ANATOMY - Forelimb Flashcards
What are cursorial vertebrates?
Cursorial vertebrates are species which have evolved to run on the ground and are structurally modified to enhance speed and endurance
What are the three main anatomical adaptations of cursorial vertebrates?
Reduced pectoral skeleton
Elongation of the proximal limbs
Elongation of the distal limbs
What are the six regions of the forelimb?
Omo
Brachium
Antebrachium
Carpus
Manus
Digit
What are the seven bones of the forelimb?
Scapula
Humerus
Radius
Ulna
Carpal bones
Metacarpal bones
Phalanges
What are the six joints of the forelimb?
Shoulder
Elbow
Carpal joint
Metacarpophalangeal joint
Proximal interphalangeal joint
Distal interphalangeal joint
In which region of the forelimb is the scapula located?
Omo region
What type of bone is the scapula?
The scapula is a flat bone
Why does the scapula have a more ventral and lateral orientation in cursorial vertebrates?
The scapula has a more vertical orientation to accommodate a longer stride length
Identify these features of the scapula (including the fossa’s)
What are the four palpable surfaces of the scapula?
Dorsal border
Cranial border
Scapular spine
Acromion process
Why is the caudal border of the scapula not palpable?
The caudal border of the scapula is covered by muscle and thus cannot be easily palpated
What are the two fossa’s on the lateral surface of the scapula?
Supraspinous fossa
Infraspinous fossa
What is the palpable landmark for the shoulder present on the lateral surface of the scapula?
Acromion process
In which species is there no acromion process?
Horses have no acromion process
What is the name of the subchondral bone of the scapula?
Glenoid cavity
Which muscle tendon originates at the supraglenoid tubercle?
Biceps brachii tendon
What is the additional bony process present proximal to the acromion process of the feline scapula?
Suprahamate process
What are the two additional features of the large animal scapula?
Tuber on the scapular spine
Cartilage extension of the dorsal border of the scapula
Where are the two centres of ossification located in the scapula?
Body of the scapula
Supraglenoid tubercle
In which region of the forelimb is the humerus located?
Brachium region
What type of bone is the humerus?
The humerus is a long bone
What is the subchondral bone at the proximal end of the humerus?
Head of the humerus
What is the palpable landmark for the shoulder present at the proximal end of the humerus?
Greater tubercle
What is the name of the tubercle located on the medial side of the proximal humerus?
Lesser tubercle
What is the name of the groove between the greater and lesser tubercle?
Intertubercular groove
Which structure runs through the intertubercular groove?
Biceps brachii tendon runs through the intertubercular groove
What is the diaphysis of the humerus known as?
Body of the humerus
What is the distal epiphysis of the humerus known as?
Condyle
What are the two projections of the condyle?
Medial epicondyle
Lateral epicondyle
What is the subchondral bone at the distal end of the humerus?
Trochlea
What is the weakest point of the humerus that is very prone to fractures?
Supratrochlear foramen
Which two structures meet to make up the supratrochlear foramen?
Radial fossa (cranial)
Ulnar fossa (caudal)
(T/F) The supratrochlear foramen is present in all domestic species
FALSE. The supratrochlear foramen is absent in large animal and feline species
Which species have a supracondyloid foramen at the distal end of their humerus?
Feline species have a supracondyloid foramen
Which two structures pass through the supracondyloid foramen present in the feline humerus?
Brachial artery
Median nerve
What are the three palpable regions of the humerus?
Greater tubercle
Medial epicondyle
Lateral epicondyle
Where are the five centres of ossification located in the humerus?
Proximal epiphysis
Body of the humerus
Medial condyle
Lateral condyle
Medial epicondyle
Which type of joint is the shoulder?
The shoulder is a synovial joint
What are the articular surfaces which make up the shoulder joint?
Glenoid cavity
Head of the humerus
What are the two palpable landmarks for the shoulder joint?
Acromion process
Greater tubercle
What is the bicipital bursa?
The bicipital bursa is an out-pouching of the shoulder joint capsule into the intertubercular groove where it envelopes the the biceps brachii tendon
Which ligament hold the bicipital bursa in place?
Transverse ligament
(T/F) The shoulder joint has no collateral ligaments
TRUE.
Which muscles provide lateral support to the shoulder?
Supraspinatous muscle
Infraspinatous muscle
What is the point of origin for the supraspinatous muscle?
Supraspinous fossa
What is the point of origin for the infraspinatous muscle?
Infraspinous fossa
What is the point of insertion for the supraspinatous and infraspinatous muscles?
Proximal lateral humerus
Which nerve innervates the supraspinatous and infraspinatous muscles?
Suprascapular nerve
Which muscle provides medial support to the shoulder?
Subscapularis muscle
What is the point of origin for the subscapularis muscle?
Subscapular fossa
What is the point of insertion for the subscapularis muscle?
Proximal medial humerus
Which nerve innervates the subscapularis muscle?
Subscapular nerve
What are the five extrinsic muscles of the forelimb?
Brachiocephalic muscle
Latissimus dorsi muscle
Serratus ventralis muscle
Trapezius muscle
Pectoral muscles
What are the two points of origin for the brachiocephalic muscle?
Skull
Cervical vertebrae
What is the point of insertion for the brachiocephalic muscle?
Cranial humerus
What are the functions of the brachiocephalic muscle?
The brachiocephalic muscle is a forelimb protractor and a shoulder extensor
In which species is the vestigial clavicle embedded in the brachiocephalic muscle?
Feline
What is the point of origin for the latissimus dorsi muscle?
Thoracic vertebrae
What is the point of insertion for the latissimus dorsi muscle?
Caudal humerus
What are the functions of the latissimus dorsi muscle?
The latissimus dorsi muscle is a forelimb retractor and a shoulder flexor
Which nerve innervates the latissimus dorsi muscle?
Brachial plexus
What are the two points of origin for the serratus ventralis muscle?
Cervical vertebrae
Thoracic wall
What is the point of insertion for the serratus ventralis muscle?
Cranial and caudal borders of the scapula
What are the functions of the serratus ventralis muscle?
The serratus ventralis muscle is both a forelimb retractor and protractor
Which nerve innervates the serratus ventralis muscle?
Brachial plexus
What are the two points of origin for the trapezius muscle?
Cervical vertebrae
Thoracic vertebrae
What is the point of insertion for the trapezius muscle?
Scapular spine
What is the function of the trapezius muscle?
The trapezius muscle is a forelimb abductor
What is the point of origin for the pectoral muscles?
Sternum
What is the point of insertion for the pectoral muscles?
Medial humerus
What is the function of the pectoral muscles?
The pectoral muscles are forelimb adductors
Which nerve innervates the pectoral muscles?
Brachial plexus
What are the two antagonistic pairs of the extrinsic muscles of the forelimb?
Brachiocephalic and Latissimus Dorsi muscles
Trapezius and Pectoral muscles
In which region of the forelimb are the radius and ulna located?
Antebrachium region
What type of bone are the radius and ulna?
The radius and ulna are long bones
Why is it more important to stabilise a diaphysial fracture of the radius than a diaphysial fracture to the ulna?
The radius has weight bearing function making it more important to stabilise a diaphysial fracture of the radius compared to the ulna
What is the proximal subchondral bone of the radius?
Head of the radius
What is the distal subchondral bone of the radius?
Distal radius
What is the purpose of the medial styloid process located at the distal end of the radius?
The medial styloid process is the point of attachment for the medial collateral ligament of the carpal joint
Where are the three centres of ossification located in the radius?
Proximal epiphysis
Body of the radius
Distal epiphysis
Identify these features of the ulna
What is the proximal subchondral bone of the ulna?
Trochlear notch
What is the palpable landmark for the elbow present at the proximal end of the ulna?
Olecranon process
Which species have a square shaped olecranon process?
Feline
What is the function of the anconeal process at the proximal end of the ulna?
The anconeal process is involved in stabilising the elbow joint through interdigitating with the ulnar fossa of the humerus
Where does the radius sit within the ulna?
The radius sits in the radial notch located between the medial and lateral coronoid processes
Which ligament hold the radius within the radial notch?
Annular ligament
What is the purpose of the lateral styloid process located at the distal end of the ulna?
The lateral styloid process is the point of attachment for the lateral collateral ligament of the carpal joint
Where are the four centres of ossification located in the ulna?
Olecranon process
Anconeal process
Body of ulna
Distal epiphysis
(T/F) The growth plate for the anconeal process should be closed in neonates
TRUE.
How can blunt force trauma to the distal epiphyseal growth plates of the radius or ulna cause angular limb deformities in young animals?
Blunt force trauma to the distal epiphyseal growth plates of the radius or ulna can cause premature closure of the growth plates which causes the distal end of the bone to stop growing. This causes the radius and ulna to grow at different rates leading to angular limb deformities
What anatomical feature allows canine and feline species to have a degree of rotation in their radius and ulna in comparison to larger species which do not?
Canine and feline species have a separate radius and ulna which allows for rotation, whereas larger domestic species have a fused radius and ulna (horses fuse proximally)
What type of joint is the elbow?
Synovial joint