Forelimb Joints

Question 1

what two things should you consider when thinking or talking about joints?

Answer 1

• nature of the movement (e.g. axes, relative mobility)
• is the movement restricted by: bone conformation, ligament arrangement, pull of muscles?

Question 2

teres minor:
- origin
- insertion
- function(s)

Answer 2

origin: distally on the caudal border of scapula

insertion: greater tuberosity

function: capsular (tense joint capsule to prevent it from becoming trapped between bones)

Question 3

shoulder joint name

Answer 3

scapulohumeral joint

Question 4

two capsular muscles of the scapulohumeral joint (which sides of the joint are they on?)

Answer 4

• teres minor (lateral)
• coracobrachialis (medial)

Question 5

coracobrachualis:
- origin
- insertion
- function(s)

Answer 5

origin: coracoid process of scapula

insertion: line between lesser and teres tuberosities

function: capsular (tense joint capsule to prevent it from becoming trapped between bones)

Question 6

where are bursae located within the forelimb?

Answer 6

infraspinatus bursa - between its tendon and proximal humerus

bicipital bursa - bicipital groove

Question 7

what supports/restricts the scapulohumeral joint?

Answer 7

• mostly ligamentar muscles
• medial and lateral collateral ligaments (thin thickenings of joint capsule due to the large ligamentar muscles and little need for ligaments)

Question 8

two differences between dog and horse scapulohumeral joint

Answer 8

• horses’ infraspinatus bursa is separate from joint (dog bursa still connected to synovial joint capsule)
• horses’ have two bicipital grooves to fit with the dumbbell shaped bicipital tendon

Question 9

name of the elbow joint

Answer 9

humeroantebrachial joint

Question 10

capsular muscle in the humeroantebrachial joint

Answer 10

anconeus

Question 11

anconeus:
- origin
- insertion
- function(s)

Answer 11

origin: caudally on lateral supra-epicondylar ridge

insertion: laterally on olecranon

function: capsular (tenses joint capsule to prevent it from becoming stuck between bones)

Question 12

ligaments in the humeroantebrachial joint

Answer 12

• medial and lateral collateral ligaments
• annular ligament
• olecranon ligament
• oblique ligament

Question 13

how do the collateral ligaments compare in the scapulohumeral and humeroantebrachial joint?

Answer 13

collateral ligaments are thicker in humeroantebrachial joint as there is less support from ligamentar muscles

Question 14

where is the annular ligament located relative to another ligament? what direction do its fibres run in? what is its function?

Answer 14

• caudal to lateral collateral ligament
• fibres run from ulna around the head of the radius
• bind the ulna and radius together

Question 15

where is the olecranon ligament located? what is its function?

Answer 15

• between the anconeal process and the medial condyle
• prevents overflexion (+ realign joint during flexion when ligament is pulled taut)

Question 16

where does the oblique ligament of the humeroantebrachial joint run from and to? what is its function?

Answer 16

• run from the craniolateral humerus
• to the craniomedial radius
• prevents oversupination (+ realign joint during extension when the ligament is pulled taut)

Question 17

joints of the carpus

Answer 17

• radiocarpal/antebrachiocarpal joint
• mid carpal joint
• carpometacarpal joint
• intercarpal joints (many held together by loads of little ligaments)

Question 18

ligaments of the carpus

Answer 18

• medial and lateral collateral ligaments
• axial and abaxial collateral ligaments
• palmar ligament
• distal radio-ulnar ligament
• inter-carpal ligaments

Question 19

what is the palmar ligament?

Answer 19

thick sheet of fibrous tissue binding carpal bones together
- resists overextension of the carpal joints (unlike horses whose carpal joints lock in a straight line)

Question 20

what three structures form the carpal canal?

Answer 20

• laterally by accessory carpal bone
• deep by the palmar carpal ligament
• medially by the flexor retinaculum

Question 21

what passes through the carpal canal?

Answer 21

• deep digital flexor
• superficial digital flexor

Question 22

where is the distal radio-ulnar ligament located? hence what is its function?

Answer 22

connects the distal ends of the radius and ulna