  • Ru, eq: ossified
• Lig. interosseum antebrachii (ca)

Structures of art. radioulnaris distalis:

• Capsula articularis
• Lig. radioulnare (ca)
  
  • At the distal ends of radius and ulna, cranially
  • Capsular ligament

Question 12

Radioulnar joint

List the muscles of the radioulnar joint

Answer 12

• Supinators:
  
  1. M. supinator (ca, sometimes sus)
  2. M. brachioradialis (Fe)
• Pronators:
  
  1. M. pronator teres (ø eq)
  2. M. pronator quadratus (ca)

Question 13

M. supinator

Answer 13

Ca, sometimes su

• Origin: Epicondylus lateralis of humerus
• Insertion: Cranial surface of proximal fourth of radius
• Action: Supination (lateral rotation)
• Innervation: N. radialis

Question 14

M. brachioradialis

Answer 14

Fe

• Origin: Crista epicondylus lateralis
• Insertion: Distal end of radius, medially
• Action: Supinates forearm and forefoor (rotates arm laterally)

Question 15

M. pronator teres

Answer 15

Ø eq (reduced to a ligament in ungulates)

• Origin: Epicondylus medialis of humerus
• Insertion: Craniomedial surface of the proximal radius
• Action: Pronation (medial rotation)
• Innervation: N. medianus

Question 16

M. pronator quadratus

Answer 16

Ca

• Attachment: apposed surface of radius and ulna, covers spatium interosseum antebrachii
• Action: Pronation
• Innervation: N. medianus