Podcast
Questions and Answers
Which muscle is not part of the superficial group of extrinsic forelimb muscles?
Which muscle is not part of the superficial group of extrinsic forelimb muscles?
- Brachiocephalicus
- Latissimus dorsi
- Trapezius
- Rhomboideus (correct)
Which muscle originates from the wing of atlas C1?
Which muscle originates from the wing of atlas C1?
- Omotransversarius (correct)
- Brachiocephalicus
- Latissimus dorsi
- Trapezius
What is the action of the Latissimus dorsi muscle?
What is the action of the Latissimus dorsi muscle?
- Elevates the shoulder
- Flexes the shoulder and advances the limb (correct)
- Extends the neck
- Adducts the limb
Which part of the Brachiocephalicus inserts at the mastoid process of the skull?
Which part of the Brachiocephalicus inserts at the mastoid process of the skull?
The trapezius muscle has its origins at which vertebrae?
The trapezius muscle has its origins at which vertebrae?
What nerve supplies the action of the Trapezius muscle?
What nerve supplies the action of the Trapezius muscle?
Which muscle is responsible for lateral and ventral flexion of the head and neck?
Which muscle is responsible for lateral and ventral flexion of the head and neck?
What is the innervation of the Latissimus dorsi muscle?
What is the innervation of the Latissimus dorsi muscle?
Which muscle acts as a medial collateral ligament to stabilize the shoulder joint?
Which muscle acts as a medial collateral ligament to stabilize the shoulder joint?
What is the primary action of the Infraspinatus muscle?
What is the primary action of the Infraspinatus muscle?
Which nerve innervates the Teres major muscle?
Which nerve innervates the Teres major muscle?
Where does the Biceps brachii muscle originate?
Where does the Biceps brachii muscle originate?
What is the primary function of the Triceps brachii muscle?
What is the primary function of the Triceps brachii muscle?
Which muscle originates from the coracoid process?
Which muscle originates from the coracoid process?
The Tensor fasciae antebrachii muscle primarily functions as which type of muscle?
The Tensor fasciae antebrachii muscle primarily functions as which type of muscle?
Which muscle's action includes flexion and stabilization of the shoulder?
Which muscle's action includes flexion and stabilization of the shoulder?
Which muscle is primarily responsible for supinating the paw?
Which muscle is primarily responsible for supinating the paw?
What is a potential consequence of injury to the suprascapular nerve?
What is a potential consequence of injury to the suprascapular nerve?
Which muscle does the musculocutaneous nerve NOT supply?
Which muscle does the musculocutaneous nerve NOT supply?
Which nerve is responsible for innervating the shoulder flexors and rotators?
Which nerve is responsible for innervating the shoulder flexors and rotators?
Which muscles participate in the action of elbow flexion?
Which muscles participate in the action of elbow flexion?
Which of the following conditions does NOT affect the brachial plexus directly?
Which of the following conditions does NOT affect the brachial plexus directly?
The radial nerve wraps around which part of the limb?
The radial nerve wraps around which part of the limb?
Which muscle action is primarily associated with the action of the subscapularis muscle?
Which muscle action is primarily associated with the action of the subscapularis muscle?
What is the primary action of the superficial pectoral muscle?
What is the primary action of the superficial pectoral muscle?
Which part of the deep pectoral muscle is also referred to as the ascending part?
Which part of the deep pectoral muscle is also referred to as the ascending part?
What is the origin of the rhomboideus muscle?
What is the origin of the rhomboideus muscle?
Which nerve innervates the serratus ventralis muscle?
Which nerve innervates the serratus ventralis muscle?
Which muscle acts primarily as a shoulder extensor?
Which muscle acts primarily as a shoulder extensor?
What distinguishes the intrinsic muscles of the thoracic limb from other muscle groups?
What distinguishes the intrinsic muscles of the thoracic limb from other muscle groups?
What is the function of the subclavius muscle in mammals?
What is the function of the subclavius muscle in mammals?
What is the primary function of the triceps brachii muscle?
What is the primary function of the triceps brachii muscle?
The deep pectoral muscle is also known as what?
The deep pectoral muscle is also known as what?
Which of the following muscles is NOT innervated by the median nerve?
Which of the following muscles is NOT innervated by the median nerve?
What symptom is associated with dysfunction of the median nerve in dogs?
What symptom is associated with dysfunction of the median nerve in dogs?
Which nerve innervates the latissimus dorsi muscle?
Which nerve innervates the latissimus dorsi muscle?
Which nerve provides sensory innervation to the palmar surface of the paw?
Which nerve provides sensory innervation to the palmar surface of the paw?
How many spinal nerves make up the brachial plexus?
How many spinal nerves make up the brachial plexus?
Which muscle is innervated by the lateral thoracic nerve?
Which muscle is innervated by the lateral thoracic nerve?
What is the primary action of the pectoral muscles?
What is the primary action of the pectoral muscles?
Study Notes
Shoulder Muscles
- Origin: supraspinous fossa
- Insertion: Greater tubercle
- Action: Extends and stabilizes the shoulder
- Nerve: Suprascapular n.
Infraspinatus
- Origin: infraspinous fossa
- Insertion: Greater tubercle
- Action: Flexes, stabilizes and abducts the shoulder
- Nerve: Suprascapular n.
Subscapularis
- Origin: subscapular fossa
- Insertion: Lesser tubercle
- Action: Extends, adducts and stabilizes the shoulder
- Nerve: Subscapular n.
Coracobrachialis
- Origin: coracoid process
- Insertion: lesser tubercle
- Action: flexes and abducts the shoulder
- Nerve: Musculocutaneous n.
Deltoideus
- Origin: spine of scapula and acromion process
- Insertion: Deltoid tuberosity
- Action: flexes the shoulder
- Nerve: Axillary n.
Teres Major and Teres Minor
- Origin: Caudal border of scapula
- Insertion: Teres major and minor tuberosities
- Action: flexes the shoulder
- Nerve: Axillary n.
Brachial Muscles
- Action: Act on the elbow joint
Flexor Muscles
- Lateral Muscles
- Biceps brachii
- Origin: Supraglenoid tubercle
- Insertion: Radial tuberosity
- Action: flexes the elbow
- Nerve: Musculocutaneous n.
- Brachialis
- Origin: Caudolateral surface of proximal humerus
- Insertion: Radial tuberosity
- Action: flexes the elbow
- Nerve: Musculocutaneous n.
- Biceps brachii
- Extensor Muscles
- Triceps brachii
- Origin: Humerus (except the long head)
- Insertion: Olecranon
- Action: extends the elbow
- Nerve: Radial n.
- Tensor fasciae antebrachii
- Action: Extends the elbow
- Nerve: Radial n.
- Triceps brachii
Extrinsic Muscles of the Forelimb
- Originate: outside of the thoracic limb
- Insert: on the thoracic limb
- 2 Groups
- Superficial Group
- Brachiocephalicus
- Omotransversarius
- Latissimus dorsi
- Trapezius
- Superficial Pectoral
- Deep Group
- Rhomboideus
- Deltoideus
- Deep Pectoral
- Superficial Group
Brachiocephalicus
- Action: lateral and ventral flexion of head & neck; extends shoulder
- Innervation: Accessory + Axillary n
Omotransversarius
- Action: advance and adduct limb; flexes neck laterally
- Nerve: Accessory n.
Latissimus dorsi
- Action: Flexes shoulder; advances limb
- Nerve: Thoracodorsal n.
Trapezius
- Action: elevates shoulder, draws scapula cranially and caudally
- Nerve: Accessory n.
Superficial Pectoral
- Action: adducts and advances the limb
- Nerve: Cr.pectoral n.
Deep Pectoral
- Action: adducts limb, retracts limb, draws trunk toward the limb
- Nerve: Caudal pectoral n.+ lateral thoracic n.
Rhomboideus
- Origin: C2 to T7 (capitis from nuchal crest)
- Insertion: dorsal border of scapula
- Action: elevates forelimb and draws scapula against the trunk
- Nerve: dorsal branches of cervical and thoracic spinal nerves
Serratus ventralis
- Action:
- Nerve: Long thoracic n.+ ventral branches of cervical spinal nerves
Subclavius m.
- Present: Horse and goat
- Absent: Carnivores
Intrinsic Muscles of the Forelimb
- Originate and insert: on the thoracic limb
Scapular Muscles
- Action: Act on the shoulder joint
Lateral Scapular Muscles
- Supraspinatus
- **Action:** Extends the shoulder
- **Nerve:** Suprascapular n.
- Infraspinatus
- **Nerve:** Suprascapular n.
Medial Scapular Muscles
- Subscapularis
- **Nerve:** Subscapular n.
- Coracobrachialis
- **Nerve:** Musculocutaneous n.
Caudal Scapular Muscles
- Teres major and minor
- **Nerve:** Axillary n.
- Deltoideus
- **Nerve:** Axillary n.
Brachial Plexus
- Formed By: ventral branch of last three cervical and first two thoracic spinal nerves (C6,7,8 &T1,2)
- Innervates: all muscles of forelimb except
- Trapezius
- Omotransversarius
- Brachiocephalicus
- Rhomboideus
- Skin over upper shoulder region
Nerves of the Forelimb
- Suprascapular n. (C6, C7)
- Muscles:
- Supraspinatus m.
- Infraspinatus m.
- Action: Stabilization and extension of the shoulder joint.
- Muscles:
- Subscapular n. (C6, C7)
- Muscles: Subscapularis m.
- Action: Adducts the limb and rotates humerus medially.
- Musculocutaneous n. (C6, C7, C8)
- Muscles:
- biceps brachii m.
- brachialis m.
- coracobrachialis m.
- Action: Shoulder extensors and Elbow flexors
- Muscles:
- Axillary n. (C7,C8)
- Muscles:
- Deltoideus m.
- Teres major m.
- Teres minor m.
- Part of the subscapularis m.
- Action: Flexors of the shoulder joint; Rotates brachium.
- Muscles:
- Radial n. (C7, C8, T1, T2)
- Muscles:
- Extensors of carpus and digits
- extensor carpi radialis
- common digital extensor
- lateral digital extensor
- Triceps brachii m. (elbow extension)
- Muscles:
- Median n. (C8.T1, T2)
- Muscles:
- Flexor carpi radialis m.
- superficial digital flexor m.
- pronator teres
- pronator quadratus
- deep digital flexor m.
- Action: most FLEXORS OF CARPUS AND DIGITS
- Muscles:
- Ulnar n. (C8, T1, T2)
- Muscles:
- Flexor carpi ulnaris m.
- Interosseous m.
- Muscles:
- Thoracodorsal n. (C8)
- Muscles: Latissimus dorsi m.
- Action: Retracts the limb.
- Lateral thoracic n. (C8, T1)
- Action of m.: Panniculus reflex - skin twitching
- Long Thoracic n.
- Muscles: Serratus ventralis
- Pectoral n. (C6-T1)
- Muscles: superficial and deep pectoral m. including subclavius
- Action: adduct the limb
Miscellaneous
- Why does the brachial plexus have 8 spinal nerves? All mammals have 7 cervical vertebrae, but the brachial plexus is formed by the ventral branch of the last three cervical and first two thoracic spinal nerves, resulting in a total of 8 nerves.
- Supinators
- Action: Supinates paw (turn paw upward)
- Nerve: Radial n.
- Muscles:
- Supinator
- Brachioradialis
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Description
This quiz assesses your knowledge of the anatomy, origins, insertions, actions, and innervation of the shoulder muscles. Test your understanding of muscles like the Infraspinatus, Subscapularis, and Deltoideus and how they contribute to shoulder movement and stability.
