4. Muscles of Axial Skeleton
remove the lamina of the vertebra to gain access to spinal cord. used for surgical repair for dorsal extrusions of intervertebral disks
dorsal laminectomy
which muscles are generally stronger? epaxial or hypaxial
epaxial
-muscles that lie dorsal to the transverse processes of the vertebrae. -function mainly as extensors of the vertebral column
epaxial group
-Decrease volume of thorax; opposite of inspiration -Ribs drawn caudally, decreasing transverse diameter and volume of thorax (Internal intercostal mm., serratus dorsalis caudalis m., abdominal muscles)
expiration
-biventer cervicis (dorsal with tendinous intersections) -complexus of the semispinalis captious of the transverse spinalis system
semispinalis capitis
often split into two parts; cranial and caudalis
serratus dorsalis
is much smaller and found on the dorsal surface of the caudal thorax, with attachments to the thoracolumbar fascia and the caudal borders of the last three (3) ribs. -Draws the last 3 ribs caudally in expiration.
serratus dorsalis caudalis
will be found on the dorsal surface of the cranial thorax, with attachments by a broad aponeurosis deep to the rhomboideus m. to the median raphe of the neck and will insert on the craniolateral surface of the ribs. -It will lift the ribs as part of inspiration
serratus dorsalis cranialis
large muscle on dorsolateral aspect of neck, deep to rhomboideus capitis -Arises from spinous processes of first 3 thoracic vertebrae, thoracolumbar fascia, and median raphe of neck and inserts on nuchal crest and mastoid region of temporal bone (skull)
splenius
what muscles are included in iliocostalis system of epaxial muscles?
1. Iliocostalis lumborum -Located in the lumbar region -Pins are across the lumbar region 2. Iliocostalis thoracis Located on the thorax Pins are across the lumbar
what muscles are included in the longissimus system of epaxial muscles?
1. Longissimus thoracis and lumborum 2. Longissimus cervicis 3. Longissimus capitis
there are ___ parallel muscle masses, or systems, affiliated with the dorsal vertebral column (epaxial muscles)
3 *backstrap muscles
identify the structures
A, Transverse section of the canine neck at the level of the fifth cervical vertebra. B, Left external jugular vein raised by thumb pressure at the base of the neck. 1, Nuchal ligament; 2, trapezius; 3, rhomboideus; 4, splenius; 5, cleidocervicalis; 6, omotransversarius; 7, cleidomastoideus; 8, sternocephalicus; 9, sternothyrohyoideus; 10, trachea; 11, esophagus; 12, external jugular vein; 13, common carotid artery, vagosympathetic trunk, and recurrent laryngeal nerve; 14, superficial cervical vessels; 15, superficial cervical lymph nodes; 16, fifth cervical vertebra; 17, vertebral vessels.
what muscles are included in the lateral group of epaxial muscles?
Iliocostalis system ilium to ribs
what muscles are included in the intermediate group of epaxial muscles?
Longissimus system ilium to head
what muscles are included in the medial group of epaxial muscles?
Transversospinalis system -Transversing the spine (sacrum to head) -sacrum to head
-multipurpose limbs -flexible trunks: allows increase stride length
biomechanics of carnivores
-trachea -esophagus -thyroid and parathyroid glands -recurrent laryngeal nerves -tracheal lymph nodes -carotid sheath: common carotid arteries, vagosympathetic trunks, internal jugular veins
cervical visceral space
there are 12 of these muscles on each right & left sides of the thoracic wall -Run caudoventrally from the caudal border of a cranial rib to the cranial border of the adjacent caudal rib -The caudal border of these muscles is near the costochondral junction -Function in respiration by drawing the ribs together
external intercostal
-muscles that lie ventral to the vertebral bodies and transverse processes. -includes the muscles of the thoracic and abdominal walls.
hypaxial group
flexors of the neck
hypaxial muscles
lie ventral to the transverse processes of the vertebrae -Will include muscles of the vertebral column and muscles of the thoracic and abdominal walls
hypaxial muscles
longus coli: -located on the ventral surfaces of the vertebral bodies (T6-C1) -extends into the thorax longus capitis: -located immediately ventral to the cervical vertebral transverse processes
hypaxial muscles
originates on wing of ilium, inserts on transverse processes of lumbar vertebrae and caudal 4-5 ribs o Fused medially with longissimus lumborum, difficult to distinguish
iliocostalis lumborum
• Attachments: ilium & transverse processes of lumbar vertebrae; inserts on cranial lumbar vertebrae and ribs with a weaker connection to the neck • Assists in bending the trunk laterally
iliocostalis system
originates on the 12th rib to the transverse process of the 7th cervical vertebra, with individual components that transverse the ribs
iliocostalis thoracis
-Increase volume of the thorax, allowing expansion of lungs -Ribs pulled cranially (External intercostal mm., rectus thoracis m., serratus dorsalis cranialis m., scalenus m)
inspiration
Longissimus system (ilium to head)
intermediate group of epaxial muscles
will be found just deep to the external intercostal mm. -Fibers run cranioventrally from caudal border of a cranial rib to the cranial border of the adjacent caudal rib -Medial to these muscles is the thoracic pleura (and therefore access to the thoracic cavity) -Function is similar to external intercostal mm.
internal intercostal
Iliocostalis system (ilium to ribs)
lateral group of epaxial muscles
distinct muscles, medial to longissimus cervicis m. and splenius m. -Originates from thoracic vertebrae 1-3 and inserts on the mastoid part of temporal bone (skull)
longissimus capitis
cranial continuation of the longissimus thoracis et lumborum system -Will be found in angle between cervical and thoracic vertebrae; insert on transverse process of caudal few cervical vertebrae
longissimus cervicis
difficult to distinguish from iliocostalis system in lumbar region -Originates from iliac crest and medial wing of ilium and supraspinous ligament and spines of lumbar and thoracic vertebrae -Inserts on various processes of lumbar and thoracic vertebrae, thoracic portion inserts on ribs and 7th cervical vertebra
longissimus thoracis et lumborum system
lies lateral to longus colli m.; extends from transverse processes of midcervical vertebrae to a process on the basioccipital bone of the skull
longus capitis
form the dorsal border of the vertical visceral space
longus coli longus capitis
spans from the cranial thoracic region to atlas, covering ventral surfaces of vertebral bodies
longus colli
Transversospinalis system -Transversing the spine (sacrum to head)
medial group of epaxial muscles
Serratus dorsalis m. -Cranialis & caudalis External intercostal mm. Internal intercostal mm. -Deep to externalcostal Scalenus m. Rectus thoracis m.
muscles of the thoracic wall
what lies between the medial surfaces of the 2 semispinalis captious muscles?
nuchal ligament
-Biventer cervicis m.: has distinct tendinous intersections; arises from thoracic vertebrae and inserts on caudal surface of the skull -Complexus m.: will be ventral to biventer cervicis m. and arises from cervical vertebrae and inserts on the nuchal crest (skull)
semipinalis capitis
Will be found deep to splenius m. Composed of two muscles
semipinalis capitis
what muscles are included in the transversospinalis system of epaxial muscles?
semispinalis capatis
the muscles of the thoracic wall are primary used for?
respiration
a group of muscles (divided into several slips that may be identified as separate dorsal, middle, and ventral parts) that will be located ventral to the cervical portion of the serratus ventralis m. -Attachments: first few ribs and transverse processes of cervical vertebrae
scalenus