Lecture 11: Brachium and Elbow Flashcards
The brachium is portion of thoracic limb between
Shoulder girdle and elbow
Movement of the arm is achieved by muscles that move the _____
Gleno-numeral joint`
What muscles extend the GH joint
Triceps brachi, supraspinatus, brachiocephalicus
What muscles flex the GH joint
Biceps brachii, teres major, teres minor, latissimus dorsi, pectoralis profundus
What muscles abduct the GH joint
Infraspinatus
What muscles adduct the GH joint
Pectoral muscles, coracobrachialis, subscapularis
What are the three joints of the elbow
Humero-radial, humero-ulnar, radio-ulnar
What does the trochlea of the humerus sit on
Ulna
What does capitulum of humerus sit on
Radius
What ligaments support the elbow
Medial and lateral collateral ligaments, annular ligament of radius, oblique ligament
Flexion and extension of the elbow is permitted along a Sagittal plane via what joints
Humero-radial and humero-ulnar
Role of collateral ligaments
Prevent excessive abduction and adduction
Role of oblique ligament
Prevents over-extension of elbow
Pronation/supination
Distal radius around the ulna and requires rotation of numeral head around proximal radio-ulnar joint
Role of annular ligament of radius
Permits pronation and supination
What artery supplies the flexor compartment of the arm
Brachial
What nerve innervate the flexor compartment of the arm
Musculocutaneous
What are the flexor muscles of the arm
Biceps brachii, brachialis
What is the artery that supplies the extensors of the arm
Deep brachial artery
What nerve innervates the extensor compartment of the arm
Radial
What muscles are in the extensor compartment of the arm
Triceps brachii (long, lateral, medial, and accessory), tensor fascia antebrachium, and anconeus
OINA for long head of triceps brachii
O:infraglenoid tubercle
I: olecranon process of ulna
N: radial
A: extend arm and forearm
OINA for lateral head of triceps brachii
O: space between teres minor and deltoid
I: olecranon process of ulna
N: radial
A: extend arm and forearm
OINA for medial head of triceps brachii
O: space between coracobrachialis and teres minor
I: olecranon process of ulna
N: radial
A: extend arm and forearm
OINA for accessory head of triceps brachii
O: caudal aspect of humerus
I: olecranon process of ulna
N: radial
A: extend arm and forearm
What is the result of avulsion fracture of olecranon
Detachment of triceps, lose ability to extend elbow, dropped elbow appearance
OINA for Biceps Brachii
O: Supraglenoid tubercle
I: two insertions: 1. Deep insertion: radial tuberosity and medial ulnar, 2: superficial insertion: antebrachium fascia (lacertus fascia)
N: musculocutaneous
A: flex arm and forearm
OINA for brachialis
O: caudal aspect of proximal humerus
I: ulnar tuberosity
N: musculocutaneous
A: flex arm and forearm
What is the fibrous band ion horse that joints the tendons of origin and insertion of biceps brachii
Internal tendon/central tendon
What is the role of internal/central tendon
At faster gaits the force necessary for rapid protraction of forelimb is beyond power of muscle so central tendon enables the muscle to store energy when stretched during support phase and then is rapidly released to accelerate forward movement of limb
What is the lacertus fibrosus
Tendon that splits away from internal/central tendon
What muscles protect the brachial plexus well
Serratus ventralis and pectoral muscles
Where does the radial nerve originate
C7-T1
What muscles does the radial nerve innervate
Triceps brachii, aconeus and tensor fascia antebrachium
What is the path of the radial nerve
Runs distally within the arm, caudal to brachial artery. Dives between long and medial head of triceps and follows groove of humerus. Enters the cranial lateral aspect of limb
Where does the musculocutaneous nerve originate
C7-C8
What muscles does the musculocutaneous innervate
Biceps brachii, brachialis, coracobrachialis
What is the path of musculocutaneous nerve in dogs
Gives proximal branch to coracobrachialis, communicating branch passes distocaudally to median nerve in distal third of arm. Nerve passes under terminal part of biceps and divides into branch to brachialis and medial cutaneous nerve of forearm
What is the musculocutaneous path in ungulates
Nerve loops around the axillary artery to join median nerve, in brachium separates from median
What is the path of musculocutaneous nerve in horses
Cutaneous branch extends beyond carpus to metacarpophalangeal joint/fetlock
Where does median nerve originate
C8-T1
What muscles does the median nerve innervate
Flexor muscles carpus and digits
What is path of median nerve in dogs
Travels does the medial surface of the arm caudal to the axillary and then brachial artery. Enters the forearm over the medial collateral ligament of the elbow joint
Where does the ulnar nerve originate
C8-T1
What muscles does the ulnar nerve innervate
Most of the flexor muscles of the carpus and digits
What is the path of the ulnar nerve
Travels down the brachium beside or united with median nerve. Splits off towards olecranon to cross the caudal aspect of the elbow joint-wraps around medial epicondyle of humerus
