LRC Exam I - Thoracic Limb Flashcards
Define Saggittal Plane, Midsaggittal Plane and Parasaggittal Plane.
Divides body into left and right halves; median plane (divides body into equal parts); divides body into unequal parts
What is the term for a structure located in between 2 other structures in the medial to lateral orientation? In the proximal to distal orientation?
Intermediate; middle
What are the primary functions of bone?
Support weight, movement in concert with muscles, protection of internal organs, growth, storage of minerals (calcium and phosphorus), storage of fat (in yellow marrow cavities), blood cell formation (hematopoiesis; in red marrow cavities)
What is included in the axial skeleton? The appendicular?
Axial: skull, thorax, vertebral column; Appendicular: limbs
Define Diaphysis, Epiphysis, Metaphysis, Metaphyseal growth plate
Main body of long bone; end parts; between diaphysis and epiphysis; between epiphysis and diaphysis in young animals (made of cartilage cells)
List some key features of long bones and give examples of long bones in the body.
Located in appendages, multiple ossification centers. Eg: humerus, radius, ulna, femur, tibia, fibula, metacarpals
List some key features of short bones and give examples of short bones in the body.
Cube-shaped, one center of ossification, no growth plates. Eg: Carpal bones, sesamoid bones.
List some key features of flat bones and give examples of flat bones in the body.
For extensive protection or large muscle attachments, intramembranous ossification, diploe. Eg: scapula, skull bones
List some key features of irregular bones and give examples of irregular bones in the body.
Short bones with multiple processes, formed by both endochondral and intramembranous ossification. Eg: Vertebrae
List some key features of sesamoid bones and give examples of sesamoid bones in the body.
Small seed like bones embedded in muscle tendons, type of short bone. Eg: proximal sesamoid bones of manus and pes, patella
What is purpose of sesamoid bones?
Increase torque, redirect line of force, eliminate tendon shear.
List the 5 types of bones
Long bones, short bones, flat bones, irregular bones, sesamoid bones
Define periosteum, endosteum, medullary cavity
Periosteum: Lines outer surface, source of osteoblast progenitor cells, rich in nerves, blood supply
Endosteum: Lines inner surface
Medullary Cavity: Storage for bone marrow
Discuss the difference between intramembranous and endochondral ossification.
Intramembranous: osteoblast with connective tissue accumulate, replaces thin connective tissue membrane with bone (eg flat bones)
Endochondral: destroys cartilage before ossification, replaces fetal cartilage skeleton with bone (eg most bones)
What is chondrodystrophy?
Genetic condition. Affects secondary centers of ossification that results in cartilage maldevelopment and stunted growth of long bones (eg dachshunds)
Discuss bone blood supply.
Nutritional vessels enter the diaphysis and epiphysis, most long bones have a single nutrient foramen (around mid-diaphysis), vessels in the periosteum supply the cortical bone.
What is a cortical bone?
Hard bone between the periosteum and endosteum
What is a diploe?
Cancellous tissue enclosed by two thin layers of cortical bone. In some areas of the skull, this is absorbed to form air sinuses.
What is Wolff’s Law?
Normal bones will remodel itself in response to the stress placed on it. If load increases on a particular area the bone will remodel to resist those forces (eg with body weight gain, muscle building)
List the 3 types of muscle tissue in the body, describe where they are in the body and whether their action is voluntary or involuntary.
Smooth Muscle: organs, blood vessels. Action is involuntary (ANS)
Cardiac Muscle: musculature of the heart. Action is involuntary (ANS).
Skeletal Muscle: attached to the skeleton. Action is voluntary (SNS).
Describe the 2 aspects of the musculoskeletal system.
Muscular System: Active component. Skeletal muscles, muscles that move limbs, trunk, head.
Skeletal System: Passive component. Bones, joints.
List the 3 types of connective tissue found around skeletal muscle fibers and describe that they do.
Epimysium: surround muscle belly.
Perimysium: divides muscle into fasicles
Endomysium: surrounds muscle fibers.
Tendons attach _______ to _______. Ligaments attach _______ to _______.
Tendons attach muscle to bone. Ligaments attach bone to bone.
What is an aponeurosis? What is its purpose?
An aponeurosis is a sheet like tendon. Allows muscles to have a broader attachment.
List the accessory structures that help to ease the effect of excessive pressure/friction associated with tendons.
Sesamoid bones, synovial bursa/bursae, synovial tendon sheath, fascia planes
Describe what a synovial bursa and a synovial tendon sheath are.
Synovial bursa: sac of fluid, one sided protection of muscle tendons (like a pillow)
Synovial tendon sheath: Synovial fluid filled sac that surrounds the muscle tendon. All around protection of muscle tendon.
Describe the difference between superficial and deep fascia.
Superficial: usually loose connective tissue.
Deep: dense collagenous connective tissue; some muscles may originate or insert here; attached to bone; surrounds and compartmentalizes muscles
Define a joint.
A point of contact or articulation between 2 or more bones or cartilage. Provides support and movement to the skeleton. Not all joints are moveable.
Define: synarthroses, amphiarthroses and diarthroses.
Synarthroses: immoveable joints.
Amphiarthroses: Semimoveable joints.
Diarthroses: moveable joints.
Explain was a fibrous joint is. and give some examples.
Strong fibrous connective tissue between articulating bones - little to no movement. In some cases bones can fuse resulting in a bony joint. Eg Suture - gradually eliminated via ossification (seams of bone in skull); Syndesmosis - bones joined by ligaments (interosseous ligaments).
Explain what a cartilaginous joint is and give some examples.
Cartilage (hyaline or fibrocartilage) between articulating bones - limited movement. Eg Synchondrosis - hyaline cartilage union (costal cartilages connecting ribs to sternum); symphysis - occurs in midline of body where articulating bones are connected via a flat disc of fibrocartilage (pelvic symphysis, intervertebral discs).
Explain what a synovial joint is and give some examples.
Freely moveable joint. Joint cavity between articulating bones. Lined with synovial membrane. Accessory structures: meniscus (located in synovial cavity), ligaments (located outside the joint capsule), fat pads (between fibrous and synovial layers)
What is stance phase vs. swing phase.
Stance phase - when foot contacts the ground. Swing phase - when limb is propelled through the air.
List the muscles that stabilize the limb to the body wall in stance phase.
Serratus ventralis, superficial and deep pectoral muscles, trapezius, rhomboideus
List the muscles that stabilize the shoulder in stance phase.
Supraspinatus, Infraspinatus, Subscapularis, Teres minor, Teres major, Coracobrachialis, Biceps brachii, triceps brachii (long head)
List the muscles that are elbow extensors in stance phase.
Tensor fasciae antebrachii, triceps brachii (all heads), anconeus
List carpus and digits flexors in stance phase.
Ulnaris lateralis, flexor carpi ulnaris
List the muscles associated with “Swing I” (limb is advanced, shoulder and elbow are extended, carpus is extended)
Brachiocephalicus, omotransversarius, trapezius, rhomboideus, serratus ventralis, biceps brachii, triceps brachii
List the muscles associated with “Swing II” (limb is pulled caudally, shoulder and elbow are flexed, carpus is flexed)
Deep pectoral, latissimus dorsi, deltoideus, teres major, triceps brachii, biceps brachii, flexor carpi radialis, ulnaris lateralis, SDF, DDF
What does synsarcosis mean?
These muscles connect the limb to the body. Eg the extrinsic muscles.
Which muscles prevent medial rotation of the glenohumeral joint?
Supraspinatus, Infraspinatus, Teres minor
Which muscles prevent lateral rotation of the glenohumeral joint?
Subscapularis, Teres Major
Which muscles stabilize the shoulder by counteracting its wanting to flex?
Coracobrachialis, biceps brachii (extensors of the shoulder)
Which muscles stabilize the humeroradioulnar joint?
Elbow wants to flex, so counteract with elbow extensors: Tensor fasciae antebrachii, Triceps brachii, anconeus
Which muscles stabilize the carpus and digits?
Carpus and digits want to hyperextend, counteract with flexors: Ulnaris lateralis, flexor carpi ulnaris, superficial digital flexor, deep digital flexor, flexor carpi radialis
Flexors of the carpus and digits originate from where? Where are the located?
Originate from the medial epicondyle of the humerus. Are on the medial side of the leg.
Extensors of the carpus and digits originate from where? Where are they located.
Originate from the lateral epicondyle of the humerus. Are on the lateral side of the leg.
What are the boundaries of the carpal canal?
Dorsal border: Palmar carpal ligament.
Lateral border: Accessory carpal bone.
Palmar border: Flexor retinaculum
Where is the interosseous muscle located? What does each interosseous muscle have?
Palmar aspect of each metacarpal bone of each digit. Each interosseous muscle has 2 proximal sesamoid bones.
In horses, the interosseous ligament is entirely tendinous and referred to as the…? What happens to this tendon as it progresses distally?
Suspensory ligament. The tendon splits near the palmar aspect of the metacarpophalangeael joint and is called the medial and lateral extensor branches of the interosseous muscle. These branches will unite with the tendon of the common digital extensor muscle.
What are the 3 sesamoidean ligaments in the horse? List them from weakest to strongest and from most superficial to deepest.
Straight (I), Oblique (V), Cruciate (X).
Weakest –> Strongest: straight, oblique, cruciate
Superficial –> Deep:
straight, oblique, cruciate
Which muscle protracts and which muscle retracts the claw in cats?
The deep digital flexor protracts the claw in the cat and the dorsal (elastic) ligament retracts the claw in the cat.
List the muscles in the lateral scapula and shoulder.
Deltoideus, Infraspinatus, Teres minor, Supraspinatus
List the muscles in the medial scapula and shoulder.
Subscapularis, Teres major, Coracobrachialis
List the muscles in the cranial arm.
Biceps brachii and brachialis.
List the muscles in the caudal arm.
Tensor fasciae antebrachii, triceps brachii, anconeus
List the muscles in the cranial and lateral forearm.
Extensor carpi radialis, Common digital extensor, Lateral digital extensor, Ulnaris lateralis, Supinator, Abductor digiti longus I
List the muscles in the caudal and medial forearm.
Flexor carpi ulnaris, superficial digital flexor, flexor carpi radialis, pronator teres.
List the extensors of the shoulder.
Infraspinatus, supraspinatus, subscapularis, coracobrachialis
List the flexors of the shoulder.
Deltoideus, teres major, teres minor
List the extensors of the elbow.
Triceps brachii, anconeus, tensor fasciae antebrachii
List the flexors of the elbow.
Biceps brachii, brachialis, supinator, pronator teres
List the extensors of the carpus and digits
Extensor carpi radialis, common digital extensor, lateral digital extensor, abductor digiti longus I
List the flexors of the carpus and digits.
Ulnaris lateralis, flexor carpi ulnaris, superficial digital flexor, deep digital flexor, flexor carpi radialis
Pronators of the antebrachium.
Pronator teres, pronator quadratus
What is the additional pectoral muscle in the horse called?
Subclavius muscle. Gives the rounded appearance of the shoulder in horses.
Which muscles form the dorsal and ventral borders of the jugular groove in horses?
Dorsal border: Brachiocephalicus (Cleidomastoideus)
Ventral border: Sternocephalicus (sternomandibularis)
Where is the superficial cervical lymph node located?
Just beneath the omotransversaius
What results in a flying scapula in horses and ruminants?
Occurs when the serratus ventralis is severed.
What are horses lacking on their scapula? What does this mean for the deltoideus muscle?
Lack an acromion. No acromial portion of the deltoideus.
What is the long tendon of the biceps brachii in horses called? Where does it go?
The lacertus fibrosus. It extends from the biceps brachii to the extensor carpi radialis.
Which muscles insert onto the accessory carpal bone?
Ulnaris lateralis and flexor carpi ulnaris
In horses, where does the common digital extensor muscle insert?
The extensor process of the coffin bone.
Which three muscles located primarily distal to the humerus are not present in large animals and why?
The supinator, the pronator teres and the pronator quadratus. They are not present because the radius and ulna are fused in large animals and thus do not allow any rotation of the antebrachium.
What forms the flexor manica and what is its purpose?
The flexor manica is formed by the SDF and it creates a space for the DDF to fit through. Distal to the flexor manica the SDF is deeper than the DDF.
What are the three annular ligaments associated with the SDF and DDF? What do they do?
The palmar annular ligament (holds down the tendons of the SDF and DDF at the metacarpophalangeal joint), the proximal annular ligament (holds down the tendons of the SDF and DDF at proximal phalanx of the digit) and the distal annular ligaments (at the middle phalanx of the digit)
What are the 2 check or accessory ligaments called? Which tendons do they come off of?
Proximal check ligament: off of SDF
Distal check ligament: off of DDF
What are the 2 additional features of the feline scapula?
The hamate and the suprahamate processes - extend from the acromion in the cat.
What are the 4 differences in the equine scapula?
very prominent scapular cartilage on dorsal border, no acromion, 2 serrated faces (cranial and caudal) (ox as well), no infraglenoid tubercle.(ox as well)
What is considered the “point” of the shoulder? How about the elbow?
Greater tubercle of the humerus; olecranon of the ulna
What is the difference in the feline humerus?
No supratrochlear foramen, instead has the supracondylar foramen near medial aspect of condyle
What are the 3 differences in the equine humerus?
Has an intermediate tubercle (creates intertubercular groove to stabilize biceps brachii tendon), lesser and greater tubercles both have cranial and caudal parts (same as ox), deltoid tuberosities are prominent (same as ox)
What is the styloid process of the radius and ulna called in equine and bovine?
Radius: Medial styloid process. Ulna: Lateral styloid process.
What is Metacarpal III also known as in the horse? How about MC II and IV?
The cannon bone; Medial splint bone; Lateral splint bone
What are the layman’s terms for proximal phalanx, middle phalanx and distal phalanx in the horse?
Long pastern bone, Short pastern bone, Coffin bone
Which carpal bones in the ox are fused? Which metacarpal bones are fused?
Carpal bones II and III are fused. Metacarpal bones III and IV are fused.
What is another word for the distal sesamoid bone in equine?
The navicular bone.
What are the palmar processes of the distal phalanx attachments for?
The medial and lateral hoof cartilages.
List the three carpal joints from most proximal to most distal.
Radiocarpal joint, intercarpal joint, carpometacarpal joint
What are the layman’s terms for the proximal metacarpophalangeal joint, the proximal interphalangeal joint and the distal interphalangeal joint?
The fetlock, pastern and coffin joints.
In the stay apparatus, what prevents the carpus from hyperextending?
The palmar carpal ligament.
In the stay apparatus, what prevents the carpus from buckling forward?
The upward force created by the lacertus fibrosus transferring the weight of the horse from the biceps brachii to the extensor carpi radialis.
Why does the elbow not flex in the stay apparatus?
Because when the shoulder is fixed (by the biceps brachii tendon engaging on the intermediate tubercle) the weight is on a nearly vertical radius and so only small corrections need to be made by the carpal and digital flexors and the collateral ligaments. The anconeus also helps to lock the elbow joint.
Why do the fetlock and pastern joints not hyperextend in the stay apparatus?
Because the downward forces activate the suspensory apparatus.
List the parts of the suspensory apparatus?
Medial and lateral extensor branches unite with the common digital extensor, the proximal sesamoids, the sesamoidean ligaments (straight, oblique, cruciate)
What prevents the fetlock from hyperextending?
The SDF transfers the force to the proximal check ligament to counteract the downward force on the fetlock joint and prevent hyperextension. The DDF and the distal check ligament also counteract the downward force but cause s the coffin to hyperflex (dig toe of hoof into ground). The distal sesamoidean ligaments also counteract hyperextension (have distal attachments to the proximal phalanx).
What counteracts the flexion of the coffin joint?
The interosseous with its medial and lateral extensor branches.
What prevents the hyperextension of the pastern joint?
The straight sesamoidean ligament due to its attachments to the proximal and middle phalanx.
What is the hoof capsule?
The outer part of the hood that is comprised of keratinized epithelium
What is the hoof wall? What are its 3 layers?
Hoof wall is the outer part of the hoof capsule that is visible. 3 layers: Outer hoof wall (thin and shiny layer that is quickly worn away), intermediate hoof layer (thick), inner lamellar layer.
What are the three regions of the hoof wall?
Toe, Quarter, Heel
What are bars on the hoof?
On the solar surface and extends from the medial and lateral heels of the hoof wall. The medial and lateral bars reflect cranially and are located between the sole and the frog.
What is the sole of the hoof?
The ground surface of the hood capsule. It fills the space between the wall and the frog. Slightly concave region of the hoof undersurface.
What is the frog of the hoof? Where are the bulbs of the heels? Where is the apex of the frog?
The central wedge shaped region on the undersurface of the hoof. Wide base closes gap between the heels and spread upwards to end as bulbs (medial and lateral) of the heels. The apex of the frog is the tip of the frog that projects towards the toe.
What is corium?
The dermal layer that is a dense connective tissue that contains vessels and nerves. It lies between the epidermis and the underlying coffin bone.
What is perioplic corium?
Thin band of corium adjacent to the haired margin of the hoof capsule.
What is coronary corium?
Broad band of dermis with microscopic cones of connective tissue that produces the bulk of the hoof wall.
What is the laminar corium?
Parallel lamina of connective tissue directed from the deeper corium to the wall that produces some of the hoof capsule.
What is the coronet band?
Where the fur and the hoof capsule meet. The hoof grows from the coronary band distally from the perioplic corium.
What are ungular cartilages?
Lateral and medial cartilages that project proximocaudally from the coffin bone. In older animals, it may be ossified.
What is the digital cushion?
Subcutis deep to the frog; occupies the space between the DDF tendon and hoof cartilages. Abundant in fat and bloot.
What is the white line?
The junction between the sole and wall (zona alba). Area for farriers to place nails for shoeing.
Where do horses walk on their hoof? How does this affect the cardiovascular system?
Horses walk on their hoof walls. The hoof wall is able to contract/expand. It expands when weight is applied and contracts when not weight bearing. There is an extensive venous supply and the expanding/contracting is thought to help the venous blood pump back up to the heart.
List the muscles associated with adduction.
Pectorals, subscapularis, coracobrachialis
List the muscles associated with abduction.
Trapezius, infraspinatus
What is the muscle responsible for the “digging” motion
Latissimus dorsi
What muscles are responsible for advancing the limb?
Brachiocephalicus, omotransversarius
What muscle is responsible for drawing the trunk cranially?
Deep pectoral
Which muscles attach to the sternum?
Superficial pectoral, deep pectoral, sternocephalicus
Which muscles attach to the greater tubercle?
Superficial pectoral, infraspinatus, supraspinatus
Which muscles attach to the lesser tubercle?
Subscarpularis, Deep pectoral, coracobrachialis, medial head of triceps brachii
Which muscles attach the the occipital/temporal bone?
Cleidocephalicus, sternocephalicus, rhomboideus
Which muscles attach to the spine of scapula?
omotransversarius, trapezius, deltoideus
Which muscles attach to the caudal border of the scapula
Teres major, long head of triceps brachii
Which muscles attach to the infraglenoid tubercle?
Teres minor
Which muscles attach to the olecranon?
Tensor fasciae antebrachii, triceps brachii (all heads), anconeus, flexor carpi ulnaris (ulnar head)
Which muscles attach to the lateral supracondylar crest?
Anconeus, extensor carpi radialis
Which muscles attach to the lateral epicondyle?
Anconeus, common digital extensor, lateral digital extensor
What runs through the carpal canal in the horse but not he dog?
The SDF
What is sweeney?
Term used to describe laxity in the shoulder joint usually due to acute or chronic repetitive injury near the point of the shoulder –> atrophy of infraspinatus, and supraspinatus
