Joints of the Thoracic Limb Flashcards by Monica Styrczula

Synovial Joints

Formed by two or more bones

Cavity between bones

Cartilaginous articulations

Joint capsule= holds everything together

Synovium = Produce synovial fluid

Stabilized by muscles and/or ligaments

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Synsarcosis

“fleshy” attachment of the thoracic limb to the trunk

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What are the joints of the thoracic limb and elbow attachments?

Shoulder joint

Elbow joint

Carpal joint

Digital joints: Metacarpophalangeal joint Proximal interphalangeal joint Distal interphalangeal joint

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Synovial Structure Composition

Filled with synovial fluid Viscous fluid Nourishes and lubricates the joint

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Synovial Joint Capsule

Synovial envelope that encloses a joint Fibrous can restrict movement Pouches

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Synovial bursae

Synovial sac lying between a tendon or muscle and an adjacent bony prominence

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What are tendon sheaths?

Synovial sac that completely surrounds a tendon

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What are the functions of ligaments in respect to joints?

Attach bone to bones

Stabilize and support the joints

*** Make sure that you specify the joint and ligament when ansswering the queston***

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Retinacula

Fibrous bands of connective tissue that bind tendons

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Carpal Canal

“Passage way” - tunnel for tendons

Flexor carpi radialis m. (muscle ends on MC2 or MC3)

Digital flexor tendons and their synovial sheaths:

Superficial digital flexor tendon
Deep digital flexor tendon

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Blood Vessels and Nerves of the Carpal Canal

Median and radial aa. Median and ulnar nn.

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Boundaries of the Carpal Canal

Palmar carpal ligament

Flexor retinaculum

Accessory carpal bone

** need to cut the flexor retinaculum to expose the carpal canal**

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Digital Joints

(Very important in large animals)

Metacarpophalangeal joint

Distal extremity of the metacarpal bone –> proximal extremity of the proximal phalanx (p1)
Fetlock joint in horses

Proximal interphalangeal joint

Distal extremity of proximal phalanx –> proximal extremity of middle phalanx
Pastern joint in horses

Distal interphalangeal joint

Distal extremity of middle phalanx –> proximal extremity of distal phalanx
Coffin joint in horses

Range of motion = flexion and extension

Supporting ligaments:

Medial and lateral collateral ligaments
Annular ligaments
- Palmal annular ligament of fetlock joint (horses)
- proximal digital annular ligament of proximal phalanx (horses)
- distal digital annular ligament of middle phalanx

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Metacarpophalangeal joint *

Distal extremity of the metacarpal bone–> proximal extremity of the proximal phalanx

**Fetlock joint in horses

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Proximal interphalangeal joint

Distal extremity of the proximal phalanx –> proximal extremity of the middle phalanx (p2)

Pastern joint in horses

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Distal interphalangeal joint

Distal extremity of the middle phalanx –> proximal extremity of the distal phalanx

Coffin joint in horses

Range of Motion for Digital Joints

Flexion and extension

What are the supporting ligaments of digital joints?

Medial and lateral collateral ligaments of the digital joint

Annular ligaments ****

Brace digital flexor tendons in MC & P1 & P2

Horse:

Palmar annular ligament at the fetlock joint (btwn MC & P1)

Proximal digital annular ligament of P1 (pastern joint)

Proximal digital annular ligament of P2

Where are Dorsal Elastic Ligaments located?

Located on each side of the common digital extensor tendon

Mainly in cats

Keep the claws retracted

Claws are protruded by simaltaneous contraction of the deep digital flexor.

Function of Dorsal Elastic Ligaments *

Keeps claws retracted Claws are protruded by simultaneous contraction of the deep digital flexor

Annular ligaments

Brace the digital flexor tendons

Proximal digital annular ligament *

Distal digital annular ligament

Interdigital Ligament in Ruminants

2- very close to the surface of the skin

Proximal interdigital ligament (flimsy)

Distal interdigital ligament (thick)

** Support the digits & prevent them from spreading**

** Can’t compromise the integrity of that ligament because Cows wont be able to stand**

Navicular Bursa in Horses

Located between the navicular bone & deep digital flexor tendon m.
protects the deep digital flexor tendon from excessive friction and pressure against the navicular bone
This is a common site of inflammation and when distended bulges above the proximal seasamoid bones
Bursitis due to injury
Puncture is most common

Glenohumeral (Shoulder) Joint

Articular surfaces:

Glenoid cavity of the scapula
Humeral head

Range of motion: Flexion and extension

Supporting Ligaments:

Joints stabilized by muscles in this region
Supraspinatus, infraspinatus, and subscapularis mm.

Associated structures:

Glenohumeral ligaments
Transverse Humeral Retinaculum
Synovial Structures

Associated structures of the Glenohumeral Joint

Synovial structures: * Infraspinous bursa * Tendon sheath of bicipital tendon * Horses= bicipital bursa instead of bicipital tendon Glenohumeral Ligaments: * Medial and lateral Transverse humeral retinaculum * Holds biceps tendon in bicipital groove

Why is the bicipital bursa easily accessed in horses?

* Horses don't have an acromion (part of Deltoideus m.) * Bicipital bursa is closely associated with the bicipital tendon

Cubital (Elbow Joints)

Articular surfaces: * Humeral condoyle * Head of radius and trochlear notch of ulna * Articular circumrence of the radius and radial notch of the ulna Range of motion : Flexion and extension Supporting Ligaments: * Medial and lateral collateral ligaments (straight up and down) Synovial structures: Caudodorsal pouch

Radioulnar Joint (Joint between radius and ulna) Only applies to the DOG! (pronation/supination)

Articular surfaces: * Articular circumfrence of the radius and radial notch of the ulna * Articular circumfrence of the ulna and ulnar notch of the radius Range of motion: Supination & Pronation Supporting Ligaments: * Interosseous ligament

Carpal (Wrist) Joint

Composite Articulations: * Antebrachiocarpal joint (btwn forearm and 1st row of carpal bones) * Middle carpal joint (btwn proximal & distal row of carpal bones) * Intercarpal joint (spaces btwn carpal bones) * Carpometacarpal joint (line btwn distal row and metacarpal bones) Range of Motion: Flexion & Extension * Antebrachiocarpal and middle carpal\* Supporting Ligaments: * Medial and lateral collateral ligaments * Palmar carpal ligament- skinny tendon covering the carpal canal * Short ligaments- just know they exist

Associated Structures of the Carpal Joint

Synovial structures: * Common joint capsule--\> separation between synovial compartaments * Exception: Middle Carpal Joint communicates with carpometacarpal joint Tendon & tendon sheaths of extensors & flexors Retinacula: Extensor retinaculum--\> extensor surface Flexor retinaculum --\> palmer surface

Clinical Application: Carpal Injection

In order to access the carpometacarpal joint, you should inject in the middle carpal because the middle carpal and carpometacarpal joints communicate with eachother. True for all species Carpometacarpal joint is immovable