Lecture 13 Flashcards
Which muscle group is derived directly from myotome portions of somites?
axial
What is metamerism?
segmental arrangement
WHich muscle groups display a metamerism?
axial and branchiometric
Which muscles are innervated by spinal nerves?
axial and appendicular
Branchiometric muscle groups are formed from
formed from embryonic mescenchyme associated with the pharyngeal arches.
Which muscle group is innervated by cranial nerves
branchiomeric
What do appendicular muscle groups form from?
limb bud mesenchyme
In gnathostomes axial muscles are typically divided into
• epaxial (more dorsal) and hypaxial (more ventral) muscles.
The Epaxial and Hypaxial parts are separated form each other by….
a fibrous tissue partition called the horizontal septum
the horizontal septum is not present in
cyclostomes
What separates individual myomers?
transverse septa
What innervates the lateral rectus muscle?
Abducens CN VI
What innervates the superior oblique?
Trochlear nerve CN IV
What does the occulomotor nerve (CNIII) Innervate?
♣ Inferior rectus
♣ Medial rectus
♣ Inferior rectus
♣ Inferior oblique
What is a myomere?
segments that make up the axial musculature
Describe the axial musculature of the amphibian and relate to that of a fish:
Reduction in epaxial muscles
Division of hypaxial mm into layers
Increase in mass and complexity of limb muscles.
NOTE: Fish need to have the axial musculature to swim… the lizards and crap need to use their limbs to get around.
describe the axial musculature of an amniote (reptile and mammal) and relate to that of a typical fish and an amphibian.
Dorsalis truncus subdivided into 3 longitudinal columns named:
transversospinalis
Longissiumus dorsi
Iliocostalis
Epaxial muscles are reduced in what reptile?
turtles
Hypaxial layers are divided into three layers as in
amphibians
Thoracic region:
external oblique
- supracostals
- innercostals
Internal oblique
-deeper intercostals
Transversus
-subcostals
Escribe Epaxial:
intrinsic
deep
above dorsal ribs and vertebral transverse processes
innervated by dorsal rami of spinal nerves
Descrive hypaxial
extrinsic
superficial
below dorsal ribs and lateral to the ventral ribs if present
innervated by the ventral rami of spinal nerves
superficial back muscles:
splenius capitis
splenius cervicis
intermediate back muscles
iliocostalis
longissiumus
spinalis
deep back muscles:
semispinalis
multifidus
rotatores
Muscles of the gill arch region arise form the _______________ embryonic mesenchyme instead of somites.
embryonic mesenchyme
Gill arch I is called
mandibular
what innervates the gill arch I
CN V trigeminal
Gill arch II is called
hyoid
What innervates gill arch II?
CN VII facial nerve
Gill arch III is innervated by
CN IX: Glossopharyngeal nerve
all the remaining gill arches are innervated by
CN X: Vagus nerve
Function of mammalian masseter:
Elevates and protracts mandible
function of mammalian temporalis:
elevates and retracts mandible
function of lateral pterygoid
protracts mandible, depresses chin (bilateral; grinding (unilateral))
Function of mammalian pterygoid:
elevates, protracts, grinding (unilateral)
All the muscles of mastication are innervated by which nerve?
CN V
Attachments for masseter:
zygomatic bone to lateral surface of ramus and coronoid process
attachments for temporalis:
temporal fossa and fascia to coronoid process
attachments lateral pterygoid
lateral pterygoid plate and sphenoid to front of mandible and TMJ
attachments of medial pterygoid:
lateral pterygoid plate and maxilla to medial surface of mandible near angle.
Why does the diagastric muscle have 2 sources of innervation?
has 2 bellies:
Anterior: supplied by trigeminal via the myohyoid nerve, a branch of the inferior alveolar nerve, itself a branch of the mandibular division of the trigeminal nerve.
Posterior belly: supplied by the digastric branch of the facial nerve
