Extrinsic Muscles Of Thoracic Limb Flashcards
Extrinsic vs. Intrinsic
Extrinsic: situated outside, coming from or originating on the outside
Intrinsic: situated entirely within
Pectoral muscles (dog)
Superficial pectoral m.
-descending
-transverse
Deep pectoral m. (ascending)
Superficial pectoral m. (descending)
Origin: first sternebrae
Insertion: crest of the greater tubercle
Innervation: cranial pectoral nn.
Action:
-when not bearing weight, adduct limb
-bearing weight, prevent limb for being abducted
Superficial pectoral m. (transverse)
Origin: sternebrae 1-3 and fibrous raphe on ventral midline
Insertion: crest of the greater tubercle
Innervation: cranial pectoral nn.
Action:
-when not bearing weight, adduct limb
-bearing weight, prevent limb for being abducted
Deep pectoral m.
Origin: stern brae 1-8 & fibrous raphe on the ventral midline, deep abdominal fascia in the region of xiphoid cartilage
Intersection: lesser tubercle, greater tubercle & crest greater tubercle via aponeurosis, medial brachial fascia
innervation: caudal pectoral nn.
Actions:
When the limb is advanced and fixed - pull the truck cranially
When the limb is not bearing weight - draw the limb caudally
Adduct the limb
Support the truck - the humeral insertion is dorsal to the sternal origin
Feline pectoral muscles
Pectoantebrachialis
origin: manubrium
Intersection: superficial fascia of proximal end ante brachium (ulna)
Action: draws the arm medically (adducts)
Xiphihumeralis
origin: xiphoid process
intersection: tendon on proximal end humerus
action: same as deep pectoral
Brachiocephalicus m.
Composition:
1. cleidocephalicus
a. cleidocervicalis
b. cleidomastoideus
2. cleidobrachialis
3. clavicular intersection
Brachiocephalicus m.
1a. cleidocervicalis
origin: clavicular intersection
Insertion: mid-dorsal cervical
1b. cleidomastoideus
origin: clavicular intersection
intersection: mastoid process
innervation: accessory n. and ventral brs. of cervical spinal nn.
Action: advance the limb, extend the shoulder jt., draw neck/head to side
Sternocephalicus m. (neck muscle)
- sterno-occipitalis m.
- steromastoideus m.
origin: first sternebra (manubrium)
insertion: - sterno-occipitalis: nuchal crest of occipital nerve
- steromastoideus: mastoid process of temporal bone
Innervation: accessory n. and ventral brs. of cervical spine nn.
Action: draw head/neck to side
Sternohyoideus m. (neck muscle)
Origin: manubrium and first costal cartilage
Insertion: basihyoid bone
innervation: ventral brs. of cervical spinal nn.
Action: draw tongue/larynx caudally
Omotransversarius m.
Origin: distal end of scapular spine and acromion
insertion: transverse process first cervical vertebra (wing atlas), basioccipital bone near tympanic bulla cat
trapezius m.
origin:
1. T. cervicis - median raphe neck (C3-C7)
2 T. thoracis - supraspinous ligament
insertion: spine scapula
innervation: Accessory n. (XI)
action:
T. cervicis - draw scapula craniodorsally
T. thoracis - draw scapula caudodorsally
together - elevate and abduct the thoracic limb
Rhomboideus m.
Origin:
1. R. capitis - nuchal crest occipital bone (substantial cat)
2. R. cervicis - median raphe neck
3. R. thoracis - spinous processes T1-T7
Insertion: dorsal border and adjacent surface scapula
Innervation: ventral brs. cervical and thoracic spinal nn.
Latissimus dorsi m.
origin: thoracolumbar fascia from spinous processes T7-L7 (dog), T4-L6 in cat. Last 2-3 ribs
Insertion: teres major tuberosity and teres major tendon
Innervation: Thoracodoral n.
Action: draw limb caudally, flex shoulder jt.
Serratus ventralis m.
Origin:
cervicis - transverse processes of C2/C3-C7
thoracis - first 7-8 ribs in dog, first 9-10 ribs in cat
thoracis - first 7-8 ribs in dog and first 9-10, ventral to middle region
insertion: serrated face
innervation: ventral brs. of cervical spinal nn. and long thoracic n.
Action: support truck by slinging body between forelimbs, depress scapula
