General yard call outs

A-Band

NEVER changes size during contraction!

Motor unit

Consists of one motor neuron and all the muscle fibers(cells) it innervates

Sarcomere definition

The basic functional unit of striated muscle, bounded from Z-disc to Z-disc

G-actin vs F-actin

Individual G-actin beads contain the active binding sites , they string together to make F-actin strands(actin itself I can explain more to yall)

Key chemical requirements for contraction

ATP(energy),Acetylcholine(ACh) at receptors on motor end plate, and Calcium(Ca) to bind troponin.

Type I(slow) vs Type IIX(fast) muscle fibers

Type I = Slow red, fatigue resistant, ABUNDANT myoglobin(imagine marathon runners) , Type IIX = Fast white , pale , low myoglobin, rapid fatigue(imagine Sprinters)

Why muscle tissue is red

myoglobin

Facial Expression muscles

Facial Nerve (Cranial Nerve VII) innervates all muscles of facial expression(IMPORTANT)

Masseter and Temporalis

Primary muscles for mastication(chewing) they elevate the mandible to close the jaw.

Platysma

Sheet like muscle in subcutaneous(right under the skin) neck tissue

Sternocleidomastoid (SCM) - his fav muscle

Bilateral contraction flexes head/neck forward , Unilateral contraction rotates head to the opposite side

Risorius

Pulls corners of mouth laterally when smiling, causes “smile of death” (rictus sardonicus)

Anterior Neck Strap Muscles (-hyoid vs -thyroid)

Sternohyoid (long) & Sternothyroid (short) depress hyoid/larynx; if suffix is -hyoid it inserts on hyoid bone, if -thyroid it inserts on thyroid cartilage

Erector Spinae Group (Lateral to Medial)

"I Like Spaghetti" mnemonic: Iliocostalis (lateral), Longissimus (middle), Spinalis (medial), extends the spine

Serratus Anterior

Serrated knife muscle, known as the “throwing muscle” for scapular protraction/abduction.

Rectus abdominis landmarks( your abs)

Enclosed in rectus sheath, divided down the middle by Linea alba and Transversly by Tendinous Inscriptions

Abdominal Obliques

External Oblique = superficial (“hands in pockets” direction), Internal = deep ( opposite diagonal)

Biceps Brachii - Insertion and Actions

Inserts on radial tuberosity, acts as an elbow flexor AND a powerful supinator of forearm

Brachialis

Deep and wide to Biceps Brachii, inserts on ulnar tuberosity as a pure elbow flexor

Humerus Epicondyles

Forearm flexors originate on Medial Epicondyle(Med to Lat) , Forearm extensors originate on Lateral epicondyle ( Lat to Med)

Major or Brevis ?

He said he will generally test “Major” or “Longus” muscles ( Rhomboid Major , Extensor Carpi radialis longus) usually skips “brevis” or “minor” so if you have to pick between minor or major always pick major (except Teres Minor and Major because Minor is a rotator cuff not Major)

Palmaris Longus

Passes over flexor retinaculum into palmar aponeurosis, absent in ~30% of people

Brachioradialis

forearm muscle, forms a "V" shape with Pronator Teres

Gluteus Medius (IM Injection Site)

Primary site for intramuscular (IM) injections to prevent damaging the thick Sciatic Nerve exiting inferior to Piriformis

Lateral Hip Rotators

Piriformis, Superior Gemellus, Obturator Internus, Inferior Gemellus, Quadratus Femoris

Iliopsoas

Iliacus + Psoas Major ("human tenderloin"); primary powerful hip flexor / kicker

Sartorius

Longest muscle in the body, flexes BOTH hip and knee (action = sitting cross-legged)

Vastus Intermedius

Deep to Rectus Femoris in the Quadriceps Femoris group

Semimembranosus

Deep and wide to Semitendinosus (medial hamstrings)

Popliteus (he may not ask according to BRC)

Located directly behind the knee, unlocks the knee joint

Tibialis Posterior( wont be on THIS exam but its 100% on finals According to Yard)

Deep posterior leg muscle, for ankle inversion and plantarflexion

Triceps Surae Group

Composed of Gastrocnemius + Soleus (soleus is deep/wide), inserts on calcaneus via Achilles tendon

Femoral Triangle Boundaries & Contents

Inguinal Ligament (superior), Sartorius (lateral), Adductor Longus (medial). Inside it/Contents(NAVL): Femoral Nerve, Artery, Vein, Lymphatics(lymph nodes)

Anatomic Snuffbox

Bounded by Extensor Pollicis Longus, Extensor Pollicis Brevis, and Abductor Pollicis Longus; clinical site to feel Radial Pulse