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==Muscles of the Forelimb==
 
==Muscles of the Forelimb==
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===[[Forelimb - Anatomy & Physiology#Extrinsic Musculature|Extrinsic Musculature]]===
 
===[[Forelimb - Anatomy & Physiology#Extrinsic Musculature|Extrinsic Musculature]]===
   −
These muscle are responsible for joining the forelimb to the trunk, forming a synsarcosis rather than a conventional joint. Collectively, they act to transfer the weight of the body to the forelimbs as well as stabilize the scapula.
+
These muscle are responsible for joining the forelimb to the trunk, forming a synsarcosis rather than a conventional joint. Collectively, they act to transfer the weight of the body to the forelimbs as well as stabilize the scapula.
    
'''''Trapezius''''': Accessory n.
 
'''''Trapezius''''': Accessory n.
*Origin: mid-dorsal raphe and supraspinous ligament
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*Insertion: spine of the scapula
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Origin: mid-dorsal raphe and supraspinous ligament.
*Body: two parts, cervical and thoracic separated by aponeurosis
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*Action: raises scapula against the trunk and swings cranially to advance the limb
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Insertion: spine of the scapula.
 +
 
 +
Body: two parts, cervical and thoracic separated by aponeurosis.
 +
 
 +
Action: raises scapula against the trunk and swings cranially to advance the limb.
    
'''''Brachiocephalic m.''''': Accessory n.
 
'''''Brachiocephalic m.''''': Accessory n.
*Two parts separated by the clavicle  
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*Origin: clavicle  
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There are two parts separated by the clavicle.
*Insertion: median raphe of the neck and the occipital bone. The ventral part attaches to the mastoid process
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*Actions:  
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Origin: clavicle.
**advances the limb and extends the shoulder joint when limb is in motion
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**draws head and neck ventrally when limb is fixed
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Insertion: median raphe of the neck and the occipital bone. The ventral part attaches to the mastoid process.
 +
 
 +
Actions: advances the limb and extends the shoulder joint when the limb is in motion; draws the head and neck ventrally when the limb is fixed.
    
'''''Omotransversarius''''': Accessory n.
 
'''''Omotransversarius''''': Accessory n.
*Origin: transverse processes of the atlas
  −
*Insertion: acromion and distal spine of the scapula
  −
*Action: advancing the limb
  −
*Innervation
     −
'''''Latissimus dorsi''''': local branch of brachial plexus
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Origin: transverse processes of the atlas.
*The '''broadest muscle of the back'''
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*Origin: thoracolumbar fascia  
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Insertion: acromion and distal spine of the scapula.
*Insertion: teres tuberosity of the humerus
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*Actions: antagonist to the brachiocephalic m.
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Action: advancing the limb.
**cranial fibers strap scapula to the chest
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**retracts free limb and flexes shoulder joint
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'''''Latissimus dorsi''''': local branch of brachial plexus.
**draws trunk forward over the fixed limb
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 +
The broadest muscle of the back.
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 +
Origin: thoracolumbar fascia.
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 +
Insertion: teres tuberosity of the humerus.
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 +
Actions: antagonist to the brachiocephalic m. It retracts the free limb and flexes the shoulder joint. It also draws the trunk forward over the fixed limb.
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 +
'''''Pectoral mm.''''': brachial plexus.
 +
 
 +
Two superficial parts; cranial and caudal.
   −
'''''Pectoral mm.''''': brachial plexus
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Origin: cranial sternum.
*Two superficial parts, cranial and caudal
  −
**Origin: cranial sternum
  −
**Insertion:
  −
***cranial ('''descending'''): crest of the humerus distal to the deltoid tuberosity
  −
***caudal ('''transverse'''): covers elbow joint to insert on the medial fascia of the forearm
  −
**Action: adduct the forelimb, assist in protraction and retraction
  −
*One deep part ('''pectoralis profundus'''), with cranial and caudal parts
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**Origin: ventral sternum and adjacent cartilage
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**Insertions:
  −
***cranial (subclavius): supraspinatus m.
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***caudal (pectoralis ascendens): lesser tubercle of the humerus
  −
**Actions:
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***slinging trunk between forelimbs
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***may also retract free limbs
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***draw trunk forward when limb is fixed
     −
'''''Serratis ventralis''''': branch of brachial plexus
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Insertion: Cranial ('''descending'''): crest of the humerus distal to the deltoid tuberosity. Caudal ('''transverse'''): covers the elbow joint to insert on the medial fascia of the forearm.
*Origin: C4 to 10th rib
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*Insertion: medial scapula and scapular cartilage
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Action: adduct the forelimb, assist in protraction and retraction.
*Action: supporting the weight of the trunk
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**reinforced by strong fascia
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One deep part ('''pectoralis profundus'''), with cranial and caudal parts.
**cervical portion can retract the limb
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**caudal portion can advance the limb
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Origin: ventral sternum and adjacent cartilage
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 +
Insertions: cranial (subclavius): supraspinatus m. Caudal (pectoralis ascendens): lesser tubercle of the humerus.
 +
 
 +
Actions: slinging trunk between forelimbs, may also retract free limbs. It draws the trunk forward when the limb is fixed.
 +
 
 +
'''''Serratis ventralis''''': branch of brachial plexus.
 +
 
 +
Origin: C4 to 10th rib.
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 +
Insertion: medial scapula and scapular cartilage.
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 +
Action: supporting the weight of the trunk. It is reinforced by strong fascia. The cervical portion can retract the limb and the caudal portion can advance the limb.
    
'''''Rhomboids''''': brachial plexus
 
'''''Rhomboids''''': brachial plexus
*Origin: nuchal ligament, 4th - 6th thoracic spine
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*Insertion: dorsal border and adjacent scapula
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Origin: nuchal ligament, 4th - 6th thoracic spine.
*Action: retracting the limb, may also raise limb
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 +
Insertion: dorsal border and adjacent scapula.
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 +
Action: retracting the limb, may also raise limb.
    
===[[Forelimb - Anatomy & Physiology#Intrinsic Musculature|Intrinsic Musculature]]===
 
===[[Forelimb - Anatomy & Physiology#Intrinsic Musculature|Intrinsic Musculature]]===
 +
 
====Muscles of the Shoulder====
 
====Muscles of the Shoulder====
 +
 
These muscles are grouped:
 
These muscles are grouped:
*Lateral:'''Supraspinatus ''' and '''Infraspinatus''', Suprascapular n. of the brachial plexus
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**Origin: the fossae of the scapula
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'''Lateral'''
**Insertion: both tubercles of the humerus
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**Action: brace the shoulder  
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'''''Supraspinatus''''' and '''''Infraspinatus''''', Suprascapular n. of the brachial plexus.
**Clinical significance: bursa between the tendon of the infraspinatus and lateral tubercle of the humerus can be the site of inflammation
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*Medial:
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Origin: the fossae of the scapula.
**'''Supscapularis''': Subscapular n. from the brachial plexus
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***Origin: Deep surface of the scapula
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Insertion: both tubercles of the humerus.
***Insertion: medial tubercle of the humerus
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***Action: braces medial shoulder joint, potential adductor
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Action: brace the shoulder.
**'''Coracobrachialis''': Musculocutaneous n. of the brachial plexus
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***Origin: medial supraglenoid tubercle
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Clinical significance: the bursa between the tendon of the infraspinatus and lateral tubercle of the humerus, can be the site of inflammation.
***Insertion: proximal shaft of the humerus
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***Action: fixator
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'''Medial'''
*Caudal (Flexors): Axillary n. of the brachial plexus
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**'''Deltoids'''
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'''''Supscapularis''''': Subscapular n. from the brachial plexus.
***Origin: acromion, the length of the scapular spine
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***Insertion: deltoid tuberosity on the humerus, fascia of the lateral arm
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Origin: Deep surface of the scapula.
***Action: Flexor of Shoulder, Abductor and outward rotator of the arm
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**'''Teres Major'''
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Insertion: medial tubercle of the humerus.
***Origin: dorsal part of the caudal scapula  
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***Insertion: teres tuberosity midway down humerus
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Action: braces medial shoulder joint, potential adductor.
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 +
'''''Coracobrachialis''''': Musculocutaneous n. of the brachial plexus.
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 +
Origin: medial supraglenoid tubercle.
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 +
Insertion: proximal shaft of the humerus.
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Action: fixator.
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'''Caudal (Flexors)'''
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'''''Deltoids''''': Axillary n. of the brachial plexus.
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Origin: acromion, the length of the scapular spine.
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Insertion: deltoid tuberosity on the humerus, fascia of the lateral arm.
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Action: Flexor of Shoulder, Abductor and outward rotator of the arm.
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 +
'''''Teres Major''''': Axillary n. of the brachial plexus.
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Origin: dorsal part of the caudal scapula.
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Insertion: teres tuberosity midway down humerus.
    
====[[Forelimb - Anatomy & Physiology#Muscles of the Elbow|Muscles of the Elbow]]====
 
====[[Forelimb - Anatomy & Physiology#Muscles of the Elbow|Muscles of the Elbow]]====
''Extensors'': Radial n. from the brachial plexus
  −
*'''Triceps brachii''': Has four heads in the dog
  −
**Long head: caudal margin of the scapula
  −
**Lateral, medial, and accessory heads: shaft of the humerus
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**Insertion: olecranon, protected by tricipital bursa against the bone and subcutaneous bursa against the skin
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*'''Tensor fasciae antebrachii'''
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**Origin: tendon and lateral surface of the latissimus dorsi
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1. '''Extensors'''
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 +
'''''Triceps brachii''''': Radial n. from the brachial plexus.
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 +
Has four heads in the dog.
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 +
Long head: From the caudal margin of the scapula.
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 +
Lateral, medial, and accessory heads: From the shaft of the humerus.
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Insertion: olecranon, protected by tricipital bursa against the bone, and subcutaneous bursa against the skin.
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 +
'''''Tensor fasciae antebrachii''''': Radial n. from the brachial plexus.
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Origin: tendon and lateral surface of the latissimus dorsi.
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 +
2. '''Flexors'''
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'''''Biceps brachii''''': Musculocutaneous n. from the brachial plexus.
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Origin: supraglenoid tubercle of the scapula.
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Insertion: medial tuberosity of proximal radius and adjacent ulna.
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Runs through the intertubercular groove of the humerus.
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 +
'''''Brachialis''''': Musculocutaneous n. from the brachial plexus.
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Origin: proximocaudal humerus.
   −
''Flexors'': Musculocutaneous n. from the brachial plexus
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Insertion: spirals to insert just proximal to biceps.
*'''Biceps brachii'''
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**Origin: supraglenoid tubercle of the scapula
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**Insertion: medial tuberosity of proximal radius and adjacent ulna
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**Runs through the intertubercular groove of the humerus
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*'''Brachialis'''
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**Origin: proximocaudal humerus
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**Insertion: spirals to insert just proximal to biceps
      
====[[Forelimb - Anatomy & Physiology#Muscles of Supination and Pronation|Muscles of Supination and Pronation]]====
 
====[[Forelimb - Anatomy & Physiology#Muscles of Supination and Pronation|Muscles of Supination and Pronation]]====
''Supinators'': Radial n. from the brachial plexus
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*'''Brachioradialis'''
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**Origin: lateral epicondyle of the humerus
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**Insertion: distal part of medial radius
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**Often much reduced and sometimes absent
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*'''Supinator'''
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**Deep to extensor muscles,  passing from lateral humeral epicondyles to upper medial radius
     −
''Pronators'': Median n. from the brachial plexus
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1. '''Supinators'''
*'''Pronator teres'''
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**Origin: medial epicondyle of the humerus
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'''''Brachioradialis''''': Radial n. from the brachial plexus.
**Insertion: dorsal surface and medial border of radius
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*'''Pronator quadratus'''
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Origin: lateral epicondyle of the humerus.
**Origin: palmar surface of radius and interosseous ligament
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**Insertion: interosseous border of the ulna
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Insertion: distal part of the medial radius.
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Often much reduced, and sometimes absent.
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 +
'''''Supinator''''': Radial n. from the brachial plexus.
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Deep to the extensor muscles, passing from the lateral humeral epicondyles to the upper medial radius.
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2. '''Pronators'''
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'''''Pronator teres''''': Median n. from the brachial plexus.
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Origin: medial epicondyle of the humerus.
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Insertion: dorsal surface and medial border of radius.
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 +
'''''Pronator quadratus''''': Median n. from the brachial plexus.
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Origin: palmar surface of radius and interosseous ligament.
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Insertion: interosseous border of the ulna.
    
====[[Forelimb - Anatomy & Physiology#Muscles of the Carpal and Digital Joints|Muscles of the Carpal and Digital Joints]]====
 
====[[Forelimb - Anatomy & Physiology#Muscles of the Carpal and Digital Joints|Muscles of the Carpal and Digital Joints]]====
''Extensors'': Radial n. from the brachial plexus
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*Craniolateral position on the forearm
  −
*Almost all originate from the lateral epicondyle of the humerus
  −
*'''Extensor carpi radialis''': most medial, inserts on middle metacarpal bone
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*'''Ulnaris lateralis''': most lateral, inserts on accessory carpal bone and 5th metacarpal
  −
*'''Extensor carpi obliquus''': aka '''abductor pollicis longus'''
  −
**Origin: cranial radius
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**Insertion: 1st metacarpal
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*Last two may also serve in medial deviation of the paw
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*'''Common Digital Extensor'''
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**Insertion: extensor process of the distal phalanx of each digit
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**Sends a medial branch to dew caw
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*'''Lateral Digital Extensor'''
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**Insertion: dorsal proximal phalanges of 3rd to 5th digit
     −
''Flexors'': Median or Ulnar n. of the brachial plexus
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1.'''Extensors'''
*Caudal position on the forearm
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*Originate from the caudal medial epicondyle of the humerus
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Craniolateral position on the forearm. They almost all originate from the lateral epicondyle of the humerus and are all innervated by the radial n. from the brachial plexus.
*'''Flexor carpi radialis''': most medial, inserts on upper 2nd/3rd metacarpal bone
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*'''Flexor carpi ulnaris''': most lateral, inserts on the accessory carpal bone
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'''''Extensor carpi radialis'''''
*'''Superficial Digital Flexor'''
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**It divides into four branches which insert on the middle phalanges of all digits
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The most medial, inserts on middle metacarpal bone.
*'''Deep Digital Flexor'''
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**Passes through carpal canal before branching and continues to palmar distal phalanges
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'''''Ulnaris lateralis'''''
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The most lateral, inserts on accessory carpal bone and 5th metacarpal.
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 +
'''''Extensor carpi obliquus''''' (aka '''''abductor pollicis longus''''')
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 +
Origin: cranial radius.
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Insertion: 1st metacarpal.
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Last two may also serve in medial deviation of the paw.
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 +
'''''Common Digital Extensor'''''
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Insertion: extensor process of the distal phalanx of each digit.
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Sends a medial branch to the dew caw.
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 +
'''''Lateral Digital Extensor'''''
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 +
Inserts on the dorsal proximal phalanges of the 3rd to 5th digit.
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 +
2. '''Flexors'''
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Caudal position on the forearm. Originate from the caudal medial epicondyle of the humerus and all innervated by the median or ulnar n. of the brachial plexus
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 +
'''''Flexor carpi radialis'''''
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The most medial, inserts on the upper 2nd/3rd metacarpal bone.
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'''''Flexor carpi ulnaris'''''
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 +
The most lateral, inserts on the accessory carpal bone.
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'''''Superficial Digital Flexor'''''
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 +
It divides into four branches, which insert on the middle phalanges of all digits.
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 +
'''''Deep Digital Flexor'''''
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 +
Passes through the carpal canal before branching, and continues to the palmar distal phalanges.
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 +
'''''Interosseus muscles'''''
   −
''Interosseus muscles''
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Support the metacarpophalnageal joints. They arise from the palmar proximal metacarpal bones, and insert on the sesamoid bones within the joints. They are continued by ligaments to the phalanges.
*Support metacarpophalnageal joints
  −
*Arise from palmar proximal metacarpal bones and insert on sesamoid bones within the joints, continued by ligaments to phalanges
      
==Vasculature of the Forelimb==
 
==Vasculature of the Forelimb==
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