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