Chapter 3 Muscle Anatomy and Functions

Deep Muscles of the Vertebral Column The Erector Spinae Group Spinalis – most medially; along the spine Longissimus – between spine and iliocostalis Iliocostalis – most lateral; along the ribs *Memory tool: “I Long for Spinach

Deep Muscles of the Vertebral Column (cont’d) Function: Keep the body in an erect/upright position. Extend spine Lateral flex spine

Muscles of the Thoracic Cage Affect the rib cage and the process of breathing: Diaphragm – separates the thoracic and abdominal cavities Intercostals – “the breathing muscles”, located between each rib Transverse Thoracic – triangular muscle, acts on the abdominal wall, pulling it inwards.

Anterior Abdominal Wall The “Abs” Named based on the direction of the fibers T - Transverse Abdominis I - Internal Obliques R - Rectus Abdominis E - External Obliques transverse = across oblique = diagonal rectus = vertical

Anterior Abdominal Wall Functions: Transverse Abdominis Internal Obliques External Obliques Trunk Flexion & Rotation “ “ “ Rectus Abdominus Trunk flexion

Effective Ab Exercises

Muscles of the Shoulder Pectoralis Major Deltoid Muscle (see previous notes)

Muscles of the Shoulder (cont’d) Rotator Cuff Muscles A group of muscles that stabilize the shoulder and hold it in place. Eg. When throwing a baseball, the rotator cuff muscles would help to decelerate arm movements All “SITS” Muscles extend from the scapula and insert on either the greater or lesser tubercle of the humerus “SITS” Muscles

Muscles of the Shoulder (cont’d) Rotator Cuff Muscles Clockwise from top: S – Supraspinatus - abduction I - Infraspinatus - lateral rotation T – Teres Minor - lateral rotation S – Subscapularis - medial rotation *The subscapularis is the only rotator cuff muscle located on the anterior portion of the scapula.

Muscles of the Shoulder (cont’d) Memory Tool for Rotator Cuff Muscles: A pro baseball player has injured his rotator cuff muscle. As a result, he “sits” out of the game and gets sent to the “minor leagues”

6 Scapula Movers (see previous notes)

3 Humerus Movers (see previous notes)

Elbow Flexors 3 “B’s” bend the elbow: Biceps Brachii Brachialis Brachioradialis

Elbow Extension Muscles which straighten the arm: Triceps brachii – elbow extension Anconeus – a small triangular muscle which assists the triceps in elbow extension

Muscles of the Forearm Anterior group – wrist flexion Posterior group – wrist extension (You don’t have to know these in detail)

Hip Flexors

Hip Flexors A group of 7 muscles which function to flex the thigh, an action which brings the leg closer to the torso/chest. All muscles in this group originate on the pelvis and insert somewhere on the femur.

The 7 Hip Flexor Muscles: Anterior Group Pectineus Iliopsoas Rectus Femoris Sartorius Adductor Brevis Adductor Longus Lateral Group Tensor Fasciae Latae

Iliopsoas The strongest hip flexor Hip Flexion External Rotation (3 deep muscles that function as one) Psoas Major Psoas Minor iliacus

Iliopsoas Iliopsoas (Iliacus and psoas muscles) Iliopsoas = Hip flexion Psoas major = Hip flexion + trunk flexion Psoas minor = weak trunk flexion The Psoas Minor muscle is present in only 40% of the population!!

Pectineus Sometimes considered an extension of the iliopsoas Upper most muscle of the medial thigh group Hip Flexion (primary action) Adduction and External Rotation

Rectus Femoris As mentioned previously, part of the quadriceps group The only muscle of the quadriceps group that crosses both the hip and the knee joint. Hip Flexion Knee Extension (Eg. Taking forward stride in walking)

Sartorius Longest muscle in the body Most superficial thigh muscle Not very powerful (assists) Helps to cross the leg Hip Flexion Outward rotation at hip Knee Flexion

http://www.livestrong.com/video/2757-strengthen-hip-flexor/

Hip Extensors

Hip Extensors Gluteus Maximus Hamstrings Strongest, most superficial Bicep Femoris Semitendinosus Semimembranosus

Gluteus Maximus Gluteus = Greek for “rump” Used mostly during power movements Hip Extension External Rotation

Gluteus Maximus Used more in running than walking because the hip must be extended more than 15 degrees to activate the gluteus. Doing sprints is an effective way to tone up the gluteus maximus!! Other power activities which build strength: Squats, Lunges,

Hamstrings Inability to touch the toes while keeping the knees extended is due to shortened, inflexible hamstring muscles

Biceps Femoris Largest Muscle in Hamstring group Located on lateral side Hip Extension Knee Flexion Outward Rotation Outward Rotation when knee is in flexed position

Semimembranosus and Semitendinosus Both Located on the medial side of the hamstring group but the semitendinosus lies on top Hip Extension Knee Flexion Internal Rotation of the hip Internal Rotation of the knee

Hip Adductors

5 Hip Adductor Muscles Also known as your “groin” area The 5 adductor muscles can be categorized in 2 groups: Short Adductors and Long Adductors The “short adductors” go from the pelvis to the femur bone, while the “long adductors” go from the pelvis to the knee.

5 Adductor Muscles Short Adductors: Long Adductors: Pectineus The Adductor Longus Muscle is the most commonly injured. Sprinters, hurdles, football players, soccer players and other athletes involved in sports, which require quick changes in direction, are particularly susceptible to groin strains. The adductor Magnus is the strongest (and largest) of the adductor muscles Short Adductors: Pectineus Adductor Brevis Adductor Longus Long Adductors: Adductor Magnus Gracilis

5 Primary Hip Adductors Pectineus Adductor Brevis Adductor Longus Adduction and hip flexion Adductor Brevis Shortest, deepest Adduction.. Hip Flexion Adductor Longus

5 Primary Hip Adductors Adductor Magnus Gracilis The strongest of the adductors Longest, deepest muscle Adduction.. Gracilis The most superficial adductor Hip Adduction, internal rotation Knee flexion

Hip Abductors

Hip Abductors Gluteus Medius Gluteus Minimus Tensor Fasciae Latae (Lateral Butt muscle) Abduction, internal rotation Gluteus Minimus (Deepest Butt Muscle) Tensor Fasciae Latae (Lateral Muscle)

Tensor Fasciae Latae Hip Abduction Hip flexion Internal Rotation Prevents external rotation of the femur when it is in the flexed position. It helps keep the foot placed straight ahead during walking and running.

Quadriceps Group Vastus = Large Vastus Lateralis Vastus Medialis Vastus Intermedius Rectus Femoris (see notes)

Conclusion Generalized Muscle landmarks in the lower body: Anterior – Posterior – Medial – Lateral – 

Practice Quiz Label #1-11

Practice Quiz

Practice Quiz

Answer Guide Iliopsoas Tensor Fasciae Latae Sartorius Vastus Lateralis Psoas Major Pectineus Adductor Longus Gracilis Rectus Femoris Vastus Medialis Rectus Femoris Tendon

Answer Guide Gluteus Maximus Gluteus Medius Adductor Magnus Psoas Major Iliacus Tensor Fasciae Latae Adductor Brevis Adductor Longus Gracilis Piriformis Pectineus