Axial muscles Flashcards
Epicranius
occipitofrontalis muscle and galea aponeurotica
Frontal belly of occipitofrontalis
Origin: frontal bone and skin of eyebrows
insertions: epicranial aponeurosis (galea aponeurotica)
action: moves the scalp, wrinkles forehead, and elevates the eyebrows
Occipital belly of occipitofrontalis
Origin: superior nuchal line
insertion: epicranial aponeurosis (galea aponeurotica)
action: moves the scalp slightly posteriorly
Orbicularis oris
First sphincter of alimentary canal
Origin: mandible and maxilla as well as fascia and fibers of other muscles
Insertion: skin of cheek and mandible
Action: pulls lower lip inferiorly, tenses skin of neck, and contributes to depression of the mandible
Buccinator
Origin: alveolar processes of mandible and maxillae
Insertion: orbicularis oris
Action: compresses cheek, holds food between teeth during chewing, aids in sucking and blowing
Facial nerve paralysis
Unilateral paralysis of the muscles of facial expression
Idiopathic facial nerve paralysis
When the cause of facial nerve paralysis is unknown. Bell palsy
Strabismus
when eyes are improperly aligned (lazy eye)
Strabismic ambylopia
when a lazy eye loses visual acuity
Causes of strabismus
Birth injuries, diseases localized to the eye or its bony orbit, improper attachment of extrinsic eye muscles, and heredity
Temporalis
Origin: superior and inferior portions of temporal bone
Insertion: coronoid process of mandible
Action: elevates and retracts mandible
Masseter
Origin: zygomatic arch
Insertion: lateral surface of coronoid process; lateral surface and angle of mandible
Action: elevates and retracts mandible; prime mover of jaw closure
Medial and lateral pterygoid
Origin: pterygoid processes of sphenoid bone
Insertion: mandible
Action: elevate and protract the mandible and move it from side to side during chewing
Tetanus
spastic paralysis caused by Clostridium tetani
botulism
Potentially fatal muscular paralysis caused by Clostridium botulinum
Sternocleidomastoid muscles
Andys favorite muscle
Origin: munibrium and sternal ends of clavicles
Insertion: mastoid processes of temporal bones
Action: When both contract, the head is pulled forward and down. when one contracts, it turns the head sideways in a direction opposite the side on which the contracting muscles is located
Congenital muscular torticollis
Commonly known as wryneck. Newborn presents w/ a shortened and tightened sternocleidomastoid muscle. Often is accompanied by plagiocephaly
Splenius capitus
origin: ligamentum nuchae
Insertion: Occipital bone and mastoid process of temporal bone
Action: When both contract it pulls the head back and extends and hyperextends the cervical vertebrae. When once contracts it turns the head sideways in a direction towards the same side on which the contracting muscle is located
Semispinalis capitus
Origin: Seventh cervical vertebrae and first six thoracic vertebrae
Insertion: between the superior and inferior nuchal lines of the occipital bones
Action: When both contract it pulls the head back and extends and hyperextends the cervical vertebrae. When once contracts it turns the head sideways in a direction towards the same side on which the contracting muscle is located
Erector spinae
maintain posture and to help us stand erect and are found along the entire vertebral column
Transversospinalis muscles
deep to the erector spinae muscles. connect and stabilize the vertebrae
External intercostals
used for restful breathing and extend inferomedially from the superior ribb to the adjacent inferior rib.
Origin: inferior border of superior rib
Insertions: superior border of inferior rib
Action: elevates the ribs by causing them to move up and out
Internal intercostals
Used for forceful exhalation
Origin: superior border of inferior rib
Insertion: inferior border of superior rib
Action: depresses the ribs during forced exhalation
Diaphragm
Origin: inferior internal surface of lower ribs, xiphoid process of sternum, costal cartilages of inferior ribs, and lumbar vertebrae
Insertion: Central tendon
Action: contraction during inhalation causes flattening of the diaphragm, thereby expanding the thoracic cavity and compressing the abdominopelvic cavity.
Rectus sheath
an aponeurosis formed by external oblique, internal oblique, and transversus abdominis.
Linea semilunaris
a cutaneous depression formed just lateral to the rectus abdominis.
What forms the “six-pack” look
three fibrous tendinous intersections
Linea alba
partitions the rectus abdominis into left and right halves
External oblique
origin: external inferior borders of lower ribs
Insertion: linea alba by a broad aponeurosis; some to the iliac crest
Action: When both contract, they compress the abdomen and flex the vertebral column. when only one contracts it causes lateral flexion of the vertebral column
Internal oblique
Origin: lumbar fascia, inguinal ligament, and iliac crest
Insertion: linea alba, pubic crest, costal cartilages and surfaces of lower ribs
Action: When both contract, they compress the abdomen and flex the vertebral column. when only one contracts it causes lateral flexion of the vertebral column
Transversus abdmoninis
Origin: iliac crest, lumbar fascia, inguinal ligament, and cartilages of lower ribs
Insertion: linea alba and pubic crest
Action: primarily compresses abdomen
Rectus abdominis
Origin: superior surface of pubis near symphysis
Insertion: xiphoid process of sternum and inferior surfaces of middle ribs
Action: flexes vertebral column and compresses the abdominal wall; used in forceful exhalation
Pelvic diaphragm
extends from the ischium and pubis of the ossa coxae across the pelvic outlet to the sacrum and coccyx.
Four significant bony landmarks of the perineum
pubic symphysis anteriorly, coccyx posteriorly, both ischial tuberosities laterally
urogenital triangle
anterior portion of perineum which contains the external genitalia and urethra
anal triangle
posterior portion of perineum that contains the anus
levator ani
largest and most important group of the pelvic diaphragm. supports the pelvic viscera and functions as a sphincter at the anorectal junction, urethra, and vagina
Pubococcygeus
one of the levator ani muscles. made famous by Dr. Arnold Kegel.
