Human Anatomy Vol 1

UPPEB LIMB

Muscle

1. Coracobrachialis
   (Figs 2.8 and 2.16)


2. Biceps brachii
   (Fis.8.3)


3. Brachialis
   (Fi9.8.5)

Muscle

1. Coracobrachialis


2. Biceps brachii

Table 8.1: Attachments of muscles

Origin from

. The tip of the coracoid process with the short head
of the biceps brachii
It has two heads of origin
. The short head arises with coracobrachialis from the
tip of the coracoid process
. The long head arises from the supraglenoid tubercle
of the scapula and from the glenoidal labrum. The
tendon is intracapsular
. Lower half of the front of the humerus, including both
the anteromedial and anterolateral surfaces and the
-anterior border
Superiorly the origin embraces the insertion of the
deltoid
. Medial and lateral intermuscular septa

Table 8.2: Nerve supply and actions of muscles

Nerve supply

Musculocutaneous nerve (C5-C7)

Musculocutaneous nerve (C5, C6)

lnseftion into

The middle 5 cm of the medial border of the

humerus

. Posterior rough part of the radial tuberosity.
The tendon is separated from the anterior
part of the tuberosity by a bursa (Fig. 8.4)
. The tendon gives off an extension called
the bicipital aponeurosis which extends to
ulna and it separates median cubital vein
from brachial artery
. Coronoid process and ulnar tuberosity
. Bough anterior surface of the coronoid
process of the ulna

lt
tr

o
CL
CL
D

o

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a

3. Brachialis. Musculocutaneous nerve is motor
   . Badial nerve is proprioceptive

5 Veins

i. The basilic vein pierces the deep fascia.

ii. Two venae comitantes of the brachial artery may

unite to form one brachial vein.

6 Neraes

i. The median nerve crosses the brachial artery from

the lateral to the medial side.

ii. The ulnar nerve pierces the medial intermuscular

septum with the superior ulnar collateral artery

and goes to the posterior compartment.

iii. The radial nerve pierces the lateral intermuscular

septum with the anterior descending (radial

collateral) branch of the profunda brachii artery

and passes from the posterior to the anterior

compartment.

iv. The medial cutaneous nerve of the arm pierces

the deep fascia.

v. The medial cutaneous nerve of the forearm

pierces the deep fascia.

Morphologically, the muscle is very important for

following reasons.

Actions

Flexes the arm at the shoulder joint

. lt is strong supinator when the forearm is flexed
All screwing movements are done with it
. lt is a flexor of the elbow
. The short head is a flexor of the arm
. The long head prevents upwards displacement of the
head of the humerus
. lt can be tested against resistance as shown in Fig.8.6
Flexes forearm at the elbow joint

Morphologically the coracobrachialis represents the

medial compartment, which is so well developed in the

thigh.

In some animals it is a tricipital muscle. In man the

upper two heads have fused and musculocutaneous

nerve passes between the two, and the lowest third head

has disappeared. Persistence of the lower head in man

is associated with the presence of "ligament of

Struthers", which is a fibrous band extending from the

trochlear spine to the medial epicondyle of the humerus,

to which the third head of the coracobrachialis is

inserted, and from the lower part of which the pronator

teres muscle takes origin. Beneath the ligament pass the

median nerve or brachial artery or both.

The front or anterior compartment of the arm is

homologous with flexor and medial compartments of

the thigh. The flexor compartments of thigh lies

posteriorly because the lower limb bud rotates medially.

The musculocutaneous nerve is the main nerve of the

front of the arm, and continues below the elbow as the

lateral cutaneous nerve of the forearm (see Fig.7.1).