Forelimb Flashcards
quadriceps femoris analagous muscle group
triceps brachii
hindlimb vs forelimb development
hindlimb and forelimb undergo diferent degrees of rotation during development leading to different planes of rotation in hip/ shoulder, stifle/ elbow, tarsus/ carpus
extrinsic forelimb muscle
on attachment on axial skeleton and one on bone of forelimb; some attach to body of scapula others to body of humerus
intrinsic forelimb muscle
both attachments on bone for the forelimb
flexion of the shoulder
decreased angle between scapula and humerus; this should not be confused with movement of the forelimb caudally
extension of the shoulder
increased angle between scapula and humerus; this should not be confused with movement of forelimb cranially
superficial pectoral muscle
Origin: cranial 1/4 of sternum (first 2-3 sternebrea)
Insertion- fascia along crest of greater tubercle of humorous
Action- adduct limb when not weight bearing; prevent abduction when bearing weight
Innervation- VB SN C7 and C8
Extrinsic limb muscle
Deep pectoral muscle
Origin- entire sternum
Insertion- lesser tubercle of humerus on med side greater tubercle of humerus on lat side, and medial fascia of arm
Action- pull body cranially with limb on ground; pull limb cranially or cd depending on limb position; moves limb if shoulder jt stable flexes shoulder jt if jt free to move
Innervation-Cd pectoral nerves (C8, T1)
Extrinsic limb muscle
Brachiocephalicus muscle
Origin- broad attachment to cranial border of humerus; clavicular intersection/ clavicle
Insertion- dorsal midline of 1/2 the neck and ventral caudolateral part of skull
Action- advance limb cranially if free to move; limb on ground muscle draws head to one side; extend shoulder jt
Innervation- accessory nerve and ventral branches of cervical spinal nerves
Extrinsic limb muscle
Omotransversarius muscle
Attachments- distal 1/3 spine of scapula and transverse process of the atlas
Action- move limb cranially or with limb on ground move head down to one side or just move head down
Innervation
Innervation- Accessory nerve
Superficial cervical lymph nodes lie deep to omotransversarius
Extrinsic limb muscle
Trapezius muscle
Origin- dorsal midline, from C3-T9 Insertion- proximal 1/3 spine of scapula Action- elevate the limb and abduct the limb Innervation- Accessory Nerve Extrinsic limb muscle
Rhomboideus muscle
Origin- dorsal aspect of the occipital bone, dorsal midline along the neck, midline of thoracic vertebrea cr to lat dorsi
Insertion- dorsal border of scapula
Action- hold scapula close to trunk, elevate limb
Innervation- VB of cervical and thoracic spina nerves
Extrinsic limb muscle
Latissimus dorsi
Origin- fascia from spinous process of lumbar and last 7-8 thoracic vertebrea
Insertion- proximal medial side of the humerus
Action- pull limb caudally; with limb planted on ground can pull body cranially over limb; can flex shoulder jt
Innervation- Thoracodorsal nerve (C7,C8,T1)
Extrinsic limb muscle
Serratus ventralis
Origin- transverse processes of last 5 cervical vertebrae and first 7-8 ribs
Insertion- dorsal medial aspect of scapula
Action- maintain weight of body against gravity
Innervation- VB of cervical spinal nerves and long thoracic nerve (C7)
Extrinsic limb muscle
Brachial plexsus
C6-T2; we will look at suprascapular subscapular Neve, axillary nerve, musculocutaneous nerve, radial nerve, medial nerve, ulnar nerve
Arteries of forlimb
like hindlimb main pipeline travels medially and changes name as it passes from region to region; subclavian -> axillary artery (shoulder) -> brachial artery (brachium) -> median artery (antebrachium)
axillary artery
supplies blood to all muscles of shoulder region including all the extrinsic limb muscles we are studying and additional muscles attaching to scapula
range of motion shoulder joint
can move in multiple planes, major plane is flexion/ extension while holding limb close to body; lat dorsi can flex shoulder but most directed movements of scapulohumeral joint are made by intrinsic limb muscles
Flexion of shoulder joint
Deltoideus muscle, trees major muscle (theoretically also lat dorsi but not intrinsic and not main shoulder flexor)
Deltoideus muscle
Origin- spine and acrimal process of scapula
Insertion- proximal lateral side of humerus on deltoid tuberosity
Action- flex shoulder
Innervation- Axillary nerve
Teres major
Origin- attaches proximally to cd angle of scapula and occupying space just deep to cd border of humerus
Insertion- teres major tuberosity of humerus (proximal medial aspect of humerus)
Action- flex shoulder
Innervation-Axillary nerve
Supraspinatus muscle
Origin- supraspinous fossa to scapula
Insertion- greater tubercle of humerus via thick tendon
Action- Shoulder extension
Innervation- Suprascapular nerve
Shoulder extension
supraspinatus muscle, biceps brachii contributes secondarily
Medial and lateral rotation of the shoulder
controlled by subscapularis muscle (med) and infraspinatus muscle and trees minor muscle (lat) these keep unwanted motion from occurring during flexion and extension fo the limb; these three counteract each other and stabilize shoulder joint
subscapularis muscle
Origin- subscapular fossa
Insertion- lesser tubercle of humerus (proximal medial aspect)
Action- Medial rotation of humerus
Innervation- subscapular nerve
Medial rotation of humerus
subscapularis muscle
Lateral rotation of humerus
infraspinatus muscle and teres minor muscle
infraspinatus muscle
Origin- infraspinous fossa
Insertion- lateral side grater tubercle of humerus
Action- lateral rotation of shoulder, flexion if limb is already far cranial or extension fi limb is already far caudal
Innervation- suprascapular nerve
Teres minor muscle
Origin- infraglenoid tubercle and distal 1/3 cd border of scapula
Insertion- teres minor tuberosity of humerus
Action- shoulder flexion, lateral rotation of shoulder
Innervaiton- Axillary Nerve
Elbow Joint
articulation of humerus with the ulna; primary action is flexion/ extension
Flexion/ extension of elbow
triceps brachii, biceps brachii, brachialis, secondarily supinator and pronator teres
Triceps brachii muscle
4 heads;
Origin- long head-cd border of scapula;
medial head- crest of lesser tubercle near teres major tuberosity
lateral head- tricipital line of humerus
accessory head- neck of humerus
Insertion- all 4 heads insert at the olecranon
Action- extend elbow, support weight of body against gravity
Innervation- Radial nerve (long head, lateral head, accessory head, and medial head)
Biceps brachii muscle
1 head
Origin- scapula (supraglenoid tubercle)
Insertion- radius and ulna (ulnar and radial tuberosities)
Action- Elbow flexor (primary), extend shoulder joint (secondary)
Innervation- musculocutaneous nerve
Brachialis muscle
Origin- proximal 1/3 lateral surface of humerus
insertion- ulnar and radial tuberosities
action- flex elbow joint
innervation- musculocutaneous nerve
Manus
has 3 regions analogous to pes, carpus, metacarpus, digits; most significant movement is flexion/ extension which is almost entirely at radiocarpal joint
flexor surface of carpus and digits
positioned on palmar surface
movement of the digits
limited to flexion/ extension
movement of the carups
flexion/ extension; pronation and supination (motion of radius relative to ulna that result in movement of carpus) (supination is rotation of forearm and palm faces sky, pronation is rotate forearm down and palm faces floor); the bone moving in pronation and supanation is the radius; abduction/ adduction (muscles that do this stabilize carpus during weight bearing)
extensor group (carpus and digits)
arises from lateral epicondyle of humerus; extensor carpi radials (primary carpal extensor), common digital extensor, lateral digital extensor (primary digital extensors), extensor carpi ulnaris (carpal flexor and abductor)
flexor group (carpus and digits)
arises from medial epicondyle of humerus; pronator teres, flexor carpi radials, superficial digital flexor, flexor carpi ulnaris, deep digital flexor
extensor surface of carpus and digits
dorsal surface of the limb
Extensor carpi radialis
Origin- lateral supracondyle crest
Insertion- proximal ends of metacarpals II and III
Action- extend carpal joints
Innervation- Radial nerve
held in place by extensor retinaculum when crossing arpus
extensor retinaculum
thick connective tissue band that aids in holding tendons as they cross dorsal of the carpus
Common digital extensor
cd lateral to extensor carpi radialis
Origin- lateral epicondyle of the humerus
Insertion- extensor process of distal phalanges of II, III, IV, V
Action- extends all 4 principal digits
Innervation- Radial nerve
*tendon also held in place by extensor reinaculum
Lateral digital extensor
cd to common digital extensor
Origin- Lateral epicondyle of the humerus
Insertion- proximal ends of phalanges of lateral most 3 digits (III, IV, V; mainly to extensor process of the distal phalanges of these digits)
Action- extend carpal joints of carpus and digits III, IV, V
Innervation- Radial nerve
Tendon also held in place by extensor reinaculum
Extensor carpi ulnaris
lateral on surface of forearm very distinctive shinny wide bright tendon that goes to proximal and lateral aspects of metacarpal 5 and to accessory carpal bone
Origin-lateral epicondyle of the humerus
Insertion- lateral aspect of proximal end of 5th metacarpal bone and accessory carpal bone
Action- abduct carpus; flexor of carpus
Innervatoin- Radial nerve
Flexor carpi radialis
Origin- medial epicondyle of humerus
Insertion- proximal palmar aspect of metacarpals II and III
Action- flex carpal joints
Innervation- Median nerve
Tendon held in place by flexor retinaculum; tendon begins halfway down antebrachium
mirror of extensor carpi radialis
Superficial digital flexor
Origin- medial epicondyle of humerus
Insertion-p2 of each of the principle 4 digits (palmar surface)
Action- flex carpal, metacarpophalangeal, and proximal interphalangeal joints of digits II, III, IV, V
Innervation- Median nerve
* Held in place by components of flexor retinaculum
Flexor carpi ulnaris
Origin- ulnar head: cd border and medial surface of olecranon; humeral head: medial epicondyle of humerus
Insertion- Accessory carpal bone
Action-Flex carpus
Innervation-Ulnar nerve
Deep Digital Flexor
Origin- 3 heads, each arise independently; one from humerus, one from radius, one from ulna (humeral head largest); all 3 join into deep digital flexor tendon
Insertion- Distally to p3 of all 4 principal digits
Action- flex carpal and metacarpophalangeal joints and proximal and distal interphalangeal joints of the digits
Innervation- Median and ulnar nerves
Pronation/ supination
pronator teres, supinator, and pronator quadratus (all have distal attachment on radius)
pronator quadratus
Attachments- apposed surfaces of radius and ulna (this fills space between radius and ulna)
Action- pronate the paw
Innervation- Median nerve
pronator teres
Origin- medial epicondyle of humerus
Insertion- medial border of radius between proximal and middle thirds
Action- rotate forearm medially so palmar surface of paw faces the ground (pronation); flex elbow
Innervation- Median nerve
Supinator
Origin- lateral epicondyle of humerus
Insertion- cr surface of proximal 4th of radius
Action- rotate forearm laterally so that palmar surface of paw faces medially (supination); flex elbow joint
Innervation-Radial nerves
primary arterial supply to the forelimb
subclavian artery -> axillary artery -> brachial artery -> median artery -> vascular arcade of the manus
Axillary artery
axillary artery supplies blood to muscles neck and shoulder
subscapular artery
last major branch of the axillary artery; travels along cd surface of the scapula supplying multiple muscles of the shoulder; runs deep to teres major and along cd border scapula
brachial artery
shortly after giving off the subscapular artery the continuation of the axillary artery is the brachial artery; courses down medial side of brachium; branches to muscles of the brachium and structures of the elbow joint; continues as median artery
common interosseous artery
branch off brachial artery cd brach runs deep in interosseous space between radius and ulna for entire length forearm into paw; provides collateral circulation to this part of limb
median artery
brachial artery turns into median artery which provides multiple branches to muscles forearm; superficially positioned branch median artery is radial artery; both of these continue into manus and participate in formation of vascular arcades on dorsal and palmar surfaces of the paw; can ID median artery in carpal canal between digital flexor tendons
Cephalic vein
common site of venipuncture
superficial cervical lymph nodes
deep to omotransversarius
axillary lymph nodes
located in arm pits
suprascapular nerve
leaves brachialplexsus; runs laterally between subscapularis and supraspinatus muscles; in jeopardy for traumatic injury as it crosses neck of the scapula
subscapular nerve
leaves brachial plexus; on medial surface enters subscapularis muscle; less likey to get damaged, runs on medial aspect of limb to innervate subscapularis muscle
musculocutaneous nerve
leaves brachial plexus; innervates elbow flexors (biceps brachii, brachialis), can see it sending branches to these muscles; provides cutaneous innervation as far distal as carpus
axillary nerve
leaves brachial plexus; short; distributed to shoulder flexors
median nerve
leaves brachial plexus; pass through medial side of limb on way to innervate muscles distal to elbow; no branching proximal to elbow; enters some of the flexor muscles of carpus and digits; continues into carpus where it receives sensory innervation from palmar surface of paw
ulnar nerve
leaves brachial plexus; pass through medial side of limb on way to innervate muscles distal to elbow; no branching proximal to elbow; enters several flexor muscles of carpus and digits; cutaneous inenrvatoin to cd surface of forearm and lateral surface of 5th digit; supplies skin on palmar surface of paw along with median and ulnar nerves
Radial nerve
RADIAL NERVE SUPPLIES MOTOR INNERVATION TO ALL EXTENSORS OF THE ELBOW CARPUS AND DIGITS; provides cutaneous innervation to skin on cr surface of forearm and dorsal surface of the paw; bc has to reach extensor muscles positioned laterally on limb it is at risk for traumatic injury; runs brachial plexus to carpus
radial nerve branches
on lateral aide at distal 1/3 of arm radial nerve terminates as deep branches that enter extensor group of muscles which attach on lat epicondyle as superficial brach that = provide cutaneous innervation to cr surface forearm and dorsal surface of paw; deep branch crosses deep surface extensor carpi radialis; superficial branch does some branching runs parallel to cephalic vein
carpal canal
space bounded by carpal bones dorsally, flexor retinaculum on palmar surface, and accessory carpal bone laterally; structures running through canal: SDF muscle, DDF muscle, flexor carpi radialis muscle, median and ulnar nerves, median artery
sympathetic innervation forelimb
directly analogous to hindlimb
