Canine Thoracic Limb - Muscles Flashcards
True or False
The thoracic limb is connected to the
body via extrinsic muscles (synsarcosis)
True
Name the 8 extrinsic muscles of the thoracic limb
- Superficial pectoral
- Deep pectoral
- Brachiocephalicus
- Omotransversarius
- Trapezius
- Rhomboideus
- Latissimus dorsi
- Serratus ventralis
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
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
The _______ _______ is a thin sheet of muscle that covers most of the dorsal, lateral, and ventral walls of the thorax and abdomen.
Cutaneus trunci
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
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
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
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
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)
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
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.)
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
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.)
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).
The tendon of this muscle joins with the tendon the teres major m.
latissimus dorsi
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
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.
In the dog, this muscle has two parts: scapular part and acromial part (which muscle is this ?)
deltoideus
Deltoideus
Origin: spine and acromial process of the scapula
Insertion: deltoid tuberosity of the humerus
Action: flex shoulder
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.
The tendon of the __________ muscle has a subtendinous synovial bursa
infraspinatus
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
To see this muscle, you will need to transect the deltoideus (both parts) and the infraspinatus muscles.
teres minor
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
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
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
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
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
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 abducts the carpus
ulnaris lateralis
This muscle inserts on the lateral aspect of the proximal end of MC V; accessory carpal bone…
ulnaris lateralis
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
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
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
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
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
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
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
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.
- 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:
- _________ ________ (over the trunk region)
- ____________ (over the neck region)
- cutaneous trunci
- platysma
True or False
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
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.
- mastoid part (ventrally)
(from sternum to the mastoid process/part of the temporal bone of the skull)
- 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
