Muscles (O, I, N, A) Flashcards
External Intercostal
O: Lower margin of rib
I: Upper margin of next lower rib (courses obliquely forward and downward)
N: 1st to 11th intercostal nerves
A: Raises ribs (inspiration); supports intercostal spaces: stabilizes chest wall
Internal Intercostals
O: Lower margin of rib
I: Lower margin of next rib (courses obliquely forward and upward from costal angle to sternum)
N: 1st to 11th intercostal nerves
A: Lowers ribs (expiration); supports intercostal spaces; stabilizes chest wall
Innermost Intercostals
O: Lower margin of rib
I: Lower margin of next lower rib (courses obliquely forward and upward from costal angle to sternum)
N: 1st to 11th intercostal nerves
A: Lowers ribs (expiration); supports intercostal spaces; stabilizes chest wall
Subcostal
O: Lower margin of lower ribs
I: Inner surface of ribs 2 to 3 ribs below
N: Variable lower intercostal nerves
A: Raises ribs (inspiration)
Transversus Thoracis
O: Sternum and xiphoid process (Inner surface)
I: 2nd to 6th ribs (costal cartilage, inner surface)
N: 2nd to 7th intercostal nerves
A: Lowers ribs (expiration)
Diaphragm
O: [C] 7th-12th ribs (inner surface; lower margin of costal arch)
[L] Med- L1-L3 bodies; IV discs, and anterior longitudinal ligament as R and L crura
Lat- Lateral and medial arcuate ligaments
[S] Xiphoid process (posterior surface)
I: central tendon
N: Phrenic nerve (C3-C5 cervical plexus)
A: Principal muscle of respiration; aides in compressing abdominal viscera
Rectus Abdominis
O: Pubis between pubic tubercle and symphysis
I: Cartilages of 5th-7th ribs, xiphoid process of sternum
N: Intercostal nerves T5-T12
A: Flexes trunk, compresses abdomen, stabilizes pelvis
Pyramidalis
O: Pubis anterior to rectus abdominis
I: Linea alba (runs within rectus sheath)
N: Subcostal nerve (12th intercostal nerve)
A: Tenses linea alba
External Oblique
O: Outer surface of 5th-12th ribs
I: Linea alba, pubic tubercle, anterior iliac crest
N: Intercostal nerves T7-T12
A: [U] bends trunk to same side, rotates trunk to opposite side
[B] flexes trunk, compresses abdomen, stabilizes pelvis
Transversus Abdominis
O: 7th-12th costal cartilages (inner surface), thoracolumbar fascia (deep layer), iliac crest, ASIS (inner lip), iliopsoas fascia
I: Linea alba, pubic crest
N: Intercostal nerves T7-T12, iliohypogastric nerve, ilioinguinal nerve
A: [U] rotates trunk to same side [B] compresses abdomen
Psoas Major
O: [SL] T12-L4 vertebral bodies and associated IV discs (lateral surfaces) [DL] L1-L5 costal processes
I: Lesser trochanter of femur, joint insertion as iliopsoas muscle
N: Direct branches from lumbar plexus (L2-L4)
A: hip joint-flexion and ext rotation lumbar spine (with femur fixed) [U] contraction bends trunk laterally [B] contraction raises trunk from supine position
Iliacus
O: Iliac fossa
I: Lesser trochanter of femur, joint insertion as iliopsoas muscle
N: Femoral nerve (L2-L4)
A: hip joint-flexion and ext rotation lumbar spine (with femur fixed) [U] contraction bends trunk laterally [B] contraction raises trunk from supine position
Quadratus Lumborum
O: Iliac crest and iliolumbar ligament
I: 12th rib, L1-L4 vertebrae (transverse processes)
N: T12, L1-L4 spinal nerves
A: [U] bends trunk to same side [B] bearing down and expiration, stabilizes 12th rib
(Levator Ani)
Puborectalis
O: Superior pubic ramus (both sides)
I: Anococcygeal ligament
N: Direct branches of sacral plexus, inferior anal nerve
A: Supports pelvic viscera
(Levator Ani)
Pubococcygeus
O: Pubis
I: Anococcygeal ligament, coccyx
N: Direct branches of sacral plexus, inferior anal nerve
A: Supports pelvic viscera
(Levator Ani)
Iliococcygeus
O: Internal obturator fascia
I: Anococcygeal ligament, coccyx
N: Direct branches of sacral plexus, inferior anal nerve
A: Supports pelvic viscera
Coccygeus
O: Sacrum
I: Ischial spine
N: Direct branches of sacral plexus
A: Supports pelvic viscera
Piriformis
O: Sacrum
I: Greater trochanter of Femur
N: Direct branches of sacral plexus
A: Ext. rot of hip, stabilization, ABD of flexed hip
Obturator Internus
O: Obturator membrane and boney boundaries
I: Greater trochanter of Femur
N: Direct branches of sacral plexus
A: Ext. rot. of hip, ABD of flexed hip
Platysma
O: Skin over lower neck and upper lateral thorax
I: Mandible, skin over lower face and angle of mouth
N: Facial nerve (CN VII)
A: Depresses and wrinkles skin of lower face and mouth; tenses skin of neck; aids in forced depression of mandible
Sternocleidomastoid
1) Sternal Head
2) Clavicular Head
O: 1) Sternum 2) Clavicle
I: Temporal bone (mastoid process), Occipital bone (superior nuchal line)
N: Accessory Nerve (CN XI)
A: [U] tilts head to same side, rotates head opposite side [B] extends head, aids in respiration when head is flexed
Trapezius (Descending Part)
O: Occipital bone, spinous processes C1-C7
I: Clavicle (lateral 1/3)
N: Accessory Nerve (CN XI)
A: [U] draws cap obliquely upward, rotates gleaned cavity downward
Digastric
1) Anterior Belly
2) Posterior Belly
O: 1) Mandible 2) Temporal bone
I: Hyoid bone via intermediate tendon
N: 1) Mylohyoid nerve (CN V3) 2) Facial nerve (CN VII)
A: Elevates hyoid bone (during swallowing), assists in opening mandible
Stylohyoid
O: Temporal bone (styloid process)
I: Hyoid bone via split tendon
N: Facial nerve (CN VII)
A: Elevates hyoid bone (during swallowing), assists in opening mandible
Mylohyoid
O: Mandible
I: Hyoid bone via median tendon of insertion
N: Mylohyoid nerve (CN V3)
A: Tightens and elevates oral floor, draws hyoid bone forward (swallowing), assists in opening mandible and moving it side to side (mastication)
Geniohyoid
O: Mandible
I: Hyoid bone
N: Anterior rams of C1
A: Draws hyoid bone forward (swallowing), assists in opening mandible
Omohyoid
O: Scapula (superior border)
I: Hyoid bone
N: Ansa cervicalis of cervical plexus
A: Depresses hyoid, draws larynx and hyoid down for phonation and terminal phases of swallowing
Sternohyoid
O: Manubrium and SC joint
I: Hyoid bone
N: Ansa cervicalis of cervical plexus
A: Depresses hyoid, draws larynx and hyoid down for phonation and terminal phases of swallowing
Thyrohyoid
O: Thyroid cartilage
I: Hyoid bone
N: C1 via hypoglossal nerve
A: Depresses and fixes hyoid, raises larynx during swallowing
Scaleneus Anterior
O: C3-C6 (ant. tubercles of trans processes)
I: 1st rib
N: Direct branches from cervical + brachial plexus
A: Elevates upper ribs; [U] bends cervical spine to same side [B] flexes neck
Scaleneus Medius
O: C1-C2 (trans processes) C3-C7 (post. tubercles of trans. processes)
I: 1st rib
N: Direct branches from cervical + brachial plexus
A: Elevates upper ribs; [U] bends cervical spine to same side [B] flexes neck
Scaleneus Posterior
O: C5-C7 (post. tubercles of trans. processes)
I: 1st rib
N: Direct branches from cervical + brachial plexus
A: Elevates upper ribs; [U] bends cervical spine to same side [B] flexes neck
Rectus Capitis Posterior Minor
O: C1 (posterior tubercle)
I: Occipital bone (inner 1/3 of inf. nuchal line)
N: Post. ramus of C1 (suboccipital nerve)
A: [U] rotates head same side [B] extends head
Rectus Capitis Posterior Major
O: C2 (spinous process)
I: Occipital bone (mid 1/3 of inf. nuchal line)
N: Post. ramus of C1 (sub occipital nerve)
A: [U] tilts head same side [B] extends head
Oblique Capitis Inferior
O: C2 (spinous process)
I: C1 (transverse process)
N: Post. rams of C1 (sub occipital nerve)
A: [U] tilts head same side, rotates to opposite side [B] extends head
Obliquus Capitis Superior
O: C1 (transverse process)
I: Occipital bone (above RCPMajor)
N: Post. rams of C1 (sub occipital nerve)
A: [U] tilts head same side, rotates opposite side [B] extends head
