Two-Jointed Muscles Flashcards
What are 2 jointed muscles ?
- also known as biarticular muscles
- muscles that cross/act on 2 joints rather than just one
- able to exert force & control movements at both ends
What are 7 examples of two-jointed muscles?
- the hamstrings group (biceps femoris/semimembranosus/semitendinosus)
- biceps/triceps brachii
- gastrocnemius
- Rectus femoris
What is the origin/insertion/innervation/joint crossed/main action of the biceps femoris ?
- O: has 2 heads, long head (Ischial tubersoity), short head (linea aspera)
- I: head of fibula
- Inn: sciatic nerve
- Jt crossed: hip & knee joint
- MA: hip extension, knee flexion, & lateral rotation of a flexed knee
What is the origin/insertion/innervation/joint crossed/main action of the semimembranosus?
- O: ischial tuberosity
- I: Posteromedial tibial condyle
- Inn: sciatic nerve
- jt crossed: hip & knee joint
- MA: hip extension, knee flexion, & medial rotation of a flexed knee
What is the origin/insertion/innervation/joint crossed/main action of the semitendinosus?
- O: ischial tuberosity
- I: medial surface of proximal tibia
- Inn: sciatic nerve
- jt crossed: hip & knee joint
- MA: hip extension, knee flexion, medial rotation of a flexed knee
What is the origin/insertion/innervation/joint crossed/main action of the Rectus femoris?
- O: has 2 heads - straight (AIIS), curved (superior acetabulum)
- I: tibial tuberosity
- Inn: femoral nerve
- jt crossed: hip & knee joint
- MA: knee extension, hip flexion
What is the origin/insertion/innervation/joint crossed/main action of the gastrocnemius ?
- O: medial/lateral femoral condyles
- I: posterior calcaneus
- Inn: tibial nerve
- jt crossed: knee & ankle joint
- MA: ankle plantar-flexion or knee flexion
What is the origin/insertion/innervation/joint crossed/main action of the biceps brachii?
- O: has 2 heads - long head (supraglenoid tubercle of scapula), short head (coracoid process of scapula)
- I: radial tuberosity
- Inn: Musculocutaneous nerve
- jt crossed: glenohumeral & elbow joint
- MA: elbow & shoulder flexion, forearm supination
What is the origin/insertion/innervation/joint crossed/main action of the triceps brachii?
- O: has 3 heads - long head (infraglenoid tubercle of scapula), lateral head (greater tubercle of posterior humerus), medial head (deep, halfway down posterior humerus shaft)
- I: olecranon process of ulna
- Inn: radial nerve
- Jt crossed: shoulder & elbow joint
- MA: elbow extension & shoulder extension (long head only)