MUSCULO-SKELETAL SYSTEM - Start Of 2nd Quarter Flashcards
One of the projecting paired appendages in an animal body specifically for movement and grasping but sometimes sensory or sexual organs.
LIMBS REGION
It segregate initially into an extensor mass and a flexor mass
Myotomes
Myotomes segregate initially into an extensor mass and a flexor mass and those masses will subsequently subdivide into an?
extensor muscle and flexor muscle
They arise from the local somatic mesoderm of the limb bud.
Bone, cartilage, and connective tissues
condenses from local mesenchyme
Cartilage
from dermatome migration into the limb bud
Dermis
grow outward from body wall somatopleure as limb buds
Limbs
Limbs – grow outward from body wall somatopleure as?
limb buds
begins as a limb field (area of somatopleure committed to form a limb)
Limb buds
What induced to form underlying mesoderm that makes the mesoderm to continue growing into a limb. (the shoulder/hip appears first, the manus/pes is the last to be added).
Simplified definition: What is a special structure on the surface of a developing limb (like an arm or leg) in an embryo. Its job is to send signals to the underlying mesoderm (a layer of cells beneath it), telling it to keep growing and forming the limb.
Apical ridge
the distal end of the limb bud (footplate) is flattened like a paddle & ectoderm along its outer margin forms a thickened?
apical ridge
It consist of:
- Elongation of a dorsoventrally flattened limb bud
- Ventroflexion of the distal half of the limb (ventral now faces medially)
- Pronation of the distal half (previous medial surface now becomes caudal)
Limb growth
inherited, systemic, premature ossification of physes of extremities.
Simplified definition:
It is a genetic condition that affects bone growth. In people or animals with this condition, the bones in the arms and legs don’t grow properly because the areas where the bones grow (called growth plates or physes) turn to bone too early. This causes shorter limbs and a shorter stature overall. It is inherited, meaning it is passed down from parents to their offspring. It’s often seen in certain dog breeds, like Dachshunds, who may have similar bone growth issues.
Achondroplasia
can result from malformed joints, denervation, abnormal muscle tension, or impaired mobility in utero.
Arthrogryposis
syndactyly (fused digits); brachydactyly (stumpy digits) [Gr. dactylos = digit]
Polydactyly (extra digits)
meromelia (absence of part of limb); micromelia (small limb) [Gr. melos = limb]
Amelia (no limb)
absence of proximal segment(s) of limb was a consequence of pregnant women taking thalidomide in the late 1950s.
phocomelia (seal limb)
consists of a cranium (which contains the brain within a cranial cavity) and a face
Head
is formed during growth of the head process
Cranium
develops from outgrowths of the frontonasal process and first pharyngeal arch.
face
Since the face and cranium have different embryonic origins, it gives rise to skeletal muscle like cranium
Mesoderm
Since the face and cranium have different embryonic origins, Mesoderm gives rise to skeletal muscle like cranium and ? for the face
Ectoderm
This myotomes migrate to the orbit (two giving rise eye muscles) or they migrate to pharyngeal arches (becoming muscles of mastication, facial expression muscles)
Somitomere
This myotomes become tongue and neck muscles and they migrate to pharyngeal arches (IV-VI), becoming pharyngeal, laryngeal & esophageal muscles
Somite
establish early connections with adjacent somitomeres & somites and accompany them to definitive muscle sites.
Cranial nerves
innervated by specific cranial nerves
Pharyngeal arch
Face, and calvaria of cranium (intramembranous) and base of cranium (endochondral)
Regions of skull
Bones of the base of the cranium develop?
endochondrally
Bones of the base of the cranium develop endochondrally ; but the relatively flat bones that comprise the calvaria (roof of the
cranium) and the face develop?
intramembranously
formed from the sclerotomes of somitomeres and the first four somites (occipital somites).
Endochondral bones
Arise from ectomesenchyme (derived from neural crest).
Intramembranous bones
gives rise to cartilage, bone, and connective tissue of the face and dorsal head (calvaria).
Ectomesenchyme
intramembranous bone articulate by means of fibrous joints
Sutures
widened suture areas, at the corners of growing bones
Fontanels
complex origin involving both endochondral and intramembranous development
Mandible
arise endochondrally from pharyngeal arches I (malleus & incus) and II (stapes)
Auditory ossicles
fills pharyngeal arches and forms connective tissue, cartilage and bone.
Ectomesenchyme
migrate into pharyngeal arches and give rise to the skeletal muscles that arise from that arch
Somitomere/somite myotomes
- Jaw bones (mandible & maxilla); also, ossicles of the middle ear (malleus & incus)
- Muscles of mastication, plus rostral digastricus, mylohyoid, & tensor tympani mm.
First arch: (innervated by cranial nerve V)
- Hyoid bones & stapes (ossicle of the middle ear)
- Muscles of facial expression, including caudal digastricus & stapedius mm.
Second arch: (innervated by cranial nerve VII)
- Hyoid bones
- One pharyngeal muscle (stylopharyngeus mm.)
Third arch: (innervated by cranial nerve IX)
- Laryngeal cartilages
- Pharyngeal mm & cricothyroid m — innervated by cranial branch of X
- Intrinsic laryngeal mm — innervated by recurrent laryngeal n. Of X
Arches IV through VI: (innervated by cranial nerve X)
First arch: (innervated by what nerve? )
cranial nerve V
Second arch: (innervated by what nerve? )
cranial nerve VII
Third arch: (innervated by what nerve? )
cranial nerve IX
Arches IV through VI: (innervated by? )
cranial nerve X
