Forelimb Anatomy: Joints

Question 2

What are the forelimb joints?

Answer 2

shoulder, elbow, carpus, fetlock, pastern, coffin

Question 3

Describe the shoulder joint?

Answer 3

scapulohumeral articulation

glenoid cavity of scapula articulates with head of humerus (large humeral head guards against dislocation)

major movement (extension and flexion)

unique (muscles provide majority of joint stability, not ligaments)

Question 4

Describe the muscles of the shoulder joint

Answer 4

abductors (laterally): deltoid, supraspinatus, infraspinatus, teres minor

adductors (medially): subscapularis, teres major, coracobrachialis, capsularis

Question 5

Describe the elbow joint

Answer 5

humeroradial and humeroulnar articular (hinge joints)

only radius supports humerus

movement: flexion and extension

collateral ligaments part of stay apparatus (caudal to rotational axis -> lock joint in extension)

olecranon prevents over extension of elbow

Question 6

Describe the muscles of the elbow joint

Answer 6

flexors (cranially): biceps brachii and brachialis

extensors (caudally): triceps brachii, tensor fasciae, antebrachii, and anconeus

Question 7

Describe the carpal joints

Answer 7

radiocarpal: flexion and extension up to 90 degrees, does not communicate with other joints

midcarpal (or intercarpal): flexion and extension up to 45 degrees, communicates with carpometacarpal joint

carpometacarpal: little movement, communicates with midcarpal joint

Question 8

Describe the ligaments and tendons of the carpal joints

Answer 8

ligaments: medial and lateral collateral ligaments stabilize carpus

tendongs: muscles bellies end at carpus, become tendons. Tendon sheath protect tendons over carpus

Question 9

Describe the carpal and digital extensors and felxors

Answer 9

extensors: craniolateral, origin - distal humerus and proximal radius

flexors: caudolateral, origin - distal humerus, proximal radius and ulna

Question 10

Describe the muscles of the carpal joints

Answer 10

flexion: flexor carpi radialis, flexor carpi ulnaris, and ulnaris lateralis

extension: extensor carpi radialis and extensor carpi obliques, structure of carpal bones prevents overextension

Question 11

Describe the fetlock joint

Answer 11

metacarpophalangeal articulation (AKA ankle)

distal MCII, proximal PI, and proximal sesamoid bones

sagittal ridge divides articular surface of MCIII into two parts

Question 12

Describe the support and movement of the fetlock joint

Answer 12

support: medial and lateral collateral ligaments, suspensory ligaments (“suspends” fetlock in partial overextension)

movement: flexion and extension, up to 140 degrees

Question 13

Describe the pastern joint

Answer 13

proximal interphalangeal articulation (PI and PII)

support: medial and collateral ligaments

Question 14

Describe the coffin joint

Answer 14

distal interphalangeal articulation (PII, PIII, and navicular bone)

support: medial and lateral collateral ligaments

Question 15

Describe the distal joints

Answer 15

flexion: superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT)

extension: common digital extensor tendon, lateral digital extensor tendon (do not unite)

Question 16

Study the parts of this on paper!