Canine Thoracic Limb - Muscles Flashcards by Zee Daws

True or False

The thoracic limb is connected to the
body via extrinsic muscles (synsarcosis)

True

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Name the 8 extrinsic muscles of the thoracic limb

Superficial pectoral
Deep pectoral
Brachiocephalicus
Omotransversarius
Trapezius
Rhomboideus
Latissimus dorsi
Serratus ventralis

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The more proximal attachement, the part that moves the least, and is usually a direct attachement of the muscle cells to the bone; is considered the ______ .

origin

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The ________ is the more distal attachment or the part that moves the most, ofen by a tendon or aponerosis extending from the muscle cells to bone.

insertion

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The _______ _______ is a thin sheet of muscle that covers most of the dorsal, lateral, and ventral walls of the thorax and abdomen.

Cutaneus trunci

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Superficial Pectoral (2 parts)

This muscle has two parts: pectoralis transversus (or transverse part of the supf. pect.) and pectoralis descendens (or descending part of the supf. pect.).

Origin: first three sternebrae; median fibrous raphe at the ventral midline

Insertion: whole crest of the greater tubercle of the humerus

Action: 1. adducts the limb when not bearing weight; 2. prevents abduction of limb while bearing weight

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Deep pectoral

Origin: Ventral part of the sternum; median fibrous raphe at the ventral midline

Insertion: Lesser tubercle of the humerus (major portion of insertion); greater tubercle and crest via aponeurosis

Action: 1. Pull trunk cranially when limb is advances and fixed 2. extend shoulder 3. Draw limb caudally when not supporting weight

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An aponeurosis of this muscle extends into the axillary region and then converges with the medial fascia of the brachium… (which muscle is this?)

Deep pectoral

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The origin of this muscle is:

Origin: Clavicular intersection and it acts to

Action: 1. advance the limb 2. extend the shoulder 3. draw the head and neck to the side What is this muscle and what is its insertion ?

Brachiocephalicus;

Insertion: Distal end of cranial aspect of the humerus; middorsal fibrous raphe of the neck; mastoid part of the temporal bone

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The brachiocephalicus muscle extends from the arm (brachio-) to the head (-cephalo) and has two main parts:

What are the two main parts ? and which muscle is further divided into another two parts ? What are the names of the 3 divisions of the brachiocephalicus ?

Two main parts of the brachiocephalicus: cleidobrachialis and cleidocephalicus

Muscle divided into another two parts: clediocephalicus

– clediocervicalis & clediomastoideus

3 divisions of the brachiocephalicus:

cleidobrachialis
clediocervicalis (or cervical part of the cleidocephalicus)
clediomastoideus (or mastoid part of the cleidocephalicus)

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True or False The term “cleido-“ means “clavicle”. The dog does not have a true clavicle, but there is a strong connective tissue where the clavicle would have been. This region is called the clavicular intersetion

True

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Omotransversarius (Hint: “Omo” = shoulder ; “transversarius” = wing of the atlas, is the transverse process of the vertebra)

Origin: wing, or transverse process, of the atlas (cervical vertebra 1)

Insertion: distal end of the spine of the scapula

Action: advance the limb; flex the neck laterally (Note: this muscle extends from the shoulder to the transverse process, or wing, of the atlas.)

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Trapezius (2 main parts)

Origin: median fibrous raphe of the neck; supraspinous ligament

Insertion: spine of the scapula

Action: elevate and abduct limb at the shoulder

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Name the two main parts of the trapezius.

cervical trapezius and 2. thoracic trapezius

(Note: parts are connected by an aponeurosis located between them dorsally that attaches both parts to the spine of the scapula.)

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Name this muscle: (Hint: has 3 parts)

Origin: base of skull (nuchal crest of occipital bone); median fibrous raphe of neck; spinous process of thoracic vertebrae

Insertion: dorsal border of scapula

Action: elevate limb; draw scapula against trunk

Rhomboideus Three (3) Parts:

rhomboideus capitis (to the head),
rhomboideus cervicis (to the neck), and
rhomboideus thoracis (to the thorax).

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The tendon of this muscle joins with the tendon the teres major m.

latissimus dorsi

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Name this muscle:

Origin: thoracolumbar fascia; last 2 - 3 ribs

Insertion: teres major tuberosity of the humerus via the teres major tendon

Action: draw limb caudally (e.g., digging); flex shoulder

latissimus dorsi

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Serratus ventralis “sling muscle” (2 parts)

“serratus” means “serrated”

Hence: “serrated face”

Two parts: cervical and thoracic part

Origin: ribs; transverse processes of cervical vertebrae

Insertion: serrated face of the scapula

Action: support trunk; depress scapula; it acts as a sling in supporting the weight of the trunk between the two “posts” of the thoracic limbs.

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In the dog, this muscle has two parts: scapular part and acromial part (which muscle is this ?)

deltoideus

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Deltoideus

Origin: spine and acromial process of the scapula

Insertion: deltoid tuberosity of the humerus

Action: flex shoulder

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These 4 muscles also lend support to the shoulder joint by preventing either lateral or medial rotation when the animal is bearing weight (in dogs and humans)

infraspinatus, supraspinatus, subscapularis, and teres minor.

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The tendon of the __________ muscle has a subtendinous synovial bursa

infraspinatus

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infraspinatus

Origin: infraspinous fossa of the scapula

Insertion: lateral side of the greater tubercule of the humerus (small, circumscribed area)

Action: 1. laterally stabilizes the shoulder (prevents medial rotation while weight-bearing); 2. abduct and laterally rotate shoulder; 3. assists other muscles in the extension or flexion of shoulder

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To see this muscle, you will need to transect the deltoideus (both parts) and the infraspinatus muscles.

teres minor

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Teres minor

Origin: infraglenoid tubercle of the scapula; distal caudal border of the scapula Insertion: teres minor tuberosity of the humerus Action: 1. laterally stabilizes the shoulder (prevents medial rotation while weight-bearing); 2. laterally rotate shoulder; 3. flex shoulder (assists other muscles)

These 2 muscles entirely fill in the fossae on the lateral side of the scapular spine. If these muscles were to atrophy, the spine of the scapula would become visibly evident and palpable on the live animal. (What are these muscles ?)

infraspinatus and supraspinatus muscles

Supraspinatus

Origin: supraspinous fossa of the scapula Insertion: greater tubercle of the humerus (thick tendon) Action: 1. laterally stabilizes the shoulder (prevents medial rotation while weight-bearing); 2. extend shoulder

This muscle covers the medial side of the scapula

subscapularis

Subscapularis

Origin: Supraspinous fossa of the scapula Insertion: Lesser tubercle of the humerus Action: 1. medially stabilizes the shoulder (prevents lateral rotation while weight-bearing); 2. adduct shoulder; 3. extend shoulder

This muscle flexes the shoulder and rotates the arm medially. (Hint: muscle is on medial side)

Teres major

Origin: caudal angle and caudal border of the scapula; subscapularis muscle Insertion: teres major tuberosity of the humerus Action: flex shoulder; rotate arm medially

The tendon of origin of this muscle is quite long and is surrounded by a synovial sheath.

coracobrachialis

Origin: coracoid process of the scapula Insertion: crest of the lesser tubercle of the humerus, near the teres major tuberosity Action: mainly a shoulder stabilizer, but can assist other muscles in adduction and/or extension of the shoulder

Very thin muscle on the medial aspect of the brachium

tensor fasciae antebrachii

Origin: fascia covering the lateral surface of the latissimus dorsi muscle Insertion: olecranon of the ulna, in common with the tendon of insertion of the triceps brachii muscle Action: extend elbow

In dogs, there are four heads of this muscle: long head, lateral head, medial head, accessory head. (Which muscle is this ?)

triceps brachii

True or False Of the four heads (of the triceps brachii), the long head is the only one to cross the shoulder joint. All heads, including the long head, cross the elbow joint. This muscle is essential for weight-bearing, as it maintains extension of the elbow.

True

Triceps brachii

Origin: caudal border of scapula (long head); tricipital line, proximal humerus (neck, lesser tubercle, and crest of the lesser tubercle) Insertion: olecranon of ulna Action: flex shoulder (long head); extend elbow (all heads)

This muscle covers the olecranon fossa and will be encountered when surgically approaching the elbow joint

anconeus

What muscle is this ? Origin: Lateral supracondylar crest of the humerus; lateral and medial epicondyles of the humerus Insertion: proximal and lateral aspect of the ulna Action: to extend the elbow

anconeus

The tendon of origin of this muscle passes between the greater and lesser tubercles within the intertubercular groove of the humerus.

biceps brachii

The ________ \_\_\_\_\_\_\_\_ retinaculum extends from the greater to the lesser tubercle over this [intertubercular] groove, thereby holding the tendon of the biceps brachii in place.

transverse humeral

The major flexor muscles of the elbow are: ..?

The biceps brachii and brachiais muscles

The biceps brachii is located on the _____ aspect of the brachium; the brachialis muscle is located within the brachialis groove which originates on the ______ side of the brachium.

medial; lateral

This muscle: Originates from the supraglenoid tubercle of the scapula Inserts on the radial and ulnar tuberosities and acts to extend the shoulder; and flex the elbow

biceps brachii

The __________ muscle is located within the brachials groove of the humerus. The proximal aspect of the muscle is located on the _____ side of the brachium, but wraps around the humerus within the brachialis groove to the ______ aspect of the humerus. It has a common insertion with the biceps brachii muscle, as both of these muscles are the major _____ of the elbow joint.

brachialis; lateral; cranial; flexors

Brachialis

Origin: proximal and lateral aspect of the humerus Insertion: radial and ulnar tuberosities Action: To flex the elbow

Of all of the antebrachial muscles, this one has the most proximal origin, which is near the origin of the anconeus muscle from the lateral epicondylar crest of the humerus.

extensor carpi radialis

What are the muscles of ECLU on the canine antebrachium ?

E - Extensor carpi radialis C - Common digital extensor L - Lateral digital extensor U - Ulnaris lateralis

This muscle inserts onto metacarpal tuberosities (dorsal aspect) of MC II and III & Acts to: Extends the carpus

extensor carpi radialis Originates from the lateral supracondylar crest of the humerus

True or False ## Footnote The ulnaris lateralis is the only muscle of (ECLU) to originate from **lateral supracondylar crest** of the humerus; all the others originate from the _lateral epicondyle_ of the humerus

False ONLY the _extensor carpi radialis_ originates from lateral supracondylar crest of the humerus;

This muscle inserts on the extensor processes of the distal phalanx of digits II, III, IV, and V

common digital extensor

Origin: lateral epicondyle of the humerus Insertion: extensor processes of the distal phalanx of digits II, III, IV, and V Action: extend the joints of the four principal digits

Lateral digital extensor

Origin: lateral epicondyle of the humerus Insertion: extensor process of the distal phalanx of digits III, IV, and V; proximal ends of all phalanges of same digits Action: Extend the joints of digits III, IV, and V

This muscle is the only flexor muscle of the antebrachium that originates from the lateral epicondyle of the humerus. (Hint: once called the extensor carpi ulnaris) - This muscle flexes and **ab**ducts the carpus

ulnaris lateralis

This muscle inserts on the lateral aspect of the proximal end of MC V; accessory carpal bone...

ulnaris lateralis

Origin: lateral epicondyle of the humerus Insertion: lateral aspect of the proximal end of MC V; accessory carpal bone Action: abducts the carpus ; flexes the carpus

The ___________ laterally rotates the antebrachium

Supinator

Origin: lateral epicondyle of the humerus Insertion: lateral aspect of the proximal end of MC V; accessory carpal bone Action: abduct the carpus; flex the carpus

The _________ \_\_\_\_\_\_\_\_\_ medially rotates the antebrachium is so that the palmar surface of the paw is planted on the ground. This muscle can also result in a slight orientation of the paw to face laterally.

Pronator teres (Note: that the antebrachium in the dog and cat, due to their stance, is in a natural state of pronation. )

Pronator teres

Origin: medial epicondyle of the humerus Insertion: medial border of the radius Action: pronation (rotate the antebrachium medially so that the palmar surface of the paw faces the ground)

The __________ \_\_\_\_\_\_\_\_\_ __________ inserts on the proximal end of metacarpal I

Abductor pollicis longus Also called: long abductor of the first digit (Note: "pollicis" means "thumb" or 1st digit of the manus)

Abductor pollicis longus

Origin: lateral and cranial border of the ulna; interosseus membrane between the radius and ulna Insertions: proximal end of metacarpal I Action: abduct digit I

True or False All of the flexor muscles of the carpus and digits originate from the medial epicondyle of the humerus.

True

The ______ \_\_\_\_\_\_\_ _______ inserts on the palmar surface of proximal MC II and III

Flexor carpis radialis

Flexor carpi radialis

Origin: medial epicondyle of the humerus; medial border of the radius Inserts: palmar surface of proximal MC II and III Action: Flexes the carpus

The superficial digital flexor muscle and tendon are located ________ (superficial/deep) to the deep digital flexor muscle in the antebrachial, carpal, and metacarpal regions. Just ______ (proximal/distal) to the metacarpophalangeal joint, the SDF forms somewhat of a sleeve so that the tendon of the DDF can pass through. This sleeve is called the ________ \_\_\_\_\_\_\_\_\_

superficial; distal; flexor manica

The SDF inserts more _______ (distally/proximally) than the DDF (hence the change in orientation). There are ______ \_\_\_\_\_\_\_ that hold down the tendons of the SDF and DDF

proximally; annular ligaments

The ______ annular ligament holds down the tendons of both the SDF and the DDF at the level of the metacarpophalangeal joint,

palmar

The _______ \_\_\_\_\_\_\_ annular ligament holds down the tendons of the SDF and DDF at the level of the proximal phalanx of the digits,

proximal digital

The _______ \_\_\_\_\_\_\_\_ annular ligament holds down the tendon of the DDF at the proximal (palmar) aspect of the middle phalanx of the digits.

distal digital

This muscle inserts on the palmar surface of the base of the middle phalanges of digits II, III, IV, and V.

Superficial digital flexor

Origin: medial epicondyle of the humerus Inserts: palmar surface of the base of the middle phalanges of digits II, III, IV, and V Action: flex digits II - V

This muscle has two heads: ulnar head and humeral head. (Which muscle is this?)

Flexor carpi ulnaris

This flexor muscle inserts on the accessory carpal bone in canine.

flexor carpi ulnaris

Flexor carpi ulnaris

Origin: medial epicondyle of the humerus; caudal and medial aspect of olecranon Insertion: accessory carpal bone Action: Flexes the carpus

This muscle has three heads: radial, humeral and ulnar. (Which muscle is this?)

Deep digital flexor

Origin: medial epicondyle of the humerus; ulna; radius Inserts: flexor tubercle (palmar surface of the base) of the distal phalanx of each digit Action: To flex the digits

This muscle is located within the space between the radius and ulna bones and acts to pronate the antebrachium.

Pronator quadratus

In the dog, there are four _________ (singular) muscles which are fleshy and similar in size and shape. They lie deep to the deep digital flexor tendons and cover the palmar surfaces of the four main metacarpal bones

interosseus [Note: Interossei (plural)]

True or False ## Footnote The tendon of each interosseus muscle divides and each tendon encompases a sesamoid bone at the level of the palmar surface of the metacarpophalangeal joint. There are thus **two proximal sesamoids** embedded in the tendon of insertion of each interosseus muscle.

True

True or False ## Footnote If each tendon of each interosseus muscle divides and attaches to two proximal sesamoids than they attach to 8 proximal sesamoid bones total.

True There are only 4 interossei muscles (none on digit 1)

True or False ## Footnote There are extensor processes that extend from the interosseus tendon to the dorsal surface of the paw and unite with the tendons of the lateral digital extensor m.

False They unite with the _Common_ digital extensor

A ______ consists of dense, regularly arranged fibe=rous connective tissue organized into a small, well-defined bundle.

Tendon

An __________ has the same consistancy as a tendon, but fibrous tissue is arranged as a thin sheet of tissue.

aponeurosis

A ________ is dense fibrous connective tissue between bones. Can be used for a variety of thin fibrous connections between organs or between an organ ans the body wall.

ligament

True or False ## Footnote The _extrinsic_ muscles of the thoracic limb are those that attach the limb to the axial skeleton; the _intrinsic_ muscles extend between the bones that compose the limb itself.

True

\_\_\_\_\_\_ ______ appears as a thin layer of loose, irregularly arranged connective tissue that often contains fat. \_\_\_\_\_\_ is a denser, more regularly arranged thin layer of connective tissue. It is more fibrous, and it envelops the body beneath the skin and encloses individual muscles or groups of muscles.

Areolar tissue ; Fascia

The _______ fascia is deep to the areolar tissue, forming the deep portion of the subcutaneous tissue that covers the entire body. It blends with the ____ fascia, which is more firmly attached to the muscle that it encloses.

superficial ; deep

The costal cartilages of the tenth, eleventh, and twelfth ribs unite with each other to form the ______ \_\_\_\_\_. Palpate this arch and the caudal border and free end of the last or thirteenth rib. This rib does not attach [here] and is therefore called a “floating rib.”

costal arch

The attachments of the cutaneus trunci are the _________ \_\_\_\_\_\_\_ of the trunk and the skin. The muscle sends a fasciculus to the medial side of the forelimb; caudal and ventral to this the fibers fray out over the deep pectoral muscle. The cutaneus trunci twitches the skin. It is innervated by the _lateral thoracic nerve_.

superficial fascia

In the male dog there is a distinct development of the cutaneous trunci muscle adjacent to the ventral midline caudal to the _xiphoid_. This is the ______ muscle, which passes caudally and radiates into the prepuce, forming an arch with the muscle of the opposite side. It functions to support the cranial end of the prepuce during the nonerect state and to pull the prepuce back over the glans penis after erection and protrusion.

preputial [muscle]

The ______ \_\_\_\_\_\_ is formed by the accessory carpal bone laterally, the palmar carpal ligament and the carpal bones dorsally, and the flexor retinaculum on the palmar surface.

carpal canal

The small pad that protrudes palmar to the carpus is the _____ pad. The largest in the paw, the ________ pad, is on the palmar side of the metacarpophalangeal joints and is triangular. The ______ pads are ovoid and flattened. Each is located palmar to the distal interphalangeal joint.

carpal ; metacarpal ; digital

Muscles of the **Stance Phase:** These muscles stabilize the limb to body wall (4):

* Serratus ventralis m. * Superficial and deep pectoral mm. * Trapezius m. * Rhomboideus m.

Muscles of the **Stance Phase:** These muscle stabilize the shoulder (8):

* Supraspinatus m. * Infraspinatus m. * Subscapularis m. * Teres minor m. * Teres major m. * Coracobrachialis m. * Biceps brachii m. * Triceps brahcii m. (long head)

Muscles of the **Stance Phase:** These muscles extend the elbow (3):

* Tensor fasciae antebrachii m. * Triceps brachii m. (all heads) * Anconeus m.

Muscles of the **Stance phase:** These muscle flex the carpus and digits:

* Ulnaris lateralis m. * Flexor carpi ulnaris m. * Flexor carpi radialis m. * SDF and DDF

Major Muscles of the **Swing Phase:** **Phase 1** (10 muscles): Limb is advanced; shoulder and carpus are extended; elbow angle varies but extended in full stretch

* Brachiocephalicus m. * Omotransversarius m. * Trapezius m. * Rhomboideus m. * Serratus ventralis (cervical) m. * Triceps brachii m. * Biceps brachii m. * Extensor carpi radialis m. * Common digital extensor m. * Lateral digital extensor m.

Major Muscles of the **Swing Phase:** **Phase 2** (10 muscles): Limb is pulled caudally; shoulder and carpus are flexed; elbow angle varies, but flexed during full gallop [![]() ](https://s3.amazonaws.com/brainscape-prod/system/cm/149/361/831/q_image_card.png?1433989592)

* Deep pectoral m. * Latissimus dorsi m. * Deltoideus m. * Teres major m. * Triceps brachii m. * Biceps brachii m. * Flexor carpi radialis m. * Ulnaris lateralis m. * SDF and • DDF mm.

The superficial cervical lymph node(s) are located under what muscle ?

Omotransversarius

Name the two cutaneous muscles: 1. _________ \_\_\_\_\_\_\_\_ (over the trunk region) 2. ____________ (over the neck region)

1. cutaneous trunci 2. platysma

True or False ## Footnote At the axillary (armpit) region the cutaneous trunci muscle become thick and leaves the skin to converge with the fibers of the deep pectoral and latissimus dorsi muscles

True

True or False ## Footnote The sternocephalicus; sternohyroideus; and sternothyroideus are NOT extrinsic muscles of the thoracic limb

True

The dorsal boarder of the sternocephalicus is adjacent to the _________ (dorsal/ventral) boarder of the cleidocephalicus and the jugular vein crosses its _______ (medial/lateral) surface obliquely.

ventral; lateral

Name the _two cranial parts_ of the sternocephalicus muscle.

1. **mastoid part** (ventrally) (from sternum to the mastoid process/part of the temporal bone of the skull) 2. **occipital part** (dorsally) [- formerly the sterno-occipitalis] (from the sternum to the nuchal crest of the occipital bone)

Sternocephalicus

**Origin**: First sternebra or manubrium **Insertion**: The mastoid part of the temporal bone and the nuchal crest of the occipital bone **Action**: To draw the head and neck to the side

Sternohyoideus [NOT an extrinsic muscle of the thoracic limb]

**Origin:** The firs sternebra and the first costal cartilage **Insertion:** The basihyoid bone **Action:** To pull the tounge and larynx caudally

True or False The sternohyoideus lies on the trachea and is covered by the sternocephalicus caudally.

True

Sternothyroideus

**Origin:** The first costal cartilage **Insertion:** The caudolateral surface of the thyroid cartilage **Action:** Same as the sternohyoideus - to draw the larynx and tounge caudally

True or False The **deep fascia of the neck** covers the sternohyoideus and sternothyroideus ventrally and surrounds the trachea, thyroid gland, larynx, and esophagus.

True

The deep fascia that covers the common carotid artery, vagosympathetic nerve trunk, internal jugular vein, and tracheal lymohatic trunk is called the:

carotid sheath