Download Extrinsic Muscles of the Thoracic (or Pectoral) Limb (Muscles that

Extrinsic Muscles of the Thoracic (or Pectoral) Limb
(Muscles that attach the thoracic limb to the body)
Muscle
Parts
Origin (or Attachments)
Insertion
Clinical note*** The following 4 muscles attach to the scapula. Scapulectomy would require cutting these 4 muscles
1. Cervical 1. Median fibrous raphe of the neck
Spine of the scapula
Trapezius
2. Thoracic 2. Supraspinous ligament and dorsal
spines of thoracic vertebrae 1-9
1. Cervical 1. Transverse processes of last 3
Serrated face of the
Serratus ventralis
cervical vertebrae
scapula
2. Thoracic
Omotransversarius
Rhomboideus
1. Capitis (only in
carnivores)
2. Cervical
2. Lateral surface of the ribs 1-8
Wing of the atlas
1. Occipital bone of skull
Lower spine of scapula
N. Supply
Action
Dorsal branch of the
accessory (CN X1) n.
Elevate and draw the
limb forward
1. Ventral branches of last 3
cervical spinal nerves
2. Long thoracic n. of the
brachial plexus
Passive support of the
trunk; thoracic part aids
inspiration; moves
scapula forward and
back
Draws scapula forward
Elevate the limb; move
scapula forward,
backward, and pull it
close to the trunk
Accessory (CN XI) n.
Ventral branches of cervical
and thoracic spinal nerves
2. Fibrous raphe of neck, spines of
thoracic vertebrae
3. Thoracic 3. Spines of thoracic vertebrae (4-6)
Clinical note*** The following 3 muscles attach to the humerus. Removal of the limb distal to the shoulder joint would require cutting these 3 muscles
Thoracodordal fascia via aponeurosis,
Teres tubercle on the
Thoracodorsal nerve of the
Draw the limb
Latissimus dorsi
lateral surface of last 3 ribs
medial shaft of the
brachial plexus
backwards; flex the
humerus
shoulder joint
1. Cleidobrachialis 1. Distal part of humeral crest
1. Nerve of the
Draw limb forward,
Brachiocephalicus
brachiocephalicus (from the
acting bilaterally;
2. Cleidocephalicus
Brachial Plexus)
unilateral neck flexion
Cleidocervicalis Cranial half of cervical raphe
2. Ventral branches of
Cleidomastoideus Mastoid part of skull
several cervical nerves as
well as accessory n.
Note***Complex innervation of brachiocephalicus m. indicates that the muscle resulted from fusion of various muscles from evolution
1. Superficial 1. First two sternebrae and associated
1. Crest of major
1. Cranial pectoral n.
Adduction of limb;
Pectoral muscles
Descending costal cartilages
tubercle of humerus
helps to draw limb
Transverse
backwards, or pull
2. Deep 2. All sternebrae
2. Greater and lesser
2. Caudal pectoral n.
trunk forward
(Ascending)
tubercles of humerus
Cat Differences
- Cleidobrachialis m. is broader, and has tendinous attachment to ulna
- Latissimus dorsi m. is partially fused to superficial pectoral in the axillary region
Why does the clavicle of the cat (but not the dog) have radiographic significance? The clavicle of the cat is well-developed and serves to stabilize the shoulder for climbing,
whereas the absence of a clavicle in the dog allows for efficient running. On a lateral radiograph, the clavicle of a cat may be mistaken for a bone in the esophagus, so two
radiographic views must be taken.
Muscles of the Neck
Muscle
Sphincter colli
superficialis
Platysma
Sphincter colli
profundus
Cutaneous trunci
Sternocephalicus
Parts
Origin (or Attachments)
Insertion
N. Supply
1. Facial
2. Cervical
Only in carnivores
Maybe derivative
of deep pectoral m.
1. Occipital
2. Mastoid (deeper)
Twitches skin over nape of neck
1. Manubrium of sternum
2. “ “
1. Nuchal line of occipital bone
2. Mastoid part of the skull
Note***External jugular vein runs on the lateral surface of the sterno-occipital part of the sternocephalicus m.
1. Sternohyoideus 1. Manubrium of sternum
1. Basihyoid bone of hyoid apparatus
Sternothyrohyoideus
2. Sternothyroideus 2. “ “
2. Lateral surface of thyroid cartilage
Longus capitis
“V”-shaped attachments
Longus colli
points on vertebral bodies
Carotid Sheath
- Made up of deep fascia, which is continuous with the fascia of the thorax
 Any infection of the carotid sheath can potentially cause infection in the thorax
- Envelops 5 structures:
 Common carotid artery
 Internal jugular vein
 Vagosympathetic trunk
 Tracheal lymph duct
 Recurrent laryngeal n.
Cat differences
- Nuchal ligament absent
Action
Lateral
thoracic n.
Accessory n.
(CN XI)
Twitches skin over body
Flexes the neck when acting
bilaterally; helps to turn the head
to one side
Draw the larynx and tongue
caudally (aids in swallowing)
Intrinsic Muscles of the Thoracic Limb
(Muscles that confine their attachments to the bones of the thoracic limb)
Muscle
Shoulder muscles:
Supraspinatus
Parts
Origin (or Attachments)
Supraspinous fossa, part of scapular
spine, scapular neck
Infraspinous fossa. scapular spine
Insertion
Greater tubercle of the humerus
N. Supply
Suprascapular n.
Action
Extension of the shoulder
Lateral aspect of the greater
Suprascapular n.
Mainly flexes the shoulder;
tubercle of the humerus
slight abduction of the limb
Clinical note***The infraspinatus m. tendon of insertion has a bursa associated with it. Bursitis of this structure may results in lameness of the shoulder
Mainly from infraglenoid tubercle
Tricipital line of humerus
Axillary n.
Flexes shoulder
Teres minor
Note***When caudal surgical approach to shoulder is attempted, teres minor m. must be reflected from joint capsule to which it closely attaches
1. Spinous 1. Spine of the scapula
1. Deltoid tuberosity
Axillary n.
Mainly flexes shoulder; slight
Deltoideus
2. Acromial 2. Acromion of scapula
2. “ “
abduction of limb
Clinical note***The deltoid m. does not have tendinous origin, but muscle fibers attach directly to acromion. In order to access shoulder joint, a surgeon cannot simply
reflect the muscle, but must perform acromiol osteotomy. Closure would require wiring of the acromial process back on the scapular spine
Subscapular fossa (medial aspect) of
Lesser tubercle of humerus
Subscapular and
Minor adduction of limb; aid
Subscapularis
scapular
axillary n.s
in flexion/extension
Caudal angle of scapula
Teres tubercle
Axillary n.
Flexes shoulder
Teres Major
Clinical note***Phylogenetically, teres major m. is part of latissimus dorsi m.
Coracoid process of scapula
Near teres tubercule
Musculocutaneous
Vestigal muscle; may extend
Coracobrachialis
n.
shoulder
Brachial muscles:
1. Long head 1. Caudal border of scapula
Olecranon
Radial n.
Flexes shoulder; extends
Triceps Brachii
2. Medial “ 2. Proximal medial shaft of humerus
elbow; crucial in supporting
(near teres tubercle)
the weight of the animal at the
3. Lateral “ 3. Tricipital line
elbow
4. Accessory “ 4. Neck of humerus
Latissimus dorsi
Olecranon
Radial n.
Extend Elbow
Tensor fascia
antebrachii
Supraglenoid tubercle
Ulnar and radial tuberosities
Musculocutaneous
Strong flexion of the elbow;
Biceps brachii
n.
weak extension of the
shoulder
Caudal aspect and neck of the
Ulnar and radial tuberosities
Musculocutaneous
Flex elbow
Brachialis
humerus
n.
Lateral epicondyle and its crest; partly Proximolateral aspect of the
Radial n.
Extend elbow
Anconeus
median epicondyle
ulna
Muscles of the carpus and digits:
Note***Most of the antebrachial muscles have tendon sheaths in the carpal region
Note***The extensors of the carpus and digits are on the craniolateral aspect of the antebrachium
Note***The brachioradialis m. has a 35% occurrence in the dog. It is always in the cat. It is an insignificant muscle located in the superficial fascia
Proximal aspect of the lateral
Distal radius
Radial n.
Aids in supination
Brachioradialis
epicondylar crest of the humerus
Infraspinatus
Extensor carpi
radialis (ECR)
Common digital
extensor (CDE)
Lateral digital
extensor (LDE)
Cephalic vein
lies on this m.
4 distal tendons
3 tendons join
w/ those of
CDE
Lateral epicondylar crest of the
humerus
Lateral epicondyle of the humerus
Lateral collateral ligament of elbow;
partly from proximal radius
Dorsal aspect of metacarpal II
and III
Ungual crest of 3rd phalanx of
digist II-V
Ungual crest of distal phalanges
of digist III-V
Radial n.
Radial n.
Radial n.
Lateral epicondyle of the humerus
Proximolateral aspect of
Radial n.
Extensor carpi
2 distal tendons
metacarpal V and accessory
ulnaris
carpal bone
(Ulnaris lateralis)
Lateral surface of radius and ulna
Proximomedial aspext of
Radial n.
Abductor pollicis
metacarpal I
longus
Lateral epicondyle of the humerus
Cranial surface of the radius
Radial n.
Supinator
Note***The flexors of the carpus and digits are located on the caudomedial aspect of the antebrachium
Interosseus surfaces on medial aspect
Median n.
Pronator quadratus
of radius and ulna
1. Ulnar head 1. Median epicondyle of humerus
Distal phalanges of all digits (I- Ulnar and Median
Deep digital flexor
2. Humeral 2. Caudal surface of ulna
V)
nerves
(DDF)
head
3. Radial head 3. Medial surface of radius
Note***If either the Ulnar or Median nerve (not both) is damaged, the DDF will still function
1. Humeral 1. Medial epicondyle of the humerus
Tendons from both heads unite
Ulnar n.
Flexor carpi ulnaris
head
to attach to accessory carpal
2. Ulnar head 2. Proximocaudal aspect of the ulna
bone
4 distal tendons Median epicondyle of the humerus
Palmar aspect of middle
Median n.
Superficial digital
phalanx of digits II-V
flexor (SDF)
Note***Each tendon of the SDF divides to permit the tendons of the DDF to pass through. This arrangement is called a manica flexoria
Medial epicondyle of the humerus
Proximolateral aspect of
Median n.
Flexor carpi radialis
metacarpals II and III
Medial epicondyle of the humerus
Cranial surface of the radius
Median n.
Pronator teres
Note***There are 4 interosseus muscles of forepaw (digits II-V)
Proximopalmar aspects of metacarpals Each muscle tendon splits into
Ulnar n.
Interosseus muscles
II-V
2 branches, eventually joining
of forpaw
the CDE tendons
Extends carpus; weak flexion
of the elbow
Extends carpus and digits
Extends lateral digits (III, IV,
and V)
May extend the carpus; may
flex the carpus
Abducts digit I; extends
carpus; may supinate paw
Supinates paw
Not much (weak pronation)
Flexes the carpus and digits
Flexes carpus
Flexes carpus and digits II-V
Flexes carpus
Pronates paw
Flexes metacarpo-phalangeal
joints
Cat Differences
- On the scapula, the hamate and suprahamate are processes of the acromion
- Biceps brachii m. attaches only to radius
- On the humerus, there is a supracondylar foramen
- Brachioradialis m. is well-defined, while absent in dog
- Complete claw-retention mechanism…HOW?
 Dorsal elastic ligaments in the car are stronger. Also, the articular facets between P2 and P3 in the cat are sloped so that when P3 is retrached, it is
displaced to the lateral surface of P2.
- Median n. and brachial artery pass through the supracondyloid foramen on cat
Muscles of the Pelvic Limb
Muscle
Parts
Origin (or Attachments)
Insertion
N. Supply
Action
Note***There are no “extrinsic” muscles of the pelvic limb because the pelvic limb articulates with the axial skeleton via attachment of the os-coxae (hipbone) to vertebrae
1. Cranial Tuber coxae, aponeurosis of middle
Lateral femoral fascia
Cranial gluteal n.
Tense lateral femoral fascia; flex
Tensor fascia latae
2. Caudal gluteus m.
hip; extend stifle (indirectly)
rd
Sacral
tuberosity
of
the
ilium
via
3
trochanter
of
the
femur
Caudal
gluteal
n.
Extends hip joint
Superficial gluteus
deep fascia, lateral sacrum, 1st caudal
vertebrae, cranial sacrotuberous
ligament
Lateral gluteal surgace of ilium
Greater trochanter
Cranial gluteal n.; Extends hip joint
Middle gluteus
sometimes caudal
gluteal n.
Fusiform m. Last sacral and 1st caudal vertebrae
Greater trochanter
Caudal gluteal n.
Extends hip joint
Pyriformis
Lateral shaft of ilium
Greater trochanter
Cranial gluteal n.
Extends hip joint
Deep gluteus
“fire hydrant” m. Intrapelvic borders surrounding
Trochanteric fossa
Sciatic n.
Abducts hip joint
Internal obturator
obturator foramen
Tendon of the internal obturator m.
Sciatic n.
Abducts hip
Gemelli
Ventral surface of ischium
Ventral to trochanteric fossa, Sciatic n.
Extends hip; weak abduction of
Quadratus femoris
caudal proximal femur
hip
1. Cranial Ischial tuberosity, distal part of
1. Patella
Sciatic n.; caudal
Extends hip, stifle, and hock;
Biceps femoris
2. Middle sacrotuberous ligament
2. Tibial crest
gluteal n.
flexes stifle
3. Caudal
3. Tuber calcaneous
Abductor cruris caudalis
Sacrotuberous ligament
Distal lateral crural fascia
Sciatic n.
Abducts limb
(caudal crural abductor)
Medial aspect of tibial crest,
Sciatic n.
Extends hip and hock; flexes
tuber calcaneus
stifle
1. Cranial belly Ventral aspect of ischiatic tuberosity 1. Distal aspect of femur
Sciatic n.
Extends hip joint; only caudal
Semimembranosus
2. Caudal belly and arch
2. Medial condyle of tibia
belly flexes the stifle
Clinical note***Do not use the semimem. and semiten. for IM injections because the sciatic nerve could be damaged. Better to use the middle gluteus or epaxial muscles
Rectus femoris m., lateral and
Patella, patellar ligament
Femoral n.
Bearing weight on pelvic limb;
Quadriceps femoris
intermediate vastus lateralis m.
attached to tibial tuberosity
flexes hip; extends stifle
1. Cranial Iliac crest
1. Patella
Femoral n.
Flexes hip; cranial part extends
Sartorius
2. Caudal
2. Medial tibial crest
stifle; caudal part flexes stifle
Muscles innervated by the obturator nerve:
Prepubic tendon
Medial lip of femur
Obturator n.
Adducts limb
Pectineus
Clinical note***Craniomedial to the pectineus m. is the inguinal canal, which is palpated to examine an inguinal hernia. Cutting this muscle may temporarily relieve pain
1. Magnus et Pelvic symphysis via symphyseal
1. Lateral lip of femur
Obturator n.
Adducts limb; may extend hip
Adductor
brevis tendon
2. Caudal femur ventral to
2. Longus
inter-trochanteric ridge
Pelvic symphysis via symphyseal
Cranial tendon to medial
Obturator n.
Adducts limb; weak stifle
Gracilis
tendon
aspect of tibial crest, caudal
extension; weak hock extension
tendon to tuber calcis
Outer margins of obturator foramen, Trochanteric fossa
Obturator n.
Adducts limb
External obturator
Semitendinosus
Ischial tuberosity
ventral aspect of hip bone
Crural muscles (those related to the tibia and fibula) of the pelvic limb:
Lateral proximal tibia, tibial crest,
Cranial tibial
extensor sulcus
Extensor fossa of femur
Long digital extensor
Peroneus longus
(fibularis longus)
Lateral condyle of tibia, proximal
aspect of fibula
Metatarsals I and II,
proximo-plantar aspect
P3 Ungual crest of digits IIV
Plantar aspect of 4th tarsal
bone, proximo-plantar aspect
of all metatarsal bones
Peroneal n.
Peroneal n.
Flexes tarsus; supination of limb;
no action on stifle
Flexes hock; extends digits
Peroneal n.
Flexes tarsus, pronation of limb
VESTIGAL
Peroneal n.
Nothing
Lateral digital
extensor
Peroneal n.
Flexes tarsal joint
Peroneus brevis
Muscles innervated by the tibial nerve:
1. Lateral head 1. Lateral supracondylar tuberosity
Tuber calcaneus
Tibial n.
Flexes stifle; extends hock
Gastrocnemius
2. Medial head 2. Medial supracondylar tuberasity
Note***Each head of the gastrocnemius m. has a sesamoid bone at its origin, called a fabella, which both form a synovial joint with the femoral condyles
Note***In the cat, the gastrocnemius m. and the soleus m. are together called the “triceps surae”
Lateral supracondylar tuberosity,
Tuber calcis, terminates in 4
Tibial n.
Flexes stifle and all digits;
Superficial digital
lateral head of gastrocnemius m.
tendons of P2 of all digits
extends tarsal joint
flexor (SDF)
Note***There is a synovial bursa under the SDF m. tendon over the calcanean tuberosity. This bursa can be inflamed and enlarged, a condition called “capped hock”
1. Lateral head 1. Caudal fibula, caudal-lateral tibia
Common tendon of talus,
Tibial n.
1.Extends tarsal joint; flexes
Deep digital flexor
2. Medial head 1. Proximo-caudal tibia
which terminates at plantar
digits
(DDF)
aspect of P3 of digits II-V
2. Nothing
Note***The DDF m. has 2 heads in carnivores and 3 heads in ungulates
Popliteal fossa of femur
Proximo-caudal tibia
Tibial n.
Flexes stifle, pronation of limb
Popliteus
5 Muscles of the Common Calcanean Tendon
- Biceps femoris m.
- Semitendinosus m.
- Gastrocnemius m.
- Superficial digital flexor (SDF) m.
- Gracilis m.
- Soleus m. (only cat)
Cat Differences
- No sacrotuberous ligament
- Sartorius m. is not divided into 2 bellies
- Caudofemoralis m. (adductor cruris cranialis m.) only in cat
Muscles of Thorax and Abdomen
(Derived from hypomeres of somites and innervated by ventral branches of the spinal nerves)
Muscle
Muscles of the thoracic wall:
Scalenus
Parts
Origin (or Attachments)
Insertion
N. Supply
Action
1. Dorsal scalenus (Dorsal and Ventral parts)
2. Middle scalenus
3. Ventral
Serratus ventralis cervicis
Serratus ventralis thoracis
Serratus dorsalis cranialis
Thoracolumbar fascia
Proximo-caudal margin of ribs 11-13 Intercostal n.s
Aids in expiration
Serratus dorsalis caudalis
Fiber direction is caudoventral (caudal edge of one rib to cranial end of succeeding rib)
Intercostal n.s
Aid in inspiration
External intercostals
Fiber direction is cranioventral (cranial edge of one rib to caudal end of preceding rib)
Intercostal n.s
Aid in expiration
Internal intercostals
1st rib
Ventral ends of ribs 2-4
Intercostal n.s
Aids in inspiration
Rectus thoracis
Muscles of the abdominal wall:
Note***Only in carnivores, the superficial fascia of the trunk is neither attached to the spinous processes nor the linea alba, but forms a continuous sheet of connective tissue
from one side of the body to the other. This is why a wet dog can move their trunk skin extensively to dry themselves
Lateral aspect of ribs,
Wide aponeurosis to linea alba,
Ventral branches of
Compresses abdomen;
External abdominal oblique
thoracolumbar fascia from Tprepubic tendon, and shaft of ileum
thoracic and lumbar aids in expiration
processes of lumbar vertebrae
n.s
Tuber coxae, thoracolumbar
Costal arch, last rib, linea alba,
Ventral branches of
Compresses abdomen;
Internal abdominal oblique
fascia
prepubic tendon
last thoracic n.s, 1st
aids in expiration
lumbar n.s
Cremaster
Tuber coxae, lumbar TLinea alba, prepubic tendon
Ventral branches of
Compresses abdomen;
Transverse abdominis
processes, costal cartilarges
last thoracic and
aids in expiration
lumbar n.s
Ventral aspect of sternum
Prepubic tendon
Thoracic and few
Compresses abdomen;
Rectus abdominis
lumbar n.s
aids in expiration
Epaxial Muscles
(Derived from epimeres, express MYF5 protein during development, innervated by dorsal branches of spinal nerves)
Muscle
Parts
Origin (or Attachments)
Insertion
N. Supply
Action
Muscles of the Transversospinalis system:
Splenius
1. Biventor 2. Complexus
Semispinalis capitis
Parts of the Longissimus system (longest muscle system in the body):
Attaches to the head
Longissimus capitis
Attaches to the cervical vertebrae (has 3-4 fascicles)
Longissimus cervicis
Longissimus thoracis
Longissimus lumborum
Parts of the Iliocostalis system:
Iliocostalis thoracis
Iliocostalis lumborum
Note***In the lumbar region, the longissimus lumborum m. and iliocostalis lumborum m. are fused, giving rise to a strong erector spinae m. (in humans)