Anatomy of muscles II Flashcards
what are the movements of the trunk?
flexion/ extension, lateral flexion, twist rotation
ABDOMINAL MUSCLES what are the 4?
- External oblique
- Internal oblique
- Rectus abdominus
- transverse abdominus
- External oblique - where and origin
- Most superficial of the abdominal muscles
- Small, flat muscle running inferior- medially (hands in pocket)
- Allows trunk to twist/flex and rotate
Origin - serration from ribs 5-12
insertion - illiac crest, posteriorly, anteriorly forms the inguinal ligament & rectus sheath
- Internal oblique - where and origin
- Second most superficial of the abdominal muscles, just inside the hip bones
- Opposing twisting motion to ext. obliques
origin - thoracolumber fascia, iliac crest, inguinal ligament
insertion - 10th - 12th ribs and linear alba
- Rectus abdominus - where and origin
Small, flat muscle running superior-medially (hands on chest)
Connective tissue bands (tendinous intersections) separate into distinct muscle ‘bellies’
Linea alba separates left and right abdominis muscles
Externally visible as the “six pack”
Flexion of trunk
Origin - Cartilage ribs 5-7
Insertion - Pubic symphysis and pubic bone
- Transverse abdominus
Lies deep to the int. obliques (deepest layer)
- Fibres run transversely (hands on hips)
- “corset” muscle
- Stabilizes trunk and maintains internal abdominal pressure
- Assists in parturition
Origin - rib cartilage 7-12, thoracolumber fascia, iliac crest, inguinal ligament
Insertion - abdominal sheath, linear alba
What 4 muscles are located on the anterior chest wall?
- Pectoralis major
- Pectoralis minor
- Serratus anterior
- Subclavius
Pectoralis major location and what movement does it involve
- Large triangle shaped muscle
- Active during forced/deep inspiration
- Involved on adduction and medial rotation of the arm
origin - medial 1/2 of clavicle, sternum, cartilages of ribs 1-7, and aponeurosis of external oblique muscle
Insertion - distal to greater tuberosity of humerus
Pectoralis Minor location and movement
• Thin, triangular muscle under the pectoralis major • Functions mainly involve movements of the scapula o Stabilization o Depression o Abduction o Internal & downward rotation also accessory muscle for inspiration origin - ribs 3-5 insertion - coracoid process of scapula
Serratus anterior
•Muscle of multiple serration, forming the side of the chest
•Involved in forward movement of the scapula, forward rotation of the arm (lifting arm overhead)
•Also supports breathing
origin - anterior part of ribs 1-8
insertion - scapula
Subclavius
• Small muscle between the clavicle and 1st rib
• Forms the anterior wall of the armpit (“axilla”)
• Stabilizes the clavicle – responsible for depression of clavicle and elevation of 1st rib
• Protects underlying brachial plexus (collection of important nerves) from a broken clavicle (most frequent
origin - rib 1
insertion - clavicle
What is the function of the intercostal muscles?
• Help form and move the chest wall – expansion and shrinkage of chest cavity during breathing
What function doe the external intercostal do, and what does the internal intercostals do?
External intercostals:
•Pull ribs together, rising rib cage during forced expiration
Internal intercostals:
•Depress the rib cage during forced expiration
•Fibres run 90’ to external intercostals
External intercostals are active in normal respiration, whereas the internal intercostals are only active during forced respiration
What are the two shoulder muscles?
- deltoid
2. rotator cuff
What movement does deltoid allow?
allows flexion and inward rotation of shoulder, and abduction and extension of arm
origin - lateral third of clavicle, acromion, and inferior boarder of scapula spine
insertion - deltoid tuberosity of the humerus
what 4 muscles are part of the rotator cuff that stabilise the shallow shoulder joint?
- supraspinatus
- infraspinatus
- teres minor
- subscapularis